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Summary Treatment with dose-adjusted EPOCH (etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone) chemotherapy and rituximab (DA-EPOCH-R) has become the standard of care for primary mediastinal B-cell lymphoma (PMBCL) at many institutions despite limited data in the multi-centre setting. We report a large, multi-centre retrospective analysis of children and adults with PMBCL treated with DA-EPOCH-R to characterize outcomes and evaluate prognostic factors. We assessed 156 patients with PMBCL treated with DA-EPOCH-R across 24 academic centres, including 38 children and 118 adults. All patients received at least one cycle of DA-EPOCH-R. Radiation therapy was administered in 14·9% of patients. With median follow-up of 22·6 months, the estimated 3-year event-free survival (EFS) was 85·9% [95% confidence interval (CI) 80·3–91·5] and overall survival was 95·4% (95% CI 91·8–99·0). Outcomes were not statistically different between paediatric and adult patients. Thrombotic complications were reported in 28·2% of patients and were more common in paediatric patients (45·9% vs. 22·9%, P = 0·011). Seventy-five per cent of patients had a negative fluorodeoxyglucose positron emission tomography (FDG-PET) scan at the completion of DA-EPOCH-R, defined as Deauville score 1–3. Negative FDG-PET at end-of-therapy was associated with improved EFS (95·4% vs. 54·9%, P

Background: In CLL/SLL, ibrutinib treatment before leukapheresis improved in vivo and ex vivo expansion of the CD19-directed chimeric antigen receptor (CAR) T cell therapy tisagenlecleucel, and concurrent ibrutinib therapy improved engraftment and therapeutic efficacy of anti-CD19 CAR T cells in human xenograft mouse models (Fraietta et al. Blood. 2016;127:1117-27). Recent studies in patients with R/R CLL suggest that CD19-directed CAR T cell therapy combined with ibrutinib improves response rates with CTL119 and JCAR014 (Gill et al. Blood. 2018;132:298; Gauthier et al. Blood. 2020;135:1650-60). Liso-cel is an investigational, CD19-directed, defined composition, 4-1BB CAR T cell product administered at equal doses of CD8+ and CD4+ CAR+ T cells. We report initial safety and preliminary efficacy from the phase 1 liso-cel and ibrutinib combination cohort of the ongoing phase 1/2 TRANSCEND CLL 004 study (NCT03331198) in patients with R/R CLL/SLL. Methods: Eligible patients with CLL/SLL met ≥1 of the following: 1) received ibrutinib and progressed at time of study enrollment; 2) had high-risk features and received ibrutinib for ≥6 months (mo) with less than a complete response (CR); 3) had a Bruton tyrosine kinase (BTK) or PLCγ2 gene mutation, with or without progression on ibrutinib; 4) had received prior ibrutinib with no contraindication to reinitiating ibrutinib. Baseline disease assessments included bone marrow (BM) biopsy, complete blood count, lymphocyte enumeration, and CT scan. At enrollment, patients started or continued ibrutinib. Patients continued ibrutinib through leukapheresis and for ≥90 days after liso-cel infusion. Patients received liso-cel infusion at 50 × 106 (dose level [DL]1) or 100 × 106 (DL2) CAR+ T cells after 3 days of lymphodepletion with fludarabine/cyclophosphamide. Primary endpoints were safety and to determine the recommended dose (RD) of liso-cel in combination with ibrutinib for R/R CLL/SLL; overall response (OR) rate (CR + CR with incomplete blood count recovery [CRi] + partial response) and pharmacokinetics (PK) were exploratory endpoints. The RD was selected based on the modified toxicity probability interval algorithm. Results: At data cutoff, 19 patients received liso-cel (DL1, n=4; DL2, n=15) with ibrutinib. Median age was 60 (range, 50‒77) years, and 18 patients (95%) had high-risk cytogenetics (del[17p], n=8; TP53 mutation, n=6; unmutated IGHV, n=16). Patients had a median of 4 (range, 2‒11) prior therapies. All patients were R/R to prior ibrutinib; 14 patients (74%) had BTK inhibitor as last prior therapy and 10 (53%) had prior venetoclax. No dose-limiting toxicities were observed at either DL. The most common grade ≥3 treatment-emergent adverse events (TEAEs) were neutropenia/neutrophil count decrease (n=17; 89%), anemia (n=9; 47%), and febrile neutropenia (n=5; 26%; Table). Six patients had infections at DL2: grade 3 and grade 2 lung infection (n=1 each) and grade 2 coccidioidomycosis, scabies, skin, and gum infections (n=1 each). Ibrutinib-related AEs included diarrhea (n=7), hypertension (n=4), atrial fibrillation (n=1), and rash (n=1). No grade 5 TEAEs occurred. Fourteen patients (74%) had cytokine release syndrome (CRS; 1 grade 3) and 6 (32%) had neurological events (NEs; 3 grade ≥3). Seven patients (37%) required tocilizumab and/or corticosteroids to manage CRS and/or NEs. Preliminary PK data showed a median time to peak liso-cel expansion of 11 days across DLs (DL1, 12 days; DL2, 11 days). Of 19 patients with ≥1-mo follow-up, 18 (95%) had an OR (DL2, 100%; DL1, 75%) and 9 (47%) had a CR/CRi. One patient (5%) had stable disease. All ORs were achieved by Day 30 postinfusion, and 15 (83%) of 18 patients maintained their response at 3-mo follow-up. Of 19 patients evaluable for minimal residual disease (MRD), 17 (89%) achieved undetectable MRD in blood via flow cytometry and 15 (79%) in BM by next-generation sequencing (both sensitivity of ≤10-4). Conclusions: Preliminary data show that liso-cel in combination with ibrutinib is associated with manageable safety, including a low incidence of grade 3 CRS and grade ≥3 NEs, and promising efficacy in heavily pretreated patients with R/R CLL/SLL. No clear difference in safety was observed across DLs, and DL2 was selected as the RD for liso-cel in combination with ibrutinib in patients with R/R CLL/SLL. Updated results from the full combination cohort and additional PK/pharmacodynamic data will be reported. Table Disclosures Dorritie: Juno Therapeutics: Research Funding; Kite-Gilead: Research Funding. Munoz:Portola: Research Funding; Incyte: Research Funding; Acrotech/Aurobindo: Speakers Bureau; Alexion: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Fosunkite: Consultancy; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Innovent: Consultancy; Genentech/Roche: Research Funding, Speakers Bureau; Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Juno/Celgene/BMS: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Beigene: Consultancy, Speakers Bureau; Millenium: Research Funding; Verastem: Speakers Bureau; Merck: Research Funding; AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Speakers Bureau; Kyowa: Consultancy, Honoraria, Speakers Bureau. Stephens:Innate: Consultancy; Verastem: Research Funding; Beigene: Consultancy; Karyopharm: Consultancy, Research Funding; Acerta: Research Funding; Gilead: Research Funding; Juno: Research Funding; MingSight: Research Funding; Arqule: Research Funding; Janssen: Consultancy; Pharmacyclics: Consultancy. Gillenwater:Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Gong:Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Yang:Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Ogasawara:Bristol-Myers Squibb: Current Employment; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Thorpe:Bristol-Myers Squibb: Current equity holder in publicly-traded company; Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment. Siddiqi:Astrazenca: Membership on an entity's Board of Directors or advisory committees; PCYC: Membership on an entity's Board of Directors or advisory committees; Juno: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BeiGene: Other: DMC member; Juno Therapeutics, Pharmacyclics LLC, an AbbVie Company, AstraZeneca, Celgene, Kite Pharma, and BeiGene: Consultancy; Pharmacyclics LLC, an AbbVie Company, Juno Therapeutics, KITE Pharma, AstraZeneca, TG Therapeutics, Celgene, Oncternal, and BeiGene: Research Funding; Pharmacyclics LLC, an AbbVie Company, Seattle Genetics, Janssen, and AstraZeneca: Speakers Bureau; AstraZeneca: Other: Travel/accommodations/expenses.

Introduction Relapses involving the central nervous system (CNSrel) occur in ~5% of patients (pts) with aggressive non-Hodgkin lymphoma (NHL) in the rituximab era (Ghose et al, Clin LML 2015) with rates exceeding 10% in high risk groups (Villa et al, Ann Onc 2010; Schmitz et al, JCO 2016). CNSrel are generally thought to occur in the first 4-6 months from diagnosis. Prophylaxis (PPx) administration, route, and frequency are not standardized, and the impact of PPx on CNSrel risk is incompletely understood. Methods We performed a multicenter retrospective analysis of pts with aggressive NHL (excluding Burkitt's) without known CNS involvement (inv) who received single-route CNS PPx with during front-line (FL) anthracycline-based therapy (tx) from 2013-2019 across 19 US academic institutions. Recipients of chemotherapy for prior CLL or indolent NHL were ineligible. Method, frequency, and outcomes of CNS PPx administration were evaluated, with significance assessed by various statistical methods via two-tailed P Results 1030 patients were identified who met eligibility criteria. Clinical features included median age 61 years (yrs; range 16-86), 40.9% female, ECOG PS 0-1 82.8%, elevated LDH 65.3%, >1 extranodal (EN) site 42.3%, stage 3/4 disease 79.2%. NHL histologies included diffuse large B cell (DLBCL; 75.2%), high grade B cell (16.3%), transformed follicular lymphoma (5.6%) and 3% other; among pts with DLBCL, 46.4% had germinal center (GCB) subtype and 40.5% had non-GCB. 26.2% (n=210) of evaluable pts had double-hit lymphoma (DHL). Among pts with known HIV status, 7.2% (n=65) were HIV-positive. 85.7% had EN inv; common sites included bone (35.4%), liver (13.7%), gastrointestinal (12.7%), lung (11.8%), and marrow (11.5%). FL regimens included RCHOP (45.9%), REPOCH (46.5% total; 79.1% with dose-adjustment), 7.6% other. PPx was given intravenously (IV) in 20% of pts vs 77% intrathecally (IT), over a median 2.9 vs 4.1 doses respectively; see Table 1 for factors associated with PPx route. PPx was generally well-tolerated, with 10.7% PPx-related toxicity reported; see Table 2. CNSrel after FL tx was 5.3% overall without significant difference by PPx route (7% IV vs 5% IT, p=0.178). This lack of difference between PPx routes was observed in all subgroup analyses performed, including by: age, stage, histology, number of EN sites, individual EN site inv, elevated LDH, CNS-IPI, DHL status, HIV status, FL regimen, number of PPx doses. There was no significant difference in anatomic site(s) of CNSrel by PPx route. CNSrel occurred bimodally: 24% by end of FL tx vs 76% delayed (average 2.3 yrs, range 0.4-5.2 yrs). Rates of CNSrel were significantly higher with CNS-IPI high vs moderate risk (8.3 vs 4.1%, p=0.03; Figure 1), elevated LDH (6.9 vs 2.6%, p=0.007) and multiple inv EN sites (7.5% for 2+ vs 4% for 0-1, p=0.01); each additional EN site further increased risk (p=0.03 for trend; Figure 2). Increased CNSrel was noted in pts with testis (13.7 vs 5%, p=0.004) and liver inv (11.1 vs 4.6%, p=0.002) vs those without inv at respective sites. No significant difference was noted at other EN sites, including renal/adrenal (4.8 vs 5.6%, p=0.71), marrow (8.9 vs 5.1%, p=0.09), or lung (8.6 vs 5.1%, p=0.12). All EN site-CNSrel correlations were unchanged when accounting for PPx route. With median follow-up of 2.3 yrs, median PFS and OS for the overall group have not been reached; 2-yr PFS and OS were 70 and 85% respectively. PFS and OS were each predicted by CNS-IPI (p Conclusion Use of single-route ppx demonstrated similar CNSrel vs established outcomes for this population in the rituximab era, with no difference by PPx route. CNSrel remains a rare but devastating complication, with greater risk even after single-route PPx in those with higher EN burden and inv of key EN sites. Disclosures Kahl: Acerta: Consultancy, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche Laboratories Inc: Consultancy; Pharmacyclics LLC: Consultancy; Genentech: Consultancy; Celgene Corporation: Consultancy; AstraZeneca Pharmaceuticals LP: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy. Spinner:Notable Labs: Honoraria. Advani:Celgene, Forty Seven, Inc., Genentech/Roche, Janssen Pharmaceutical, Kura, Merck, Millenium, Pharmacyclics, Regeneron, Seattle Genetics: Research Funding; Astra Zeneca, Bayer Healthcare Pharmaceuticals, Cell Medica, Celgene, Genentech/Roche, Gilead, KitePharma, Kyowa, Portola Pharmaceuticals, Sanofi, Seattle Genetics, Takeda: Consultancy. Voorhees:AstraZeneca: Research Funding. Grover:Genentech: Research Funding; Tessa: Consultancy. Huntington:Genentech: Consultancy; Novartis: Consultancy; Celgene: Consultancy, Research Funding; TG Therapeutics: Research Funding; Pharmacyclics: Honoraria; Bayer: Consultancy, Honoraria; DTRM: Research Funding; Astrazeneca: Honoraria; AbbVie: Consultancy. Spurgeon:Beigene: Research Funding; Gilead: Research Funding; Genentech: Research Funding; Bristol-Myers Squibb: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy, Research Funding; VelosBio: Consultancy, Research Funding; Cardinal Health: Honoraria; Verastem: Research Funding; Genmab: Research Funding; AstraZeneca: Research Funding; Acerta: Research Funding. Olszewski:Spectrum Pharmaceuticals: Research Funding; Genentech, Inc.: Research Funding; Adaptive Biotechnologies: Research Funding; TG Therapeutics: Research Funding. Landsburg:Seattle Genetics: Speakers Bureau; Morphosys: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Curis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Triphase: Research Funding. Kamdar:Roche: Research Funding. Caimi:Kite Pharma: Other: Advisory Board; ADC Therapeutics: Other: Advisory Board, Research Funding; Verastem: Other: Advisory Board; Amgen: Other: Advisory Board; Bayer: Other: Advisory Board; Celgene: Speakers Bureau. Karmali:Takeda: Research Funding; BeiGene: Speakers Bureau; AstraZeneca: Speakers Bureau; Karyopharm: Honoraria; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau. Stephens:Pharmacyclics: Consultancy; Innate: Consultancy; Verastem: Research Funding; Karyopharm: Consultancy, Research Funding; Janssen: Consultancy; Gilead: Research Funding; Arqule: Research Funding; Juno: Research Funding; MingSight: Research Funding; Acerta: Research Funding; Beigene: Consultancy. Smith:Genentech/Roche: Consultancy, Other: Support of parent study and funding of editorial support, Research Funding; TG Therapeutics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy; BMS: Consultancy; Karyopharm: Consultancy, Research Funding; FortySeven: Research Funding; Pharmacyclics: Research Funding; Acerta: Research Funding. Khan:Celgene: Research Funding; Pharmacyclics: Honoraria; Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding; Janssen: Honoraria. Cohen:Genentech, BMS, Novartis, LAM, BioInvent, LRF, ASH, Astra Zeneca, Seattle Genetics: Research Funding; Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo: Consultancy. Portell:Bayer: Consultancy; Xencor: Research Funding; BeiGene: Consultancy, Research Funding; Infinity: Research Funding; Roche/Genentech: Consultancy, Research Funding; Amgen: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy; AbbVie: Research Funding; TG Therapeutics: Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding.

BACKGROUND: Ibrutinib is a BTK inhibitor approved for relapsed/refractory MCL. We evaluated the safety and efficacy of single-agent ibrutinib maintenance (I-M) following frontline chemo-immunotherapy for MCL in a multicenter phase II trial. Herein, we report preliminary results. METHODS: Patients (Pts) received I-M 560 mg daily for up to 4 years after complete/partial response (CR/PR) to frontline chemo-immunotherapy (+/- autoSCT). The 3-year PFS rate was the primary endpoint. Secondary endpoints were PR to CR conversions, median OS and toxicity. After identifying a trackable clone using archived tissue obtained at diagnosis, minimal residual disease (MRD) was measured using NGS (detection resolution of 1 cell per million; clonoSEQ®; Adaptive Biotechnologies) on peripheral blood at 4 time-points: baseline (after induction but prior to starting I-M) and then at 1, 6 and 18-24 mo(s) after initiation of I-M. RESULTS: 36 pts were enrolled between 7/2014-7/2018. Median age was 60 years (range 46-90). For induction, 17 (47%) received BR, 18 (50%) a cytarabine-containing regimen and 1 (3%) R-CHOP. Eighteen (50%) had autoSCT in CR1. Post-induction +/- autoSCT, 33 (92%) had a CR and 3 (8%) had a PR as best response respectively. One patient converted from PR to CR on I-M. Median f/u was 34.6 months. 5 (14%) pts completed the 4-year I-M course and 15 (42%) remain on I-M (median 31 cycles, range 2-52). Sixteen (44%) pts discontinued I-M early due to: treatment related adverse events (TRAEs; n=12), second malignancies considered unrelated to I-M (n=2), PD (n=1) and death of unknown cause (n=1). Three pts died, 2 deaths deemed unrelated to I-M (aspiration pneumonia, 2nd malignancy) and 1 from unknown cause; 1 pt was lost to follow-up. The most common grade ≥ 3 TRAEs during I-M were neutropenia, HTN, infection, bleeding and atrial fibrillation/flutter (Table 1). TRAEs led to permanent dose reductions in 9 (25%) pts, most commonly for neutropenia (n=3), and I-M discontinuation in 12 (33%), 6 for new onset atrial fibrillation/flutter, 1 each for myalgias, rash, pericardial effusion, mucositis, TIA, subdural hematoma/bleed. Notably, I-M was discontinued in the majority of pts with new onset atrial fibrillation/flutter though not typical of current practice. At the time of data cut-off, MRD was assessed in 21 of 36 pts at varying time points (Figure 1) with remaining samples not yet collected/analyzed. After induction but prior to I-M, 16 pts were confirmed MRD (-), 4 were MRD indeterminate and 1 was MRD (+). Four pts MRD (-) prior to I-M became MRD (+) with follow-up, 2 induced with hyperCVAD, 1 with BR and 1 with R-CHOP + autoSCT prior to I-M; 2 of these pts reverted back to MRD (-) status with ongoing I-M. Of the 2 pts with persistent MRD (+) disease, 1 had clinical progression and the other maintains radiographic CR. Post induction, all MRD indeterminate pts were MRD (-) when checked after 1 month on I-M. The pt who was MRD (+) after front-line treatment (Nordic regimen + autoSCT) remains MRD (+) after 30 cycles of I-M without clinical relapse. MRD correlations with PFS and OS have not yet been performed. CONCLUSION: I-M 560 mg daily is feasible in pts with MCL after response to frontline chemo-immunotherapy. Grade ≥ 3 rates of atrial fibrillation/flutter are consistent with ibrutinib's known safety profile. NGS-based assessments demonstrate that most pts are MRD negative after intensive induction. Longer follow-up and correlation of MRD with PFS and OS are needed to determine the clinical relevance of I-M and MRD status. Disclosures Karmali: BeiGene: Speakers Bureau; AstraZeneca: Speakers Bureau; Karyopharm: Honoraria; Takeda: Research Funding; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau. Stephens:Arqule: Research Funding; Innate: Consultancy; Juno: Research Funding; Acerta: Research Funding; MingSight: Research Funding; Janssen: Consultancy; Karyopharm: Consultancy, Research Funding; Beigene: Consultancy; Pharmacyclics: Consultancy; Gilead: Research Funding; Verastem: Research Funding. Winter:Norvartis: Consultancy, Other: DSMB; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: advisory board; Epizyme: Other: DSMB; Delta Fly Pharma: Consultancy; Amgen: Consultancy; CVS/Caremark: Consultancy; Ariad/Takeda: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees, Other: advisory board. Ma:Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; BeiGene: Honoraria, Research Funding, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding; Bioverativ: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Juno: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Kite: Consultancy, Honoraria; TG Therapeutics: Research Funding. Petrich:AbbVie: Current equity holder in publicly-traded company; Daiichi-Sankyo: Current Employment. Hochberg:Intervention Insights: Consultancy; Leuko: Consultancy. Kuhr:Adaptive Biotechnologies: Current Employment. Gordon:Zylem Biosciences: Patents & Royalties: Patents, No Royalties. Pro:Verastem Oncology: Research Funding. OffLabel Disclosure: maintenance ibrutinib after frontline therapy in MCL

