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Background: Rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) remains standard therapy for previously untreated diffuse large B-cell lymphoma (DLBCL). We previously reported that adding pembrolizumab to RCHOP (PR-CHOP), shows no significant additive toxicity and a promising 2-year progression free survival of 83% (Smith B J Haem 2019), with no progression events among 19 pts with known PDL-1+ tumors. In that analysis, we noted 83% of patients had tumor PDL-1 expression by IHC using a centralized standard assay, including 18/23 (78%) and 13/23 (56%) demonstrating positivity in ≥5% and ≥30% of lymphoma cells respectively. Herein we report long-term clinical follow up, as well as results of high-resolution molecular karyotyping using chromosome genomic array testing (CGAT), to assess whether 9p24.1 abnormalities explained the extent of PDL1 tumor expression. Methods: Pts age 18 years or older with previously untreated DLBCL, transformed lymphoma and grade 3 B follicular lymphoma eligible for 6-cycle, curative-intent RCHOP were eligible. Steroids within 7 days of treatment, active autoimmune disease, or history of pneumonitis were excluded. This phase I study combined pembrolizumab (200 mg IV q 3 weeks x 6) to RCHOP x 6, with supportive care per standard practice. There was no maintenance or consolidation therapy. Baseline PDL1 expression was analyzed centrally (Merck/Qualtek). CGAT was performed from DNA extracted from formalin-fixed, paraffin-embedded tissue sections using the OncoScan platform (ThermoFisher). H&E slides of adjacent sections of the tissue used for CGAT were evaluated by a pathologist to ensure a minimum of 30% tumor content. Patients were followed for relapse and survival. Results: Among 30 treated pts with a median follow up of 32 months, there have been no additional DLBCL relapses or deaths since the published report. There has been one relapse of follicular lymphoma in a patient with initial composite lymphoma , who is now in remission 1 year after autologous stem cell transplantation. 3-year estimated PFS is 83% and OS is 86%. On univariate analysis, only tumor bulk 7.5 cm or greater (p=.02) and absence tumor PDL-1 expression by IHC (p=.001) predicted inferior PFS. Tumor bulk, (p=.03), IPI 3 or higher (p=.01), and absence of tumor PDL-1 expression (p=.001) predicted worse overall survival. PFS and OS were unaffected by cell of origin by IHC, double expresser status, or diagnosis to treatment interval greater than median (29 days). Regarding safety, there were late cases of paraneoplastic pemphigus and rheumatoid arthritis 5 and 8 months from last dose of pembrolizumab, respectively. Both of these were managed successfully with immunosuppression. Chromosome genomic array testing CGAT) was performed to assess copy number aberrations (CNAs) and copy neutral loss of heterozygosity (cnLOH), particularly for the presence of gains or amplifications involving locus 9p24.1, containing the CD274 (PDL1) gene. Of 15 tested pretreatment baseline diagnostic tissue specimens, 14 provided informative result with 12 abnormal and 2 normal. Notably, no gain or amplification in 9p24.1 were seen; there was one case of deletion and 1 with cnLOH. The percent genome altered among abnormal cases ranged from 2% to 37% (median 12%). Complex karyotype, defined as genomic aberrations involving at least 3 chromosome arms (or % genome altered greater than 5% by CGAT), was seen in 10/14 pts (71%). This 14-sample data set included 6/14 pts with >30% PDL1 tumor expression (and 10 with 5% or greater PDL1-tumor expression). Conclusions: No additional safety signals have been observed, and PFS/OS remain favorable for the combination of pembrolizumab + RCHOP in this single arm trial with the best results in PDL-1+ disease. Despite frequent tumor PDL1-expression at baseline, no gains or implications of 9p24.1 were observed suggesting alternative mechanisms for overexpression of PDL-1. Further study this regimen and others testing combinations of immune checkpoint inhibition with first-line DLBCL therapy are warranted, to better ascertain the potential superiority of this strategy in this setting. Disclosures Smith: Portola: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Karyopharm: Consultancy; Beigene: Consultancy; Seattle Genetics: Research Funding; AstraZeneca: Consultancy; Millenium/Takeda: Consultancy; Pharmacyclics: Research Funding; Merck: Research Funding; De Novo Biopharma: Research Funding; Bayer: Research Funding; Ayala: Research Funding; Bristol Meyers Squibb: Research Funding. Fromm:Merck: Research Funding. Till:Mustang: Patents & Royalties, Research Funding. Shadman:Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding; Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy. Lynch:Bayer: Research Funding; Rhizen Pharmaceuticals: Research Funding; Incyte: Research Funding; TG Therapeutics: Research Funding; Takeda: Research Funding; Juno Therpeutics: Research Funding; MorphoSys: Consultancy; Genentech: Research Funding; Cyteir: Research Funding. Cowan:Janssen: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Sanofi: Consultancy; Cellectar: Consultancy; Abbvie: Research Funding. Ujjani:Gilead/Kite: Consultancy, Research Funding; Atara: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; MorphoSys: Consultancy; Verastem Oncology: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding. Shustov:Seattle Genetics: Research Funding. Cassaday:Vanda Pharmaceuticals: Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Merck: Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Consultancy, Research Funding; Kite/Gilead: Consultancy, Research Funding. Gopal:Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; IgM bio, BMS, merck: Research Funding; imab bio, takeda,astrazeneca,gilead: Research Funding.

Background: Ibrutinib (I) and venetoclax (V) have each demonstrated modest single-agent activity in relapsed/refractory follicular lymphoma (FL) (Gopal A, JCO 2018; Davids M, JCO 2017). Preclinical data have shown synergy with these agents in B-cell cell lines (Kuo H, Mol Cancer Ther 2017). Based on these observations, we proposed the first trial to combine I and V in FL. Results from the phase Ib portion of this multi-institutional investigator-initiated trial are presented here (NCT02956382). Methods: This phase Ib/II trial is open at Georgetown/Lombardi CCC, Hackensack/John Theurer CC, and University of Washington/Fred Hutchinson/Seattle Cancer Care Alliance. Eligibility criteria include WHO grade 1-3a FL, >1 prior systemic therapy, measurable disease warranting therapy by standard criteria or physician discretion, ECOG performance status < 2, adequate marrow, hepatic, renal function. Patients (pts) were enrolled in a standard phase I 3+3 design at a starting dose level (DL) of I 420 mg daily, V 400 mg daily (DL0). The highest initially planned dose level was DL3: I 560 mg daily, V 800 mg daily. There was no dose ramp up of V based on monotherapy experience in FL. Pts at high risk for tumor lysis syndrome (TLS), defined as node ≥ 8 cm and/or significant lymphocytosis, were hospitalized for initial dose. Pts received study drugs until progression or unacceptable toxicity. Response was assessed by PET-CT and bone marrow biopsy (if marrow involvement present at time of enrollment). Results: Sixteen pts were enrolled between November 2017 - May 2020. Median age was 66 years (range 50-87); 75% were male; 75% were Stage III/IV, 94% had WHO grade 1/2 FL (Table 1). FLIPI score at enrollment was 25% low risk, 44% intermediate risk, 31% high risk. Two pts were considered high risk for TLS. Pts received a median of 2 prior therapies (range 1-8); 19% were refractory to last line of therapy. Cohort enrollment was: DL0 (n=3), DL1 (n=6), DL2 (n=6), DL3 (n=1). The protocol was amended to close DL3 based on pharmacokinetic data from DL2 indicating a 1.8-fold higher mean steady-state ibrutinib plasma exposure compared to ibrutinib 560 mg monotherapy and concern for potential toxicity. Grade 3 adverse events (AE) included neutropenia (25%), thrombocytopenia (13%), lung infection (13%), upper respiratory infection (6%), neutropenic fever (6%), atrial fibrillation (6%), ALT/AST elevations (6%), mucositis (6%), failure to thrive in setting of progression (6%), abdominal pain (6%). There were no grade 4/5 AE. Grade 1/2 AE occurring in > 20% of pts included diarrhea (75%), nausea (63%), bruising (38%), rash (31%), headache (31%), constipation (25%), fatigue (25%). There was no evidence of clinical TLS; 19% had grade 1 hyperuricemia. The pt enrolled at DL3 had grade 1 diarrhea, grade 1 neutropenia. One dose limiting toxicity (DLT) occurred at DL1 (I 560 mg, V 400 mg): grade 3 neutropenia with fever and infection. There were no other DLTs. Therefore, DL2 (I 560 mg, V 600 mg) was determined to be the recommended phase 2 dose (RP2D). The ORR was 69% (0.413, 0.890); CR 25% (0.073, 0.524). The ORR at the RP2D was 83% (CR 33%). Responses by dose level are listed in Table 2. The regimen demonstrated activity in the bone marrow; 2 pts had eradication of involvement and 1 had a decrease from 60% to 0.5% by flow cytometry. Response by lines of prior therapy: 1 (86%, 6/7), > 2 (56%, 5/9). Most pts (91%) had a response by time of first assessment (12 weeks). The median progression-free survival (PFS) was 8.3 months (5.6 months, NA) (Figure 1). Of note, 2 responding pts chose to withdraw from study due to travel and were censored in the PFS analysis at time of discontinuation. One remained in a CR at least 9 months after study withdrawal as documented by PET-CT performed off protocol. No pts discontinued due to toxicity. Conclusion: In the first clinical trial to combine a BTK inhibitor and a BCL-2 inhibitor in relapsed/refractory FL, we found the I-V doublet to demonstrate a toxicity profile similar to that seen in mantle cell lymphoma and CLL. While our sample size is small, there was no evidence of clinical TLS, despite omission of the V ramp up. Preliminary results of anti-tumor activity are encouraging and further evaluation at the RP2D (I 560 mg, V 600 mg) is ongoing in the phase II trial. The combination of ibrutinib and venetoclax may provide an effective option for FL, utilizing a targeted approach distinct from other novel agents currently approved for this malignancy. Disclosures Ujjani: Verastem Oncology: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; MorphoSys: Consultancy; Atara: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Gilead/Kite: Consultancy, Research Funding. Lai:Agios: Consultancy; Macrogenics: Consultancy; Astellas: Speakers Bureau; Jazz: Speakers Bureau; Abbvie: Consultancy. Leslie:Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; KitePharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; Celgene: Speakers Bureau; BeiGene: Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Epizyme: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Bayer: 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; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Broome:sanofi: Honoraria; argenx: Honoraria; apellis: Honoraria; Alexion: Honoraria. Gopal:IgM bio, BMS, merck: Research Funding; imab bio, takeda,astrazeneca,gilead: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding. Smith:Beigene: Consultancy; Millenium/Takeda: Consultancy; AstraZeneca: Consultancy; Portola: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; De Novo Biopharma: Research Funding; Bristol Meyers Squibb: Research Funding; Ayala: Research Funding; Acerta Pharma BV: Research Funding; AstraZeneca: Research Funding; Bayer: Research Funding; Karyopharm: Consultancy. Till:Mustang: Patents & Royalties, Research Funding. Lynch:Morphosys: Consultancy; Takeda: Research Funding; Bayer: Research Funding; TG therapeutics: Research Funding; Incyte: Research Funding; Juno: Research Funding; Cyteir: Research Funding; Genentech: Research Funding; Rhizen: Research Funding. Shadman:Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG therapeutics: Research Funding; Celgene: Research Funding; Sunesis: Research Funding; Gilead: Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Meyers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Verastem: 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; Atara Biotherapeutics: 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, Research Funding; Cellectar: 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; Mustang Bio: Research Funding; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Ended employment in the past 24 months; MophoSys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sound Biologics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Maloney:Novartis: Consultancy, Honoraria; Bioline Rx: Consultancy, Honoraria; Juno Therapeutics: Consultancy, Honoraria, Patents & Royalties: Patents are pending, but not issued, licensed, no royalties, no licensees., Research Funding; A2 Biotherapeutics: Consultancy, Current equity holder in publicly-traded company, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Gilead Sciences: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria. Cheson:TG Therapeutics: Speakers Bureau; Symbio: Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy; Trillium: Research Funding; Abbvie: Consultancy, Research Funding; Jannsen: Consultancy; Pharmacyclics: Consultancy, Research Funding; Parexel: Consultancy; GSK: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: We are presenting data regarding the use of venetoclax and ibrutinib in follicular lymphoma.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy is an effective strategy for patients (pts) with B-cell non-Hodgkin lymphomas (B-NHLs). However, long-term remissions are only observed in ~40% of pts with large cell lymphomas (LCL) treated with FDA-approved CD19-targeted products and there is currently no approved CAR-T for other histologies other than mantle cell lymphoma (MCL). CD20 is a proven therapeutic target for B-NHL, supported by previously approved naked and radiolabeled anti-CD20 antibodies and promising results from bispecific antibodies. CD20-targeted CAR-T is another potential adoptive immunotherapy option that could be utilized in combination or in sequence with CD19 CAR-T. We present interim results of our ongoing phase I/II clinical trial investigating safety and efficacy CD20 CAR-T for high-risk B-NHLs (NCT03277729). Methods: MB-106 is a fully human third-generation CD20-targeted CAR-T with both 4-1BB and CD28 costimulatory domains. We use a continuous reassessment method dose escalation design to find the maximally tolerated dose. Lymphodepletion (LD) consists of cyclophosphamide (Cy) ± fludarabine (Flu). CAR-T cells are administered at one of 4 dose levels (DL): DL1: 3.3 x 105, DL2: 1 x106, DL3: 3.3x106, DL4: 1x107 CAR T cells/kg. CAR-T is infused in the outpatient setting except for the first pts of each dose cohort (overnight observation). Pts with CD20+ B-NHL are eligible, including but not limited to LCL, follicular lymphoma (FL)/indolent histologies and MCL. Prior treatment with CD19 CAR-T is permitted. Treatment response is assessed on day 28 using 2014 Lugano criteria. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded per 2014 Lee criteria and the ASTCT consensus grading, respectively. Results: Between 2018-2020, 12 pts underwent leukapheresis (LA) and 11 (92%) were treated on the protocol. The first 7 pts (3 FL, 3 MCL, 1 hairy cell variant) were treated using the original cell manufacturing method with separate culturing of CD4+ and CD8+ cells ("original process"). First 4 of those 7 pts (2 treated at DL1 and 2 at DL2) only received Cy for LD and the other 3 (all at DL1) were treated after LD with Cy-Flu. There was no evidence of ICANS in those 7 pts and only 1 pt developed CRS (grade 3 - unexplained elevated alkaline phosphatase (ALP) in the setting of fever). Responses at 4 weeks for pts treated with the "original process" included stable disease (SD) in 4 and progressive disease (PD) in 3 pts. Given the challenges in meeting the protocol requirements for CD4+ and CD8+ specific doses, poor CAR-T expansion, and lack of clinical responses, enrollment was placed on a hold and cell manufacturing process underwent a major revision which included changing to a combined culture of CD4+ and CD8+ cells, among other modifications ("modified process"). Since December 2019 enrollment was reinitiated at DL1 under the "modified process." Four pts were treated after LD with Cy-Flu at DL1 (2 FL) and dose level 2 (1 FL and 1 MCL) (details in Table 1). Target cell doses were achieved in all 4 patients and treatment was tolerated with no occurrence of CRS (any grade) or ICANS (any grade). Responses were observed at both dose levels and included complete remissions (CRs) in 2 FL pts (1 treated at DL1 and 1 at DL2), partial remission (PR) in a MCL pt treated at DL2 and PD in a FL pt who was treated at DL1. Robust CAR-T expansion was seen in 3 of the 4 patients, with peak blood levels of CAR+ T cells of 161, 5.5, and 401 CAR+ cells/µl, corresponding to 80%, 23%, and 72% of all CD8+ cells. Combining all 11 pts treated under the "original" and "modified" processes, no dose-limiting toxicity (DLT) was observed. Grade ≥ 3 toxicities included: anemia (n=4, 36%), lymphopenia (n=3,27%), febrile neutropenia (n=2, 18%), hypertension (n=1, 9%) , hypotension (n=1, 9%), thromboembolic event (n=1, 9%), neutropenia (n=1, 9%), elevated ALP (n=1, 9%), pneumonia (n=1, 9%), bacteremia (n=1, 9%), hyperglycemia (n=1, 9%), pleural effusion (n=1, 9%) and generalized pain (n=1, 9%). Conclusion: Early results of our ongoing study of CD20 CAR-T for high-risk NHLs suggests an extremely favorable safety profile (no CRS or ICANS of any grades) with the modified manufacturing process. There is also evidence of clinical activity even at low dose levels with observed CRs at DLs 1 and 2. Enrollment at higher DLs is currently ongoing and the data will be updated at the time of presentation. Disclosures Shadman: Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy; Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding. Yeung:OBI;Pfizer: Research Funding; Adaptive Biotechnology;Eli Lilly;Merck: Consultancy. Ramachandran:Mustang Bio: Current Employment. Graf:TG Therapeutics: Research Funding; BeiGene: Research Funding; MorphoSys: Consultancy; Acerta Pharma: Research Funding. Gopal:IgM bio, BMS, merck: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; imab bio, takeda,astrazeneca,gilead: Research Funding; Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding. Gauthier:JMP, Eusapharma, Multerra Bio: Honoraria. Cassaday:Pfizer: Honoraria, Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Vanda Pharmaceuticals: Research Funding; Kite/Gilead: Consultancy, Research Funding; Merck: Research Funding; Amgen: Consultancy, Research Funding. Kiem:Magenta Therapeutics, CSL,Homology Medicines, Vor Biopharma , Enochian, Umoja, Rocket Pharma: Consultancy. Turtle:Novartis: Consultancy; Myeloid Therapeutics: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Allogene: Consultancy; PACT Pharma: Consultancy; Arsenal Bio: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Physician Education Resource: Consultancy; AstraZeneca: Consultancy, Research Funding; Nektar Therapeutics: Consultancy, Research Funding; Juno/BMS: Patents & Royalties, Research Funding; Century Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Humanigen: Consultancy; Kite/Gilead: Consultancy. Maloney:Pharmacyclics: Consultancy, Honoraria; Juno Therapeutics: Consultancy, Honoraria, Patents & Royalties: Patents are pending, but not issued, licensed, no royalties, no licensees., Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Gilead Sciences: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria; Bioline Rx: Consultancy, Honoraria; A2 Biotherapeutics: Consultancy, Current equity holder in publicly-traded company, Honoraria; Genentech: Consultancy, Honoraria. Till:Mustang: Patents & Royalties, Research Funding.