Background: Lisocabtagene maraleucel (liso-cel) is an investigational, CD19-directed, defined composition, 4-1BB chimeric antigen receptor (CAR) T cell product administered at equal target doses of CD8+ and CD4+ CAR+ T cells. Liso-cel is being studied in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) in the ongoing, open-label, phase 1/2 TRANSCEND CLL 004 study (NCT03331198). Here, we report outcomes of patients in the phase 1 monotherapy cohort after a median follow-up of 18 months (mo). Methods: Eligible patients had received ≥3 (standard-risk disease) or ≥2 (high-risk disease: del[17p], TP53 mutation, unmutated IGHV, or complex karyotype) lines of prior therapy, including a Bruton tyrosine kinase inhibitor (BTKi) unless contraindicated. Patients with active untreated central nervous system disease, Eastern Cooperative Oncology Group performance status >1, or Richter transformation were excluded. After 3 days of lymphodepletion with fludarabine and cyclophosphamide, patients received liso-cel infusion at 1 of 2 dose levels (DLs): 50 × 106 (DL1) or 100 × 106 (DL2) CAR+ T cells. Dose-limiting toxicities were evaluated for 28 days postinfusion. Responses were assessed using 2018 International Workshop on CLL criteria. Minimal residual disease (MRD) was assessed in blood by flow cytometry and/or in bone marrow (BM) by next-generation sequencing (both with a sensitivity of ≤10-4). Persistence of liso-cel was monitored by quantitative polymerase chain reaction. Results: Overall, 23 and 22 patients were evaluable for safety and efficacy, respectively. Median age was 66 (range, 49‒79) years, median number of prior therapies was 6 (range, 3‒13), and 83% of patients (n=19/23) had high-risk disease. All patients (N=23) had received prior ibrutinib, with 91% (n=21) refractory to, or who relapsed on, ibrutinib and 9% (n=2) who were intolerant to ibrutinib; overall, 48% (n=11) were refractory to both a prior BTKi and venetoclax. The safety profile was similar to that previously reported; no late or delayed adverse events of concern have emerged with the longer follow-up (Table). Among the 22 efficacy-evaluable patients, overall response rate (ORR; complete response [CR]/CR with incomplete blood count recovery [CRi] + partial response) was 82% (n=18); the CR/CRi rate was 45% (n=10). By Day 30, 68% of patients (n=15) achieved an overall response. At 15 mo and 18 mo, 53% (n=10/19; 6 CRs) and 50% (n=7/14; 5 CRs) of patients maintained their responses, respectively. At a median follow-up of 18 mo, the median duration of response was not reached (NR) in patients who had achieved a response to liso-cel (n=18), and median progression-free survival was 18 mo (95% CI, 3.0-NR) in all efficacy-evaluable patients. Two patients who completed the study maintained their response through 24 mo on study and have enrolled in a long-term follow-up study. Five of 8 patients who progressed had Richter transformation. The subgroup of patients refractory to both a prior BTKi and venetoclax had a similar ORR compared with the total evaluable population, with a CR rate of 60% (n=6/10; Table). Of 20 MRD-evaluable patients, 15 (75%) had undetectable MRD (uMRD) in the blood, 13 (87%) of whom also had uMRD in the BM, with most (60%) achieving uMRD in the BM by Day 30. Preliminary data show that liso-cel was detectable in the blood for up to 18 mo postinfusion in 4 (36%) of 11 patients. Conclusions: Liso-cel treatment resulted in a high rate of uMRD in this heavily pretreated, high-risk population of patients with R/R CLL/SLL, including those refractory to both a BTKi and venetoclax. Responses were rapid and durable, with liso-cel detectable for up to 18 mo postinfusion. No late or delayed adverse events of concern emerged with longer follow-up. The phase 2 monotherapy expansion of the study is currently enrolling at DL2. Disclosures Siddiqi: AstraZeneca: Other: Travel/accommodations/expenses; Pharmacyclics LLC, an AbbVie Company, Seattle Genetics, Janssen, and AstraZeneca: Speakers Bureau; Juno: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics LLC, an AbbVie Company, Juno Therapeutics, KITE Pharma, AstraZeneca, TG Therapeutics, Celgene, Oncternal, and BeiGene: Research Funding; PCYC: Membership on an entity's Board of Directors or advisory committees; Astrazenca: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BeiGene: Other: DMC member; Juno Therapeutics, Pharmacyclics LLC, an AbbVie Company, AstraZeneca, Celgene, Kite Pharma, and BeiGene: Consultancy. Soumerai:Genentech/Roche: Research Funding; BostonGene: Research Funding; Beigene: Consultancy, Research Funding; GlaxoSmithKine: Research Funding; TG Therapeutics: Research Funding; AbbVie: Consultancy; AstraZeneca: Consultancy; Verastem: Consultancy. Dorritie:Kite-Gilead: Research Funding; Juno Therapeutics: Research Funding. Stephens:Beigene: Consultancy; Acerta: Research Funding; MingSight: Research Funding; Arqule: Research Funding; Verastem: Research Funding; Janssen: Consultancy; Juno: Research Funding; Gilead: Research Funding; Karyopharm: Consultancy, Research Funding; Pharmacyclics: Consultancy; Innate: Consultancy. Riedell:Karyopharm Therapeutics: Honoraria; Bayer: Honoraria; Kite Pharmaceuticals/Gilead: Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Verastem Oncology: Honoraria; Celgene/Bristol-Myers Squibb Company: Honoraria, Research Funding; Morphosys: Research Funding. Arnason:Juno: Consultancy; Regeneron: Consultancy. Kipps:Pharmacyclics/ AbbVie, Breast Cancer Research Foundation, MD Anderson Cancer Center, Oncternal Therapeutics, Inc., Specialized Center of Research (SCOR) - The Leukemia and Lymphoma Society (LLS), California Institute for Regenerative Medicine (CIRM): Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Ascerta/AstraZeneca, Celgene, Genentech/F. Hoffmann-La Roche, Gilead, Janssen, Loxo Oncology, Octernal Therapeutics, Pharmacyclics/AbbVie, TG Therapeutics, VelosBio, and Verastem: Membership on an entity's Board of Directors or advisory committees; Oncternal Therapeutics, Inc.: Other: Cirmtuzumab was developed by Thomas J. Kipps in the Thomas J. Kipps laboratory and licensed by the University of California to Oncternal Therapeutics, Inc., which provided stock options and research funding to the Thomas J. Kipps laboratory, Research Funding; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; VelosBio: Research Funding; Celgene: Honoraria, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Gillenwater:Bristol-Myers Squibb: Current equity holder in publicly-traded company; Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment. Gong:Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Yang:Bristol-Myers Squibb: Current equity holder in publicly-traded company; Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment. Ogasawara:Bristol-Myers Squibb: Current equity holder in publicly-traded company; Bristol-Myers Squibb: Current Employment.

Background Ibrutinib is a small-molecule inhibitor of Bruton tyrosine kinase (BTK) approved for various B-cell malignancies and cGVHD. Rates of serious infection—defined as requiring hospitalization or parenteral antimicrobials— and invasive fungal infection (IFI) in patients on ibrutinib are as high as 11.4% and 4.2% respectively (Varughese T, et al. Clin Infect Dis 2018;67(5):687-92), which may be related to off-target inhibition of interleukin-2-inducible T-cell kinase or macrophage function. Methods We retrospectively reviewed infection complications in patients receiving ibrutinib at our institution between 06/01/2014 and 08/31/2019, including patients who received single-agent or combination ibrutinib. In this study, serious infection was defined as above, or a diagnosis of pneumonia regardless of hospitalization or parenteral antimicrobial therapy. Logistic regression was used to identify risk factors. Results Baseline characteristics of 134 included patients are in Table 1. Infection and serious infection occurred in 96 (72%) and 48 (36%) patients, respectively. When pneumonia was not included as a criterion for serious infection, the serious infection rate was 22%. Prior allogeneic stem cell transplant (allo-HSCT) (OR 4.50; 95% CI 1.19 – 17.00) and corticosteroid use (OR 5.42; 95% CI 1.49 – 19.82) were significant risk factors for serious infection without pneumonia (Table 2). Of 37 patients (28%) who received primary HSV/VZV prophylaxis with acyclovir, there was one case of suspected herpes zoster infection (3%). IFI developed in 7 patients (5%): 5 with Pneumocystis jirovecii pneumonia (PJP), 1 with invasive aspergillosis, and 1 with a filamentous fungus, species unknown. Other identified organisms are detailed in Figure 1. Classical risk factors for IFI, including diabetes, allo-HSCT, and concurrent corticosteroid use, were not significant predictors in this group. Table 1. Baseline Characteristics Table 2. Risk Factor Analysis Figure 1. Identified Organisms in Serious Infection Conclusion Serious infections developed at a higher rate than previously reported in the literature, with IFI rates similar to those previously described. Prior allo-HSCT and steroid use were found to be risk factors for serious infection without pneumonia. Treating physicians should have a high index of suspicion for pneumonia, IFI, and PJP in this population. Disclosures All Authors: No reported disclosures

Venetoclax in combination with obinutuzumab is an efficacious and tolerable combination that provides a fixed-duration, chemotherapy-free option for patients with previously untreated chronic lymphocytic leukemia (CLL). With the expanding number of therapeutic alternatives available for CLL, discussion of efficacy and potential adverse effects is paramount to formulating the optimal treatment regimen for each individual patient. Many ongoing studies will further define the ideal combination and long-term efficacy of these novel therapies in a prospective manner.

The Bruton tyrosine kinase (BTK) inhibitor ibrutinib improves patient outcomes in chronic lymphocytic leukemia (CLL); however, some patients experience adverse events (AEs) leading to discontinuation. Acalabrutinib is a potent, covalent BTK inhibitor with greater selectivity than ibrutinib. We evaluated the safety and efficacy of 100 mg of acalabrutinib twice daily or 200 mg once daily in patients with CLL who discontinued ibrutinib because of intolerance as determined by the investigators. Among 33 treated patients (61% men; median age, 64 years; range, 50-82 years), median duration of prior ibrutinib treatment was 11.6 months (range, 1-62 months); median time from ibrutinib discontinuation to acalabrutinib start was 47 days (range, 3-331 days). After a median of 19.0 months (range, 0.2-30.6 months), 23 patients remained on acalabrutinib; 10 had discontinued (progressive disease, n = 4; AEs, n = 3). No acalabrutinib dose reductions occurred. During acalabrutinib treatment, the most frequent AEs included diarrhea (58%), headache (39%), and cough (33%). Grade 3/4 AEs occurred in 58%, most commonly neutropenia (12%) and thrombocytopenia (9%). Of 61 ibrutinib-related AEs associated with intolerance, 72% did not recur and 13% recurred at a lower grade with acalabrutinib. Overall response rate was 76%, including 1 complete and 19 partial responses and 5 partial responses with lymphocytosis. Among 25 responders, median duration of response was not reached. Median progression-free survival (PFS) was not reached; 1-year PFS was 83.4% (95% confidence interval, 64.5%-92.7%). Acalabrutinib was well tolerated with a high response rate in patients who were previously intolerant to ibrutinib. This trial was registered at www.clinicaltrials.gov as #NCT02029443.

Intravascular large B-cell lymphoma (IVLBCL) is a rare entity, with a generally aggressive course that may vary based on geographic presentation. While a United States (US) registry study showed relatively good outcomes with IVLBCL, clinicopathological and treatment data were unavailable. We performed a detailed retrospective review of cases identified at 8 US medical centres, to improve understanding of IVLBCL and inform management. We compiled data retrieved via an Institutional Review Board-approved review of IVLBCL cases identified from 1999 to 2015 at nine academic institutions across the US. We characterized the cohort's clinical status at time of diagnosis, presenting diagnostic and clinical features of the disease, treatment modalities used and overall prognostic data. Our cohort consisted of 54 patients with varying degrees of clinical features. Adjusting for age, better performance status at presentation was associated with increased survival time for the patients diagnosed in vivo (hazard ratio: 2·12, 95% confidence interval 1·28, 3·53). Based on the data we have collected, it would appear that the time interval to diagnosis is a significant contributor to outcomes of patients with IVLBCL.

e19525 Background: Survivors of non-Hodgkin lymphoma (NHL) are at increased risk of secondary malignancies (SM). We quantified this risk in survivors with over 40 years of follow-up, and evaluated differences in risk by treatment modality. Methods: Standardized incidence ratios (SIR, observed-to-expected [O/E] ratio), which accounts for patient years at risk, and absolute excess risk of SM were assessed in 142,837 patients diagnosed with NHL as a first malignancy between 1975 and 2016 in the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. Follow up was available through 2016. Non-melanoma skin cancers were not counted as SM. SIRs were also evaluated for patients stratified by age at and latency from diagnosis. Results: In all, 14,101 patients received radiotherapy alone (RT), 68,424 received chemotherapy alone (CT), and 18,339 received chemotherapy and radiation (CRT). In total, 15,979 patients (11%) developed SM, more than the endemic rate (O/E 1.29; P < .01). Overall, patients treated with any RT (RT+CRT) had a similar risk of SM as those who did not receive RT (O/E 1.29 for both compared to endemic rate). Patients treated with RT had more risk of female breast cancer and less risk of leukemia than unirradiated patients (P < .05). Patients treated with any CT (CT+CRT) had increased SM rates compared with those who did not receive CT [O/E 1.33 (95% CI 1.30-1.35) vs 1.24 (95% CI 1.21-1.26), respectively], which included increased risks of leukemia, Kaposi sarcoma, kidney, pancreas, rectal, head and neck, and colon cancers and decreased risk of prostate cancer (P < 0.05). When stratified by four treatment groups (no CT or RT, RT alone, CT alone, CRT), there were no differences in SM rates between the no therapy and RT alone groups (O/E 1.24 95% CI 1.21-1.27 and O/E 1.23 95% CI 1.18-1.28 respectively). CT alone and CRT were associated with increased risk of secondary malignancy compared to the no therapy group (O/E 1.32 95% CI 1.29-1.35 and O/E 1.35 95% CI 1.29-1.40 respectively). CT alone was also associated with increased risk of leukemia, Kaposi sarcoma, kidney, head and neck and thyroid cancers, and a decreased risk of prostate cancer (P < .05). CRT was associated with increased risk of head and neck and female breast cancers (P < .05). There was no difference in the overall risk of SM between the CT alone and CRT groups and female breast cancer was the only site at which CRT was associated with higher risk than CT alone. Of note, female breast cancer risk was highest in those diagnosed under 25 years of age and at latencies of greater than 10 years. Conclusions: This is the largest study to examine secondary malignancy risk in patients with NHL and has the longest follow-up. Patients treated with RT alone did not have an increased SM risk compared to those who received no RT or CT. The risk of SMs was increased overall for NHL survivors and varied with treatment modality.

Purpose Utility of combined-modality therapy for patients with limited-stage diffuse large B-cell lymphoma (DLBCL) was shown in the Southwest Oncology Group (SWOG) S8736 study, where three cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) plus radiotherapy (CHOP3RT) improved 5-year progression-free (PFS) and overall survival (OS) compared with eight cycles of CHOP (CHOP8). Subsequent analysis showed an unexpected overlap of the PFS curves. We aimed to confirm and investigate this observation by performing long-term analysis of SWOG S8736 and evaluating these data alongside data from similar patients receiving rituximab and CHOP3RT (SWOG S0014 study). Patients and Methods A subset of patients with limited-stage DLBCL randomly assigned to CHOP8 (n = 150) or CHOP3RT (n = 158) in S8736 was analyzed along with a 56-patient subset treated in S0014 for long-term PFS and OS. Results Median follow-up in S8736 was 17.7 years. In patients receiving CHOP8 and CHOP3RT, median PFS was 12.0 (95% CI, 8.8 to 14.3) and 11.1 years (95% CI, 8.9 to 14.4), respectively. There were no statistically significant differences in PFS between the groups (P = .73). Median OS was 13.0 (95% CI, 10.4 to 15.2) and 13.7 years (95% CI, 11.1 to 19.4) for patients treated with CHOP8 and CHOP3RT, respectively. Similarly, there were no statistically significant differences in OS between the groups (P = .38). With a median follow-up time 12 years in S0014, 5- and 10-year OS were 82% and 67%, respectively, with a persistent pattern of relapse despite the addition of rituximab. Conclusion Although 5-year PFS and OS were improved after early analysis in patients with limited-stage DLBCL receiving CHOP3RT versus CHOP8, extended survival data showed similar PFS and OS, with continuous treatment failure. The addition of rituximab (S0014) to combined-modality therapy did not mitigate the continued relapse risk, underscoring the value of prolonged clinical trial patient observation and possible unique biology of limited-stage DLBCL.

REPLY: Mesguich et al. ([1][1]) commented on our publication, which reported the long-term outcome of patients with advanced-stage Hodgkin lymphoma undergoing interim 18F-FDG PET (after 2 cycles of chemotherapy; PET2) and PET2 response-adapted change in therapy in the SWOG S0816 trial ([2][2],[3][3

Chronic lymphocytic leukemia (CLL) is the most common type of adult leukemia and is considered incurable. Hyperactivity of B-cell receptor signaling is a central driver of CLL's molecular pathogenesis. Targeting this pathway with Bruton's tyrosine kinase inhibitors (BTKi) has improved clinical outcomes for CLL patients when compared to standard chemo-immunotherapies (Woyach, NEJM 2018; Shanafelt, NEJM 2019). To characterize cancer evolution in CLL patients who received BTKi treatment, we collected blood samples from 4 CLL patients at 3 timepoints: pre-treatment, 1 year, and 2 years after initiation of treatment. Sorted B and T cells (normal control) were subjected to 200X WES and 60X WGS. Using somatic mutations and their allele frequencies from WGS/WES data across the 3 timepoints, we reconstructed the subclonal evolution of the malignant B cell population using our subclone deconvolution algorithm SubcloneSeeker (Qiao, Genome Biol. 2014). Our analysis revealed diverse patterns of subclonal genomic evolution across patients in terms of (1) presence or absence of subclonal evolution between time points; (2) emergence of new subclones across time points; and (3) clonal replacement across time points.To elucidate subclone-specific phenotypic behavior in each patient, we collected single-cell RNA sequencing (sc-RNA-seq) and IgG VDJ sequencing (sc-VDJ-seq) from unsorted blood samples at the same time points at which we had the genomic data. Using our new scBayes algorithm (manuscript in preparation), we assigned individual cells in the scRNA-seq data to genomic subclones based on the presence or absence of subclone-defining DNA mutations. This allowed us to isolate and examine the expression phenotype corresponding to subclonal populations. We observed three patterns: 1) no/minimal genomic and transcriptomic evolution across time points; 2) no/minimal genomic subclonal evolution but transcriptomic shift of the same subclones across time points; 3) clonal/subclonal replacement with distinct transcriptomic and VDJ profiles. We found that the two patients in our study with no/minimal genomic and transcriptomic evolution had progressive disease. In contrast, the two other patients whose tumor showed transcriptomic shift and/or clonal replacement had clinically complete remission. Although larger sample sizes are needed to draw further biological conclusions, this study highlights the power of multi-omic, and especially single-cell transcriptional profiling of BTKi treatment impact on CLL patients. Citation Format: Xiaomeng Huang, Yi Qiao, Philip Moos, Szabolcs Tarapcsák, Jennifer A. Woyach, John C. Byrd, Deborah M. Stephens, Gabor T. Marth. The integration of bulk DNA sequencing and single-cell analysis reveals diverse clonal evolution in CLL patients treated with BTKi [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1517.

8024 Background: The next-generation Bruton tyrosine kinase inhibitor acalabrutinib was approved in patients (pts) with treatment-naïve (TN) and relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) based on two complementary phase 3 studies, ELEVATE-TN and ASCEND. This report of ACE-CL-001 (NCT02029443), the first phase 2 study of acalabrutinib, provides the longest safety and efficacy follow-up to date in symptomatic TN CLL pts. Methods: Adults with TN CLL/SLL were eligible if they met iwCLL 2008 criteria for treatment, were inappropriate for/declined standard chemotherapy and had ECOG performance status 0–2. Pts received acalabrutinib 100 mg BID or 200 mg QD, later switching to 100 mg BID, until progressive disease (PD) or unacceptable toxicity. Primary endpoint was safety. Events of clinical interest (ECI) were based on combined AE terms for infections, bleeding events, hypertension, and second primary malignancies (SPM) excluding non-melanoma skin, and on a single AE term for atrial fibrillation. Additional endpoints included investigator-assessed overall response rate (ORR), duration of response (DOR), time to response (TTR), and event-free survival (EFS). Results: Ninety-nine pts (n = 62 100 mg BID; n = 37 200 mg QD), were treated [median age: 64 years, 47% Rai stage 3–4 disease, 10% del(17p), 62% unmutated IGHV]. At median follow-up of 53 months (range, 1–59), 85 (86%) pts remain on treatment; most discontinuations were due to AEs (n = 6) or PD (n = 3 [n = 1 Richter transformation]). Most common AEs (any grade) were diarrhea (52%), headache (45%), upper respiratory tract infection (44%), arthralgia (42%), and contusion (42%). All-grade and grade ≥3 ECIs included infection (84%, 15%), bleeding events (66%, 3%), and hypertension (22%, 11%). Atrial fibrillation (all grades) occurred in 5% of pts (incidence: 1% in years 1, 2, 4; 3% in year 3). SPMs excluding non-melanoma skin (all grades) occurred in 11%. Serious AEs were reported in 38% of pts; those in > 2 pts were pneumonia (n = 4) and sepsis (n = 3). ORR was 97% (7% complete response; 90% partial response). Median TTR was 3.7 months (range, 2–22). Response rates were similar across high-risk groups. Median DOR and median EFS were not reached; 48-month DOR rate was 97% (95% CI, 90%–99%), and 48-month EFS rate was 90% (95% CI, 82%–94%). Conclusions: Long-term data from ACE-CL-001 further support the favorable results with acalabrutinib in phase 3 studies and demonstrate durable responses with no new long-term safety issues. Clinical trial information: NCT02029443 .

8064 Background: Acala is a next-generation, highly selective, covalent Bruton tyrosine kinase inhibitor approved in the US for patients (pts) with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and previously treated mantle cell lymphoma (MCL). We evaluated the safety profile of acala monotherapy (monotx) in multiple B cell malignancies. Methods: Data from pts with activated B-cell diffuse large B-cell lymphoma, CLL, follicular lymphoma, MCL, multiple myeloma, prolymphocytic leukemia, Richter syndrome, SLL, or Waldenström macroglobulinemia treated with ≥1 dose of acala monotx in 9 studies were pooled. Acala was administered at 100 mg BID in most pts (100–400 mg total dose daily). Adverse events (AE) were assessed. Results: A total of 1040 pts were included (median age: 67 y [range: 32–90]; ECOG status ≤1: 93%; median exposure duration: 24.6 mo [range: 0–58.5]). A total of 360 (34%) pts discontinued acala, most commonly due to progressive disease (PD; 17%). AEs led to acala discontinuation in 97 (9%) pts; those in > 2 pts were pneumonia (n = 5) and thrombocytopenia (n = 4). Incidence of AEs, including the most common (any grade and grade ≥3), are shown in the Table. Events of clinical interest (ECIs) included atrial fibrillation (afib) of any grade in 46 (4%) pts and grade ≥3 in 13 (1%) pts; major hemorrhage (any grade) in 37 (4%) pts; grade ≥3 infection in 183 (18%) pts; hypertension (any grade) in 79 (8%) pts and grade ≥3 in 36 (4%) pts; and second primary malignancies (SPM) excluding non-melanoma skin cancer (NMSC; any grade) in 68 (7%) pts. Median (range) time to first onset in days for each ECI (any grade) was: afib, 522 (8–1280); major hemorrhage, 293 (4–1327); infections, 92 (1–1317); hypertension, 157 (2–1345); SPM excluding NMSC, 339 (7–1499). Death was reported in 139 (13%) pts, most commonly due to PD (6%) and AEs (5%). Conclusions: Acala monotx has a favorable tolerability profile with increased exposure across multiple mature B cell malignancies. Additional analyses will further explore the longitudinal characteristics of AEs. [Table: see text]

Chronic lymphocytic leukemia (CLL) therapy has changed dramatically with the introduction of several targeted therapeutics. Ibrutinib was the first approved for use in 2014 and now is used for initial and salvage therapy of CLL patients. With its widespread use in clinical practice, ibrutinib’s common and uncommon adverse events reported less frequently in earlier clinical trials have been experienced more frequently in real-world practice. In particular, atrial fibrillation, bleeding, infections, and arthralgias have been reported. The management of ibrutinib’s adverse events often cannot be generalized but must be individualized to the patient and their long-term risk of additional complications. When ibrutinib was initially developed, there were limited therapeutic alternatives for CLL, which often resulted in treating through the adverse events. At the present time, there are several effective alternative agents available, so transition to an alternative CLL directed therapy may be considered. Given the continued expansion of ibrutinib across many therapeutic areas, investigation of the pathogenesis of adverse events with this agent and also clinical trials examining therapeutic approaches for complications arising during therapy are needed. Herein, we provide strategies we use in real-world CLL clinical practice to address common adverse events associated with ibrutinib.

A jumping translocation (JT) is a rare cytogenetic aberration that can occur in haematological malignancy. It involves the translocation of the same fragment of donor chromosome onto two or more recipient chromosomes, typically in different cells. In this study, we describe the first series of chronic lymphocytic leukaemia (CLL) patients with JTs reported to date. Following a review of 878 CLL patient karyotypes, we identified 26 patients (3%) with 97 JTs. The most commonly occurring breakpoint in these translocations was 17p11.2. Loss of TP53 was identified prior to or at the same time as JT in 23 of 26 patients (88%). All patients eventually developed a complex karyotype. All but one patient has required treatment for CLL, with estimated median time to treatment of 11.5 months. This study establishes JTs as a recurrent abnormality found in CLL patients with aggressive disease. JTs contribute to complex karyotypes and, in many cases, are involved in chromosomal rearrangements that result in loss of the tumour suppressor gene TP53.

Given the limited treatment options for relapsed lymphoma post-allogeneic hematopoietic cell transplantation (post-allo-HCT) and the success of programmed death 1 (PD-1) blockade in classical Hodgkin lymphoma (cHL) patients, anti-PD-1 monoclonal antibodies (mAbs) are increasingly being used off-label after allo-HCT. To characterize the safety and efficacy of PD-1 blockade in this setting, we conducted a multicenter retrospective analysis of 31 lymphoma patients receiving anti-PD-1 mAbs for relapse post-allo-HCT. Twenty-nine (94%) patients had cHL and 27 had ≥1 salvage therapy post-allo-HCT and prior to anti-PD-1 treatment. Median follow-up was 428 days (range, 133-833) after the first dose of anti-PD-1. Overall response rate was 77% (15 complete responses and 8 partial responses) in 30 evaluable patients. At last follow-up, 11 of 31 patients progressed and 21 of 31 (68%) remain alive, with 8 (26%) deaths related to new-onset graft-versus-host disease (GVHD) after anti-PD-1. Seventeen (55%) patients developed treatment-emergent GVHD after initiation of anti-PD-1 (6 acute, 4 overlap, and 7 chronic), with onset after a median of 1, 2, and 2 doses, respectively. GVHD severity was grade III-IV acute or severe chronic in 9 patients. Only 2 of these 17 patients achieved complete response to GVHD treatment, and 14 of 17 required ≥2 systemic therapies. In conclusion, PD-1 blockade in relapsed cHL allo-HCT patients appears to be highly efficacious but frequently complicated by rapid onset of severe and treatment-refractory GVHD. PD-1 blockade post-allo-HCT should be studied further but cannot be recommended for routine use outside of a clinical trial.

The front-line management of patients with chronic lymphocytic leukemia (CLL) has evolved significantly in recent years due to introduction of novel, targeted agents. Upon CLL diagnosis, physicians should determine whether treatment or careful observation is indicated. Once treatment is required, choice of therapy should be based on the age and fitness of the patient and the distinct molecular profile of their disease. As multiple novel agents are in various stages of development, all patients regardless of their age, fitness, and disease risk should be evaluated for clinical trial participation before initiating any front-line therapy. If no clinical trial is available, we provide our recommendations for front-line treatment of CLL patients. Healthy, young patients with low-risk disease (mutated IgVH, del (13q)) should be offered fludarabine, chlorambucil, and rituximab (FCR), while similar patients with high-risk disease (unmutated IgVH, del (17p), del (11q), and complex karyotype) should be considered for ibrutinib therapy. For those young, fit patients with high-risk disease and a contraindication to ibrutinib, FCR, or high-dose methylprednisolone and rituximab are options. In regard to older, unfit patients, a careful assessment of their fitness and ability to tolerate treatment should be undertaken before starting therapy. Those who have poor performance and multiple medical comorbidities should be considered for palliative care alone. However, those who are fit enough for treatment can be offered ibrutinib. If there is a contraindication to ibrutinib, they can be separated into low- and high-risk molecular groups. For the low-risk patients, bendamustine and rituximab or obinutuzumab and chlorambucil can be considered. For the high-risk patients, treatment with rituximab and lenalidomide is an option. Herein, we provide an evidence-based front-line treatment algorithm for CLL patients based upon fitness and molecular risk.

Introduction Blocking Bruton tyrosine kinase (BTK) with ibrutinib has demonstrated efficacy in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) patients (pts). However, resistance to therapy is common. Preclinical data suggest selinexor (oral selective inhibitor of nuclear export) downregulates BTK (Hing 2015). We hypothesized that dual BTK blockade by combining ibrutinib and selinexor would be tolerable and efficacious in CLL/NHL pts. Herein, we report the phase I combination study with expansion cohorts. Methods Pts with histologically confirmed CLL/NHL were enrolled (n=33). Eligible pts were age ≥18 years (yrs), had ≥1 prior therapy and ECOG performance status of 0-1. CLL pts met iwCLL 2008 criteria for therapy. Pts received selinexor orally 1-2 times weekly (3 weeks of 4-week cycle) and daily oral ibrutinib (420mg) starting Cycle 1 Day 8. Treatment cycles were repeated until disease progression, intolerance, death or discontinuation of trial participation. Primary endpoint was determination of maximum tolerated dose (MTD). Dose-finding proceeded using a modified continual reassessment method targeting a probability of dose limiting toxicity (DLT) Results Median age was 66 yrs (50-80). Included pts had CLL (n=16), Richter's transformation (RT=8), diffuse large B-cell lymphoma (DLBCL, n=6), and mantle cell lymphoma (MCL=3). Median number of prior therapies was 4 (1-14) and 58% had received ibrutinib. Baseline characteristics are detailed in Table 1. The combination was tolerated. MTD was 40mg of selinexor (D1, 8, 15) and 420mg daily ibrutinib [dose level 1 (DL1)]. Two pts were treated with selinexor 30mg twice weekly and 420mg of daily ibrutinib (DL2) and both experienced significant fatigue and discontinued therapy. These adverse events (AE) were considered DLTs. The remainder of pts received DL1. Grade ≥3 hematologic AEs were rare with 3 (9%) and 1 (3%) pt experiencing neutropenia and anemia, respectively. Most common non-hematologic AEs of any grade were nausea (39%) diarrhea (33%), fatigue (33%), and anorexia (27%). Grade ≥3 non-hematologic AEs were uncommon with 2 pts (6%) experiencing hypertension and 1 pt each (3%) experiencing diarrhea, nausea, elevated alkaline phosphatase, cataract, weight gain, upper respiratory tract infection, pancreatitis, pneumonitis, and multi-system organ failure. Other AEs of interest were weight loss, bleeding, and tachycardia, experienced by 5 (15%), 4 (12%), and 3 (9%) pts, respectively. There were 5 pt deaths while on study; 3 related to disease progression and 2 related to infection. In total, 81% achieved disease control with 33% achieving CR or PR (partial response) and 48% achieving stable disease (SD; Table 2). All CLL pts who received prior ibrutinib or had complex karyotype achieved at least SD, and all who did not receive prior ibrutinib had CR or PR. Two CLL pts with known BTK mutation had response to therapy and 7 had SD. One CLL pt who received 1 prior therapy achieved CR with no detectable residual disease. One of the 8 RT pts achieved CR and 5 achieved SD. In the 11 pts who achieved at least PR, the median duration of response was not reached (NR). In the 15 pts with SD and >2 mos of follow-up, 20% (3/15) maintained SD for >6 mos. Median PFS for pts with CLL and NHL was 8.9 (95%CI:4.6-NR) and 2.7 (95%CI:0.7-NR) mos, respectively (Figure 1). For CLL pts who received and did not receive prior ibrutinib, 64% (7/11) and 20% (1/5) progressed, respectively. For CLL pts who received 1-2 and ≥3 prior therapies 20% (1/5) and 64% (7/11) progressed, respectively. With median follow-up of 5.3 (range:1.2-22.5) and 5.5 (range:0.7-33.1) mos, median OS for CLL and NHL pts was NR (95%CI:15.4-NR) and 5.4 (95%CI:2.6-NR) mos, respectively (Figure 2). Conclusions Ibrutinib (420mg daily) and selinexor (40mg weekly) was tolerable and demonstrated efficacy in this heavily pretreated, high-risk population of CLL/NHL pts. Efficacy may be greater in earlier lines of therapy. Further investigation is needed to optimize response rates and durability. Disclosures Stephens: Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Rogers:Janssen: Research Funding; Acerta: Consultancy; Abbvie: Research Funding; Genentech: Research Funding. Bhat:Janssen: Consultancy; Pharmacyclics: Consultancy. William:Guidepoint Global: Consultancy; Defined Health: Consultancy; Techspert: Consultancy; Celgene Corporation: Consultancy; Kyowa Kirin, Inc.: Consultancy. Jaglowski:Kite: Consultancy, Other: advisory board, Research Funding; Novartis: Consultancy, Other: advisory board, Research Funding; Juno: Consultancy, Other: advisory board; Unum Therapeutics Inc.: Research Funding. Glenn:BMS: Research Funding; Merck: Research Funding; Genentech: Research Funding. Byrd:Genentech: Research Funding; Acerta: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Genentech: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Acerta: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. OffLabel Disclosure: Selinexor is an oral inhibitor of nuclear export. This presentation will describe the combination of ibrutinib and selinexor, which is an off-label use for the drug.