Background: CD19-targeted chimeric antigen receptor-engineered T cell(CAR-T) therapy with axicabtagene ciloleucel (axi-cel) is approved for patients (pts) with large cell lymphoma (LCL) [diffuse large cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma (PMBCL) and transformed follicular lymphoma (tFL)] after ≥ 2 lines of treatment. In addition to cytokine-release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), prolonged cytopenias may occur after axi-cel and can limit eligibility for subsequent treatments, especially clinical trials. In this study, we sought to determine the rate of clinically significant cytopenias and identify pre- and post- treatment factors associated with cytopenias after axi-cel. Methods: Pts with DLBCL, PMBCL, or tFL who received axi-cel between Feb 2018 and Feb 2020 were included. We collected details about patients' demographics, disease characteristics, pre-CAR-T treatments, and post CAR-T specific toxicities (Table 1 footnote). We included details on blood counts, and transfusion/growth factor support needs from 30 days before leukapheresis (LA) until 30 days after treatment with axi-cel. We defined severe cytopenia if at least one of the following were present: (1) grade ≥ 3 thrombocytopenia (< 50x109/L), (2) neutropenia (< 1.0 x109/L), or (3) anemia (Hb < 8.0 g/dl) at day 30 after axi-cel, or (4) need for ≥ 2 doses of G-CSF, (5) ≥ 2 red blood cell (RBC) transfusions, or (6) ≥ 2 platelet (plt) transfusions between days 20-30 after axi-cel. Univariate and multivariable logistic regression was used to evaluate the association between each risk factor and the primary endpoint of severe cytopenia (Yes vs. No). For multivariable analysis, a novel high dimensional inference (HDI) approach was applied, which provides the de-biased estimates of the regression coefficients. HDI allows computation of adjusted odds ratios, confidence intervals and p values from high-dimensional datasets. This approach solves variable selection issues in CAR-T cell studies with small sample sizes and large number of predictors. Results: 53 pts (41 DLBCL, 1 PMBCL, 11 tFL) received axi-cel during the study period. Median age was 63 (25-79) and 17 (32%) were female. Nineteen pts (36%) had bulky disease (> 5 cm) and 23 (43%) had elevated LDH (>210 U/L). Median number of therapies before CAR-T including stem cell transplant (SCT) and bridging therapy was 3 (2-9). Seventeen pts (32%) had a prior stem cell transplant (SCT) (16 autologous, 1 allogeneic) before CAR-T. Median time from last treatment to CAR-T was 4 weeks (0.3-130). Twenty six pts (49%) received bridging therapy between LA and lymphodepletion (LD). Following CAR-T, 37 (74%) patients achieved complete or partial remission (CR/PR) while 13 patients (26%) had progressive or stable disease (PD/SD). 45 (85%) pts developed CRS (grade 3-4: 5; 11% of all pts) and 31 (59%) developed ICANS (grade 3-4: 9; 15% of all pts). Forty two (79%) patients had severe cytopenia as defined by one or more of the categories (Cat) listed in the methods; 24 (45%) by Cat 1 (thrombocytopenia), 19 (36%) by Cat 2 (neutropenia), 1 (2%) by Cat 3 (anemia), 10 (19%) by Cat 4 (GCS-F need), 11 (21%) by Cat 5 (RBC transfusion), or 15 (28%) by Cat 6 (plt transfusion). Severe cytopenia was more common in non-responders (SD/PD) vs. responders (PR/CR) (100% vs. 70%; P=.01). In the univariate analysis, lower pre-LA hematocrit (hct) (P=.005), pre-LD hct (P Conclusion: Severe cytopenia is common after axi-cel, -especially in non-responders in need of subsequent therapies. Our detailed analysis of pre- and post- CAR-T variables identified pre-CAR-T cytopenia and transfusion needs as well as post-CAR-T steroid use as potential predictors of day 30 severe cytopenia in pts with LCL receiving axi-cel. Disclosures Gauthier: JMP, Eusapharma, Multerra Bio: Honoraria. Cassaday:Amgen: Consultancy, Research Funding; Vanda Pharmaceuticals: Research Funding; Pfizer: Honoraria, Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Kite/Gilead: Consultancy, Research Funding; Merck: Research Funding. Kiem:Magenta Therapeutics, CSL,Homology Medicines, Vor Biopharma , Enochian, Umoja, Rocket Pharma: Consultancy. Lynch:TG Therapeutics: Research Funding; Takeda: Research Funding; MorphoSys: Consultancy; Genentech: Research Funding; Cyteir: Research Funding; Bayer: Research Funding; Rhizen Pharmaceuticals: Research Funding; Incyte: Research Funding; Juno Therpeutics: Research Funding. Ujjani:Atara: Consultancy, Honoraria; Gilead/Kite: Consultancy, Research Funding; Verastem Oncology: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria; MorphoSys: Consultancy. Smith:AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Beigene: Consultancy; Millenium/Takeda: Consultancy; AstraZeneca: Consultancy; Portola: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; De Novo Biopharma: Research Funding; Ayala: Research Funding; Bristol Meyers Squibb: Research Funding; Bayer: Research Funding; Karyopharm: Consultancy. Gopal:Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; imab bio, takeda,astrazeneca,gilead: Research Funding; IgM bio, BMS, merck: Research Funding. Till:Mustang: Patents & Royalties, Research Funding. Turtle:Kite/Gilead: Consultancy; Humanigen: Consultancy; Physician Education Resource: Consultancy; Century Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Research Funding; PACT Pharma: Consultancy; Allogene: Consultancy; T-CURX: Membership on an entity's Board of Directors or advisory committees; Myeloid Therapeutics: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Arsenal Bio: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar Therapeutics: Consultancy, Research Funding; Juno/BMS: Patents & Royalties, Research Funding; Novartis: Consultancy. Maloney:Genentech: Consultancy, Honoraria; A2 Biotherapeutics: Consultancy, Current equity holder in publicly-traded company, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bioline Rx: Consultancy, Honoraria; Juno Therapeutics: Consultancy, Honoraria, Patents & Royalties: Patents are pending, but not issued, licensed, no royalties, no licensees., Research Funding; MorphoSys: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Gilead Sciences: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria. Shadman:Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding; Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy.

Background Chimeric antigen receptor T-cell (CAR-T) therapy has shown promising efficacy in high-risk CLL but progressive disease after CAR-T is not uncommon. We studied outcomes of pts with relapsed or refractory CLL after CAR-T to establish a benchmark for trials in this setting. Methods CLL pts treated with CD19-specific CAR-T on a clinical trial (NCT01865617) were reviewed. We identified pts with stable or progressive disease (SD/PD) on initial assessment or with relapse after a complete or partial response (CR/PR). Multivariable models included variables related to disease, treatment and CAR-T procedure. Results 28 pts had SD/PD (n=16; 57%) or relapsed (n=12; 43%) disease after CAR-T. Five pts (18%) had prior allo-SCT. Five pts (18%) received bridging therapy after leukapheresis. CAR-T adverse events included CRS in 22 pts (grade 3 in 2) and NT in 7 (grade 3 in 5). 5 of 11 pts who received Venetoclax (Ven) after CAR-T had progressed on it before but had a median duration of response (DOR) of 5 months (2-8) which was not different from pts who were Ven responsive before CAR-T [5 months (1-10); p = 0.95). This was not true for Ibrutinib (IB) with DOR of 2 months (0.5-7) in pre-CAR-T IB failed vs. 12.25 months (6-18.5) in pre-CAR-T IB responsive pts (p = 0.001). Fourteen pts (51%) had repeat CAR-T therapy (CR=3, PR=3) with DOR after second CAR-T of 5.5 months (1-33). Six pts (23%) received an allo-SCT median 6.5 months after CAR-T progression (CR=2, PR=1). History of progression on both IB and Ven before CAR-T was strongly associated with poor OS [hazard ratio (HR) 11.2 (95% CI: 2.5-50.5); p=0.002]. Receiving an allo-SCT after CAR-T progression was associated with an improved OS [HR 0.14 (95% CI: 0.02-0.97); p=0.04]. [Fig-1] Conclusion This data sets a benchmark for clinical trials that intend to improve outcome of CLL pts with progression after CAR-T. OS after CAR-T progression was significantly shorter in pts who received CAR-T after failing both IB and Ven compared to others. This finding supports referring high-risk CLL pts for CAR-T treatment after progression on IB and while still responsive to Ven. For eligible pts, allo-SCT seems to provide a higher chance of survival in pts who progress after CAR-T.

Background CD19-targeted chimeric antigen receptor-engineered (CD19 CAR)-T cell immunotherapy has shown efficacy for relapsed or refractory (R/R) B-cell malignancies, but absence of complete response or relapses are still observed in a significant portion of patients (pts). Objectives To evaluate outcomes after repeat infusion of CD19 CAR-T cells, and identify the factors associated with response, CAR-T cell in vivo expansion, and progression-free survival (PFS). Methods We analyzed data from pts with R/R B-cell malignancies who received a second infusion of CD19 CAR-T cells (CART2) on a phase 1/2 trial (NCT01865617) at our institution. Responses were evaluated 4 weeks after CAR-T cell infusion and defined according to the 2018 NCCN guidelines for acute lymphoblastic leukemia (ALL), 2018 iwCLL for chronic lymphocytic leukemia (CLL), and the Lugano criteria for non-Hodgkin lymphoma (NHL). Results Forty-four pts evaluable for response were included in this study (see Table). Pts were heavily pre-treated (median prior therapies, 6), and 16 pts (36%) had bulky (e" 5cm) disease. Prior to CART2, 15 pts (32%) had not responded to CART1, 22 (50%) relapsed or progressed after initial response (complete response [CR], n=15; partial response [PR], n=7) to CART1, and 7 (16%) were in ongoing PR. We observed responses to CART2 in 3 of 14 ALL pts (21%; all CR/CRi), 4 of 11 CLL pts (36%; CR/CRi, n=3; partial response [PR], n=1), and 9 of 19 NHL pts (47%; CR, n=2; PR, n=7). After a 43-month median follow-up, the estimated 4-year PFS and OS probabilities in responders were 23% (95% CI, 9-59%) and 36% (95% CI 19-71%), respectively. Multivariable logistic regression identified lymphodepletion intensity before CART1 (high-intensity cyclophosphamide and fludarabine [CyFlu] vs Other, OR=12.19, p=0.04; high intensity versus low intensity CyFlu, OR=3.83, p=0.08) and the peak blood CAR-T cell count after CART2 (OR=2.31 per log10 CD8+ CAR-T cell/µL increase, p=0.01) as predictors of response to CART2. In a multivariable Cox model, higher peak CD8+ CAR-T cell count after CART2 (HR=0.47 per log10 CD8+ CAR-T cell/µL increase, p Conclusion Outcomes after second infusions of CD19 CAR-T cells might be improved with high-intensity CyFlu lymphodepletion prior to CART1 and by increasing the CAR-T cell dose at the time of CART2.

Purpose Double-hit lymphomas and triple-hit lymphomas (DHL/THL), also known as high-grade B-cell lymphoma with MYC and BCL2 or BCL6 rearrangements, are associated with chemoresistance and inferior survival. However, whether radiation therapy (RT) efficacy is altered in DHL/THL is less well characterized. Among patients with relapsed or refractory large B-cell lymphoma (R/R LBCL), we compared rates and durability of response between patients with and without DHL/THL. Methods and Materials We retrospectively reviewed consecutive R/R LBCL patients who were irradiated at a single institution from January 2008 to June 2017. Patients in whom c-MYC rearranged status was known were evaluated for response to RT, in-field control, progression-free, and overall survival. Results Among 245 irradiated patients with LBCL, 41 patients with confirmed c-MYC status were treated for R/R disease (14 DHL/THL, 27 non-DHL/THL) and formed our cohort. Compared with non-DHL/THL, more DHL/THL patients had progressive disease at RT (71% vs 48%), had larger gross tumor volumes (GTV; median 696 mL vs 117 mL), and were treated with palliative intent (71% vs 41%). Despite similar RT doses (median 35 Gy), radiographic complete response rate was lower among DHL/THL patients: 14.3% versus 64.7% (P = .01). With a median 2 years of follow-up, one in-field failure was observed in each group. DHL/THL patients had inferior progression-free survival (7% vs 46%; P = .02) and overall survival (14% vs 68%; P = .03) at 6 months. Conclusions R/R LBCL is responsive to RT, although rates of response are lower among DHL/THL patients. Given poor survival after RT, in-field control was hard to evaluate in this cohort. Larger cohorts are required to better elucidate whether differences in response rates are driven by larger disease burden at RT versus tumor biology. These findings are of increasing pertinence in light of use of RT as bridging therapy to cellular immunotherapies.

Allogeneic hematopoietic cell transplantation (allo-HCT) is offered to selected patients after chimeric antigen receptor-modified T-cell (CAR-T) therapy. Lymphodepleting chemotherapy and CAR-T therapy have immunosuppressive and immunomodulatory effects that could alter the safety profile of subsequent allo-HCT. We reviewed our experience with 32 adults (acute lymphoblastic leukemia [ALL], n = 19; B-cell non-Hodgkin lymphoma [NHL]/chronic lymphocytic leukemia [CLL], n = 13) who received an allo-HCT after CAR-T therapy, with a focus on posttransplant toxicities. Myeloablative conditioning (MAC) was used in 74% of ALL patients and 39% of NHL/CLL patients. The median time from CAR-T therapy to allo-HCT was 72 days in ALL patients and 122 days in NHL/CLL patients. Cumulative incidences of grade 3-4 acute graft-versus-host disease (GVHD) and chronic GVHD were 25% and 10%, respectively. All patients had neutrophil recovery (median, 18.5 days) and all but 3 had platelet recovery (median, 12 days). Twenty-two percent had viral or systemic fungal infection within 100 days after allo-HCT. The 100-day and 1-year cumulative incidences of NRM were 16% and 21%, respectively, for ALL patients and 15% and 33%, respectively, for NHL/CLL patients. In ALL patients, later utilization of allo-HCT after CAR-T therapy was associated with higher mortality. In NHL/CLL patients, MAC was associated with higher mortality. Toxicities did not exceed the expected incidences in this high-risk population.

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.