Introduction: Outcomes in CLL are highly variable and influenced by both biologic and clinical factors. The Cumulative Illness Rating Scale (CIRS) is frequently used to assess comorbidities in CLL. Our group has demonstrated that CIRS correlates with survival in patients treated with either CIT or ibrutinib. Yet, CIRS has not become part of common clinical practice due to complexities in scoring since 14 systems need to be evaluated. Furthermore, the relative contribution of individual comorbidities to patient outcomes is unknown. Here we report the impact of specific comorbidities in a large cohort of CLL patients and propose a simplified CLL-comorbidity index (CLL-CI). Methods: We conducted a retrospective analysis of patients with CLL treated with either CIT or kinase inhibitors at 10 US academic medical centers between 2000-2018. CIRS score was calculated as in Salvi et al, 2008. Patients were randomly divided into a training-set (n=381) and validation-set (n=189). Random survival forests (RSF) were constructed on the training-set to select variables for Cox regression models. Discrimination of models was tested in the validation-set. CIRS score in each organ system, relapse/refractory (R/R) disease, treatment type, age, and del(17p) were included as features for RSF modeling of event-free survival (EFS), defined as time from treatment to death, disease progression or next therapy. For each RSF, features were scored and ranked according to variable importance (VI; the decrease in prediction accuracy when the specific variable is randomly permuted) and minimal depth (MD; the minimum distance between the root node of a tree and the first node that splits on the specific variable). After 200 RSF's, VI and MD ranks were averaged. Organ system variables whose average rank for both predictive measures was ≤10 were chosen for Cox regression modeling of EFS and OS. Three sets of Cox models were fit on the training data and applied to the validation-set to compute c-statistics depicting each model's ability to predict EFS. Cox models assessed the addition of either CIRS or CLL-CI to known prognostic factors. Results: The data set contained 614 patients; 570 (93%) with complete data were included in our analysis. Median age was 67 years (range 30-91). Median CIRS was 7 (range, 0-29) with CIRS≥7 in 302 patients (53%). Median follow up was 31 months. Del(17p) and/or TP53 mutation was present in 113 patients (20%) and 299 (52%) were assessed in the R/R setting. Ibrutinib was the most common treatment (n=338, 59%), followed by fludarabine (n=163) and bendamustine (n=116). In the training-set, four organ system variables ("musculoskeletal", "renal", "endocrine" and "upper GI"), were selected based on RFS average predictive measure ranks and summed to derive the CLL-CI score. Median CLL-CI was 2 (range, 0-11) in the training cohort with a value of 3 identified as the optimal cut-point for association with EFS; 236 (41%) had a high CLL-CI score (≥3). Cox models that included either CLL-CI or CIRS (alongside age, disease status, type of treatment, and del(17p)/TP53 mutation) yielded c-statistics of 0.68 (95% CI: 0.65-0.69) and 0.68 (95% CI: 0.65-0.70), respectively. These discrimination estimates were modestly superior to the model without a comorbidity variable (c-statistic, 0.64). In the complete data set, R/R disease and age were associated with decreased EFS (HR=2.14, p Conclusion: In this large data set, we utilized random forests to identify "musculoskeletal", "upper GI", "endocrine", and "renal" comorbidities as the most prognostic of EFS in patients with CLL. Using only these 4 CIRS variables, we developed and validated a simplified comorbidity score (CLL-CI) which performed similar to CIRS, but has lower complexity and therefore can be easily incorporated into clinical practice. Disclosures Patel: Sunesis: Consultancy; Pharmacyclics/Janssen: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Genentech: Consultancy, Speakers Bureau. Persky:Sandoz: Consultancy; Morphosys: Other: Member, Independent Data Monitoring Committee; Debiopharm: Other: Member, Independent Data Monitoring Committee; Bayer: Consultancy. Cohen:Genentech, Inc.: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; LAM Therapeutics: Research Funding; UNUM: Research Funding; Hutchison: Research Funding; Astra Zeneca: Research Funding; Lymphoma Research Foundation: Research Funding; ASH: Research Funding. Choi:Rigel: Consultancy, Research Funding; Gilead: Consultancy, Speakers Bureau; Oncternal: Research Funding; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Genentech: Consultancy, Speakers Bureau; Abbvie: Consultancy, Research Funding, Speakers Bureau. Hill:Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Honoraria; Amgen: Research Funding; Takeda: Research Funding; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Research Funding; Kite: Consultancy, Honoraria; TG therapeutics: Research Funding. Shadman:Sunesis: Research Funding; Pharmacyclics: Consultancy, Research Funding; Celgene: Research Funding; ADC Therapeutics: Consultancy; Atara Biotherapeutics: Consultancy; Genentech: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; Mustang Bio: Research Funding; Verastem: Consultancy; Astra Zeneca: Consultancy; AbbVie: Consultancy, Research Funding; BeiGene: Research Funding; TG Therapeutic: Research Funding; Sound Biologics: Consultancy; Acerta Pharma: Research Funding. Stephens:Acerta: Research Funding; Karyopharm: Research Funding; Gilead: Research Funding. Brander:Tolero: Research Funding; MEI: Research Funding; Acerta: Research Funding; Genentech: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Research Funding; Novartis: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; BeiGene: Research Funding; DTRM Biopharma: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Teva: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria, Research Funding. Danilov:Celgene: Consultancy; Curis: Consultancy; Bayer Oncology: Consultancy, Research Funding; Seattle Genetics: Consultancy; AstraZeneca: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Verastem Oncology: Consultancy, Other: Travel Reimbursement , Research Funding; Janssen: Consultancy; Pharmacyclics: Consultancy; Aptose Biosciences: Research Funding; Bristol-Meyers Squibb: Research Funding; TG Therapeutics: Consultancy; Takeda Oncology: Research Funding; MEI: Research Funding; Abbvie: Consultancy; Genentech: Consultancy, Research Funding.

Background: MCL carries a poor overall prognosis despite high response rates to induction chemotherapy. Maintenance strategies have impacted survival in MCL but optimal strategies have yet to be defined. Despite profound activity of ibrutinib, a selective BTK inhibitor, in relapsed/refractory MCL, ibrutinib maintenance (I-M) following induction for treatment-naive MCL has not been explored. We report preliminary results of a multicenter phase II trial assessing efficacy and safety of I-M for MCL after frontline induction. Methods: Patients (pts) with MCL with complete or partial response (CR/PR) to frontline chemo-immunotherapy +/- autologous stem cell transplantation (autoSCT) received I-M 560 mg daily for up to 4 years. The primary objective was 3 year PFS rate with I-M. Secondary objectives were PR to CR conversions, median OS after 4 years and toxicity. Measurable residual disease (MRD) assessments using an NGS-MRD Assay (detection resolution of < 1 cell per million; Adaptive Biotechnologies) on peripheral blood and/or PBMCs were planned at 4 time points: prior to I-M initiation and at 1, 6 and 18-24 mo(s) after initiation of I-M. Results: Accrual is complete (n=36). Median age was 60 (range 46-90), 28 pts (78%) were males, 28 (78%) had advanced stage and 9 (25%) had extranodal disease. 18 (50%), 7 (19%) and 11 (31%) had low vs intermediate vs high risk MIPI respectively. For induction, 17 (47%) received bendamustine-rituximab (BR), 18 (50%) a cytarabine-based regimen, and 1 (3%) R-CHOP. 18 (50%) had autoSCT in CR1 prior to enrollment. 33 (92%) and 3 (8%) had CR and PR with induction respectively with 1 PR to CR conversion on I-M. Median follow-up from initiation of induction therapy was 33 mos. With a median follow-up of 24.5 mos from initiation of I-M, 1 pt had disease progression (PD) and 2 others died, 1 from hepatic cholangiocarcinoma 2 years after I-M discontinuation for toxicity (atrial fibrillation) and 1 from unknown cause. 20/36 (56%) pts remain on I-M (median 24 cycles, range 1-52). Sixteen pts discontinued ibrutinib, including 3 for completion of 4 years of I-M. Of the remaining 13 who discontinued, TRAEs accounted for 10 (77%) and the other 3 were for uterine cancer (n=1), PD (n=1), and death of unknown cause (n=1) (Table 1). Atrial fibrillation/atrial flutter accounted for 50% (n=5) of TRAEs that led to I-M discontinuation. 9 (25%) pts required permanent dose reductions for TRAEs with neutropenia (n=3), myalgias (n=2), and fatigue (n=2) being the most common. Collectively, TRAEs led to dose reductions/ interruptions/ discontinuations in 25 (69%) pts. At time of data cut-off, (July 2019), using a trackable dominant clone identified from tissue at diagnosis, MRD was assessed in 12 patients at varying time points (Figure 1). In these 12 pts, 6 were induced with BR, 5 with a cytarabine-based regimen, and 1 with R-CHOP and 5 were consolidated with autoSCT prior to enrollment. Prior to I-M initiation, 9 pts were MRD (-) and 3 had indeterminate MRD status. Indeterminate results corresponded with total cell counts below the level of detection and quantification with our assay. Those with indeterminate MRD status were confirmed to be MRD (-) with subsequent evaluation after 1 month of I-M. 3 of 12 (25%) pts became MRD (+) on I-M. The first reverted back to MRD (-) status and remains MRD (-) with clinical CR on > 3 years of I-M. The second pt was treated with hyperCVAD with PR prior to I-M. This patient required several dose interruptions for neutropenia just prior to MRD detection with clinical PD leading to discontinuation of therapy after 9 months of I-M. The third pt was treated with R-CHOP + autoSCT with PR prior to I-M and maintains a PR despite MRD conversion on > 2 years of I-M. Further analysis of dynamic changes in dominant and non-dominant clones associated with I-M is ongoing. Conclusions: I-M is feasible in MCL pts who respond to frontline chemo-immunotherapy +/- autoSCT with manageable toxicities consistent with the known safety profile of ibrutinib. Guidelines to discontinue I-M for atrial fibrillation were strictly upheld in this protocol though not typical of current practice. NGS can be used to assess MRD with induction and maintenance therapy and demonstrates that most pts are MRD negative after intensive induction. Longer follow-up, evaluation of dynamic changes in MRD, and PFS and OS data are needed to assess clinical relevance of I-M and importance of MRD status, and may support larger, controlled studies. Disclosures Karmali: Gilead/Kite; Juno/Celgene: Consultancy, Speakers Bureau; Takeda, BMS: Other: Research Funding to Institution; Astrazeneca: Speakers Bureau. Abramson:AbbVie Inc, Amgen Inc, Bayer HealthCare Pharmaceuticals, Celgene Corporation, EMD Serono Inc, Genentech, Gilead Sciences Inc, Janssen Biotech Inc, Juno Therapeutics, a Celgene Company, Karyopharm Therapeutics, Kite Pharma Inc, Merck, Novartis, Seattle Gen: Consultancy. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Winter:Merck: Consultancy, Research Funding. Ma:Genentech: Consultancy; Gilead: Research Funding; Astra Zeneca: Consultancy, Research Funding, Speakers Bureau; Acerta: Research Funding; Abbvie: Research Funding; Incyte: Research Funding; Janssen: Consultancy, Speakers Bureau; Kite: Consultancy; Juno: Research Funding; Xeme: Research Funding; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Beigene: Research Funding; Bioverativ: Consultancy; Novartis: Research Funding. Petrich:Abbvie: Employment, Equity Ownership. Kuhr:Adaptive Biotechnologies: Employment, Other: shareholder. Gordon:Zylem LLC: Other: co-founder; research in nanoparticles in cancer; Bayer: Other: Advisory Board; Juno/Celgene: Other: Advisory Board, Research Funding; Gilead: Other: Advisory Board. Pro:Takeda: Consultancy, Honoraria, Other: Travel Expenses; Celgene: Consultancy, Honoraria; Kyowa Hakka Kirin: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Other: Travel Expenses, Research Funding. OffLabel Disclosure: We will discuss results of our trial looking at ibrutinib maintenance in frontline MCL

Background: Follicular lymphoma (FL) is the most common indolent lymphoma and is generally characterized by prolonged survival with multiple relapses throughout the disease course. There is no standard of care as to the initial choice or sequencing of treatments for relapsed disease. Novel agents approved in the relapsed setting include lenalidomide in combination with rituximab (R2) and PI3K inhibitors (PI3Ki) including idelalisib, duvelisib, and copanlisib. However, there are no prospective data comparing the safety/efficacy of these novel agents to guide treatment selection. We aimed to examine the characteristics and outcomes of patients with relapsed follicular lymphoma treated with these novel agents. Methods: We conducted a retrospective analysis of adult patients with FL treated with commercially-available novel agents at 10 US academic cancer centers. Patients were excluded if they received one of these therapies as first line therapy or for the treatment of transformed disease. Treatment with lenalidomide or PI3Ki was determined by the treating physician, as was the decision to incorporate monoclonal antibody (mAb). For patients who received both classes of novel agent, baseline and treatment characteristics were grouped by first novel class used. The Fisher's Exact test was used to compare categorical variables and the Mann Whitney U test for continuous variables. Progression-free survival (PFS) was defined as time from the initiation of the first novel agent to progression of disease (POD), either FL or transformed disease, or death from any cause. Overall survival (OS) was defined as time from the initiation of the first novel agent to death from any cause. Outcomes were estimated using the Kaplan-Meier method and compared using the log-rank test. Results: 98 patients were included. Available baseline characteristics at diagnosis are described in Table 1. The median time from the end of the last FL treatment to the start of the first novel agent was 12 months (range 0-79). The first novel agent was lenalidomide +/-mAb in 49% (n=48) of the patients and a PI3Ki +/- mAb in 51% (n=50) of patients. Idelalisib was the most commonly used PI3Ki (n=47) followed by copanlisib (n=2) and duvelisib (n=1). The median number of therapies prior to the first novel agent was 2 (range 1-8) and not significantly different between treatment classes. Reason for discontinuation of novel agent was significantly different between groups with greater discontinuations due to toxicity (40% vs 28%) and transformed disease (15% vs. 3%) for the PI3Ki ± mAb group vs. lenalidomide ± mAb group, respectively (p = 0.02). The median PFS and OS for the entire cohort was 10 months (95% CI 7.6-14) and 120 months (95% CI, 49-NA), respectively (Figure A). When comparing outcomes to current FDA approvals-lenalidomide + mAb (n=43) versus PI3Ki monotherapy (PI3Ki, n=38), the median PFS was significantly longer in the lenalidamide + mAb group compared to the PI3Ki group (15 vs. 6 months, p=0.016), as was the OS (120 vs. 37 months, p=0.002, respectively, Figure B). Conclusions: In this multi-center analysis, despite multiple relapses, the median survival for FL patients treated with novel agents was 120 months from the initiation of the first novel therapy. With the caveat of retrospective comparison, lenalidomide + mAb (i.e. R2) appears superior to PI3Ki as first novel agent in the relapsed setting with the recognition that a high proportion of patients discontinued PI3Ki due to toxicity. Because the majority of the patients received idelalisib conclusions cannot be drawn about alternative PI3Ki which may have lower toxicity profiles or intermittent dosing strategies, allowing for safer and more prolonged treatment. Future prospective studies are needed to directly compare these agents and determine optimal sequencing of therapies. Disclosures Landsburg: Takeda: Research Funding; Triphase: Research Funding; Triphase: Research Funding; Takeda: Research Funding; Curis, INC: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Speakers Bureau; Seattle Genetics: Speakers Bureau; Curis, INC: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kahl:AbbVie Inc, Acerta Pharma - A member of the AstraZeneca Group, AstraZeneca Pharmaceuticals LP, BeiGene, Celgene Corporation, Genentech, Pharmacyclics LLC, an AbbVie Company, Roche Laboratories Inc.: Consultancy. Maddocks:Merck: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Novartis: Research Funding. Danilov:TG Therapeutics: Consultancy; Bayer Oncology: Consultancy, Research Funding; Celgene: Consultancy; Curis: Consultancy; Seattle Genetics: Consultancy; Aptose Biosciences: Research Funding; Takeda Oncology: Research Funding; Bristol-Meyers Squibb: Research Funding; MEI: Research Funding; Janssen: Consultancy; Abbvie: Consultancy; Pharmacyclics: Consultancy; Gilead Sciences: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Verastem Oncology: Consultancy, Other: Travel Reimbursement , Research Funding. Ujjani:Pharmacyclics: Honoraria; PCYC: Research Funding; Atara: Consultancy; Atara: Consultancy; Genentech: Honoraria; AbbVie: Honoraria, Research Funding; Gilead: Consultancy; Pharmacyclics: Honoraria; PCYC: Research Funding; Astrazeneca: Consultancy; Genentech: Honoraria; AbbVie: Honoraria, Research Funding. Lynch:Juno Therapeutics: Research Funding; Rhizen Pharmaceuticals S.A: Research Funding; T.G. Therapeutics: Research Funding; Incyte Corporation: Research Funding; Takeda Pharmaceuticals: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy. Nastoupil:Gilead: Honoraria; Bayer: Honoraria; Celgene: Honoraria, Research Funding; Spectrum: Honoraria; TG Therapeutics: Honoraria, Research Funding; Novartis: Honoraria; Janssen: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding. Ghosh:Forty Seven Inc: Research Funding; Celgene: Consultancy, Research Funding, Speakers Bureau; Genentech: Research Funding; T G Therapeutics: Consultancy, Research Funding; Gilead/Kite: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Speakers Bureau; Spectrum: Consultancy, Speakers Bureau; Astra Zeneca: Speakers Bureau. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Cohen:ASH: Research Funding; Lymphoma Research Foundation: Research Funding; Astra Zeneca: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; LAM Therapeutics: Research Funding; UNUM: Research Funding; Hutchison: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy. Hill:Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Takeda: Research Funding; Genentech: Consultancy, Research Funding; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; TG therapeutics: Research Funding; AstraZeneca: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite: Consultancy, Honoraria.

Background: Ibrutinib (ibr) for the treatment of chronic lymphocytic leukemia (CLL) has improved progression-free survival (PFS) compared to other treatments, especially in high-risk patients (pts). However, resistance occurs and is associated with mutations in the drug binding target (BTK) and its immediate downstream target (PLCg2). These ibr resistance mutations (IRmut) are detectable months prior to developing progressive disease (PD) and predict clinical relapse. Prospectively determining the time from starting ibr to development of IRmut and from IRmut detection to PD will improve our understanding of how to manage these patients. Venetoclax (ven) is highly effective after ibr and decreases IRmut. Adding ven to ibr for ibr resistance is a rational choice as this combination is safe and effective in CLL. Adding an agent rather than stopping ibr avoids disease flare associated with ibr discontinuation. This phase 2 study was designed to follow CLL pts taking ibr and at high risk for resistance (observation cohort) and to test ven in combination with ibr for those who develop PD (intervention cohort). This will determine: the incidence of IRmut and PD in this population, the ORR with ibr/ven, and the ability of this combination to eliminate IRmut. Trial Design and Methods: This multisite study will open at 4 centers initially. Eligible pts are adults with CLL taking ibr for ≥12 months and at high risk for ibr resistance defined as having ≥2 prior treatments and del(17p)(p13.1) on FISH panel and/or a complex karyotype. Pts with known IRmut or who cannot continue ibr for any reason are excluded. Enrolled pts enter the observation cohort and are followed every 3 months with a clinic visit, blood counts, and testing for IRmut. Pts who develop IRmut will also have CT scans at their visits to detect PD. Those with IRmut who develop PD by iwCLL 2018 criteria will enter the intervention cohort. Pts in the intervention cohort will start ven in addition to ibr. Ven will be ramped-up over 5 weeks to a target dose of 400mg. Pts will take combination ibr/ven for 12 cycles of 28 days in length. After 12 cycles they will undergo response assessment and those achieving a complete remission (CR) with no detectable leukemia (uMRD) in both the blood and bone marrow will stop ven and continue ibr alone. Those who do not achieve CR with uMRD will continue ibr/ven until cycle 24 and undergo a second response assessment. If in a CR with uMRD after 24 cycles they continue on ibr alone. If a CR with uMRD is not achieved after 24 cycles patients continue ibr/ven until PD, intolerance, death, or end of study which is 30 months after the last patient enters the intervention cohort (Figure). In the intervention cohort all pts will be tested for IRmut in the blood every 3 months with bone marrow testing at response assessments. The study has co-primary endpoints of ORR to combination ibr/ven after 12 cycles and the rate of IRmut negative status at that time in the intervention cohort. ORR will be tested first using a single-stage phase 2 design with a null hypothesis that the rate is ≤50% versus the alternative hypothesis that it is ≥75%. Only if the combination is effective in ORR will the rate of IRmut negative status be formally tested. Constraining overall Type I and II errors to 0.10 using this sequential testing strategy, 26 evaluable pts are required and 28 will be accrued. Secondary endpoints for the intervention cohort are the PFS and overall survival since starting the combination ibr/ven and the incidence and type of adverse events with ibr/ven. Secondary endpoints in the observation cohort are the incidence of IRmut during ibr treatment and the PFS after developing an IRmut. We estimate that 180 pt-years of follow up for the observation cohort will be needed. The yearly rate of mutation development in this population is approximately 20%, therefore this will identify 36 pts with IRmut. Of those with IRmut, approximately 80% will remain eligible to enter the intervention cohort. Accrual to the observation cohort will stop once 28 pts enter the intervention cohort. Conclusion: This multicenter phase 2 trial examines the development of IRmut and clinical resistance to ibr in a cohort of high-risk CLL pts and will determine the efficacy of adding ven to ibr in those who develop PD. We expect to determine the natural course of molecular and clinical ibr resistance in CLL and if adding ven is an effective treatment strategy. Figure Disclosures Rogers: Acerta: Consultancy; Genentech: Research Funding; Abbvie: Research Funding; Janssen: Research Funding. Bhat:Pharmacyclics: Consultancy; Janssen: Consultancy. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Ye:Janssen: Research Funding; Karyopharm: Research Funding; Portola: Research Funding; MingSight: Research Funding; Sanofi: Research Funding. Byrd:Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Genentech: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; BeiGene: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. OffLabel Disclosure: This abstract discussion the use of combination ibrutinib and venetoclax in CLL.

Introduction: A positive interim PET scan (PET2) following 2 cycles of ABVD for Hodgkin lymphoma (HL) is associated with a poor prognosis; several studies in advanced stage demonstrate benefit from escalating therapy. Definition of positivity (Deauville 3 (D3) vs Deauville 4/5 (D4/5)), initial treatment and response adaptive decisions may vary among clinicians. Data examining practice patterns in managing positive PET2 scans is lacking. We report practice patterns and outcomes for patients (pts) with positive PET2 results including D3 and D4/5 outcomes. Methods: Adult pts with classical HL and PET2 findings of D3, D4, and D5 after initial therapy between 01/01/2015 and 07/01/2019 were identified. Pts enrolled in clinical studies were excluded. Retrospective demographic, clinical, and treatment data were obtained and described from 14 academic and community sites across North America (NA). Progression-free survival (PFS) and overall survival (OS) were summarized by Kaplan-Meier curves and compared by log-rank test. Results: 166 PET2 positive pts were identified. Clinical characteristics included 54% (89/166) with advanced stage (III/IV) and 46% (77/166) with early stage (IA-IIB) disease. 152 pts (92%) were treated with initial ABVD like therapy and 14 pts (8%) with an alternate regimen (Table 1). After initial treatment, 163 pts demonstrated PET2 scores of D3 (n=33), D4 (n=99) and D5 (n=31). Of the 130 D4/5 pts; 23% (30/130) underwent therapeutic escalation and 77% (100/130) did not escalate. The complete response rate (CR) at end of treatment (EOT) for all D4/5 patients receiving escalation was 37% (11/30) compared to 45% (45/100) without escalation (p=0.43). (Table 2) The 12 month PFS was 54% (38.2-76.3) versus (vs) 69.2% (60.4-79.2) for escalation and no escalation respectively. Of the 66 D4/5 pts with advanced stage disease; 21% (14/66) had therapeutic escalation and 79% (52/66) did not escalate. CR at EOT was noted in 29% (4/14) with escalation vs 31% (16/52) without escalation (p=0.88). (Table 2) The 12 month PFS was 54.2% (32.9-89.3) vs 57.5% (44.9-73.7) for escalation and no escalation respectively. (Figure 1; Log Rank p=0.38). Of the 64 D4/5 pts with early stage disease; 75% (48/64) did not undergo escalation and 25% (16/64) had escalation. CR at EOT was noted in 44% (7/16) with escalation vs 60% (29/48) without escalation (p=0.26). (Table 2) The 12 month PFS was 54.7% (34.5-86.7) vs 80.8% (70.2-92.9) for escalation and no escalation respectively. Of the 33 D3 pts; 52% (17/33) de-escalated with the remainder (16/33) continuing on initial therapy. No D3 pt underwent escalation. In the 12 D3 pts with early stage disease, 50% (6/12) de-escalated. Of the 21 D3 pts with advanced stage disease; 52% (11/21) had de-escalation and 48% (10/21) did not de-escalate. CR at EOT was noted in 71% (12/17) with de-escalation vs 81% (13/16) without de-escalation (p=0.50). (Table 2) Progression was noted in 29% (5/17) of patients who underwent de-escalation compared to 38% (6/16) without de-escalation. The 12 month PFS was 76.5% (85.8-99.6) vs 72.1% (52.2-99.7) for de-escalation and no de-escalation respectively. Conclusion: This is the first study evaluating clinical practice patterns and outcomes of PET adaptive therapy in NA. In this retrospective study, less than a quarter of advanced stage ABVD-treated D4/5 pts had therapy escalation despite prior studies reporting benefit. Our data suggest that outcomes for advanced stage PET positive pts are suboptimal irrespective of therapeutic escalation. In addition, pts with D3 findings represent a heterogeneous population and demonstrate favorable outcomes compared to D4/5 pts. Longer follow up time and further studies with larger numbers of pts are essential for confirming the reported findings. Disclosures Rutherford: Seattle Genetics: Consultancy, Honoraria; Verastem: Consultancy, Honoraria; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Heron: Consultancy, Honoraria; Janssen Scientific Affairs: Consultancy, Honoraria; Juno Therapeutics Inc: Consultancy, Honoraria. Bartlett:ADC Therapeutics: Consultancy, Research Funding; Affimed: Research Funding; Forty Seven: Research Funding; Celgene: Research Funding; Bristol-Myers Squibb: Research Funding; Genenetech: Research Funding; Gilead: Research Funding; Immune Design: Research Funding; Janssen: Research Funding; Merck: Research Funding; Millenium: Research Funding; Pfizer: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding. Maddocks:Novartis: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; BMS: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees. Feldman:Takeda: Honoraria, Speakers Bureau; Viracta: Research Funding; Trillium: Research Funding; Roche: Research Funding; Portola Pharma: Research Funding; Pfizer: Research Funding; Kyowa Hakko Kirin: Research Funding; Eisai: Research Funding; Corvus: Research Funding; Roche: Research Funding; Cell Medica: Research Funding; Seattle Genetics: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; AbbVie: Honoraria, Other: Travel expenses, Speakers Bureau; Pharmacyclics: Honoraria, Other: Travel expenses, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Kite Pharma: Honoraria, Other: Travel expenses, Speakers Bureau; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau. Magarelli:Tevan Oncology: Speakers Bureau. Advani:Merck: Research Funding; Infinity Pharma: Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kura: Research Funding; Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Millennium: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agensys: Research Funding; Seattle Genetics: Consultancy, Research Funding; Stanford University: Employment, Equity Ownership; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Regeneron: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cell Medica, Ltd: Consultancy; Forty-Seven: Research Funding; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Patel:Sunesis: Consultancy; Genentech: Consultancy, Speakers Bureau; Pharmacyclics/Janssen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau. Tees:Celgene: Speakers Bureau; Pharmacyclics: Speakers Bureau. Karmali:Gilead/Kite; Juno/Celgene: Consultancy, Speakers Bureau; Takeda, BMS: Other: Research Funding to Institution; Astrazeneca: Speakers Bureau. Cheson:Portola: Research Funding; Kite: Research Funding; Gilead: Research Funding; Symbios: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Trillium: Research Funding; Epizyme: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Yazdy:Bayer: Honoraria, Speakers Bureau; Octapharma: Consultancy; Genentech: Research Funding; Abbvie: Consultancy. Pagel:AstraZeneca: Consultancy; Gilead Sciences: Consultancy; Pharmacyclics: Consultancy. Ramchandren:Seattle Genetics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Merck: Research Funding; Sandoz-Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics LLC, an Abbvie company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Background: Targeted inhibition of Bruton tyrosine kinase (BTK) has improved clinical outcomes for patients with chronic lymphocytic leukemia (CLL). Acalabrutinib is a highly selective, covalent BTK inhibitor. A recently completed phase 3 trial showed acalabrutinib improved progression-free survival (PFS) vs idelalisib or bendamustine + rituximab in relapsed/refractory (R/R) CLL patients (ASCEND: Ghia et al. EHA 2019;273259:LB2606). This is an updated analysis with extended follow-up of a phase 1-2 multicenter study (NCT02029443) in patients with R/R CLL/small lymphocytic lymphoma (SLL), to demonstrate the durability of response and long-term tolerability of acalabrutinib. Methods: Patients with CLL or SLL were eligible if they were R/R after ≥1 prior treatment. Eligible patients were ≥18 years of age with an Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2. Oral acalabrutinib 100 mg was administered twice daily. All patients were treated until progressive disease or unacceptable toxicity occurred. Study endpoints included overall response rate (ORR), PFS, duration of response (DOR) and safety, with post hoc analysis of event-free survival (EFS). Response rates were based on the International Workshop on Chronic Lymphocytic Leukemia 2008 criteria (Hallek et al., 2008) with modification for lymphocytosis (Cheson et al., 2012). Nine patients had longitudinal peripheral blood mononuclear cell samples from pre-treatment baseline, during treatment and at progression analyzed for whole exome sequencing, to assess acquired mechanisms of treatment resistance. Results: In total, 134 patients with R/R CLL/SLL received ≥ 1 dose of acalabrutinib. The median age was 66 years (range, 42-85 years). Baseline characteristics included ECOG PS ≤1 (97%), bulky lymph nodes ≥5 cm (39%), unmutated immunoglobulin heavy chain variable region (IGHV; 73%), chromosome 17p13.1 deletion (23%), chromosome 11q22.3 deletion (18%), and complex karyotype (≥3 abnormalities; 35%). The median number of prior therapies was 2 (range, 1-13). Patients received acalabrutinib for a median of 41 months (range, 0.2-58 months). Most adverse events (AEs) were mild to moderate, and most commonly were diarrhea (52%), headache (46%), and upper respiratory tract infection (36%). Grade ≥3 AEs occurred in 66% of patients; most commonly (≥5% of patients) neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%) and diarrhea (5%). AEs of interest included atrial fibrillation (7% all grades; 3% Grade ≥3) and major bleeding events (5% all grades; 3% Grade ≥3). Most patients (56%) remained on treatment. The most common reasons for discontinuing treatment were progressive disease (21%) and AEs (11%). AEs leading to discontinuation occurring in ≥1 patient included pneumonia (4 events), anemia, neutropenia, and thrombocytopenia (2 events each). The ORR (partial response with lymphocytosis or above) was 94% (95% confidence interval [CI]: 89-97%); with 4% of patients having complete response, 84% having partial response and 6% having partial response with lymphocytosis (Table). The median DOR, PFS and EFS were not reached; the estimated 42-month DOR was 61% (95% CI: 49-71%), PFS was 68% (95% CI: 59-76%) and EFS was 64% (95% CI: 54-71%). Responses were similar regardless of genomic features, including unmutated IGHV, chromosomal deletions and complex karyotype (Table). Upon relapse during acalabrutinib treatment, whole exome sequencing detected BTK mutations in 6 of 9 (67%) tested patients that were not detectable at baseline. Of the 6 patients with detectable BTK C481X mutations, 4 had expansion to high allele frequency of the BTK mutation at progression (up to 58%). In a longitudinal analysis of patients who had a sample after 6 months of treatment, the BTK mutation was not detectable. No PLCG2 gene mutations were detected using exome analysis in the 9 patients analyzed. Conclusions: These updated results confirm the earlier reports of acalabrutinib efficacy for the treatment of CLL and provide additional data on DOR and long-term tolerability. Reported AEs indicate a tolerable and consistent safety profile, with a low rate of major bleeding events. Genomic profiling in a small subset of patients indicated that acquired mutation of BTK was the most frequent mechanism of acalabrutinib resistance. Disclosures Furman: Genentech: Consultancy. Wierda:Loxo Oncology Inc.: Research Funding; Janssen: Research Funding; Xencor: Research Funding; Cyclcel: Research Funding; Oncternal Therapeutics Inc.: Research Funding; Miragen: Research Funding; Sunesis: Research Funding; KITE pharma: Research Funding; Juno Therapeutics: Research Funding; Gilead Sciences: Research Funding; Acerta Pharma Inc: Research Funding; Pharmacyclics LLC: Research Funding; Genentech: Research Funding; AbbVie: Research Funding; GSK/Novartis: Research Funding. Schuh:Roche: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria. Devereux:Servier: Speakers Bureau; Roche: Consultancy, Other: Travel expenses, Speakers Bureau; GlaxoSmithKline: Consultancy; Gilead: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; MSD: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau. Brown:Pfizer: Consultancy; Sun: Research Funding; Verastem: Consultancy, Research Funding; TG Therapeutics: Consultancy; Teva: Honoraria; Sunesis: Consultancy; Pharmacyclics: Consultancy; Morphosys: Other: Data safety monitoring boards ; Sun Pharmaceuticals, Inc: Research Funding; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; BeiGene: Consultancy; Catapult Therapeutics: Consultancy; Dynamo Therapeutics: Consultancy; Genentech/Roche: Consultancy; Gilead: Consultancy, Research Funding; Invectys: Other: other; Janssen: Honoraria; Kite: Consultancy, Research Funding; Loxo: Consultancy, Research Funding; Novartis: Consultancy; Octapharma: Consultancy. Hillmen:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding; Roche: Research Funding; Gilead: Research Funding; Apellis: Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees. Martin:Karyopharm: Consultancy; Teneobio: Consultancy; Celgene: Consultancy; I-MAB: Consultancy; Sandoz: Consultancy; Janssen: Consultancy. Awan:Sunesis: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; Innate Pharma: Research Funding; Gilead: Consultancy; Janssen: Consultancy; Abbvie: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding. Stephens:Acerta: Research Funding; Gilead: Research Funding; Karyopharm: Research Funding. Ghia:Sunesis: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; ArQule: Consultancy, Honoraria; BeiGene: Consultancy, Honoraria; Dynamo: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Juno/Celgene: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Acerta/AstraZeneca: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy. Barrientos:Bayer: Consultancy; AstraZeneca: Consultancy; AbbVie: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Genentech: Consultancy; Gilead: Consultancy; Janssen: Honoraria; Sandoz: Consultancy; Oncternal Therapeutics: Research Funding. Pagel:AstraZeneca: Consultancy; Gilead Sciences: Consultancy; Pharmacyclics: Consultancy. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. Burke:AstraZeneca: Employment, Equity Ownership. Covey:Acerta Pharma: Employment, Equity Ownership; AstraZeneca: Equity Ownership. Gulrajani:AstraZeneca: Equity Ownership; Acerta Pharma: Employment, Equity Ownership. Hamdy:Acerta Pharma: Employment, Equity Ownership. Izumi:Acerta Pharma: Employment, Equity Ownership. Frigault:Acerta Pharma: Employment; AstraZeneca: Employment, Equity Ownership. Patel:Acerta Pharma: Employment, Equity Ownership. Rothbaum:Acerta Pharma: Employment, Equity Ownership. Wang:AstraZeneca: Equity Ownership; Acerta Pharma: Employment. O'Brien:Eisai: Consultancy; Celgene: Consultancy; TG Therapeutics: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; GlaxoSmithKline: Consultancy; Gilead: Consultancy, Research Funding; Verastem: Consultancy; Vaniam Group LLC: Consultancy; Astellas: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Acerta: Research Funding; Alexion: Consultancy; Amgen: Consultancy; Aptose Biosciences, Inc: Consultancy; Regeneron: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Janssen: Consultancy, Honoraria; Kite: Research Funding. Byrd:Ohio State University: Patents & Royalties: OSU-2S; BeiGene: Research Funding; Acerta: Research Funding; Genentech: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Genentech: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau. OffLabel Disclosure: This is a Phase 1/2 investigational study of acalabrutinib in chronic lymphocytic leukemia

Introduction: Resistance to covalent BTK inhibitors such as ibrutinib and acalabrutinib is a common mechanism of resistance that portends a poor long-term clinical outcome. ARQ 531 is a potent, reversible inhibitor of both wild type and ibrutinib-resistant C481S-mutant BTK. ARQ 531 suppresses oncogenic BCR signaling in CLL cells resistant to ibrutinib and has demonstrated antitumor activity superior to ibrutinib in CLL, Richter's transformation, and DLBCL mouse models. Methods: The primary objectives of the clinical study were to assess the safety and tolerability of ARQ 531, and to determine the recommended Phase 2 dose (RP2D) and schedule. The secondary objectives were to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of anti-tumor activity. Eligible patients had relapsed/refractory CLL/SLL, B-cell NHL or Waldenstrom's macroglobulinemia, had received at least 2 prior lines of systemic therapy and had good organ function including creatinine clearance ≥ 60 mL/min as estimated by the Cockcroft-Gault equation or by 24-hour urine collection, absolute neutrophil count ≥ 1000/µL, platelet count ≥ 50,000/µL and hemoglobin ≥ 8.0 g/dL. Prior therapy for CLL must have included an irreversible BTK inhibitor. Dose escalation was performed according to a 3+3 study design. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v.4.03. Tumor responses were evaluated per disease specific guidelines. Results: As of July 19, 2019, a total of 40 patients have been treated: CLL/SLL (n=26), Richter's transformation (n=6), DLBCL (n=3), FL (n=4), MCL (n=1). Baseline demographics were: median age 65.5 (range 47-82) years, male/female 36/4 and median number of prior lines of therapy 4 (range 2-12). BTK-C481S mutation was documented in 22/26 (85%) CLL patients. Enrolled patients received ARQ 531 orally once daily, continuously, in 28- day cycles at doses of 5, 10, 15, 20, 30, 45, 65 and 75 mg QD. The most common drug-related TEAEs that occurred in > 2 patients were nausea (n=4), diarrhea (n=4), fatigue (n=3), neutrophil count decreased (n=3), dysgeusia (n=3) and rash (n=3). The majority of the drug-related TEAEs were grade 1 or 2. Drug-related grade 3 or 4 TEAEs included neutrophil count decreased (n=3), as well as febrile neutropenia, cellulitis, platelet count decreased, lipase increased, and rash (one each). One subject treated at 65 mg experienced a DLT of grade 3 rash. The 65 mg cohort was expanded to a total of 10 patients, and no other DLTs were observed. At the 75 mg QD dose level (n =4), drug-related grade 2 adverse events were reported which led to dose reduction to 65 mg QD (n=3) or treatment discontinuation (n=1). Preliminary PK data show that patients receiving ARQ 531 at 65 mg QD exhibit steady-state trough concentrations (Cmin) above 1 µM; the estimated plasma half-life generally ranged from 20-30 hours and was associated with complete pBTK inhibition. Clinical responses to ARQ 531 were observed in multiple patients with B-cell malignancies. Ten partial responses (PRs) were achieved mainly in the higher dose cohorts, and included patients with CLL (n=7), Richter's transformation (n=1), DLBCL (n=1) and follicular lymphoma (n=1). Of the 7 CLL patients who attained PRs, 5 were initiated at 65 mg, 1 was initiated at 45 mg and was dose escalated to 65 mg and 1 was initiated at 75 mg and dose reduced to 65 mg. Together, the safety, PK/PD and clinical activity results suggest that ARQ 531 at 65 mg QD is safe, well tolerated and has clear signs of anti-tumor efficacy. Thus, 65 mg QD dose has been selected as the RP2D in patients with B-cell malignancies. Conclusion: ARQ 531 has a manageable safety profile and shows anti-tumor activity as single agent therapy in heavily pre-treated patients with B-cell NHL and in patients with CLL resistant to covalent BTK inhibitor. The Phase 1 dose escalation portion of this study is complete. Enrollment of patients with multiple B-cell malignancies is ongoing at 65 mg QD in the phase 1b expansion portion of the study. Updated safety, PK, biomarker and anti-tumor activity data will be presented. Disclosures Woyach: Morphosys: Research Funding; Verastem: Research Funding; Loxo: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Flinn:F. Hoffmann-La Roche Ltd: Research Funding; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; AbbVie, Seattle Genetics, TG Therapeutics, Verastem: Consultancy; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; Acerta Pharma, Agios, Calithera Biosciences, Celgene, Constellation Pharmaceuticals, Genentech, Gilead Sciences, Incyte, Infinity Pharmaceuticals, Janssen, Karyopharm Therapeutics, Kite Pharma, Novartis, Pharmacyclics, Portola Pharmaceuticals: Research Funding. Bhat:Pharmacyclics: Consultancy; Janssen: Consultancy. Savage:ArQule, Inc.: Employment. Chai:ArQule, Inc.: Employment. Eathiraj:ArQule, Inc.: Employment. Granlund:ArQule, Inc.: Employment. Schwartz:ArQule, Inc.: Employment. Byrd:Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; BeiGene: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Ohio State University: Patents & Royalties: OSU-2S; Genentech: Research Funding.