Background: Tumor programmed death-ligand 1 (PD-L1) expression in diffuse large B-cell lymphoma (DLBCL) is associated with inferior outcomes. We hypothesized that the first-line immunologically-replete setting may be an opportune time for introducing PD-1 inhibition. We thus evaluated pembrolizumab in combination with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) in untreated patients with DLBCL. Methods: Eligible patients were age 18 or older, had adequate organ function, and had DLBCL or grade 3B FL requiring full-course therapy. Patients received pembrolizumab 200 mg/cycle with R-CHOP for 6 cycles, every 21 days, measuring toxicity as the primary endpoint. Response assessment utilized standard criteria, and PD-L1 staining was performed at a validated central laboratory. Findings: Among 30 treated patients, toxicity was comparable to standard R-CHOP but with two grade ≥3 immune related adverse events (rash, pneumonitis). The overall and complete response rate was 90% and 77%. Only 1 of 4 partial responders has progressed. With 25·5 months of median follow-up, 2-year progression-free survival (PFS) is 83%. PD-L1 tumor expression was associated with non-GCB subtype, and improved PFS and survival.InterpretationPembrolizumab can safely be added to R-CHOP, and is associated with a high CR rate and 2-year PFS. Improved PFS with PR-CHOP in PD-L1 expressing tumors contradicts historical data in R-CHOP treated patients, and supports further trials evaluating PD-L1 as a biomarker to identify DLBCL patients who may benefit from this first-line strategy. Trial Registration: NCT02541565. Funding Statement: In addition to primary funding from Merck Sharpe and Dohme Corp, the authors recognize additional support from grant K24CA184039, NIH/NCI Cancer Center Support Grant P30 CA015704, and donations from Frank and Betty Vandermeer and Sonya and Tom Campion. Declaration of Interests: S.D.S. reports grants and nonfinancial research support from Acerta Pharma BV, Astrazeneca, De Novo Biopharma, Genentech, Jannsen Pharmaceuticals, Incyte Corporation, Merck Sharp and Dohme Corp., Pharmacyclics, Portola Pharmaceuticals, and Seattle Genetics; S.D.S.’ spouse receives research support from Ayala, Bristol Myers Squibb, Merck Sharp Dohme Corp, and Ignyta. S.D.S reports personal fees from Merck Sharp and Dohme Corp and Astrazeneca. A.K.G. reports grants and nonfinancial research support from Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector; Personal fees and nonfinancial support from Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Compliment, Asana Bio, and Incyte. H.R., K.B., J.V., Q.W. report no relevant financial disclosures. M.S. reports grands and nonfinancial research support from Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Acerta Pharma, Merck Sharp and Dohme Corp; personal fees and nonfinancial support from Abbvie, Genentech, Astra Zeneca, Sound Biologics, Verastem, ADC therapeutics and Atara Biotherapeutics. B.G.T. reports grants and nonfinancial research support from Mustang Bio and RocheGenentech, and patents/royalties from Mustang Bio. R.C.L. reports grants and nonfinancial research support from Incyte Corporation, TG Therapeutics, Takeda, Juno Therapeutics, Rhizen Pharmaceuticals. A.J.C. reports grants and nonfinancial research support from Janssen, AbbVie, Juno Therapeutics, and Celgene; personal fees and nonfinancial support from Celgene. C.U. reports grants and nonfinancial research support from Pharmacyclics, Abbvie, and Celgene; personal fees and nonfinancial support from Amgen, bayer, Pfizer, Gilead, Astrazeneca, Genentech, Pharmacyclics, Abbvie, and Atara. A.R.S. reports grants and nonfinancial research support from Seattle Genetics, Spectrum Pharmaceuticals, and personal fees and nonfinancial support from Kyowa Hakko Kirin. R.D.C reports grants and nonfinancial research support from Merck Sharp and Dohme Corp., Incyte, Seattle Genetics, Vanda Pharmaceuticals, Amgen, Pfizer, Kite/Gilead; and personal fees and nonfinancial support from Amgen, Pfizer, Jazz, and Adaptive Biotechnologies. Ethics Approval Statement: This study was approved by the Fred Hutchinson Cancer Center- University of Washington Consortium IRB and all patients provided written informed consent to participate in the trial.

7503 Background: Optimal initial therapy for mantle cell lymphoma (MCL) remains uncertain. The randomized phase 2 NCTN trial E1411 tested if progression-free survival (PFS) is prolonged by addition of bortezomib (V) (1.6 mg/m2 SC/IV days 1, 8) to bendamustine-rituximab (BVR vs BR) induction and/or by addition of lenalidomide (L) to rituximab (LR vs R) consolidation. Here we report efficacy and toxicity of induction BVR vs BR. Methods: 373 pts, accrued 2012–16, stratified by MIPI and age (≥60) received 1 of 4 arms: A) BR induction x 6 followed by R x 2 yrs, B) BVR followed by R, C) BR followed by LR or D) BVR followed by LR. Eligible pts had untreated MCL, ≥ age 18 (amended from ≥60 when S1106 for < 65 closed), ECOG PS 0-2 and adequate hematologic and organ function. Pts without progressive disease during induction proceeded to consolidation. Primary induction objective was whether adding bortezomib (BVR) (Arms B + D) to BR (Arms A + C) improves PFS, irrespective of consolidation R vs LR. Design of 360 eligible treated pts would provide 93.8% power to detect 10% improvement in 2-yr PFS from 70% hypothesized for BR, corresponding to 37.4% reduction in hazard using stratified log-rank test at 1-sided 10% alpha. Efficacy population was 179 (BVR) and 180 (BR), induction treatment completed in 144 vs 153, progressive disease during induction 6 vs 7 and registration to consolidation 140 vs 145. Results: Baseline demographics did not differ between the groups, with median age 67 (range 42-90) and 13% < 60 yr, 73% men, ECOG PS 0-1 97%, MIPI Low/Med/Hi 37/29/34%. Estimated PFS at 2 yrs 79.6% BVR (95% CI 73.8-85.9) vs 74.5% BR (95% CI 68.2-81.4) (1-sided stratified log-rank p = 0.268). With median PFS follow-up 51 mos, median PFS estimated at 64.1 and 64.0 mos. Overall response rate (ORR) for BVR was 88.9% (CR 65.5%) vs 89.5% (CR 60.5%) BR (z-test 1 sided p = 0.577 for ORR). Treatment related deaths during induction were 2 in BVR (cardiac arrest, hepatitis) and 1 in BR (tumor lysis). Grade ≥ 3 toxicities were 88.1% (163/185) BVR vs 77.5% (145/187) BR. For BVR vs BR grade ≥ 3 neutropenia occurred in 52 vs 39 pts, though febrile neutropenia (7 vs 6), anemia (7 vs 8) and thrombocytopenia (18 vs 16) did not differ. Peripheral neuropathy (PN) grade 2 was 8 sensory for BVR vs 2 sensory/1 motor for BR, while grade 3 PN was 6 sensory/1 motor for BVR vs 0 with BR. The only non-hematologic grade ≥ 3 toxicity in > 5% of pts was rash (9 vs 12 pts). Conclusions: Bortezomib did not significantly improve the primary endpoint of PFS when added to BR as initial MCL therapy. ORR and CR rates at end of induction were also similar. Follow-up continues to assess the entire treatment regimen, including consolidation R vs LR, but the PFS > 5 yrs, high ORR and MRD negativity rate (Smith et al ASH 2019) in this BR-based trial support BR as a platform for MCL induction therapy. Clinical trial information: NCT01415752.

CD20 is an attractive immunotherapy target for B-cell non-Hodgkin lymphomas, and adoptive transfer of T cells genetically modified to express a chimeric antigen receptor (CAR) targeting CD20 is a promising strategy. A theoretical limitation is that residual serum rituximab might block CAR binding to CD20 and thereby impede T cell–mediated anti-lymphoma responses. The activity of CD20 CAR-modified T cells in the presence of various concentrations of rituximab was tested in vitro and in vivo. CAR-binding sites on CD20+ tumor cells were blocked by rituximab in a dose-dependent fashion, although at 37°C blockade was incomplete at concentrations up to 200 μg/mL. T cells with CD20 CARs also exhibited modest dose-dependent reductions in cytokine secretion and cytotoxicity, but not proliferation, against lymphoma cell lines. At rituximab concentrations of 100 μg/mL, CAR T cells retained ≥50% of baseline activity against targets with high CD20 expression, but were more strongly inhibited when target cells expressed low CD20. In a murine xenograft model using a rituximab-refractory lymphoma cell line, rituximab did not impair CAR T-cell activity, and tumors were eradicated in >85% of mice. Clinical residual rituximab serum concentrations were measured in 103 lymphoma patients after rituximab therapy, with the median level found to be only 38 μg/mL (interquartile range, 19–72 μg/mL). Thus, despite modest functional impairment in vitro, the in vivo activity of CD20-targeted CAR T cells remains intact at clinically relevant levels of rituximab, making use of these T cells clinically feasible. Cancer Immunol Res; 4(6); 509–19. ©2016 AACR. See related Spotlight by Sadelain, p. 473.

Factors associated with durable remission after CD19 chimeric antigen receptor (CAR)-modified T-cell immunotherapy for aggressive B-cell non-Hodgkin lymphoma (NHL) have not been identified. We report multivariable analyses of factors affecting response and progression-free survival (PFS) in patients with aggressive NHL treated with cyclophosphamide and fludarabine lymphodepletion followed by 2 × 106 CD19-directed CAR T cells/kg. The best overall response rate was 51%, with 40% of patients achieving complete remission. The median PFS of patients with aggressive NHL who achieved complete remission was 20.0 months (median follow-up, 26.9 months). Multivariable analysis of clinical and treatment characteristics, serum biomarkers, and CAR T-cell manufacturing and pharmacokinetic data showed that a lower pre-lymphodepletion serum lactate dehydrogenase (LDH) level and a favorable cytokine profile, defined as serum day 0 monocyte chemoattractant protein-1 (MCP-1) and peak interleukin-7 (IL-7) concentrations above the median, were associated with better PFS. MCP-1 and IL-7 concentrations increased after lymphodepletion, and higher intensity of cyclophosphamide and fludarabine lymphodepletion was associated with higher probability of a favorable cytokine profile. PFS was superior in patients who received high-intensity lymphodepletion and achieved a favorable cytokine profile compared with those who received the same intensity of lymphodepletion without achieving a favorable cytokine profile. Even in high-risk patients with pre-lymphodepletion serum LDH levels above normal, a favorable cytokine profile after lymphodepletion was associated with a low risk of a PFS event. Strategies to augment the cytokine response to lymphodepletion could be tested in future studies of CD19 CAR T-cell immunotherapy for aggressive B-cell NHL. This trial was registered at www.clinicaltrials.gov as #NCT01865617.

Background Initial treatment of mantle cell lymphoma (MCL) incorporating autologous stem cell transplantation affords long-term remissions, but relapses still occur. Optimal pretransplant therapy will afford high complete response rates and not impair stem cell collection. Incorporation of bortezomib represents a natural evolution of pretransplant therapy, given its proven first-line efficacy and minimal impact on stem cell collection. Patients and Methods At the University of Washington/Seattle Cancer Care Alliance and the Cleveland Clinic Foundation, we developed modified VR-CAP/R+ara-C (bortezomib, rituximab, cyclophosphamide, doxorubicin, and prednisone, alternating with rituximab and high-dose cytarabine), for transplant-eligible patients with MCL. This regimen was administered as standard-of-care, pretransplant therapy to consecutive patients with MCL from April 2015 to the present. Results A total of 37 patients were treated with this regimen, including 18 at the University of Washington/Seattle Cancer Care Alliance and 19 at the Cleveland Clinic Foundation. Most patients had intermediate- or high-risk disease by both (mantle-cell lymphoma international prognostic index (MIPI)-B and MIPI-C category. Complete response to induction was achieved in 32 (86%) of 37 evaluable patients; 2 achieved partial response, and 3 had primary refractory disease. Stem cell collection was successful in 1 attempt in 30 of 32 patients. The median follow-up of survivors measured from start of treatment is 17.4 months. Five patients have progressed, and 4 have died (2 owing to lymphoma, 2 from toxicity). Conclusion Modified VR-CAP/R+ara-C is feasible pretransplant therapy for patients with MCL and is associated with a high rate of complete response and eligibility for autologous stem cell transplantation.

Maintenance therapy has evolved as a strategy to prolong remissions in patients with diffuse large B cell lymphoma (DLBCL) or mantle cell lymphoma (MCL), typically following a more intensive therapy, such as induction therapy or stem cell transplantation. In randomized, controlled clinical trials, this approach has successfully prolonged overall survival in some MCL clinical settings, including after autologous stem cell transplantation and after R-CHOP induction, but has generally been unsuccessful in DLBCL. This most likely reflects differences in the biology and natural history of each disease. In DLBCL, a majority of patients are cured with frontline therapy, leaving fewer who can potentially benefit from maintenance. When the disease relapses, it is usually within the first 2 years and is usually clinically aggressive and difficult to control with low-intensity therapy. In contrast, nearly all patients with MCL will eventually relapse, and the disease may remain quiescent for many years. There may also be differences in sensitivity of minimal residual disease to maintenance treatments. Thus, future strategies to improve DLBCL treatments should focus on improved induction and possibly consolidation regimens rather than maintenance. In MCL, maintenance therapy will continue to play a role in the near future, although in both diseases, applying novel immunotherapies with the potential to eradicate residual disease clones persisting after induction may be the most successful strategy to improve patient outcomes.

Introduction Programmed cell death-1 (PD-1) inhibition therapy has changed the treatment paradigm of metastatic renal cell carcinoma (MRCC) and non-small cell lung cancer (NSCLC). However, attempts to use the drug as a single agent have achieved only limited clinical success. To further enhance the clinical benefits of monotherapy, combination therapies will likely be necessary. Cytokine-induced killer (CIK) cells are a heterogeneous subset of ex vivo expanded T lymphocytes that have been shown to prolong the survival of cancer patients. We are conducting a study to evaluate the efficacy of PD-1 inhibitor in combination with CIK cells in relapsed/refractory MRCC and NSCLC and to analyze potential biomarkers to predict which patients will benefit most from the combined therapy. Case presentation The results of two patients treated in an ongoing clinical trial for MRCC and NSCLC are described here. The tumor biopsy from Patient 1 exhibited moderate CD3+ T cell infiltration, but no PD-1 or PD-L1 expression. The tumor cells from Patient 2 strongly expressed PD-L1, and there was extensive tumor infiltration by CD3+ T cells; however, no PD-1 staining was seen. Non-synonymous single nucleotide variant (nsSNVs), along with higher indel mutations, in Patient 1 and nsSNVs along with higher tumor mutation burden in Patient 2 correlate with tumor-infiltrating CD3+ lymphocyte density. Patient 1 achieved a complete response, and Patient 2 achieved a near-complete response. Conclusion A PD-1 inhibitor in combination with CIK cells led to potent antitumor activity in MRCC and NSCLC; CD3+ T cell infiltration in baseline tumor biopsies is a potential predictive biomarker. This approach is being further investigated in an ongoing phase I trial.