Background: The advent of oral-targeted drugs has improved treatment outcomes for patients (pts) with CLL. Nonetheless, some pts prove intolerant or resistant to therapy and/or fail to achieve complete response (CR) with uMRD. Liso-cel is an investigational, anti-CD19, defined composition, 4-1BB CAR T cell product administered at a target dose of CD4+ and CD8+ CAR T cells. TRANSCEND CLL 004 is an open-label phase 1/2 study of liso-cel in pts with R/R CLL/SLL (NCT03331198). Methods: Eligible pts with CLL/SLL had received at least 3 (standard-risk disease) or at least 2 (high-risk disease: del[17p], TP53 mutation, unmutated IGHV, or complex karyotype) prior lines of therapy, including a Bruton's tyrosine kinase inhibitor unless contraindicated. Pts with active untreated central nervous system disease, Eastern Cooperative Oncology Group performance status >1, or Richter's transformation were excluded. After 3 days of lymphodepletion with fludarabine/cyclophosphamide, pts received liso-cel infusion; 2 dose levels (DLs) were tested: DL1=50×106 and DL2=100×106 CAR+ T cells. Dose-limiting toxicities (DLTs) were evaluated for 28 days postinfusion. Responses were assessed by 2018 International Workshop on CLL criteria. MRD was assessed at a sensitivity of ≤10-4 in blood and/or bone marrow (BM) lymphocytes. Liso-cel CAR T cells were monitored by flow cytometry of blood cells from treated pts over time. Serum cytokines and chemokines were assessed via an electrochemiluminescence platform. Results: At data cutoff, 23 pts were evaluable for safety and 22 for efficacy. Median age was 66 (range, 49‒79) years; 83% (19/23) of pts had high-risk disease. Pts had a median of 5 (range, 2‒11) prior therapies. All pts had received prior ibrutinib; 56.5% (13/23) had progressed on ibrutinib and received therapy with venetoclax; 91% (21/23) were refractory to, or had relapsed on, ibrutinib; and 9% (n=2) were intolerant to ibrutinib. Liso-cel was successfully manufactured in 96% of pts, with the established process. Nine pts were treated at DL1 and 14 pts at DL2. Two pts had DLTs (all at DL2: grade 4 hypertension in 1 pt; grade 3 encephalopathy, grade 3 muscle weakness, and grade 4 tumor lysis syndrome in 1 pt). The most common grade 3/4 treatment-emergent adverse events were thrombocytopenia, 70%; anemia, 96%; neutropenia, 56.5%; leukopenia, 43.5%. Two pts had grade 3 cytokine release syndrome (CRS); 5 pts had grade ≥3 neurological events (NEs), including encephalopathy (n=3). Median time to onset of CRS and NE was 4 (range, 1-10) days and 4 (range, 2-21) days, respectively. The median duration of CRS and NE was 5 (range, 2-30) days and 21 (range, 6-169) days, respectively. To manage CRS and/or NE, 61% (n=14) of pts received tocilizumab and 48% (n=11) received corticosteroids. Lymph node tumor burden correlated with NE (P=0.025). Additional disease distribution correlates are being evaluated and will be presented. Cytokine analyses revealed that NE onset was preceded by elevated TNFα and IL16 early after liso-cel infusion (P Conclusions: In this population of heavily pretreated pts with R/R CLL/SLL (all received prior ibrutinib and half failed both prior venetoclax and ibrutinib), liso-cel toxicities, including CRS and NE, were manageable at both DLs tested. Objective responses, CRs, and uMRD were rapidly achieved, with durable responses past 6 months. Updated safety, pharmacokinetic, and efficacy results from the phase 1 monotherapy part of the study will be reported. The phase 2 portion of the study is currently enrolling at DL2. Disclosures Siddiqi: Kite, A Gilead Company: Research Funding; TG Therapeutics: Research Funding; Celgene: Research Funding; Janssen: Speakers Bureau; Seattle Genetics: Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; PCYC: Consultancy, Research Funding, Speakers Bureau; Juno Therapeutics: Consultancy, Other: travel support, Research Funding; BeiGene: Research Funding. Soumerai:BeiGene: Research Funding; BostonGene: Research Funding; AbbVie: Consultancy; Verastem: Consultancy; Genentech/Roche: Research Funding; TG therapeutics: Research Funding. Dorritie:Juno: Research Funding. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Riedell:Bayer: Honoraria, Speakers Bureau; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Arnason:Regeneron Pharmaceuticals, Inc.: Consultancy; Celgene/Juno: Consultancy. Kipps:Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Velos-Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jannsen Pharmaceutical Companies of Johnson & Johnson: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca, Inc.: Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees. Gillenwater:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Gong:Celgene: Employment, Equity Ownership. Dubovsky:Celgene: Employment. Rytlewski:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership; Adaptive Biotechnologies: Equity Ownership. Yang:Juno Therapeutics, a Celgene Company: Employment. Wierda:AbbVie: Research Funding; Genentech: Research Funding; Pharmacyclics LLC: Research Funding; Acerta Pharma Inc: Research Funding; Gilead Sciences: Research Funding; Xencor: Research Funding; Juno Therapeutics: Research Funding; Sunesis: Research Funding; KITE pharma: Research Funding; Oncternal Therapeutics Inc.: Research Funding; Miragen: Research Funding; GSK/Novartis: Research Funding; Cyclcel: Research Funding; Janssen: Research Funding; Loxo Oncology Inc.: Research Funding.

Introduction Limited stage disease accounts for 30-40% of Diffuse Large B-cell Lymphoma (DLBCL), with better overall survival than advanced stage disease, but with increased late relapses regardless of treatment strategy (Stephens 2016). Preferred treatment for these patients (pts) per NCCN guidelines is abbreviated R-CHOP followed by radiotherapy. Based on promising results of radioimmunotherapy consolidation in SWOG S0313 (Persky 2015), and of PET-directed experience by the BC Cancer Agency (Sehn 2011), we designed a National Clinical Trials Network (NCTN) PET-directed study to tailor therapy after 3 cycles of R-CHOP, to improve outcomes and decrease toxicities. Methods Pts had non-bulky (< 10 cm) stage I/II untreated DLBCL. Mediastinal, HIV-associated, testicular, central nervous system, and indolent lymphoma were excluded. Pts received standard R-CHOP therapy and had an interim PET scan on day 15-18 of cycle 3, which was centrally reviewed in real time. Pts with negative PET scan (Deauville 1-3, iPET-neg) proceeded with 1 additional cycle of R-CHOP. Pts with positive PET scan (Deauville 4-5, iPET-pos) initiated 36 Gy of involved field radiation therapy (IFRT), plus additional boost to FDG-avid area up to 9 Gy, within 5 weeks of 3rd cycle of R-CHOP. This was followed by ibritumomab tiuxetan (IFRT-Zevalin) 3-6 weeks after completing IFRT. Final PET scan was performed 12 weeks after treatment completion. Results The study completed accrual in June 2016. Safety, response, interim PET, and immunohistochemistry-based cell of origin (COO) and MYC/BCL2 analyses were presented previously (Persky 2017, Stephens 2017). Of 159 pts enrolled, 1 was upstaged by PET, and 26 pts were ineligible - due to incorrect histology (mostly concurrent indolent or follicular lymphoma grade 3B) (21), lack of diagnostic tissue submission for central pathology review (3), and bulky disease (2). In 132 eligible pts, median age was 62 years, 62% had stage I, 17% had B symptoms, 14% had elevated LDH, 43% had extranodal involvement, and 66% had exclusive involvement of the head and neck region. Stage modified IPI (smIPI, Miller 1998) was 0 in 27%, 1 in 42%, 2 in 28%, and 3 in 4% of the pts. COO by Lymph2Cx was assessable in 87 pts - 68% were GCB, 23% were ABC, and 9% were unclassifiable. Double protein expressers (MYC and BCL2, DPE) were 16%, while 4 (3%) pts had "double hit" lymphoma (DHL) - 2 with MYC/BCL2 and 2 with MYC/BCL6 rearrangements - none of which were DPE. Of 132 eligible pts, 128 had an interim PET scan centrally reviewed, of which 110 were iPET-neg. Only 18 were iPET-pos, 4 of them due to infection (Deauville X) which were treated as iPET-neg. Of 14 truly iPET-pos pts (11%), 2 refused radiation, and 12 pts received IFRT-Zevalin. Eight pts (67%) converted from PR to CR after IFRT-Zevalin and 4 (33%) had PR, for an overall CR of 92% and PR of 4% (with 4% unevaluable). With median follow up of 4.5 yrs (range 1.1 - 7.5 yrs), only 5 pts progressed and 2 died from lymphoma. Of 5 progressors, 3 received R-CHOP x 4, 1 was iPET-pos but declined radiation, and 1 went off treatment after 1 cycle of R-CHOP. Eleven pts died from non-lymphoma causes, including 1 pt from secondary AML (iPET-neg arm), and 1 of lung adenocarcinoma diagnosed upon iPET. S1001 5-yr PFS estimate is 87% and OS estimate is 90% (figure 1), with iPET-pos and iPET-neg pts having similar outcomes - PFS 86% vs. 88%, OS 93% vs. 91%, respectively. Five-yr PFS by smIPI was 97% for smIPI of 0, 86% for 1-2, and 30% for 3. GCB had 5-yr PFS of 95%, vs. 70% for ABC and 47% for unclassifiable. DPE pts had 5-yr PFS of 70, vs. 89% for non-DPE pts. All 4 DHL pts maintain remission. Conclusions S1001 is the largest US study of limited stage DLBCL in the rituximab era, with best NCTN results in this disease subset. Only 5 patients progressed and 2 died from lymphoma. Our study confirms the distinct biology of limited stage DLBCL, with predominance of GCB origin (68%), and head and neck location (66%). Due to small number of lymphoma events, no strong conclusions about prognostic ability of smIPI, COO, DPE, or DHL, could be made. S1001 demonstrated that 89% of pts maintained excellent outcomes after R-CHOP x 4 with PET-directed therapy. Only 11% of pts were iPET-pos and required radiation, but they also had excellent outcomes. Together with the FLYER trial in younger pts (Poeschel 2018), this NCTN trial establishes R-CHOP x 4 alone as the new standard approach to limited stage disease for majority of the pts. Disclosures Persky: Sandoz: Consultancy; Morphosys: Other: Member, Independent Data Monitoring Committee; Debiopharm: Other: Member, Independent Data Monitoring Committee; Bayer: Consultancy. Stephens:Acerta: Research Funding; Karyopharm: Research Funding; Gilead: Research Funding. Park:BMS: Consultancy, Research Funding; Rafael Pharma: Membership on an entity's Board of Directors or advisory committees; G1 Therapeutics: Consultancy; Teva: Consultancy, Research Funding; Gilead: Speakers Bureau; Seattle Genetics: Research Funding, Speakers Bureau. Bartlett:Seattle Genetics: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Pfizer: Research Funding; Millenium: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Genenetech: Research Funding; Immune Design: Research Funding; Gilead: Research Funding; Forty Seven: Research Funding; Janssen: Research Funding; Affimed: Research Funding; Merck: Research Funding; Pharmacyclics: Research Funding. Swinnen:Pharmacyclics: Consultancy; AbbVie: Consultancy. Barr:Celgene: Consultancy; Merck: Consultancy; Seattle Genetics: Consultancy; Genentech: Consultancy; Verastem: Consultancy; Gilead: Consultancy; Astra Zeneca: Consultancy, Research Funding; Janssen: Consultancy; AbbVie: Consultancy; Pharmacyclics LLC, an AbbVie company: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding. Leonard:Nordic Nanovector: Consultancy; Akcea Therapeutics: Consultancy; BeiGene: Consultancy; Gilead: Consultancy; Miltenyi: Consultancy; ADC Therapeutics: Consultancy; Nordic Nanovector: Consultancy; Akcea Therapeutics: Consultancy; Sandoz: Consultancy; ADC Therapeutics: Consultancy; Miltenyi: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Karyopharm Therapeutics: Consultancy; Epizyme, Inc: Consultancy; Sutro Biopharma: Consultancy; AstraZeneca: Consultancy; AstraZeneca: Consultancy; Bayer Corporation: Consultancy; Bayer Corporation: Consultancy; Celgene: Consultancy; Epizyme, Inc: Consultancy; Celgene: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Merck: Consultancy; MorphoSys: Consultancy; Karyopharm Therapeutics: Consultancy; Gilead: Consultancy; Sutro Biopharma: Consultancy; BeiGene: Consultancy; Merck: Consultancy; MorphoSys: Consultancy; Sandoz: Consultancy. Kahl:TG Therapeutics: Consultancy; ADC Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; BeiGene: Consultancy. Fisher:Celgene: Consultancy; AstraZeneca: Consultancy; Barclays: Honoraria; prIME: Honoraria. Rimsza:NanoSting: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution]. Smith:Portola Pharmaceuticals: Research Funding. Friedberg:Bayer: Honoraria, Other: Data & Safety Monitoring Committee; Acerta: Other: Data & Safety Monitoring Committee. OffLabel Disclosure: Ibritumomab tiuxetan in diffuse large B-cell lymphoma

Introduction: CAR T-cell therapy has revolutionized treatment for patients with relapsed/refractory (r/r) diffuse large b-cell lymphoma (DLBCL). Although impressive durable responses can be achieved, this is weighted by adverse events including neurotoxicity and cytokine release syndrome (CRS). Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) is a validated score that utilizes comorbidities to predict outcomes in patients receiving allogeneic stem cells transplants, but it not validated in CAR T-cell recipients. Meanwhile, the Cumulative Illness Rating Scale (CIRS) is a comprehensive tool which has been incorporated into clinical research in lymphoma. Here we report the impact of comorbidities, as measured by the HCT-CI and CIRS, on survival and tolerance of CAR T-cell therapy in patients with r/r DLBCL treated off clinical protocols. Methods: We conducted a retrospective analysis of patients with r/r DLBCL treated with commercial CART product at 4 academic medical centers after approval by the respective institutional review boards. Comorbidity data was assessed at the time of T-cell collection, and outcome data was assessed per last known follow-up. CIRS score was calculated as in Salvi et al, 2008. HCT-CI score was calculated as in Sorror et al, 2005. High comorbidity burden was defined as CIRS score ≥7, presence of severe impairment (CIRS score of 3 or 4 in ≥1 organ system; CIRS-3+), or HCT-CI ≥3. Cox proportional hazards models adjusted for age, ECOG performance status, number of prior therapies, type of product, cell of origin, MYC positivity on FISH, and comorbidities were used to assess effect on progression free survival (PFS) and overall survival (OS). Results: We analyzed 59 patients, with a median age of 63 years (range, 25-82). 80% of patients had an ECOG PS of 0 or 1. Median number of prior therapies was 3 (range, 2-6). 15 patients received tisagenlecleucel, and 44 patients received axicabtagene ciloleucel. 30 patients had germinal center B-cell (GCB) subtype DLBCL, and 29 were non-GCB as determined by Hahn's algorithm. 13 patients exhibited a MYC rearrangement by FISH, of which 9 also had BCL2 or BCL6 chromosomal translocation. Four patients did not receive CAR T-cells (3 died of disease progression; 1 died of an unrelated event). All patients (N=59) were used in the analysis. Median total CIRS was 10 (range, 1-20). 40 patients had score ≥7 and 29 had a CIRS-3+. 16 patients had neither total CIRS score ≥7 or CIRS-3+. The most common comorbidities were seen in the upper GI, endocrine and vascular/hematopoietic systems. Median HCT-CI was 2 (range, 0-13). Median follow-up was 154 days. Significant comorbidities assessed by CIRS (either total score ≥7 or CIRS-3+) were associated with inferior PFS (HR 3.65, p=0.037) and OS (OS; HR 5.31, p=0.025) compared to patients without significant comorbidities in univariate analyses. Median PFS was not reached, and OS was 305 days for patients without significant comorbidities, and was 170 and 237 for patients with significant comorbidities respectively (Figure 1,2). HCT-CI ≥3 was not predictive of PFS (HR 0.85, p=0.70) or OS (HR 1.06, p=0.90). MYC positivity was associated with inferior OS (HR 2.64, p=0.033). Presence of comorbidities assessed by CIRS and HCT-CI, were not associated with incidence of neurotoxicity or CRS. Presence of comorbidities by CIRS retained independent significance in multivariate models of PFS (HR 8.64, p=0.002) and OS (HR 15.44, p=0.042) when adjusted for all covariates. MYC also retained independent significance regarding OS (HR 3.23, p=0.032). Interestingly, older age was associated with superior PFS (HR 0.54, p=0.001) and OS (HR 0.59, p=0.007). Conclusions: In this multicenter retrospective analysis we show that CIRS has prognostic significance in patients with r/r DLBCL treated with commercial CAR T-cell therapy, as increased comorbidities, defined by presence of total CIRS score ≥7 or CIRS-3+, were associated with both a shorter PFS and OS. We did not find an association between the HCT-CI score and survival, nor did we see an association between comorbidities and incidence of neurotoxicity or CRS, however numbers were small. These findings show that evaluating comorbidities in patients eligible to receive CAR T-cell therapy should be considered. Further validation is needed to determine the extent that patient comorbidities predict survival in DLBCL patients undergoing CAR-T therapy. Disclosures Bishop: Novartis Pharmaceuticals: Consultancy. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Hill:Amgen: Research Funding; TG therapeutics: Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Takeda: Research Funding; Kite: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria. Danilov:Seattle Genetics: Consultancy; MEI: Research Funding; Genentech: Consultancy, Research Funding; TG Therapeutics: Consultancy; Verastem Oncology: Consultancy, Other: Travel Reimbursement , Research Funding; Bayer Oncology: Consultancy, Research Funding; Pharmacyclics: Consultancy; Aptose Biosciences: Research Funding; Janssen: Consultancy; Celgene: Consultancy; Curis: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Takeda Oncology: Research Funding; Bristol-Meyers Squibb: Research Funding.