Introduction CD19 chimeric antigen receptor (CAR)-T cell therapy has shown efficacy in Non-Hodgkin lymphoma (NHL), but the factors associated with durable remission have not been identified. Objectives We report multivariate analyses of factors impacting progression-free survival (PFS) in NHL patients (pts) treated with cyclophosphamide and fludarabine (Cy/Flu) lymphodepletion (LD) and CD19 CAR-T cells. Methods We conducted a phase 1/2 open-label clinical trial (NCT01865617) with the primary objective of evaluating the feasibility and safety of a defined composition of CD19 CAR-T cells after LD in pts with R/R CD19+ B-cell malignancies. PFS was defined as the time from CAR-T cell infusion until disease progression or death. Multivariate models using elastic net were performed for analysis of response and PFS. Results Characteristics of the 57 pts in the study are shown in Tbl 1. Thirty-six (63%) received high-intensity (HI) Cy/Flu and 21 (37%) received low-intensity (LI) Cy/Flu LD (Tbl 1). All pts received 2 × 106 CD19 CAR-T cells/kg. The best overall response (OR) rate was 57%, with 48% complete remission (CR). Pts who achieved CR had a median PFS not reached (median follow-up [fu] 20.2 months; mo), with only 1 relapse beyond 12 mo after CAR-T cell infusion (Fig. 1). Eight of 9 pts with indolent NHL achieved CR (89%) and none relapsed (median fu 14.5 mo). For the 47 pts with aggressive NHL, the best OR rate was 51%, with 40% CR. The median PFS of aggressive NHL pts achieving CR was 20.0 mo (median fu 26.9 mo), and 24-mo probabilities of PFS and OS were 46% and 72%, respectively. In aggressive NHL, multivariate analysis showed that the probability of CR was associated with lower pre-LD serum LDH and greater increase in serum MCP-1 concentration from LD to the day of CAR-T cell infusion. HI LD was associated with more CAR-T cells in blood, but there was no difference in response in pts who received HI (CR 14/31, 45%) compared to LI LD (CR 5/16, 31%; P = .53). Multivariate analysis in aggressive NHL showed that lower pre-LD serum LDH and higher day 0 MCP-1 and peak IL-7 after CAR-T cell infusion were associated with better PFS. The IL-7 peak after CAR-T cell infusion (median day 4) correlated with day 0 IL-7, consistent with an effect of LD. MCP-1 and IL-7 increased after LD, independent of prior bridging therapy, and their concentrations correlated with Cy/Flu LD intensity. However, LD intensity was not independently associated with CR or PFS. Independent of LD intensity, a subset of pts had a robust increase in day 0 MCP-1 and peak IL-7 after LD and achieved better responses (CR 10/16, 63%) compared to those with limited cytokine increase (CR 9/30, 30%; P = .06). Conclusion Multivariate analyses show that cytokines associated with effective LD are, unlike the intensity of Cy/Flu LD, independently associated with CR and PFS. Strategies to augment biological LD efficacy could be tested in studies of CD19 CAR-T cells for aggressive NHL.

Background In relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) patients (pts) who had previously failed ibrutinib, we observed durable responses after CD19 chimeric antigen receptor-modified T-cell immunotherapy (Turtle CJ et al, JCO, 2017; NCT01865617). The combination of CD19 CAR-T cells with ibrutinib might improve response and decrease toxicity. Objectives To evaluate the efficacy and toxicity of CD19 CAR-T cell immunotherapy alone or in combination with ibrutinib for R/R CLL. Methods Our phase 1/2 study of CD19 CAR-T cell immunotherapy established a preferred regimen for R/R CLL pts of cyclophosphamide and fludarabine (Cy/Flu) lymphodepletion followed by 2 × 106 CD19 CAR-T cells/kg (Turtle, JCO, 2017). We then compared outcomes of these pts (No-ibr cohort) with a subsequent cohort receiving Cy/Flu with 2 × 106/kg JCAR014 CAR-T cells with concurrent ibrutinib (420 mg/d) from at least 2 weeks prior to leukapheresis until at least 3 months after JCAR014 infusion (Ibr cohort). Results We treated 19 and 17 pts in the No-Ibr and Ibr cohorts, respectively. Pt characteristics were comparable (Table 1). Median follow-up in responders was 764 and 98 days in the No-ibr and Ibr cohorts, respectively. Administration of ibrutinib with Cy/Flu and CD19 CAR-T cells was well tolerated in most pts; ibrutinib was reduced or discontinued in 6 pts (35%) at a median of 21 days after JCAR014 infusion. In the Ibr cohort 1 pt with grade 2 CRS (Lee, Blood, 2014) developed fatal presumed cardiac arrhythmia and 1 pt developed a subdural hematoma in the setting of trauma and thrombocytopenia. Although the proportions of pts with grade ≥1 CRS were similar between cohorts (76% vs 89%, P = 0.39), the severity of CRS (grade ≥3 CRS: Ibr, 0%; No-Ibr, 26%; P = 0.05) and serum peak IL-8 (P = 0.04), IL-15 (P = 0.003) and MCP-1 (P = 0.004) concentrations were lower in the Ibr cohort. However, we found higher peak CD4+ CAR-T cell counts (P = 0.06) and comparable peak CD8+ CAR-T cell counts (P = 0.29) in blood in the Ibr compared to the No-Ibr cohort. Sixteen pts (94%) and 18 pts (95%) in the Ibr and No-ibr cohorts, respectively, were evaluable for response. We observed a higher proportion of responders (complete response and partial response) by 2008 IWCLL criteria in the Ibr compared to the No-ibr cohort (88% vs 56%, respectively, P = 0.06). In pts with no disease by BM flow cytometry after treatment (N = 23), a higher proportion of pts in the Ibr cohort had no malignant IgH sequences at 4 weeks (83% vs 60%, P = 0.35). Using multivariable logistic regression (Table 2), treatment in the Ibr cohort and a lower pre-treatment SUVmax were associated with a higher probability of response (Ibr cohort, OR = 14.02, P = 0.05; SUVmax, OR = 1.31 per SUV unit decrease, P Conclusion The combination of ibrutinib with CD19 CAR-T cell immunotherapy was well tolerated in most pts, and might decrease the incidence of severe CRS and improve responses in pts with R/R CLL.

α-Emitting radionuclides deposit a large amount of energy within a few cell diameters and may be particularly effective for radioimmunotherapy targeting minimal residual disease (MRD). To evaluate this hypothesis, (211)At-labeled 1F5 monoclonal antibody (mAb) (anti-CD20) was studied in both bulky lymphoma tumor xenograft and MRD animal models. Superior treatment responses to (211)At-labeled 1F5 mAb were evident in the MRD setting. Lymphoma xenograft tumor-bearing animals treated with doses of up to 48 µCi of (211)At-labeled anti-CD20 mAb ([(211)At]1F5-B10) experienced modest responses (0% cures but two- to threefold prolongation of survival compared with negative controls). In contrast, 70% of animals in the MRD lymphoma model demonstrated complete eradication of disease when treated with (211)At-B10-1F5 at a radiation dose that was less than one-third (15 µCi) of the highest dose given to xenograft animals. Tumor progression among untreated control animals in both models was uniformly lethal. After 130 days, no significant renal or hepatic toxicity was observed in the cured animals receiving 15 µCi of [(211)At]1F5-B10. These findings suggest that α-emitters are highly efficacious in MRD settings, where isolated cells and small tumor clusters prevail.

Minimal detectable disease confirmed by flow cytometry and poor outcome after autologous stem cell transplantation in peripheral T-Cell lymphomas

Immunotherapy has shown great promise in the fight against cancer, as evidenced by the clinical efficacy of chimeric antigen receptor T cells in hematologic malignancies and checkpoint blockade in certain solid tumors. However, a considerable number of patients fail to respond to these therapies. Induction of myeloid-derived suppressor cells (MDSCs) by growing tumors has been shown to be one important factor limiting the efficacy of cancer immunotherapy. Recently, several chemotherapeutic agents used in conventional cancer chemotherapy have been found to reduce MDSC numbers in tumor tissues as well as in the peripheral lymphoid organs, and combining these agents with immunotherapy improved survival of tumor-bearing hosts. In this review, we will highlight the effects of chemotherapeutic agents on MDSC accumulation, and examine the various factors likely to influence these effects.

Constitutive B-cell receptor signaling leads to overexpression of the antiapoptotic BCL-2 protein and is implicated in the pathogenesis of many types of B-cell non-Hodgkin lymphoma (B-NHL). The BCL-2 small-molecule inhibitor venetoclax shows promising clinical response rates in several lymphomas, but is not curative as monotherapy. Radiotherapy is a rational candidate for combining with BCL-2 inhibition, as DNA damage caused by radiotherapy increases the activity of pro-apoptotic BCL-2 pathway proteins, and lymphomas are exquisitely sensitive to radiation. We tested B-NHL responses to venetoclax combined with either external beam radiotherapy or radioimmunotherapy (RIT), which joins the selectivity of antibody targeting with the effectiveness of irradiation. We first tested cytotoxicity of cesium-137 irradiation plus venetoclax in 14 B-NHL cell lines representing five lymphoma subtypes. Combination treatment synergistically increased cell death in 10 of 14 lines. Lack of synergy was predicted by resistance to single-agent venetoclax and high BCL-XL expression. We then assessed the efficacy of external beam radiotherapy plus venetoclax in murine xenograft models of mantle cell (MCL), germinal-center diffuse large B-cell (GCB-DLBCL), and activated B-cell (ABC-DLBCL) lymphomas. In each model, external beam radiotherapy plus venetoclax synergistically increased mouse survival time, curing up to 10%. We finally combined venetoclax treatment of MCL and ABC-DLBCL xenografts with a pretargeted RIT (PRIT) system directed against the CD20 antigen. Optimal dosing of PRIT plus venetoclax cured 100% of mice with no detectable toxicity. Venetoclax combined with radiotherapy may be a promising treatment for a wide range of lymphomas Cancer Res; 77(14); 3885–93. ©2017 AACR.

Normalization of fluorodeoxyglucose positron emission tomography (FDG PET) imaging prior to high-dose therapy and autologous stem cell transplantation (ASCT) improves outcomes in relapsed and refractory (RR) Hodgkin lymphoma (HL), but many patients refractory to platinum-based salvage regimens are unable to achieve this goal. We therefore investigated whether brentuximab vedotin (BV) could normalize FDG PET in platinum-refractory HL prior to ASCT. Fifteen consecutive patients with RR HL and FDG PET positive disease after platinum-based salvage therapy were treated with a median of 4 cycles of BV. Normalization of FDG PET (Deauville ≤2) occurred in 8/15 (53%) patients but was only observed in patients that had achieved partial remission or stable disease after platinum-based salvage therapy. All patients eventually proceeded to ASCT, regardless of FDG PET status. Our data suggest that BV can normalize FDG PET in a subset of patients with platinum-refractory HL prior to ASCT.

The rapidly expanding field of T-cell immunotherapy has experienced clinical successes along with some serious toxicities. “T Cell Immunotherapy: Optimizing Trial Design,” a workshop sponsored by the National Institutes of Health’s (NIH’s) Office of Biotechnology Activities (OBA), brought together researchers to discuss the scientific advances and share new data on key trial design issues, including the selection of new targets, optimizing the T-cell population, preconditioning regimens, strategies to promote persistence of cells, and analysis and management of acute reactions to T-cell infusions with the goal of identifying best practices and a research agenda that will facilitate further development and maximize the safety of this promising approach.

BACKGROUND: Mantle cell lymphoma (MCL) demonstrates a male to female ratio of 4:1. While the pathobiology underlying this gender-distribution imbalance is unknown, anecdotal clinical observations, as well as in vitro evidence of relative androgen receptor (AR) overexpression in MCL cell lines and response to androgen blockade, implicate the AR signaling axis as a potential driver of lymphomagenesis in MCL (Mostaghel et al. Experimental Hematology 2017). Thus, we hypothesized that blocking the AR axis could be a potential treatment strategy for MCL. Here, we report results from our pilot study using the second-generation AR antagonist enzalutamide for treatment of MCL. METHODS: A single arm pilot study was carried out at the Fred Hutchinson Cancer Research Center/University of Washington/Seattle Cancer Care Alliance. Patients ≥ 18 years, with relapsed/refractory or untreated MCL, metabolically active disease > 1.5 cm in long axis, ECOG ≤ 2, ANC ≥ 1000/mm3 & platelet ≥ 50,000/mm3, and acceptable liver and renal function were eligible. Enzalutamide 160 mg was administered daily until disease progression, intolerance, or decision of patient or physician to stop study drug. The primary endpoint was overall response rate (ORR) including complete response (CR) and partial response (PR). The secondary endpoints were time to treatment failure (TTF), progression free survival (PFS), overall survival (OS), adverse events (AEs) as measured by NCI-CTCAE version 4.0, and disease control rate. Correlative studies included impact of AR expression and changes in sex hormone levels on clinical outcomes. RESULTS: Eight patients were enrolled between September 2015 and January 2018. Median age at enrollment was 60 (range 47-79), six were male, median number of prior treatments was 2.5 (range 0-5), three received prior Bruton's tyrosine kinase (BTK) inhibitor therapy, and four had a prior autologous stem cell transplant. Mantle cell lymphoma international prognostic index (MIPI) scores were low (1), intermediate (4) and high (3). The median Ki-67 was 28% (range < 5 to 60). Patients were treated for a median of 3.5 28-day cycles. Reasons for discontinuation included progressive disease (6) and development of rash at day 10 (1). One patient remains on study and without disease progression at 16 months. Best responses in the six response-evaluable patients included three with stable disease (ranging from 5 to 8 months) and three with progressive disease. Low response rates led to closure of the study. Median PFS and OS were 157 days (range 38 to 248) and 1168 days (range 187 to 1289), respectively (figure 1). All patients had tumor AR expression available for review and stained positive (6 variably positive, 1 uniformly positive, and 1 weakly focally positive). No clinical factor, AR staining nor baseline or changes in hormone levels were correlated with response or PFS, though the single patient with ongoing disease control >15 months is the only evaluable female on study who is receiving enzalutamide as first-line therapy. Two grade 3 (abdominal pain, agitation) and one grade 4 (leukocytosis) AEs were reported. CONCLUSIONS: Blocking the AR axis with enzalutamide in the treatment of MCL was well tolerated but did not appear to translate into a meaningful ORR despite supportive preclinical data. This study was approved and funded in part by the National Comprehensive Cancer Network (NCCN) Oncology Research Program from general research support provided by Astellas. Disclosures Smith: Merck Sharp & Dohme Corp: Consultancy, Research Funding; Pharmacyclics: Research Funding; Incyte Corporation: Research Funding; Genentech: Research Funding; Denovo Biopharma: Research Funding; Portola Pharmaceuticals: Research Funding; Ayala (spouse): Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Seattle Genetics: Research Funding; Ignyta (spouse): Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma BV: Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding. Graf:AstraZeneca: Research Funding; TG Therapeutics: Research Funding; BeiGene: Research Funding. Gopal:Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy. OffLabel Disclosure: Enzalutamide is FDA approved for metastatic and non-metastatic castration-resistant prostate cancer.

Introduction: CD19-specific chimeric antigen receptor (CAR) T-cell therapy is FDA approved in patients with relapsed or refractory large B-cell lymphomas. While 35-40% of patients may achieve a durable complete response (CR), the toxicity incurred with CAR-T therapy could impact the ability to receive subsequent treatment in those who progress after CAR-T infusion. Our prior data suggested that patients who experienced early progression had inferior overall survival. We now update our results and evaluate the impact of laboratory abnormalities and comorbidities at the time of progression on overall survival. Methods: Adults with large B-cell lymphomas who received CD19-specific CAR T-cells at the University of Washington/Seattle Cancer Care Alliance were included. Patients who received CAR T-cell therapy with additional concurrent protocol-specified therapy were excluded. Those who exhibited progressive disease (PD) or persistent lymphoma after CAR T-cell therapy were the focus of this study. We defined patients who progressed or received additional lymphoma directed therapy after last CAR-T cell infusion as early PD, with all other patients defined as late PD. We collected laboratory data closest to the date of progression. We defined an absolute neutrophil count < 1000, platelet count < 75K, Creatinine > upper limit of normal (ULN), INR > ULN, AST/ALT > 2.5x ULN, total bilirubin > ULN, and LDH > ULN as abnormal. Primary endpoint of this analysis was overall survival (OS) landmarked to date of progression. Secondary endpoints include sub-group analyses based on early PD as well as lab abnormalities at the time of progression. A multi-variate analysis with select baseline and progression variables was also performed. Results: We identified 66 patients who met the above criteria. Median follow up for the entire cohort is 30.4 months (range 0.1-64 months) by reverse KM method. Median time from last planned CAR infusion to progression was 43.5 days (range 11-658). Median OS of the entire cohort was 5.43 months (95% CI 3.75-12.2). 25 (38%) patients experienced early PD, which was associated with inferior OS (median 3.75 vs. 10.4 months, P=0.02). LDH > ULN at the time of progression defined a group with inferior outcomes (median OS 3.16 vs. 17.5 months, P1 indicator of hematologic and/or organ dysfunction (excluding LDH) at the time of progression had worse outcomes compared to those with one or fewer abnormalities (median OS 1.74 vs. 7.14 months, P=0.001). Multivariate analysis identified pre-CAR IPI score 4-5 (HR 6.33, 95% CI 1.97-20.36), LDH > ULN at progression (7.01, 95% CI 2.89-17.013), and abnormal creatinine at progression (5.32, 95% CI 1.71-16.53), as factors associated with increased risk of death. Conclusions: Patients with PD post CD19-specific CAR T-cell therapy, particularly those with early PD, elevated LDH, or renal failure experience extremely poor outcomes. These data can inform discussion of prognosis for patients who progress after CAR T-cell therapy and may predict which patients may benefit from additional anti-lymphoma therapy. Figure Disclosures Lynch: Johnson Graffe Keay Moniz & Wick LLP: Consultancy; Juno Therapeutics: Research Funding; Takeda Pharmaceuticals: Research Funding; T.G. Therapeutics: Research Funding; Incyte Corporation: Research Funding; Rhizen Pharmaceuticals S.A: Research Funding. Maloney:A2 Biotherapeutics: Honoraria, Other: Stock options ; Celgene,Kite Pharma: Honoraria, Research Funding; Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria. Turtle:Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Ad hoc advisory board member; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Allogene: Other: Ad hoc advisory board member; Kite/Gilead: Other: Ad hoc advisory board member; Humanigen: Other: Ad hoc advisory board member. Smith:Portola Pharmaceuticals: Research Funding; Pharmacyclics: Research Funding; Ignyta (spouse): Research Funding; Genentech: Research Funding; Denovo Biopharma: Research Funding; Ayala (spouse): Research Funding; Bristol-Myers Squibb (spouse): Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma BV: Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Seattle Genetics: Research Funding; Incyte Corporation: Research Funding. Shadman:TG Therapeutic: Research Funding; Mustang Bio: Research Funding; Atara Biotherapeutics: Consultancy; Pharmacyclics: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Sunesis: Research Funding; Verastem: Consultancy; Astra Zeneca: Consultancy; ADC Therapeutics: Consultancy; Sound Biologics: Consultancy; Celgene: Research Funding; Gilead: Consultancy, Research Funding; BeiGene: Research Funding; Acerta Pharma: Research Funding. Ujjani:Pharmacyclics: Honoraria; Atara: Consultancy; Gilead: Consultancy; Genentech: Honoraria; Astrazeneca: Consultancy; AbbVie: Honoraria, Research Funding; PCYC: Research Funding. Cassaday:Amgen: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Other: Spouse's disclosure: employment, stock and other ownership interests. Till:Mustang Bio: Patents & Royalties, Research Funding. Shustov:Seattle Genetics, Inc.: Research Funding. Gopal:Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria; Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding.