Background: Bruton tyrosine kinase (BTK) is a critical component of B-cell receptor signaling pathway and a validated therapeutic target for CLL. Acalabrutinib is a highly selective, potent, covalent BTK inhibitor with minimal off-target activity that has been shown to have an overall response rate (ORR) of 95% (85% partial response [PR]; 10% PR with lymphocytosis [PRL]) after a median follow-up of 14.3 months in the relapsed CLL cohort of the Phase 1/2 ACE-CL-001 study. We present an updated analysis of the safety and efficacy results from the TN cohort of CLL patients from ACE-CL-001. Methods: Patients with TN CLL/small lymphocytic lymphoma (SLL) were eligible if they met International Workshop on Chronic Lymphocytic Leukemia (IWCLL) 2008 criteria for treatment, had an ECOG performance status of ≤2, and declined or were not appropriate candidates for chemotherapy. Patients received oral acalabrutinib 100 mg twice daily (BID) or 200 mg daily (patients were started on 200 mg QD and then switched to 100 mg BID) until progressive disease or unacceptable toxicity. Safety was the primary endpoint. Secondary endpoints were investigator-assessed overall response rate (ORR) by IWCLL 2008 criteria with modification for lymphocytosis, duration of response (DOR) and progression-free survival (PFS). Time to response (TTR; ≥ PR) and event-free survival (EFS) were exploratory endpoints. Results: A total of 99 patients (100 mg BID, n=62; 200 mg QD, n=37) were treated. The median age was 64 years (range 33-85), 46% of patients had bulky lymph nodes ≥5 cm, 47% had Rai stage III-IV disease at baseline, 10% (9/91) of patients had del(17p), and 62% (57/92) of patients had unmutated IGHV. As of December 1, 2017, the median time on study was 33 (1-39) months, with 91% of patients remaining on study treatment. Nine patients discontinued therapy: adverse events (n=5; 5%), pregnancy, disease progression, patient withdrawal, and initiation of subsequent therapy (n=1 each; 1%). The most common AEs (all grades; >20% of patients) were diarrhea (47%), headache (44%), contusion (34%), upper respiratory tract infection (33%), weight increase (30%), arthralgia (29%), nausea (26%), and cough (23%); the majority of these most common AEs were Grade 1/2. Grade 3/4 AEs occurred in 49% (49/99) of patients, most commonly (>2% of patients) neutropenia (7%), diarrhea (5%), headache (5%), nausea (4%), pneumonia (4%), hypertension (3%), and syncope (3%). Atrial fibrillation and hypertension (all grades vs grade 3/4) occurred in 6% vs 1% of patients and 14% vs 3% of patients, respectively. The most common bleeding events (>15%) were contusion (34%), petechiae (18%), and ecchymosis (16%); all bleeding events (60%) were Grade 1/2 except for 2 Grade 3 events (hematuria, upper gastrointestinal hemorrhage). Approximately 34% (34/99) of patients reported serious AEs (all grades), most commonly (≥5 patients) infection (pneumonia [4 patients], influenza [2 patients], and sinusitis [2 patients]). One grade 5 event (multiorgan failure due to neutropenic sepsis/pneumonia) was reported, which was considered unrelated to acalabrutinib. AEs leading to treatment discontinuation (5%) were secondary malignancies (angiosarcoma, glioblastoma multiforme, small cell lung cancer), neutropenic sepsis (Grade 2), rash (Grade 3), and urinary tract infection (Grade 3). ORR was high (97%) for this patient cohort (Table). Median DOR for the 96 responders (≥ PR) and median PFS for the 99 treated patients were not reached (NR) (95% CI: NR, NR; Figure 1). The 36-month DOR and PFS rate was 99% (95% CI: 91%, 100%) and 98% (95% CI: 92%, 100%), respectively. The EFS (with events defined as progression, death, discontinuation due to AE, or start of new anticancer therapy) was estimated to be 94.9% (95% CI: 88.2%, 97.9%) at 24 months (Figure 2). Median TTR was 3.7 months (range 2-22). For the 5 patients who achieved complete response (CR), the median time to CR was 28 months. One CLL progression was reported. No Richter's transformation occurred. Conclusion: Acalabrutinib monotherapy produced high response rates and demonstrated an acceptable safety profile in patients with TN CLL. Disclosures Furman: Gilead: Consultancy; Loxo Oncology: Consultancy; Acerta: Consultancy, Research Funding; Genentech: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy; Incyte: Consultancy, Other: DSMB; Janssen: Consultancy; AbbVie: Consultancy. Martin:Gilead: Consultancy; Janssen: Consultancy; Bayer: Consultancy; Seattle Genetics: Consultancy; AstraZeneca: Consultancy; Kite: Consultancy. O'Brien:Janssen: Consultancy; GlaxoSmithKline: Consultancy; Acerta: Research Funding; Pfizer: Consultancy, Research Funding; Alexion: Consultancy; Pharmacyclics: Consultancy, Research Funding; Amgen: Consultancy; Sunesis: Consultancy, Research Funding; Celgene: Consultancy; Vaniam Group LLC: Consultancy; Astellas: Consultancy; Abbvie: Consultancy; Aptose Biosciences Inc.: Consultancy; Gilead: Consultancy, Research Funding; Kite Pharma: Research Funding; Regeneron: Research Funding; TG Therapeutics: Consultancy, Research Funding. Brown:Celgene: Consultancy; Verastem: Consultancy, Research Funding; Janssen: Consultancy; Genentech: Consultancy; Sunesis: Consultancy; Boehringer: Consultancy; Sun Pharmaceutical Industries: Research Funding; Gilead: Consultancy, Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy; Beigene: Membership on an entity's Board of Directors or advisory committees; Acerta / Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy; TG Therapeutics: Consultancy; Roche/Genentech: Consultancy; Invectys: Membership on an entity's Board of Directors or advisory committees; Loxo: Consultancy. Barrientos:Pharmacyclics/Abbive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees. Devereux:Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Other: Personal fees. Hillmen:Novartis: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Alexion Pharmaceuticals, Inc: Consultancy, Honoraria; Acerta: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Research Funding; Gilead Sciences, Inc.: Honoraria, Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Pagel:Gilead: Consultancy; Pharmacyclics, an AbbVie Company: Consultancy. Chen:Acerta Pharma: Employment. Hamdy:Acerta Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: various patents for ACP-196. Izumi:Acerta Pharma: Employment, Equity Ownership, Patents & Royalties: Acerta Pharma, various patents for ACP-196. Patel:Acerta Pharma: Employment, Equity Ownership. Wang:Acerta Pharma: Employment. Jain:Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Novimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Pfizer: Research Funding; Abbvie: Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Infinity: Research Funding; Incyte: Research Funding; BMS: Research Funding; ADC Therapeutics: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; BMS: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Infinity: Research Funding; Pfizer: Research Funding; Celgene: Research Funding; ADC Therapeutics: Research Funding; Astra Zeneca: Research Funding; Seattle Genetics: Research Funding; Servier: Research Funding; Verastem: Research Funding; Incyte: Research Funding; Cellectis: Research Funding; Celgene: Research Funding; Adaptive Biotechnologioes: Research Funding; Astra Zeneca: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Research Funding; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cellectis: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologioes: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Wierda:AbbVie, Inc: Research Funding; Genentech: Research Funding.

7501 Background: Eradication of MRD in CLL patients may be necessary for deep and durable responses. We assessed safety, pharmacokinetics, and efficacy of liso-cel, an investigational, anti-CD19 CAR T cell product administered as a defined composition of CD4+/CD8+ CAR T cells, in the ongoing phase 1/2 TRANSCEND CLL 004 study. Methods: Eligible pts had CLL/SLL, received ≥2 prior lines of therapy (including Bruton’s tyrosine kinase inhibitors [BTKi] unless medically contraindicated), and had ECOG PS ≤1. Post lymphodepleting chemotherapy, pts received liso-cel infusion at either dose level (DL)1 = 50 × 106 or DL2 = 100 × 106 total CAR+ T cells. Patients were monitored for dose-limiting toxicities (DLTs). Response was assessed by iwCLL 2008 criteria. MRD was assessed by flow cytometry in blood (10−4) and by NGS in bone marrow (BM; 10−6). Results: At data cutoff, 16 pts received liso-cel: DL1, n = 6; DL2, n = 10. 75% of pts had high-risk features ( TP53 mutation, complex karyotype, or del17p); 100% had prior ibrutinib and 50% had prior venetoclax. Median (range) number of prior lines of therapy was 4.5 (2‒11). There was 1 DLT of grade (G) 4 hypertension (DL2). The most common G3/4 treatment-emergent adverse events were cytopenias (thrombocytopenia, 75%; anemia, 69%; neutropenia, 63%; leukopenia, 56%). 1 pt had G3 cytokine release syndrome (CRS); 3 pts had G3 neurological events (NE). Best overall response rate (ORR) in 15 evaluable pts was 87% (13/15). 7 pts (47%) achieved complete remission with/without complete blood count recovery (CR/CRi). ORR at 6 mo was 83% (5/6). 10/15 pts (67%) achieved undetectable MRD (uMRD) in blood by day 30 and in 7/8 pts (88%) in BM. MRD-negative CRs were seen in patients who had failed both BTKi and venetoclax. Median time to peak blood CAR+ T cell level was 16 days (4‒30). Conclusions: In this study of heavily pretreated pts with standard- and high-risk CLL/SLL and previous ibrutinib treatment, liso-cel-related toxicities (ie, CRS and NEs), were manageable. Pts rapidly achieved CR/CRi and uMRD. Additional follow-up will be presented. Clinical trial information: NCT03331198.

7542 Background: Maintenance rituximab in MCL has improved survival, though the optimal approach is not yet defined. Ibrutinib, a selective BTK inhibitor, has profound activity in R/R MCL. Ibrutinib maintenance (I-M) following induction for treatment-naive MCL has not been explored. We report preliminary results of a multicenter phase II trial assessing efficacy and safety of I-M for MCL after frontline induction. Methods: Patients with MCL with CR/PR to frontline chemo-immunotherapy (+/- autoSCT) received I-M 560 mg daily for up to 4 years. Primary objective was 3 year PFS rate. Secondary objectives were PR to CR conversions, median OS at 4 years and toxicity with MRD assessments planned. Results: Accrual is complete with 36 patients, median age of 60 (range 46-90), 28 males, 28 with advanced stage and 9 with extranodal disease. 18 (50%), 7 (19%) and 11 (31%) had low vs intermediate vs high risk MIPI respectively. 8/24 patients had a Ki-67 > / = 30%. For induction, 17 (47%) received BR, 18 (50%) a cytarabine-based regimen, 1 (3%) R-CHOP. 18 (50%) had autoSCT in CR1 prior to enrollment. 33 (92%) and 3 (8%) had CR and PR with induction respectively with 1 PR to CR conversion on I-M. At median follow-up of 19 mos, 24/36 (67%) patients remain on I-M (median 15 cycles, range 1-49) with 1 PD and 1 death. TRAEs led to dose reductions/interruptions in 25 (69%) patients, including permanent dose reductions in 7 (19%) and treatment discontinuation in 9 (25%; Table). 3 additional patients discontinued I-M, 1 for endometrial adenocarcinoma, 1 PD, 1 death, cause unknown. Conclusions: Ibrutinib maintenance is feasible in MCL patients who respond to frontline chemo-immunotherapy +/- autoSCT with manageable toxicities consistent with prior reports of ibrutinib. Additional follow-up and MRD status correlations with PFS and OS will provide insight on clinical relevance for this approach. Clinical trial information: NCT02242097. [Table: see text]

Little is known about outcomes of patients with chronic lymphocytic leukemia (CLL) with del(17p13.1) karyotype at diagnosis. We reviewed 114 de novo del(17p13.1) CLL patients seen at our institution. Using proportional hazards models to identify pretreatment clinical variables significantly associated with treatment-free survival (TFS) and overall survival (OS), we developed a simplified risk score for de novo del(17p13.1) CLL patients to predict TFS and OS based on these variables. These scores, particularly the very highest, can be utilized to identify high-risk patients for expedient enrollment on clinical trials. Our data support careful observation for low-risk patients, potentially preventing unnecessary use of aggressive therapies. Am. J. Hematol. 90:967–969, 2015. © 2015 Wiley Periodicals, Inc.

Alvocidib has demonstrated efficacy in high-risk chronic lymphocytic leukemia (CLL) patients. In this phase I study, we combined cyclophosphamide, alvocidib and rituximab (CAR) in a schema designed to mitigate tumor lysis syndrome (TLS) seen previously with alvocidib. Nine nucleoside analog-naïve, high-risk patients received escalating doses of CAR therapy. Dose limiting toxicity was not experienced. No instances of TLS were observed. Patient responses included three complete remissions and four partial remissions. CAR was tolerable and active in high-risk CLL patients without TLS toxicity. With continued monitoring of toxicities, a phase Ib/II study of this combination as frontline therapy is warranted.

Therapy for chronic lymphocytic leukemia (CLL) has evolved dramatically throughout the years. In 1997, rituximab (Rituxan), a CD20 monoclonal antibody (mAb), became the first mAb approved by the Food and Drug Administration for marketing in the treatment of cancer, specifically targeting B-cell malignancies. Over the last 10 years, rituximab or other mAbs including alemtuzumab and ofatumumab have become an integral part of the standard of care for CLL patients as single agents or in combination with chemotherapy or other immunotherapy. This review discusses the currently approved and novel mAbs for the treatment of CLL.

Background Irreversible inhibition of Bruton's tyrosine kinase (BTK) by ibrutinib represents an important therapeutic advance for the treatment of chronic lymphocytic leukemia (CLL). However, ibrutinib also irreversibly inhibits alternative kinase targets, which potentially compromises its therapeutic index. Acalabrutinib (ACP-196) is a more selective, irreversible BTK inhibitor that is specifically designed to improve on the safety and efficacy of first-generation BTK inhibitors. Methods In this uncontrolled, phase 1-2, multicenter study, we administered oral acalabrutinib to 61 patients who had relapsed CLL to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of acalabrutinib. Patients were treated with acalabrutinib at a dose of 100 to 400 mg once daily in the dose-escalation (phase 1) portion of the study and 100 mg twice daily in the expansion (phase 2) portion. Results The median age of the patients was 62 years, and patients had received a median of three previous therapies for CLL; 31% had chromosome 17p13.1 deletion, and 75% had unmutated immunoglobulin heavy-chain variable genes. No dose-limiting toxic effects occurred during the dose-escalation portion of the study. The most common adverse events observed were headache (in 43% of the patients), diarrhea (in 39%), and increased weight (in 26%). Most adverse events were of grade 1 or 2. At a median follow-up of 14.3 months, the overall response rate was 95%, including 85% with a partial response and 10% with a partial response with lymphocytosis; the remaining 5% of patients had stable disease. Among patients with chromosome 17p13.1 deletion, the overall response rate was 100%. No cases of Richter's transformation (CLL that has evolved into large-cell lymphoma) and only one case of CLL progression have occurred. Conclusions In this study, the selective BTK inhibitor acalabrutinib had promising safety and efficacy profiles in patients with relapsed CLL, including those with chromosome 17p13.1 deletion. (Funded by the Acerta Pharma and others; ClinicalTrials.gov number, NCT02029443 .).