Background: Patients infected with HIV have an 8 to 150-fold risk of lymphoma compared to HIV uninfected patients, with certain aggressive non-Hodgkin lymphoma (NHL) histologies being AIDS-defining. Despite the decrease in incidence of both NHL and Hodgkin lymphoma (HL) in the current anti-retroviral treatment (ART) era, HIV-infected patients remain at significantly increased risk of lymphoma compared to the general population. Over the last decade, advances have been made in the treatment of both NHL and HL with 18 agents approved since 2009. Unfortunately, safety and efficacy data in the HIV-infected population have been lacking in part due to exclusion of such patients from clinical trials. As such, the optimal treatment of HIV-associated lymphomas is unknown. In 2017, the National Comprehensive Care Network (NCCN) and the American Society of Clinical Oncology (ASCO) advocated expanding clinical trial opportunities for HIV-infected patients. However, exclusion criteria precluding HIV-infected patient participation likely persist. We sought to document and describe the current status of clinical trial exclusion criteria for NHL and HL as they relate to HIV infection. Methods We extracted data from the National Institute of Health's (NIH) registry of clinical trials (ClinicalTrials.gov) using the search term 'lymphoma' and reviewed all clinical trials (independent of funding source) in the United States that were recruiting or not yet recruiting adult patients for therapeutic trials (phase 1, 2, or 3) as of June 2019. A total of 734 trials met the above criteria; of these 206 were excluded as they were not primarily adult lymphoma trials (allogeneic transplant [n=87], leukemia [n=79], pediatric [n=87], lung cancer [n=12], and other [n=12]). As such, 526 clinical trials were included in the final sample. The primary outcome measure was whether HIV infection was an exclusion criterion for participation in the clinical trial. With the exception of the sample size, which was measured as a continuous variable, explanatory variables were dichotomized and included funding source (NIH vs. non-NIH), phase (phase 1 vs. phase 2 or 3), start date (start date prior to January 2018 vs. start date on or after January 2018), and recruitment status (recruiting vs. not yet recruiting). If the lymphoma under study was an aggressive subtype it was dichotomized as an AIDS-defining malignancy (aggressive NHL vs. other). We assessed whether these explanatory variables were associated with the primary outcome measure. We utilized bivariate analyses to identify measures with p < 0.20 for inclusion in a multivariate logistic regression model. Results: Of the 526 lymphoma-related trials, 352 (66.9%) excluded HIV-infected patients. Among all studies, the target sample sizes of these studies ranged from 6 to 6,542 (median 52) and were primarily phase 1 (219; 41.6%) or phase 2 (277; 52.7%) studies. Only 30 of the clinical trials were phase 3 (5.7%). The majority of studies (493; 93.7%) were actively recruiting and were initiated prior to January 1, 2018 (302; 57.4%). The majority of the 526 trials (320; 60.8%) included patients with aggressive NHL. The remaining trials included patients with indolent lymphoma, HL, or NHL with an unspecified subtype. Only 39 (7.4%) of all studies were funded strictly by NIH; the remainder were funded strictly by industry (192; 36.5%), 'other' (107; 20.3%), or a combination (188; 35.7%).[Table 1] Of the explanatory variables, funding source, sample size, and a start date on or after January 1, 2018 were associated with the outcome measure in the bivariate analysis and were included in a multivariate model. In the multivariate analyses, NIH-funded studies (OR 0.34 [0.17, 0.67], studies which began recruitment after January 1, 2018 (OR 0.66 [0.45, 0.97]) and larger studies (OR 0.998 [0.996, 0.999] were less likely to exclude HIV-infected patients. [Table 2] Conclusions: Despite support from ASCO and specific NCCN guidance which advocates that the participation in cancer clinical trials of patients living with HIV/AIDS "should be encouraged whenever feasible," the majority of interventional clinical trials for the treatment of lymphoma currently exclude participants based on infection with HIV. This goal of inclusion could be accomplished by adding an additional HIV-specific safety and efficacy cohort to most studies which could potentially be mandated by the FDA for all registrational trials. Disclosures Lynch: Rhizen Pharmaceuticals S.A: Research Funding; Takeda Pharmaceuticals: Research Funding; T.G. Therapeutics: Research Funding; Incyte Corporation: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy; Juno Therapeutics: Research Funding. Shadman:Sound Biologics: Consultancy; Acerta: Research Funding; Pharmacyclics: Consultancy, Research Funding; Celgene: Research Funding; Gilead: Research Funding; TG Therapeutics: Research Funding; Atara: Consultancy; Verastem: Consultancy; Mustang Biopharma: Research Funding; Bigene: Research Funding; ADC Therapeutics: Consultancy; Merck: Research Funding; AbbVIe: Consultancy, Research Funding; Sunesis: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Emergent: Research Funding; AstraZeneca: Consultancy. Shustov:Spectrum Pharmaceuticals: Consultancy, Research Funding. Smith:AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma BV: Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Denovo Biopharma: Research Funding; Genentech: Research Funding; Ignyta (spouse): Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Ayala (spouse): Research Funding; Pharmacyclics: Research Funding; Portola Pharmaceuticals: Research Funding; Seattle Genetics: Research Funding; Incyte Corporation: Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding. Ujjani:PCYC: Research Funding; Pharmacyclics: Honoraria; Pharmacyclics: Honoraria; Genentech: Honoraria; PCYC: Research Funding; Gilead: Consultancy; Gilead: Consultancy; Astrazeneca: Consultancy; Astrazeneca: Consultancy; Atara: Consultancy; Genentech: Honoraria; Atara: Consultancy; AbbVie: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Uldrick:Roche: Other: commercial research support through a CTA with Fred Hutchinson Cancer Research Center; Merck: Other: drug for a clinical trial from Merck through a CRADA with the NCI; Celgene: Other: research support from Celgene through a CRADA at the NCI; Patent: Patents & Royalties: co-inventor on US Patent 10,001,483 entitled . Gopal:Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria; Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding.

Background: Treatment of high-risk CLL remains challenging despite the introduction of novel therapeutic agents. Chimeric antigen receptor T-cell (CAR-T) therapy has shown promising efficacy in these patients (pts) (Turtle, JCO, 2017; Gauthier, ASH, 2019), but progressive disease after CAR-T is not uncommon. Understanding the outcomes of pts with relapsed or refractory CLL after CAR-T is important for establishing a benchmark for trials in this setting and to study optimal treatment sequencing in high-risk CLL. Methods: CLL pts treated with CD19-specific CAR-T on a clinical trial (NCT01865617) at Fred Hutch/University of Washington were reviewed. Using the 2018 IWCLL definitions, we identified pts who had stable or progressive disease (SD/PD) on initial assessment (4 weeks) or had a relapse after a complete or partial response (CR/PR) at any time. Overall survival (OS) was calculated using the Kaplan-Maier estimates. For univariate models, we included del17p, complex karyotype (CK), ibrutinib (IB) and venetoclax (Ven) failure before CAR-T, number of prior treatment lines, Richter's transformation (RT), use of bridging treatment, bulky disease (>5cm) before CAR-T, cytokine release syndrome (CRS; ≥ grade 3), neurotoxicity (NT; ≥ grade 3), refractory vs. relapsed (after CAR-T), use of IB, Ven, idelalisib (Idela), repeat CAR-T or allogeneic transplant (allo-SCT) after CAR-T progression. Only factors with significant association in the univariable models (p < 0.05) were included in the multivariable analysis. Results: 28 pts were identified with refractory (n=16; 57%) or relapsed disease [n=12; 43% - median time to relapse after CAR-T was 11 months (1.8-23)] after CAR-T. Median age was 60 (41-70) and 25% were female. Nine pts (32%) had a history of RT. Cytogenetic changes were: del17p (71%), CK (78%), del11q (37%), del13q (43%) and +12 (11%). Details of pre-CAR-T treatments are outlined in table-1. Before CAR-T, 24 pts (86%) had progressed on IB, 10 (36%) on Ven and 6 (21%) on Idela. Nine pts (32%) had progressed on both IB and Ven before CAR-T and 5 pts (18%) had prior allo-SCT. Five pts (18%) received bridging therapy after leukapheresis. Lymphodepletion (LD) was with cyclophosphamide and fludarabine (CyFlu) in 25 pts (89%). CAR-T adverse events included CRS in 22 pts (grade 3 in 2 pts, no grade 4) and NT in 7 (grade 3 in 5 and no grade 4). Details of Post CAR-T failure treatments are summarized in table-2 Both IB and Ven were used after CAR-T even if pts had progressed on them before. For Ven, 5 of 11 patients who received Ven after CAR-T had progressed on it before but had a median duration of response (DOR) of 5 months (2-8) which was not different from pts who were Ven responsive before CAR-T [5 months (1-10); p = 0.95). This was not true for IB with DOR of 2 months (0.5-7) in pre-CAR-T IB failed vs. 12.25 months (6-18.5) in pre CAR-T IB responsive pts (p = 0.001). Fourteen pts (51%) had repeat CAR-T therapy on the same protocol and 6 had CR (3) or PR (3). Four of these patients relapsed later with a DOR after second CAR-T of 5.5 months (1-33). Six pts (23%) received an allo-SCT median 6.5 months after CAR-T progression (2-14) and 3 achieved a CR (2) or PR (1), 2 did not respond (PD=1; SD=1) and one died before assessment. Two of these pts relapsed 9 and 39 months after allo-SCT. Chemotherapy was used in 7 pts with no responses. From variables tested in univariable models, only 4 were entered to the multivariate analysis (p < 0.05) and all remained significantly associated with OS: history of progression on both IB and Ven before CAR-T was strongly associated with poor OS [hazard ratio (HR) 11.2 (95% CI: 2.5-50.5) ; p=0.002]. Receiving an allo-SCT after CAR-T progression was associated with an improved OS [HR 0.14 (95% CI: 0.02-0.97); p= 0.04]. Other factors were post CAR-T progression treatment with IB [HR 0.16 (95% CI: 0.04-0.68); p = 0.01] or Ven [HR 0.17 (95% CI: 0.03-0.8); p = 0.02]. Median OS for the entire cohort was 10.4 months (0.23-59). [Fig-1] Conclusion: This data sets a benchmark for clinical trials that intend to improve outcome of CLL pts with progression after CAR-T. OS after CAR-T progression was significantly shorter in pts who received CAR-T after failing both IB and Ven compared to others. This finding supports referring high-risk CLL pts for CAR-T treatment while still responsive to either IB (BTKis) or Ven. For eligible pts, allo-SCT seems to provide a higher chance of survival in pts who progress after CAR-T. Disclosures Shadman: Verastem: Consultancy; Acerta Pharma: Research Funding; Genentech: Consultancy, Research Funding; TG Therapeutic: Research Funding; Pharmacyclics: Consultancy, Research Funding; Sound Biologics: Consultancy; AbbVie: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Gilead: Consultancy, Research Funding; Celgene: Research Funding; Mustang Bio: Research Funding; Sunesis: Research Funding; BeiGene: Research Funding; Atara Biotherapeutics: Consultancy; Astra Zeneca: Consultancy. Hirayama:DAVA Oncology: Honoraria. Lynch:Takeda Pharmaceuticals: Research Funding; Juno Therapeutics: Research Funding; Rhizen Pharmaceuticals S.A: Research Funding; T.G. Therapeutics: Research Funding; Incyte Corporation: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy. Smith:Pharmacyclics: Research Funding; Portola Pharmaceuticals: Research Funding; Incyte Corporation: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Denovo Biopharma: Research Funding; Ayala (spouse): Research Funding; Seattle Genetics: Research Funding; Genentech: Research Funding; Ignyta (spouse): Research Funding; Acerta Pharma BV: Research Funding. Ujjani:AbbVie: Honoraria, Research Funding; Pharmacyclics: Honoraria; PCYC: Research Funding; Astrazeneca: Consultancy; Genentech: Honoraria; Gilead: Consultancy; Pharmacyclics: Honoraria; PCYC: Research Funding; Atara: Consultancy. Kiem:Rocket Pharma: Consultancy, Equity Ownership; Homology Medicines: Consultancy, Equity Ownership; CSL Behring: Consultancy; Magenta Therapeutics: Consultancy. Till:Mustang Bio: Patents & Royalties, Research Funding. Gopal:Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria. Maloney:Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; Celgene,Kite Pharma: Honoraria, Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria; A2 Biotherapeutics: Honoraria, Other: Stock options . Turtle:Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Humanigen: Other: Ad hoc advisory board member; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Allogene: Other: Ad hoc advisory board member; Kite/Gilead: Other: Ad hoc advisory board member; Novartis: Other: Ad hoc advisory board member. OffLabel Disclosure: CAR-T is not an approved treatment for CLL

Background: Although the median survival for patients with multiple myeloma has improved dramatically, almost all patients will eventually relapse and become resistant to standard therapies. Chimeric antigen receptor T cells (CAR T cells) targeting B cell maturation antigen (BCMA) have shown early promise in MM, with high initial response rates. Responses are often incomplete and durability has been a key concern, with most patients relapsing within 1 year (Raje N et al NEJM 2019). We have previously demonstrated that gamma secretase inhibitors (GSI) increase BCMA surface density, decrease soluble BCMA levels and augment anti-tumor efficacy of BCMA CAR T cells in preclinical models. In a phase I first-in-human trial (NCT03502577), we combined CAR T cells expressing a fully human BCMA scFv with an orally administered gamma secretase inhibitor (JSMD194). Methods: Eligible patients had relapsed/refractory MM, with ≥ 10% plasma cells in the bone marrow by CD138 IHC, and measurable disease by IMWG criteria. BCMA was measured on CD138+ plasma cells by flow cytometry. CD8+ and CD4+ T cells were isolated via positive selection. The T cells were stimulated in separate cultures and transduced with lentiviral vector encoding a fully human BCMA scFv in conjunction with 41BB and CD3 zeta signaling domains. Following expansion, the cell product was formulated in a 1:1 ratio of CD4+:CD8+ BCMA CAR T cells. To assess the discreet impact of the GSI on plasma cell BCMA expression, patients received a GSI (JSMD194) monotherapy "run-in" involving three oral doses (25 mg) administered 48 hours apart over 5 days. A bone marrow aspirate was obtained on day 5 and BCMA expression on tumor cells was compared to baseline. Then, after lymphodepleting chemotherapy, BCMA CAR T cells were infused at a total starting dose of 5 x 10^7 EGFRt+ cells, in combination with JSMD194 dosed at 25 mg thrice weekly for three weeks, starting on the day of CAR infusion. Results: Eight patients, with a median age of 64.5 (range, 50-70 years) and a median of 10 prior regimens (range, 4-23), were screened, and seven patients have been treated. One patient had not responded to prior treatment with BCMA CAR T cells using a different construct, and another had progressed on a clinical trial employing a BCMA bispecific antibody. Median bone marrow plasma cell involvement by IHC was 32.5% (range, 10-80%) at enrollment. High-risk features were present in 75% of patients. Median involved serum free light chain at screening was 68.7 mg/dL (range18.45 - 365.61 mg/dL) and median monoclonal protein was 2.55 g/dL (range 0.1 - 5.1 g/dL). Following 3 oral doses (run in) of JSMD194, the percent of plasma cells expressing BCMA increased from 75% to 99% (7.6 to 98% pre, 75 to 100% post), soluble BCMA decreased by 2.0 fold (range 1.6 to 2.6 fold) after 3 oral doses, and BCMA antigen binding capacity increased from a median of 718 receptors to 13355 receptors per cell, or a median of 20-fold (range, 7.55-fold to 156.68-fold). Among 6 assessable patients, the best overall response rate was 100% (5 VGPR, 1 PR), with 5/6 patients MRD negative by flow. At data cutoff of July 15, 2019, no patient has relapsed, with a median follow-up of 5 months (range 1-11 months). One patient died at day 33 post-CAR T cell in the setting of cytokine release syndrome and concurrent fungal infection. The most common non-hematologic ≥ Grade 3 AE was neutropenic fever in 70%. CRS occurred in 100% of patients, primarily grades 1-2 (Lee Criteria), and neurotoxicity in 70%. Conclusions: Although BCMA CAR T cell therapy has demonstrated potent anti-tumor efficacy in multiple myeloma, a significant proportion of patients relapse. The mechanism of myeloma recrudescence requires further study, however BCMA antigen loss has been observed after CAR T cell therapy and is a putative pathway for tumor escape. In this study we demonstrate that gamma secretase inhibition with JSMD194 routinely increases BCMA surface density on myeloma cells in treated patients and reduces soluble BCMA. The combination of a gamma secretase inhibitor with BCMA CAR T cells leads to rapid responses including in patients that have failed prior BCMA targeted therapy. These responses are achieved with low CAR T cell doses. Longer follow up is required to determine if the durability of response is improved. Disclosures Cowan: Cellectar: Consultancy; Juno: Research Funding; Sanofi: Consultancy; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Abbvie: Research Funding. Pont:Fred Hutchinson Cancer Research Center: Other: Inventor on a patent. Sather:Lyell Immunopharma: Employment. Turtle:T-CURX: Membership on an entity's Board of Directors or advisory committees; Allogene: Other: Ad hoc advisory board member; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Humanigen: Other: Ad hoc advisory board member; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Other: Ad hoc advisory board member; Novartis: Other: Ad hoc advisory board member. Till:Mustang Bio: Patents & Royalties, Research Funding. Libby:Alnylam: Consultancy; Abbvie: Consultancy; Pharmacyclics and Janssen: Consultancy; Akcea: Consultancy. Becker:AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding; Accordant Health Services/Caremark: Consultancy; The France Foundation: Honoraria. Blake:Celgene: Employment, Equity Ownership. Works:Celgene: Employment, Equity Ownership. Maloney:Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; Celgene,Kite Pharma: Honoraria, Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria; A2 Biotherapeutics: Honoraria, Other: Stock options . Riddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Adaptive Biotechnologies: Consultancy; Lyell Immunopharma: Equity Ownership, Patents & Royalties, Research Funding. Green:Juno Therapeutics: Consultancy, Patents & Royalties, Research Funding; GSK: Consultancy; Celgene: Consultancy; Seattle Genetics: Research Funding; Cellectar: Research Funding. OffLabel Disclosure: Gamma secretase inhibitor to increase BCMA expression in multiple myeloma

Background: Chimeric antigen receptor T-cells (CAR-T) targeting CD19 have shown clinical efficacy in high-risk B-cell lymphomas, which has led to approval of 2 such therapies (axicabtagene ciloleucel and tisagenlecleucel) for large B-cell lymphoma after 2 lines of treatment. Despite the promising results, complete remission (CR) is achieved in ~ 50% of patients, and with longer follow-up progression-free survival is around 40%. Therefore, finding effective treatments for high-risk B-NHLs remains an unmet need. CD20 is a proven therapeutic target for B-Cell Non-Hodgkin Lymphomas (B-NHL), supported by previously approved naked and radiolabeled anti-CD20 monoclonal antibodies and a number of studies investigating novel bispecific antibodies targeting this antigen. CD20-targeted CAR-T is another potential adoptive immunotherapy option that could be utilized in combination or sequentially before or after CD19 CAR-T, depending on efficacy. Here, we present our ongoing phase I/II clinical trial investigating safety and efficacy of CD20 CAR-T for high-risk B-NHLs (NCT03277729). Methods: MB-106 is a fully human third-generation CD20 targeted CAR-T with both 4-1BB and CD28 costimulatory domains. In the phase I portion of the study we use a continual reassessment method dose escalation design to find the maximally tolerated dose. Lymphodepletion (LD) chemotherapy consists of fludarabine and cyclophosphamide. Patients (pts) will undergo a mandatory biopsy before LD to confirm the diagnosis and CD20 expression. A repeat research biopsy will be done between 10-16 days after CAR-T infusion (Figure 1). Except for the first patient of each dose cohort, treatment is given in the outpatient setting (Fred Hutch/Seattle Cancer Care Alliance) and pts will only be admitted to the University of Washington Medical Center if clinically indicated after CAR-T infusion. Response to treatment will be assessed on day 28 using Lugano criteria. Patients with relapsed or refractory CD20 positive B-NHL are eligible, including but not limited to DLBCL, primary mediastinal lymphoma, follicular lymphoma or other indolent histologies, and mantle cell lymphoma. Prior treatment with CD19 CAR-T is permitted as long as there is evidence of B-cell recovery in peripheral blood (≥ 20 B cells/µl) as a functional test to rule out persistent CD19 CAR-Ts. Patients need to meet standard organ function criteria and have adequate blood counts (ANC >750, Hb >8.5, Plts >50,000). Patients with significant neurologic conditions, active CNS lymphoma, or need for systemic immunosuppressive therapy are excluded from the study. Disclosures Shadman: Mustang Bio: Research Funding; Verastem: Consultancy; Genentech: Consultancy, Research Funding; Atara Biotherapeutics: Consultancy; Pharmacyclics: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Celgene: Research Funding; Sound Biologics: Consultancy; TG Therapeutic: Research Funding; Acerta Pharma: Research Funding; Sunesis: Research Funding; Gilead: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; BeiGene: Research Funding; Astra Zeneca: Consultancy. Gopal:Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy; Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding. Smith:Pharmacyclics: Research Funding; Genentech: Research Funding; Ignyta (spouse): Research Funding; Portola Pharmaceuticals: Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Ayala (spouse): Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma BV: Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Incyte Corporation: Research Funding; Seattle Genetics: Research Funding; Denovo Biopharma: Research Funding. Lynch:Juno Therapeutics: Research Funding; Rhizen Pharmaceuticals S.A: Research Funding; Takeda Pharmaceuticals: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy; Incyte Corporation: Research Funding; T.G. Therapeutics: Research Funding. Ujjani:Pharmacyclics: Honoraria; PCYC: Research Funding; Gilead: Consultancy; Astrazeneca: Consultancy; Atara: Consultancy; Genentech: Honoraria; AbbVie: Honoraria, Research Funding. Turtle:T-CURX: Membership on an entity's Board of Directors or advisory committees; Humanigen: Other: Ad hoc advisory board member; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Allogene: Other: Ad hoc advisory board member; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; Kite/Gilead: Other: Ad hoc advisory board member; Novartis: Other: Ad hoc advisory board member. Yeung:Pfizer: Research Funding; OBI Pharmaceutical: Research Funding; Merck: Consultancy; DiaCarta: Consultancy. Sersch:Mustang Bio: Employment. Maloney:Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; Celgene,Kite Pharma: Honoraria, Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria; A2 Biotherapeutics: Honoraria, Other: Stock options . Till:Mustang Bio: Patents & Royalties, Research Funding.

Initial therapy for MCL is effective, but most patients eventually relapse. Validated intermediate biomarkers for MCL are important to provide early assessment of treatment efficacy, prognostic information and potentially guide consolidation. The US-Canadian Intergroup trial E1411 randomly assigned patients (pts) to receive induction with BR ± bortezomib (V), followed by consolidation with R ± L. As a planned correlative, MRD was assessed after cycle 3 (I3), end of induction (EOI) and after 4 cycles of consolidation (C4) by two methods: a research version of clonoSEQ® a next generation sequencing (NGS) MRD assay, (Adaptive Biotechnologies, Seattle, WA) that leverages multiplex PCR followed by NGS to identify and track rearrangements of IgH, V-J, D-J and IgK/L loci as well as translocations in Bcl1/2-IgH, and flow cytometry (FC) (I3 and EOI only) at a central laboratory (Mayo Clinic). While outcomes by treatment arm remain blinded, we report here the results of the MRD assessments by each method and the associated progression free survival (PFS). In E1411, 373 pts, accrued between May 2012 - Sept. 2016, were randomly assigned (stratified by MIPI and age ( BR-based initial MCL therapy achieved early MRD negativity (< 10-4) in a high proportion of patients. Analyzing PB at mid-induction (I3): by NGS 89% MRD-, 9% MRD+ and 2% indeterminate, whereas by FC 87% MRD-, 12% MRD+ and 1% indeterminate. Concordance was high with 127 MRD- by both methods, 13 MRD+ by both, and 6 NGS-/FC+ (Kappa Statistic = 0.79, p-value = 0.031). By NGS, of 12 pts MRD+ at I3, 7 became MRD- at EOI, and 4 remained MRD+ (1 indeterminate). Analyzing at EOI: MRD- rates were 91% by NGS analysis of PB (147/161) and 90% in BM (96/107), vs 95% (174/183) by FC in PB. As some were indeterminate, only 7% were MRD+ by NGS in BM, 3% by NGS in PB and 5% by FC. In 88 informative samples with EOI NGS in both BM and PB, concordance was high, with 81 negative in both, 1 positive in both and 6 BM+/PB- (Kappa Statistic = 0.23, p-value = 0.031). Of 101 pts with data at all 3 timepoints, I3, EOI, and C4: 7 were MRD+ at I3, 5 of these were MRD- at EOI, but 2 of these 5 were again MRD+ at C4. Of 2 MRD+ EOI, 1 became MRD- at C4. By FC, of 17 patients MRD+ at I3, 11 (65%) became MRD- at EOI. MRD status correlated with progression-free survival (PFS). Due to the low MRD+ rate at EOI and C4, we focus here on MRD status at I3 (10-4 cutoff for both NGS and FC), using a landmark analysis of 4 months on study. Median PFS (Figure) for pts MRD- at I3 mid-induction was 58.9 months by either NGS or FC, while for those MRD+ by NGS it was 26.9 months, vs 29.9 months MRD+ by FC. Conclusions: Both NGS and FC were feasible to assess MRD status in this multi-center trial. Results of NGS and FC are concordant at the 10-4 cutoff. NGS can be more sensitive when adequate material is available, and analysis of this subgroup is ongoing. The high MRD- rate (≥ 90%) at EOI in this BR-based trial and MRD correlation with PFS supports its use as a platform for MCL trials, although consolidation may confound PFS. Early interim MRD testing at cycle 3 identifies a high-risk population who may benefit from alternative treatment strategies. Analysis by treatment arm with longer follow-up, as well as comparison with centrally reviewed PET/CTs included in this study, will help define the most informative method(s), cutoff values, and timing for assessing degree of response in MCL. Figure. Disclosures Smith: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Parekh:Foundation Medicine Inc.: Consultancy; Celgene Corporation: Research Funding; Karyopharm Inc.: Research Funding. Martin:Sandoz: Consultancy; Karyopharm: Consultancy; Teneobio: Consultancy; Celgene: Consultancy; Janssen: Consultancy; I-MAB: Consultancy. Till:Mustang Bio: Patents & Royalties, Research Funding. Leonard:Gilead: Consultancy; Akcea Therapeutics: Consultancy; Bayer Corporation: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; BeiGene: Consultancy; Celgene: Consultancy; Akcea Therapeutics: Consultancy; Nordic Nanovector: Consultancy; ADC Therapeutics: Consultancy; Sandoz: Consultancy; MorphoSys: Consultancy; Sutro Biopharma: Consultancy; Karyopharm Therapeutics: Consultancy; Karyopharm Therapeutics: Consultancy; Merck: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Epizyme, Inc: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy; Epizyme, Inc: Consultancy; Bayer Corporation: Consultancy; Miltenyi: Consultancy; Celgene: Consultancy; ADC Therapeutics: Consultancy; MorphoSys: Consultancy; Sandoz: Consultancy; Miltenyi: Consultancy; AstraZeneca: Consultancy; Nordic Nanovector: Consultancy; Merck: Consultancy; BeiGene: Consultancy; Sutro Biopharma: Consultancy. Friedberg:Bayer: Honoraria, Other: Data & Safety Monitoring Committee; Acerta: Other: Data & Safety Monitoring Committee. Kahl:TG Therapeutics: Consultancy; ADC Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; BeiGene: Consultancy.