In this issue of Blood , Connors et al report promising 5-year outcomes that support the replacement of bleomycin with brentuximab vedotin in combination with doxorubicin, vinblastine, and dacarbazine (AVD) for the front-line treatment of patients with advanced-stage Hodgkin lymphoma. 1

Background Anti-CD20 mAbs are an important element in the therapeutic armamentarium for B-cell malignancies such as chronic lymphocytic leukemia (CLL). Although new targeted drugs (Ibrutinib & Idelalisib) and recently developed anti-CD20 mAbs (obinutuzumab & ofatumumab) have significant activity, the clinical management is limited by toxicity or low sensitivity to anti-CD20 mAbs. Herein we propose Drug-Free Macromolecular Therapeutics (DFMT) as a novel class of therapeutics that amplifies CD20 crosslinking and triggers apoptosis. The unique features of DFMT include augmentation of multivalent CD20 crosslinking, immune effector independence and no cytotoxic agents. Its effectiveness has been demonstrated in vitro and in preclinical Non-Hodgkin Lymphoma (NHL) models including a CD20-deficient rituximab (RTX)-resistant model, in which DFMT combined with a long-circulating polymer-gemcitabine conjugate (2P-GEM), induced prolonged survival and tumor clearance from bone marrows.[Zhang R, et al. PNAS 2014; Li L, et al. ACS Nano 2018] Therefore, we conducted assessment of DFMT on patient samples. Methods Malignant B cells were isolated from patients diagnosed by the hematologic malignancies service at the Huntsman Cancer Institute. The majority of isolates were from CLL patients. CD20 expression of each sample was evaluated by flow cytometry. DFMT consisting of two nanoconjugates was used to treat the cells in consecutive administration: first, cells were incubated with Fab'-MORF1 (bispecific engager, Fab' fragment of RTX conjugated with a morpholino oligonucleotide); after 1 h, a crosslinking effector (CLE) containing multiple copies of complementary morpholino oligonucleotide (MORF2) was added and the cells were continually incubated for another 6-20 h (depending on assays). The CLE can be prepared by conjugation of MORF2 to either N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer precursor or human serum albumin. Crosslinking of CD20 receptors is initiated by the multiple hybridization of MORF1/MORF2 at the cell surface, and results in apoptosis (Fig. 1A). Annexin V and caspase 3 assays were used to quantify B-cell apoptosis. RTX followed by goat-anti-human (GAH) secondary antibody was used for comparison. GAH was added to imitate the function of Fcγ+ immune effector cells for crosslinking of RTX. When enough cells were available, a detailed evaluation of apoptosis induction was performed, i.e. plasma membrane rupture, genomic DNA fragmentation, mitochondrial membrane permeabilization, Bcl-2 inhibition and confocal imaging to document specific biorecognition at the cell surface. In some samples, pretreatment with GEM or 2P-GEM for 48 hours followed by DFMT or RTX/GAH was conducted, and the effect of GEM in enhancing apoptosis induction was evaluated. Results The efficacy of DFMT was assessed in 44 samples including 35 CLL along with a few other B cell lymphomas such as diffuse large B cell lymphoma (DLBCL), marginal zone lymphoma (MZL), follicular lymphoma (FL), etc. DFMT induced apoptosis in 65.9% of patient samples. High-risk mutations such as 17p13 and 11q22 deletions, usually considered as poor prognostic factors in CLL, did not hamper the therapeutic efficacy of DFMT treatment. In cases with poor responses, we noted low CD20 expression levels (Fig 1B). We previously showed that pre-treatment with GEM can enhance surface CD20 expression and restore responsiveness to anti-CD20 mAb. Therefore, we pre-treated the low CD20 patient samples with GEM followed by treatment of DFMT, which induced significantly more apoptosis than RTX/GAH control (Fig 1C). In addition to increased target expression (CD20), this superior activity is likely due to synergy between GEM and DFMT, as we have shown that CD20 crosslinking triggered by DFMT stimulates a cascade of apoptotic events that eventually lead to up-regulation of the pro-apoptotic proteins Bax and inhibition of NF-ĸB, which in turn sensitizes cells to GEM.[Li L, et al. ACS Nano 2018] Conclusion DFMT effectively increased apoptosis of tumor cells from patients with a variety of B-cell malignancies, irrespective of genomic aberrations. The apoptotic response to DFMT was significantly correlated with CD20 expression, and could be enhanced by GEM-induced upregulation of CD20. DFMT alone or in combination with 2P-GEM warrants further evaluation as a therapeutic for refractory B cell malignancies. Disclosures Yang: Baston Biologics Company: Membership on an entity's Board of Directors or advisory committees; University of Utah: Patents & Royalties: PCT/US2014/023784 and PCT/US2017/37736. Deininger:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint: Consultancy. Shami:Lone Star Biotherapies: Equity Ownership; Pfizer: Consultancy; JSK Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Baston Biologics Company: Membership on an entity's Board of Directors or advisory committees. Kopeček:University of Utah: Patents & Royalties: PCT/US2014/023784 and PCT/US2017/37736; Baston Biologics Company: Membership on an entity's Board of Directors or advisory committees.

Introduction: Given the availability of several active treatment (tx) options for CLL, providers frequently make tx recommendations based on their interpretation of objective data from consensus criteria and clinical trials. There are limited data describing patient (pt) experience, values, and insights when encountering multiple tx choices. The CLL Society, a pt-driven, physician-curated nonprofit organization focused on the unmet needs of the CLL community, sought to explore how CLL pts make tx decisions. Methods: A 64 question survey was distributed online and in paper to CLL pts from Oct-Dec 2017. The survey was developed by CLL experts. The research was IRB-approved. Chi square was used for statistical comparison; all other analyses are descriptive in nature. Results: 1147 pts from 48 states completed the survey. Median age was 65 (range 28-86), 46% male, 96% Caucasian. Who Influences Tx: Of the 79% of pts who have seen a CLL expert, defined as a provider focused on CLL at an academic/research center, 95% rated their provider as very/extremely influential. 83% of pts rated their own opinions as influential, and 59% rated the opinion of a general hematologist/oncologist (gen heme/onc), a provider who sees a variety of cancer types, as influential. Only 27% let their provider unilaterally decide on tx. Of these pts, 19% trusted their provider to select the best tx and 5% didn't have enough understanding to be involved in the decision. 64% were influenced by outside sources of information, such as family members, live CLL support groups, or online sources including pt experts and forums. Factors in Deciding Tx: Of the 67% pts surveyed who have been treated, 73% were offered > 1 tx choice by their provider. In deciding on a specific tx, 94% of respondents stated that it was very/extremely important to know there were tx options beyond their current regimen. The most important factors in selecting tx were response rate (91%), overall survival (88%), progression-free survival (86%), long-term side effects (82%), ability to achieve undetectable MRD (80%), cost/insurance coverage (66%), and location of tx (50%) with significant differences between subgroups (Table 1). Tx was impacted by cost or insurance issues for 16% (n=104). Of these 104 pts, cost/insurance issues resulted in tx delay for 34 and change in tx plan for 24 pts. 16 pts reported that an appeal led to coverage and 16 pts received financial assistance. Pts' willingness to accept potentially curable but high-risk tx was heavily influenced by availability of alternate options. For example, 18% of pts would be willing to consider cytotoxic chemotherapy if alternate options were available vs. 72% if no options were available. Similar patterns were seen with CAR-T tx (28% vs. 79%) and bone marrow transplantation (BMT) (15% vs. 66%) with significant differences between subgroups (Table 2). 82% were willing to take a life-long tx for long-term control without potential for cure. Willingness to accept long-term tx was significantly higher in treated vs. untreated pts (84% vs. 77%, p=.006) and men vs. women (84% vs. 78%, p=.008). Clinical Trial Education: Of those treated by a gen heme/onc, 31% received no education on clinical trials. Only 15% reported good understanding of trial opportunities vs. 52% treated by a CLL expert (p Summary: Most respondents want to be and are involved in tx decisions. While providers are influential in decision making, CLL pts also rely on outside sources. Gender, age, and tx status influence which factors drive decision making. Pts select tx based on response rate, survival, side effects, and ability to achieve deep response and want a plan in place for sequencing tx. The majority are willing to consider long-term tx without cure. Few want chemotherapy, CAR-T, or BMT unless they have no other options. A significant opportunity for improvement in education on clinical trial opportunities was identified. This description of pt experience, values, and preferences enriches the informed consent process and may lead to more tailored and patient-centered care. Disclosures Kennard: AbbVie, Gilead, Verastem: Consultancy. Furman:TG Therapeutics: Consultancy; Loxo Oncology: Consultancy; Sunesis: Consultancy; Verastem: Consultancy; Incyte: Consultancy, Other: DSMB; Genentech: Consultancy; Acerta: Consultancy, Research Funding; Gilead: Consultancy; Janssen: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; AbbVie: Consultancy. Pagel:Pharmacyclics, an AbbVie Company: Consultancy; Gilead: Consultancy. Davids:Sunesis: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; MEI Pharma: Consultancy, Research Funding; Surface Oncology: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Merck: Consultancy; Merck: Consultancy; MEI Pharma: Consultancy, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; MEI Pharma: Consultancy, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Sunesis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Verastem: Consultancy, Research Funding; Surface Oncology: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Roche: Consultancy; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Verastem: Consultancy, Research Funding; BMS: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Surface Oncology: Research Funding; Verastem: Consultancy, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy; Roche: Consultancy. Nabhan:Cardinal Health: Employment, Equity Ownership. Kay:Acerta: Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees. Siddiqi:Juno Therapeutics: Other: Steering committee. Brander:Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Teva: Consultancy, Honoraria; Novartis: Consultancy, Other: DSMB; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Wierda:AbbVie, Inc: Research Funding; Genentech: Research Funding. Hill:Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Cheson:AbbVie, Roche/Genentech, Pharmacyclics, Acerta, TG Therapeutics: Consultancy. Choi:Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Gilead: Speakers Bureau; Rigel: Consultancy; Genentech: Speakers Bureau; AbbVie, Inc: Consultancy, Speakers Bureau. Mato:AstraZeneca: Consultancy; Prime Oncology: Honoraria; Portola: Research Funding; Johnson & Johnson: Consultancy; Medscape: Honoraria; Celgene: Consultancy; TG Therapeutics: Consultancy, Research Funding; Acerta: Research Funding; Pharmacyclics, an AbbVie Company: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Regeneron: Research Funding.

Introduction Transformation of chronic lymphocytic leukemia (CLL) into Hodgkin lymphoma (HL) is a rare, but recognized complication of CLL. The prognosis of CLL with HL Transformation (HT) appears significantly worse than de novo HL, but most series are small and there are limited published data. These reports have prompted several groups to recommend aggressive therapy with stem cell transplantation (SCT) in first complete remission (CR1). We describe the largest reported series of HT patients (pts) with analyses of the clinicobiologic characteristics, treatment patterns, and clinical outcomes based upon our multi-institutional clinical experience. Methods Pts diagnosed with HT from 01/2000 - 01/2018 were retrospectively identified in 13 tertiary cancer centers. Clinicobiologic characteristics, treatment type, and survival outcomes for each pt were analyzed. Overall survival (OS) was measured from the time of HT diagnosis until time of death. OS estimates were calculated using the Kaplan-Meier method. The log-rank test was used to calculate differences in survival. Results Ninety-four pts with HT were identified. Median age at HT was 67 years (yrs; range, 38-85) and 81% of the pts were male. Median time from CLL diagnosis to HT was 5.5 yrs (range, 0-20.2; 7 pts with simultaneous diagnosis of CLL and HL). At initial CLL diagnosis, 31%, 34%, 21%, 10%, and 4% were Rai Stage 0, 1, 2, 3, and 4, respectively. At CLL diagnosis, 67% (25/37) had an un-mutated IgVH gene, 36% (21/59) had del(13q), 32% (14/44) had trisomy 12, 24% (14/59) had del(11q), and 15% (9/61) had del(17p). Prior to HT diagnosis, pts had a median of 2 (range, 0-12) therapies for CLL. Seventeen (18%) had no prior CLL treatments. Forty-three (46%) and 25 (27%) patients had received purine analogue- and ibrutinib-based therapy prior to HT, respectively. Baseline characteristics at HT are described in Table 1. As initial therapy for HL, the majority of pts (61%, n = 62) received ABVD-based regimens (adriamycin, bleomycin, vinblastine, and dacarbazine) at full (n = 48) or reduced (n = 14) doses. Of these, CD20 monoclonal antibody was added in 6 and Bruton-tyrosine kinase inhibitor was added in 2. Ten (11%) received a brentuximab-based regimen. Seven (7%) received an RCHOP-based regimen (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). Six patients (6%) received no therapy for HT due to frailty. Subsequent therapy included autologous SCT and allogeneic SCT in 7 (7%) and 11 (12%) of patients, respectively. Two (2%) and 5 (5%) pts received their autologous and allogeneic SCT while in CR1, respectively. The median number of treatments for HT per pt was 1 (range, 0-5) with 59 (61%) pts only receiving one line of therapy. After HT diagnosis, pts had a median follow-up of 1.6 yrs (range, 0.0 - 15.1). Two-yr OS after HT diagnosis was 72% (95%CI 62 - 83%). The pts who received any CLL directed therapy (n = 80) prior to HT had a significantly lower estimated 2-yr OS of 69% (95%CI 58 - 82%) compared with pts who did not receive any prior CLL-directed therapy (n = 17; 93%; 95%CI 82-100%; p 0.02; Figure 1). Pts who received purine-analogue-based therapy for their CLL prior to HT had a significantly lower estimated 2-yr OS of 60% (95%CI 46 - 79%) compared with pts who did not receive purine-analogue-based CLL-directed therapy prior to HT (n = 51; 83%; 95%CI 73 - 96%; p 0.009; Figure 2). Although limited by small sample size, the pts who underwent SCT for HT in CR1 had a similar 2-yr OS (n = 7; 67%; 95%CI 38-100%) to pts who did not undergo SCT for HT in CR1 (n = 87; 72%; 95%CI 63 - 84%; p 0.46; Figure 3). Conclusions In this retrospective analysis, we describe the largest reported series of pts with HT from CLL. Two-yr survival in pts with HT was shorter than what is historically expected in patients with de novo HL, but longer than what is expected in CLL pts who transform to diffuse large B-cell lymphoma. Pts with HT who have received prior CLL-directed therapies (specifically purine-analogue-based treatments) are estimated to have a shorter 2-yr OS, likely due to underlying immunosuppression. The majority of pts (61%) only received 1 line of HL therapy and only 20% went on to receive SCT (7% while in CR1), indicating that these patients can have prolonged OS after achieving response to first-line therapy for HT and may not require SCT in CR1. Further study of this rare population is required to determine optimum management. Disclosures Kander: AstraZeneca: Consultancy. Parikh:Gilead: Honoraria; AstraZeneca: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Janssen: Research Funding; MorphoSys: Research Funding; Pharmacyclics: Honoraria, Research Funding. Shadman:Acerta Pharma: Research Funding; Verastem: Consultancy; Celgene: Research Funding; Gilead Sciences: Research Funding; Mustang Biopharma: Research Funding; Pharmacyclics: Research Funding; AstraZeneca: Consultancy; Beigene: Research Funding; Genentech: Research Funding; Qilu Puget Sound Biotherapeutics: Consultancy; AbbVie: Consultancy; TG Therapeutics: Research Funding; Genentech: Consultancy. Pagel:Pharmacyclics, an AbbVie Company: Consultancy; Gilead: Consultancy. Mato:Portola: Research Funding; AstraZeneca: Consultancy; Acerta: Research Funding; Prime Oncology: Honoraria; Regeneron: Research Funding; Celgene: Consultancy; Pharmacyclics, an AbbVie Company: Consultancy, Research Funding; Medscape: Honoraria; TG Therapeutics: Consultancy, Research Funding; Johnson & Johnson: Consultancy; AbbVie: Consultancy, Research Funding. Hill:Amgen: Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Danilov:Verastem: Consultancy, Research Funding; Aptose Biosciences: Research Funding; Takeda Oncology: Research Funding; Genentech: Consultancy, Research Funding; TG Therapeutics: Consultancy; Bayer Oncology: Consultancy, Research Funding; Astra Zeneca: Consultancy; Gilead Sciences: Consultancy, Research Funding. Phillips:Abbvie: Research Funding; Bayer: Consultancy; Gilead: Consultancy; Genentech: Consultancy; Pharmacyclics: Consultancy, Research Funding; Seattle Genetics: Consultancy. Brander:Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Novartis: Consultancy, Other: DSMB; Teva: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Smith:BMS: Consultancy; Portola: Honoraria. Davids:Surface Oncology: Research Funding; Roche: Consultancy; Sunesis: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Sunesis: Membership on an entity's Board of Directors or advisory committees; Verastem: Consultancy, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Surface Oncology: Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy; MEI Pharma: Consultancy, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Consultancy, Research Funding; Roche: Consultancy; Sunesis: Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; BMS: Research Funding; MEI Pharma: Consultancy, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy; Merck: Consultancy; Celgene: Consultancy; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy; Celgene: Consultancy; BMS: Research Funding; Surface Oncology: Research Funding; MEI Pharma: Consultancy, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Verastem: Consultancy, Research Funding.

Background: Aberrant activation of B-cell receptor (BCR) signaling is considered to be a major oncogenic mechanism that leads to the development and progression of multiple B-cell malignancies. ARQ 531 is a reversible ATP competitive inhibitor of BTK that inhibits ibrutinib-resistant BTK-C481S mutant CLL cells and has demonstrated antitumor activity in CLL, Richter's transformation, and DLBCL mouse models. Objectives: The primary objectives of the clinical study are to assess the safety and tolerability, and to determine the recommended Phase 2 dose and schedule of ARQ 531. The secondary objectives are to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of anti-tumor activity of ARQ 531. Methods: This is a first in human, Phase 1 dose escalation study in patients with relapsed or refractory CLL/SLL, Waldenstrom's macroglobulinemia, or B-cell NHL who received at least 2 prior lines of systemic therapy. Prior therapy must have included a BTK inhibitor, if FDA approved for their disease. Dose escalation was performed according to a 3+3 study design. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v.4.03. Tumor responses were evaluated per disease specific guidelines. Results: A total of 16 patients enrolled (median age 65.5 years, male 93.8%, 2 DLBCL, 2 follicular lymphoma, 12 CLL/SLL, 5 median prior systemic regimens) and were treated at dose levels of 5, 10, 15, 20 and 30mg QD. No dose limiting toxicities have been reported with ARQ 531. Drug related TEAEs included diarrhea, nausea, vomiting, fatigue, pneumonia, amylase increased, lipase increased, neutrophil count decreased, platelet count decreased, decreased appetite, hypernatraemia, arthralgia, groin pain, dizziness, facial paralysis, headache, tremor and restlessness in one patient (6.3%) each. Drug related grade 3 or worse TEAEs included lipase increased and platelet count decreased in one patient (6.3%) each. No drug related serious TEAEs were reported. Among the 12 patients who have received at least 1 dose of study drug and have at least 1 post-treatment tumor measurement data, 5 achieved stable disease (SD) (1 follicular lymphoma, 1 DLBCL, 3 CLL) and 7 had progressive disease (6 CLL, 1 follicular lymphoma). Three of 5 SD patients (1 follicular lymphoma, 1 DLBCL, 1 CLL) had 35%, 34% and 29% tumor reduction and 2 of them are ongoing on study treatment at 53 and 18 weeks. The CLL patient with 29% tumor reduction had BTK C481S mutation. Preliminary PK data showed ARQ 531 exposure was close to dose proportional and the estimated plasma half-life generally ranged from 20-24 hours. Consistent with increases in exposure, pBTK knockdown was observed. In Cohort 4 (20mg QD), all three patients showed 100% pBTK knockdown at a mean plasma Cmax exposure of 300nM (~4h post dose). Levels of CCL3 protein, a plasma biomarker for BCR pathway activation, was significantly suppressed in CLL patients. Conclusions: ARQ 531 has demonstrated a manageable safety profile to date. Diminished pBTK signaling and CCL3 protein levels have been observed in CLL patients. Additionally, preliminary anti-tumor activity has been observed at doses of ARQ 531 that were not predicted to completely inhibit BTK. Updated safety, PK, biomarker and anti-tumor activity data will be presented at the meeting. Disclosures Flinn: Gilead: Research Funding; Infinity: Research Funding; Incyte: Research Funding; Celgene: Research Funding; Pfizer: Research Funding; Kite: Research Funding; Verastem: Consultancy, Research Funding; Pharmacyclics: Research Funding; Novartis: Research Funding; Curis: Research Funding; Seattle Genetics: Research Funding; Merck: Research Funding; Janssen: Research Funding; ArQule: Research Funding; Calithera: Research Funding; Genentech: Research Funding; Forma: Research Funding; Agios: Research Funding; Constellation: Research Funding; Trillium: Research Funding; Verastem: Research Funding; Portola: Research Funding; Takeda: Research Funding; TG Therapeutics: Research Funding; Forty Seven: Research Funding; BeiGene: Research Funding. Savage:ArQule, Inc.: Employment. Eathiraj:ArQule, Inc.: Employment. Tith:ArQule, Inc.: Employment.