INTRODUCTION While chemoimmunotherapy is effective in indolent B-cell non-Hodgkin lymphoma (iBCL), most patients are older and may benefit from a chemotherapy-free approach. Pembrolizumab is an immune checkpoint inhibitor which blocks the PD-1 receptor. Upon chronic antigen stimulation, T-cells can lose their anti-tumor activity due to PD-1 signaling. Multiple in vitro and in vivo studies have demonstrated that blockade of PD-1 can reverse the T-cell dysfunction induced by the tumor microenvironment. Pembrolizumab has shown an excellent safety and toxicity profile. Pembrolizumab as a single agent is FDA approved for numerous solid tumors and some lymphoma subtypes including Hodgkin lymphoma and primary mediastinal B-cell lymphoma. PD-1 inhibitors have also shown activity in the relapsed/refractory iBCL with overall responses reported to range from 10 to 60% (Ding et al., 2017; Lesokhin et al., 2016; Nastoupil et al., 2017a). However, the overwhelming majority of the patients in these studies had received prior chemotherapy. Patients with untreated iBCL have a relatively intact immune system and may have a greater capacity to mount an effective anti-tumor immune response upon reversal of T-cell dysfunction. OBJECTIVES The primary objective is evaluate the efficacy of pembrolizumab as monotherapy for patients with untreated iBCL based on ORR measured at the end of a 6-cycle treatment period. Secondary objective include: Safety and toxicity.Efficacy including complete response, clinical benefit rate (complete response + partial response + stable disease) ≥6 months, time to next therapy, progression-free survival, and duration of response. SUBJECTS AND METHODS Patients ≥ 18 years of age with previously untreated radiographically measurable follicular or marginal zone lymphoma with an indication for treatment are included. These indications include significant symptoms, end organ damage, cytopenias, or steady progression. Major exclusions include known autoimmune disease, major organ dysfunction, or ECOG ≥ 2. Treatment consists of 200 mg pembrolizumab IV on day 1 of each 21-day cycle. Initial response assessment occurs after 6 cycles. Patients with a complete or partial response can remain on the trial. Patients who have stable disease or progressive disease and are asymptomatic (excluding hyperprogression) will receive 3 additional cycles and then will be restaged to account for a delayed response. Those patients with a complete or partial response after those additional cycles can remain on the trial. Subsequently, response assessment occurs every 3 cycles. Patients without progressive disease or unacceptable toxicity are able to continue up to 18 cycles. Up to 33 patients will be enrolled, and follow-up may continue for an additional 2 years. STATISTICAL METHODS The primary efficacy endpoint is the overall response rate (CR + PR). Secondary endpoints include duration of response, progression free survival, and time to next therapy (see treatment schema). A sample size of 33 participants is planned to provide 80% power at the 5% significance level to distinguish the observed overall response rate from a true rate of ≥ 40% versus ≤ 20%) using a Simon 2-stage minimax design. The trial will be terminated early if fewer than 5 of the first 18 patients have a response. The thresholds used in this design are based on what is considered to be a clinically meaningful response rate with a novel agent with very low rates of adverse events and toxicity compared to standard regimens. This response rate threshold is also higher than what has been observed using anti-PD-1 therapy in the relapsed/refractory setting. RECRUITMENT Three patients have been accrued to the study. To date, all patients have remained on study with no grade 3-5 adverse events. CORRELATIVE STUDIES Given that pembrolizumab is known to modulate the tumor immune microenvironment, we are also performing clinical correlates on a companion protocol. Using several 22 color flow cytometry panels and 6-color multiplex immunohistochemistry, we will analyze pre- and post-treatment lymph nodes and peripheral blood. These studies will examine over 50 populations of immune cells in addition to T-cell activation/exhaustion markers such as PD-1, TIM-3, LAG-3, CTLA-4, and PD-L1. TRIAL REGISTRATION Clinicaltrials.gov (NCT03498612). Funding for both the trial and correlative studies has been provided by Merck. Figure Disclosures Gopal: Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte.: Consultancy; Seattle Genetics, Pfizer, Janssen, Gilead, Sanofi, Spectrum, Amgen, Aptevo, BRIM bio, Acerta, I-Mab-pharma, Takeda, Compliment, Asana Bio, and Incyte: Honoraria; Teva, Bristol-Myers Squibb, Merck, Takeda, Seattle Genetics, Pfizer, Janssen, Takeda, and Effector: Research Funding. Lynch:Rhizen Pharmaceuticals S.A: Research Funding; Johnson Graffe Keay Moniz & Wick LLP: Consultancy; T.G. Therapeutics: Research Funding; Takeda Pharmaceuticals: Research Funding; Incyte Corporation: Research Funding; Juno Therapeutics: Research Funding. Ujjani:Pharmacyclics: Honoraria; PCYC: Research Funding; Astrazeneca: Consultancy; Atara: Consultancy; Gilead: Consultancy; Genentech: Honoraria; AbbVie: Honoraria, Research Funding. Shadman:ADC Therapeutics: Consultancy; Genentech: Consultancy, Research Funding; Sound Biologics: Consultancy; Mustang Bio: Research Funding; TG Therapeutic: Research Funding; Pharmacyclics: Consultancy, Research Funding; Verastem: Consultancy; Gilead: Consultancy, Research Funding; Celgene: Research Funding; AbbVie: Consultancy, Research Funding; Acerta Pharma: Research Funding; BeiGene: Research Funding; Sunesis: Research Funding; Astra Zeneca: Consultancy; Atara Biotherapeutics: Consultancy. Smith:Denovo Biopharma: Research Funding; Incyte Corporation: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Ignyta (spouse): Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma BV: Research Funding; Ayala (spouse): Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Seattle Genetics: Research Funding; Portola Pharmaceuticals: Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding. Fromm:Merck, Inc.: Research Funding. Shustov:Seattle Genetics, Inc.: Research Funding. OffLabel Disclosure: Pembrolizumab for the treatment of indolent non-Hodgkin lymphoma

Background CD19-targeted chimeric antigen receptor-engineered (CD19 CAR)-T cell immunotherapy has shown promising efficacy in patients with relapsed or refractory (R/R) B-cell malignancies. The potential benefits of repeat infusions of CD19 CAR-T cells are unknown, and the factors associated with response, CAR-T cell in vivo expansion, and progression-free survival (PFS) after repeat infusion of CD19 CAR-T cells have not been investigated. Methods We analyzed the outcomes of patients with R/R B-cell malignancies after a second infusion of CD19 CAR-T cells (CART2) on a phase 1/2 trial (NCT01865617) at our institution. Responses after CAR-T cell therapy were evaluated around day 28 after infusion and defined according to the 2018 NCCN guidelines for acute lymphoblastic leukemia (ALL), 2018 iwCLL for chronic lymphocytic leukemia (CLL), and the Lugano criteria for non-Hodgkin lymphoma (NHL). Logistic, Cox and linear regression were used for multivariable analyses of response, progression-free survival and peak CD8+ CAR-T in blood, respectively. Bayesian model averaging was performed for variable selection. Results Forty-four patients evaluable for response (ALL, n=14; CLL, n=11; NHL, n=19) were included in this study. The median age at the time of CART2 was 58 (range, 23-73). Patients were heavily pre-treated (median prior therapies, 6; range, 2-13), and 16 patients (36%) had bulky (≥ 5cm) nodal or extramedullary disease. The median time from the first CAR-T infusion (CART1) to CART2 was 70 days (range, 28-712). Twenty-eight patients (64%) had received a CART1 dose ≥ 2x106 CAR-T cells/kg. Fifteen patients (32%) had not responded to CART1, 22 (50%) relapsed or progressed after having initially responded (complete response [CR], n=15; partial response [PR], n=7) to CART1; 7 (16%) received CART2 in PR after CART1. All characteristics are shown in the Table. We observed responses in all disease types, including 3 of 14 ALL patients (21%; all CR/CRi), 4 of 11 CLL patients (36%; CR/CRi, n=3; partial response [PR], n=1), and 9 of 19 NHL patients (47%; CR, n=2; PR, n=7). After a median follow-up of 43 months (range, 16-66) in alive and responding patients, the estimated 4-year PFS probability in responders was 23% (95% CI, 9-59%). The 4-year overall survival probability in responders was 36% (95% CI 19-71%) compared to 24% (95% CI, 12-47) in non-responders. Multivariable logistic regression modeling identified predictors of response after CART2: CART1 lymphodepletion (high-intensity cyclophosphamide and fludarabine [CyFlu] vs no CyFlu, OR=12.19, 95% CI, 1.10-1689.85, p=0.04), and peak of in vivo CAR-T cell expansion after CART2 (OR=2.31 per log10 CD8+ CAR-T cell/µL increase, 95% CI, 1.17-5.29, p=0.01). In a multivariable Cox model, a higher peak of CD8+ CAR-T cells after CART2 (HR=0.47 per log10 CD8+ CAR-T cell/µL increase, 95%CI, 0.33-0.68, p CART1 cell dose was associated with longer PFS (HR=0.36, 95% CI, 0.16-0.86, p=0.02). This suggested that CD8+ CAR-T cell peak after CART2 and factors increasing CART2 peak (e.g. prevention of immune rejection or increase in the infused cell dose) are key elements associated with outcomes of CART2. Hence, we looked at factors associated with higher CD8+ CART2 peak. In multivariable linear regression, CART1 CyFlu predicted a higher peak of CD8+ CAR-T cells after CART2 (high-intensity CyFlu vs no CyFlu, p CyFlu being the most commonly used lymphodepletion prior to CAR-T cell therapy, we evaluated the impact of CART1 CyFlu lymphodepletion intensity by comparing high-intensity to low-intensity CyFlu in our multivariable models. Logistic regression suggested higher probabilities of response to CART2 in patients who received high-intensity compared to low-intensity CyFlu prior to CART1 (OR=3.83, 95%CI, 0.85-21.83, p=0.08). In multivariable analysis, CART1 high-intensity CyFlu was associated with higher CD8+ CAR-T cell numbers at day 60 after CART2 compared to low-intensity CyFlu (p=0.01) after adjusting for disease type and total CD19+ cell count in the blood. Conclusion Our findings suggest outcomes after second infusions of CD19 CAR-T cells might be improved with high-intensity CyFlu lymphodepletion prior to CART1 and by increasing the CAR-T cell dose at the time of CART2. Table Disclosures Hirayama: DAVA Oncology: Honoraria. Till:Mustang Bio: Patents & Royalties, Research Funding. Kiem:Rocket Pharma: Consultancy, Equity Ownership; Homology Medicines: Consultancy, Equity Ownership; CSL Behring: Consultancy; Magenta Therapeutics: Consultancy. Shadman:Mustang Biopharma: Research Funding; Gilead: Research Funding; Bigene: Research Funding; AstraZeneca: Consultancy; Merck: Research Funding; Atara: Consultancy; AbbVIe: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; TG Therapeutics: Research Funding; Sound Biologics: Consultancy; Pharmacyclics: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Verastem: Consultancy; Celgene: Research Funding; Acerta: Research Funding; Emergent: Research Funding; Sunesis: Research Funding. Cassaday:Amgen: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Other: Spouse's disclosure: employment, stock and other ownership interests. Riddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Adaptive Biotechnologies: Consultancy; Lyell Immunopharma: Equity Ownership, Patents & Royalties, Research Funding. Maloney:BioLine RX, Gilead,Genentech,Novartis: Honoraria; Juno Therapeutics: Honoraria, Patents & Royalties: patients pending , Research Funding; Celgene,Kite Pharma: Honoraria, Research Funding; A2 Biotherapeutics: Honoraria, Other: Stock options . Turtle:Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Patents & Royalties: Co-inventor with staff from Juno Therapeutics; pending, Research Funding; Caribou Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Other: Ad hoc advisory board member; Allogene: Other: Ad hoc advisory board member; Nektar Therapeutics: Other: Ad hoc advisory board member, Research Funding; T-CURX: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Ad hoc advisory board member; Humanigen: Other: Ad hoc advisory board member.

Excitement is growing for therapies that harness the power of patients’ immune systems to combat their diseases. One approach to immunotherapy involves engineering patients’ own T cells to express a chimeric antigen receptor (CAR), to treat advanced cancers, particularly those refractory to conventional therapeutic agents. Although these engineered immune cells have made remarkable strides in the treatment of patients with certain hematologic malignancies, success with solid tumors has been limited, probably due to immunosuppressive mechanisms in the tumor niche. In nearly all studies to date, T cells bearing αβ receptors have been used to generate CAR T cells. In this review, we highlight biological characteristics of γδ T cells that are distinct from those of αβ T cells, including homing to epithelial and mucosal tissues and unique functions such as direct antigen recognition, lack of alloreactivity, and ability to present antigens. We offer our perspective that these features make γδ T cells promising for use in cellular therapy against several types of solid tumors, including melanoma and gastrointestinal cancers. Engineered γδ T cells should be considered as a new platform for adoptive T cell cancer therapy for mucosal tumors.

Mantle cell lymphoma (MCL) comprises around 6% of all non-Hodgkin's lymphoma (NHL) diagnoses. In younger patients, age less than 60 to 65 years, aggressive induction often followed by consolidation with autologous stem cell transplant has suggested improved outcomes in this population. Less intensive therapies in older patients often followed by maintenance have been studied or are under active investigation. However, despite recent advances, MCL remains incurable, with a median overall survival of around five years. Patients with high-risk disease have particularly poor outcomes. Treatment varies widely across institutions, and to date no randomized trials comparing intensive vs less intensive approaches have been reported. Although recent data have highlighted the heterogeneity of MCL outcomes, patient assessment for treatment selection has largely been driven by patient age with little regard to fitness, disease biology, or disease risk. One critical advance is the finding that minimal residual disease status (MRD) after induction correlates with long-term outcomes. As such, its use as a potential end point could inform clinical trial design. In order to more rapidly improve the outcomes of MCL patients, clinical trials are needed that prospectively stratify patients on the basis of MCL biology and disease risk, incorporate novel agents, and use MRD to guide the need for additional therapy.

Streptavidin (SA)-biotin pretargeted radioimmunotherapy (PRIT) that targets CD20 in non-Hodgkin lymphoma (NHL) exhibits remarkable efficacy in model systems, but SA immunogenicity and interference by endogenous biotin may complicate clinical translation of this approach. In this study, we engineered a bispecific fusion protein (FP) that evades the limitations imposed by this system. Briefly, one arm of the FP was an anti-human CD20 antibody (2H7), with the other arm of the FP an anti-chelated radiometal trap for a radiolabeled ligand (yttrium[Y]-DOTA) captured by a very high-affinity anti-Y-DOTA scFv antibody (C825). Head-to-head biodistribution experiments comparing SA-biotin and bispecific FP (2H7-Fc-C825) PRIT in murine subjects bearing human lymphoma xenografts demonstrated nearly identical tumor targeting by each modality at 24 hours. However, residual radioactivity in the blood and normal organs was consistently higher following administration of 1F5-SA compared with 2H7-Fc-C825. Consequently, tumor-to-normal tissue ratios of distribution were superior for 2H7-Fc-C825 (P < 0.0001). Therapy studies in subjects bearing either Ramos or Granta subcutaneous lymphomas demonstrated that 2H7-Fc-C825 PRIT is highly effective and significantly less myelosuppressive than 1F5-SA (P < 0.0001). All animals receiving optimal doses of 2H7-Fc-C825 followed by 90Y-DOTA were cured by 150 days, whereas the growth of tumors in control animals progressed rapidly with complete morbidity by 25 days. In addition to demonstrating reduced risk of immunogenicity and an absence of endogenous biotin interference, our findings offer a preclinical proof of concept for the preferred use of bispecific PRIT in future clinical trials, due to a slightly superior biodistribution profile, less myelosuppression, and superior efficacy. Cancer Res; 76(22); 6669–79. ©2016 AACR.

The average age of patients diagnosed with mantle cell lymphoma appears to be increasing. Although the majority of patients are now diagnosed in their seventh or eighth decade of life, the populations reported in clinical trials tend to be considerably younger. Recently, cooperative groups around the world have begun to focus on older patients, with clinical trials yielding important and sometimes surprising results. Novel (and some not-so-novel) therapies are increasingly being evaluated as a means to improve quality of life, not just progression-free survival. Simultaneously, a growing interest in geriatric oncology has resulted in improvements in our ability to identify individuals at risk for treatment-related morbidity and mortality. Treatment recommendations for the older patient must take into account all of these developments and should take care not to oversimplify or dichotomize patients based on chronological age alone. Just as there are some older patients that may benefit from more aggressive therapies, there are likely some younger patients that would benefit from less intensive regimens. As always, a better understanding of lymphoma biology will lead the way to better treatments, and enrollment in clinical trials is recommended.

Purpose High-dose therapy (HDT) and autologous stem-cell transplantation (ASCT) are frequently used in an attempt to improve outcome in patients with mantle-cell lymphoma (MCL); however, the importance of intensive induction regimens before transplantation is unknown. Patients and Methods To address this question, we evaluated baseline characteristics, time to treatment, induction regimen, disease status at the time of transplantation, and MIPI score at diagnosis and their associations with survival in 118 consecutive patients with MCL who received HDT and ASCT at our centers. Results The MIPI was independently associated with survival after transplantation in all 118 patients (hazard ratio [HR], 3.5; P < .001) and in the 85 patients who underwent ASCT as initial consolidation (HR, 7.2; P < .001). Overall survival rates were 93%, 60%, and 32% at 2.5 years from ASCT for all patients with low-, intermediate-, and high-risk MIPI, respectively. Low-risk MIPI scores were more common in the intensive induction group than the standard induction group in all patients (64% v 46%, respectively; P = .03) and in the initial consolidation group (66% v 45%, respectively; P = .03). After adjustment for the MIPI, an intensive induction regimen was not associated with improved survival after transplantation in all patients (HR, 0.5; P = .10), the initial consolidation group (HR, 1.1; P = .86), or patients ≤ 60 years old (HR, 0.6; P = .50). Observation of more than 3 months before initiating therapy did not yield inferior survival (HR, 2.1; P = .12) after adjustment for the MIPI in patients receiving ASCT. Conclusion An intensive induction regimen before HDT and ASCT was not associated with improved survival after adjusting for differences in MIPI scores at diagnosis.

BACKGROUND: Current manufacturing paradigms for chimeric antigen receptor (CAR) modified T cells require ex vivo T cell activation, genetic modification, and expansion in cytokine-containing cell cultures. Most CAR T cell studies infuse cell products generated from unselected cells, in which the CD4:CD8 ratio is determined by what is collected during leukapheresis. The proportion of each subset can vary greatly in these products, reflecting the high heterogeneity of the CD4:CD8 ratio present in patients' (pts) blood at the time of treatment. Preclinical data demonstrate superior in vivo anti-tumor efficacy of cell products consisting of equal numbers of CD4+ and CD8+ T cells, and a recent clinical trial, in which CD19-targeted CAR T cell products were infused at a 1:1 ratio of CD4:CD8 T cells, showed clear dose-response and dose-toxicity relationships. However, CAR T cell manufacturing using parallel CD4+ and CD8+ CAR T cell cultures adds significant cost and complexity compared with a single-stream culture. Additionally, we have found that CD8+ T cell cultures from heavily treated pts often exhibit suboptimal expansion. We therefore evaluated whether CAR T cell products with approximately equal ratios of CD4+ to CD8+ cells could be generated by mixing CD4+ and CD8+ cells at a defined ratio at culture initiation, and whether the presence of ex vivo CD4+ help can improve CD8+ cell expansion. METHODS: CD4+ and CD8+ T cells were isolated from apheresis peripheral blood mononuclear cell products of lymphoma pts (n=15) treated in one of three CD20-targeted CAR T cell trials or healthy donors (n=5) using positive (CD4) and negative (CD8) immunomagnetic bead selection. Cell cultures (1x106 cells each) were established by activating CD4+ and CD8+ cells with anti-CD3/CD28-coated paramagnetic beads, mixing them at various ratios in 24-well plates, and transducing 24 hours later with a lentivirus encoding the 1.5.3-NQ-28-BB-z CD20 CAR. Beads were removed at day 4, and cells were expanded in IL-2 containing medium. At day 7, cells were counted and analyzed by flow cytometry for CD4, CD8, and CAR expression, and then restimulated 1:1 with irradiated CD20+ lymphoblastoid cells to boost growth. On day 14 cells were again counted and analyzed by flow cytometry for CD4, CD8, and CAR expression, as well as immunophenotype. In some cases CAR+CD4+ and CAR+CD8+ cells were flow-sorted from either CD4-only, CD8-only, and mixed cultures, stained with CFSE, and restimulated with irradiated CD20+ Raji tumor cells. Proliferation and cytokine secretion were measured by flow cytometry and Luminex, respectively. In vivo T cell activity was assessed using an NSG mouse model in which T cells were infused 7 days after i.v. injection of Raji-ffLuc cells. Suboptimal doses of T cells were used to distinguish differences between conditions, since higher doses cure most mice. Mice received either: (1) 70:30 mixed CD4:CD8 CAR+ cultures (n=8), (2) 1:1 ratio of CD4:CD8 CAR+ cells grown separately (n=8), (3) Mixed CD4:CD8 empty vector cells (n=5), or (4) no treatment (n=5). RESULTS: An initial CD4:CD8 ratio of 70:30 yielded a median CD4/CD8 ratio of 1.1 for pts (Figure 1A) and 1.3 for donors at day 7, and a ratio of 0.6 and 1.0 for pts and donors, respectively, at day 14. Mixed cultures resulted in CD8+ cell expansion that was significantly higher than in separate cultures. At day 7, mean CD8+ cell expansion was 12.1-fold vs. 4.6-fold for 70:30 mixed vs. separate cultures for donors, and 2.9-fold vs. 0.7-fold for pts (Figure 1B). At day 14 CD8+ mean cell expansion was 105-fold (70:30 mixed) vs. 25-fold (separate) for donors and 40-fold vs. 1.9-fold for pts. CD8+ cells grown in mixed cultures also exhibited higher expression of memory markers (CD62L and CCR7), lower levels of exhaustion markers (Lag-3 and PD-1), and better proliferation compared with CD8 cells grown in separate cultures. In the mice we found that tumor growth inhibition was superior in the 70:30 mixed culture group than in mice receiving a 1:1 ratio of CD4:CD8 cells grown separately (Figure 1C). CONCLUSIONS: A single-stream CAR T cell culture initiated at a defined CD4:CD8 ratio of 70:30 yielded on average approximately equal numbers of CD4+ and CD8+ cells in the final cell product. Mixed CD4+ and CD8+ cultures generated CD8+ T cells with a less differentiated phenotype, and superior expansion, proliferative capacity, and in vivo activity compared with CD4+ and CD8+ cells manufactured in parallel. Disclosures Green: Juno Therapeutics: Patents & Royalties, Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding.

Introduction Autologous T cells expressing a CD19-specific chimeric antigen receptor (CAR) have produced impressive minimal residual disease-negative complete remission (MRD-neg CR) rates in relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) patients (pts). Factors associated with durable remission in pts achieving MRD-neg CR after immunotherapy with T cells engineered with a CD19 CAR (FMC63.41bb.3ζ) have not been elucidated. Methods We studied factors impacting disease-free survival (DFS) of adults with B-ALL treated with lymphodepletion chemotherapy and CD19 CAR-T cells in a phase I/II clinical trial (NCT01865617). Pts were eligible for this analysis if they had bone marrow leukemia identified by flow cytometry and/or extramedullary disease before CAR-T cell therapy, and received CAR-T cells at or below the previously determined maximum tolerated dose (MTD; Turtle, JCI 2016). Anti-tumor response after CAR-T cell infusion was assessed by bone marrow aspiration and biopsy, with PET-CT performed in pts with extramedullary disease. High resolution (1:10,000) flow cytometry was used to identify marrow MRD, and marrow from pts in MRD-neg CR was evaluated by high throughput sequencing (HTS) of IGH, IGK, TRB, TRD, and TRG genes. Cox regression univariate and stepwise multivariable modeling were performed to identify factors associated with DFS. Results Of 57 pts who received lymphodepletion and CD19 CAR-T cells, 53 were evaluable for response and 4 were not evaluable (one MRD-neg CR before CAR-T cell infusion; 2 received CAR-T cells above the MTD; one fatal neurotoxicity prior to restaging). Forty-five of 53 restaged pts (85%) achieved MRD-neg CR after CAR-T cell therapy. With a median follow-up of 30.9 months, DFS and overall survival (OS) were longer in pts who achieved MRD-neg CR compared to those who did not (Fig 1A; median DFS, 7.6 vs 0.8 months, P < .0001; median OS, 20.0 vs 5.0 months, P = .014). Twenty-eight of the 45 pts who achieved MRD-neg CR had a leukemic clone identified by HTS prior to CAR-T cell infusion, and in 20 of these pts (71%), the leukemic clone was not detected in marrow 3 weeks after CAR-T cell infusion. DFS was better in MRD-neg CR pts with no detected malignant clone compared to those with a persistent clone by HTS (Fig 1B; median DFS, 8.4 vs 3.6 months, P = .036). We then used stepwise multivariable modeling to determine factors impacting DFS in the pts who achieved MRD-neg CR (n = 45). Better DFS was seen in pts with a higher pre-lymphodepletion platelet count (hazard ratio, HR 0.65 [95% CI; 0.47-0.88] per 50,000/μL increment P = .006), lower pre-lymphodepletion LDH (HR 1.39 [1.12-1.74] per 100 U/L increment, P = .003), and with incorporation of fludarabine into the cyclophosphamide-based lymphodepletion (Cy/Flu; HR 0.34 [0.15-0.78], P = .011). Similar findings were noted in analysis of MRD-neg CR pts who had no malignant clone by HTS after CAR-T cells. Pts with platelets ≥100,000/μL and normal LDH before lymphodepletion who received Cy/Flu (good risk, n = 15) had 2-year point estimates of DFS and OS of 78% and 86%, respectively. Allogeneic hematopoietic cell transplantation (HCT) is standard of care in suitable R/R adult B-ALL pts after achieving MRD-neg CR. Eighteen pts in MRD-neg CR after CAR-T cells underwent HCT a median of 2.3 months after CAR-T cell infusion. We analyzed the effect on DFS of HCT after CAR-T cell therapy by treating HCT as a time-dependent covariate. After adjusting for LDH, platelets, and Cy/Flu lymphodepletion, pts undergoing HCT after CAR-T cell therapy had lower risk of failure for DFS compared to those who did not undergo HCT (Table 1). No significant interaction effect was seen between HCT and risk group (P = .51). With a median follow-up of 28.4 months after HCT, 2-year point estimates of DFS and OS were 61% and 72% respectively. The 2-year cumulative incidence of relapse was 17% and non-relapse mortality was 23%. Conclusion A high rate of MRD-neg CR was seen following CD19 CAR-T cell therapy in adult B-ALL pts and is associated with improved DFS and OS. Absence of the index clone by HTS after CAR-T cells was associated with better DFS, suggesting deeper responses are associated with improved outcomes. Stepwise multivariable modeling identifies better DFS in pts with higher pre-lymphodepletion platelet count and lower LDH, and with use of Cy/Flu lymphodepletion. After adjusting for these factors, HCT after CD19 CAR-T cells may also be associated with better DFS. Disclosures Hay: DAVA Oncology: Honoraria. Hirayama:DAVA Oncology: Honoraria. Li:Juno Therapeutics: Employment, Equity Ownership. Till:Mustang Bio: Patents & Royalties, Research Funding. Kiem:Rocket Pharmaceuticals: Consultancy; Homology Medicine: Consultancy; Magenta: Consultancy. Ramos:Seattle Genetics: Employment, Equity Ownership. Shadman:Qilu Puget Sound Biotherapeutics: Consultancy; AstraZeneca: Consultancy; Pharmacyclics: Research Funding; Genentech: Consultancy; Mustang Biopharma: Research Funding; AbbVie: Consultancy; Celgene: Research Funding; Verastem: Consultancy; Acerta Pharma: Research Funding; Genentech: Research Funding; TG Therapeutics: Research Funding; Beigene: Research Funding; Gilead Sciences: Research Funding. Cassaday:Adaptive Biotechnologies: Consultancy; Amgen: Consultancy, Research Funding; Incyte: Research Funding; Seattle Genetics: Other: Spouse Employment, Research Funding; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Research Funding; Pfizer: Consultancy, Research Funding; Merck: Research Funding. Acharya:Juno Therapeutics: Research Funding; Teva: Honoraria. Riddell:Adaptive Biotechnologies: Consultancy; NOHLA: Consultancy; Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Cell Medica: Membership on an entity's Board of Directors or advisory committees. Maloney:Seattle Genetics: Honoraria; Roche/Genentech: Honoraria; GlaxoSmithKline: Research Funding; Janssen Scientific Affairs: Honoraria; Juno Therapeutics: Research Funding. Turtle:Adaptive Biotechnologies: Consultancy; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics / Celgene: Consultancy, Patents & Royalties, Research Funding; Gilead: Consultancy; Nektar Therapeutics: Consultancy, Research Funding; Caribou Biosciences: Consultancy; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Consultancy; Aptevo: Consultancy.

Introduction Autologous T cells engineered to express a CD19-specific chimeric antigen receptor (CAR) have shown high overall response rates (ORR) in otherwise treatment-refractory CD19+ B-cell non-Hodgkin lymphoma (NHL); however, not all patients (pts) achieve complete remission (CR). PD-L1 expression on tumor cells and/or other tissues could impair the function of PD-1+ CAR-T cells and the efficacy of CD19 CAR-T cell immunotherapy. PD-1 pathway blockade may enhance the function and antitumor activity of CD19 CAR-T cells. Here we report preliminary data from a phase 1 dose-finding study (NCT02706405) of the safety and feasibility of combination therapy with JCAR014 CD19-specific 4-1BB-costimulated CAR-T cells and escalating doses of durvalumab, an anti-PD-L1 monoclonal antibody, in adults with relapsed/refractory aggressive B-cell NHL. Methods Pts are treated in one of two groups. All pts receive lymphodepletion chemotherapy with cyclophosphamide and fludarabine followed by infusion of JCAR014. Pts in group 1 receive the first infusion of durvalumab (225 mg, 750 mg, or 1500 mg) 21-28 days after treatment with JCAR014. Pts in group 2 receive the first dose of durvalumab (7.5 mg, 22.5 mg, 75 mg, 225 mg, 750 mg, or 1500 mg) 1 day prior to JCAR014 infusion. Up to 10 doses of durvalumab are administered after JCAR014 at the highest identified safe dose at 4-week intervals until toxicity or disease progression. We evaluated the safety, tolerability, and efficacy of the combination therapy and the pharmacokinetic profile of JCAR014 after infusion. Adverse events were graded using the Common Terminology Criteria for Adverse Events (CTCAE) v4.03, with the exception of cytokine release syndrome (CRS), which was graded according to consensus criteria (Lee, Blood 2014). Positron emission tomography/computed tomography was performed approximately 1, 2, 4, 6, 9, and 12 months after JCAR014 infusion and the best anti-tumor response was reported according to the Lugano criteria (Cheson, JCO 2014). Results Patient characteristics are shown in Table 1. Fifteen pts have been treated, including 6 in group 1 who received post-JCAR014 durvalumab doses of 225 mg (n = 3) and 750 mg (n = 3), and 9 in group 2 who received pre-JCAR014 durvalumab doses of 7.5 mg (n = 1), 22.5 mg (n = 1), 75 mg (n = 3), or 225 mg (n = 4). Durvalumab dose escalation is ongoing. JCAR014 manufacturing was successful for all pts. All pts received 2 x 106 JCAR014 CAR-T cells/kg, except the first 2 pts treated on the study who received 7 x 105 CAR-T cells/kg. Of the 13 pts who received JCAR014 at 2 x 106 CAR-T cells/kg, 5 pts (38%) developed CRS (2 grade 1, 2 grade 2, and 1 grade 4) and one (8%) developed grade 1 neurotoxicity. CRS and/or neurotoxicity occurred within 4 weeks of JCAR014 infusion, and were not observed when durvalumab was administered after JCAR014. With the exception of B cell aplasia, no autoimmune adverse events were observed. Twelve of 13 pts who received 2 x 106 CAR-T cells/kg were evaluable for response. One patient, who had grade 4 CRS and biopsy evidence of extensive CAR-T cell infiltration into persistent sites of disease, elected to receive hospice care and died on day 32 after JCAR014 infusion without full response evaluation. The overall response rate was 50% (5 CR, 42%; 1 PR, 8%). Of the 5 pts who achieved CR, 3 were in CR at the first restaging after JCAR014 and 2 subsequently converted to CR after the first post-JCAR014 durvalumab infusion. Only one patient who achieved CR has relapsed (median follow-up 10.6 months, range 3.7-11.8). Continued stable disease or evidence of regression was seen in 4 of 6 (67%) initially non-responding pts who continued durvalumab therapy (median 5 doses, range 1-6). CAR-T cell counts expanded in the peripheral blood within 14 days of JCAR014 infusion in all pts. Higher peak and day 28 CAR-T cell copy numbers in blood by qPCR were observed in responding pts. CAR-T cells were detected for a median of 5.1 months (range, 1.7 to 9.1 months) in responding pts. In vivo re-accumulation of CAR-T cells after the first post-JCAR014 durvalumab dose was observed in the blood of two patients in group 2. Conclusion The combination of JCAR014 with durvalumab for the treatment of adult pts with aggressive B-cell NHL appears safe; however, dose escalation is ongoing. Complete responses were observed both at initial restaging after JCAR014 infusion, and also subsequently in pts continuing durvalumab therapy after initially failing to achieve CR. Disclosures Hirayama: DAVA Oncology: Honoraria. Hay:DAVA Oncology: Honoraria. Till:Mustang Bio: Patents & Royalties, Research Funding. Kiem:Homology Medicine: Consultancy; Magenta: Consultancy; Rocket Pharmaceuticals: Consultancy. Shadman:Verastem: Consultancy; Beigene: Research Funding; Mustang Biopharma: Research Funding; Gilead Sciences: Research Funding; TG Therapeutics: Research Funding; AbbVie: Consultancy; Genentech: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Qilu Puget Sound Biotherapeutics: Consultancy; Genentech: Consultancy; AstraZeneca: Consultancy; Acerta Pharma: Research Funding. Cassaday:Jazz Pharmaceuticals: Consultancy; Amgen: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Other: Spouse Employment, Research Funding; Pfizer: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Kite Pharma: Research Funding; Incyte: Research Funding. Acharya:Juno Therapeutics: Research Funding; Teva: Honoraria. Riddell:Cell Medica: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Adaptive Biotechnologies: Consultancy; NOHLA: Consultancy. Maloney:Roche/Genentech: Honoraria; Juno Therapeutics: Research Funding; Janssen Scientific Affairs: Honoraria; GlaxoSmithKline: Research Funding; Seattle Genetics: Honoraria. Turtle:Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy; Bluebird Bio: Consultancy; Gilead: Consultancy; Nektar Therapeutics: Consultancy, Research Funding; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics / Celgene: Consultancy, Patents & Royalties, Research Funding; Caribou Biosciences: Consultancy; Aptevo: Consultancy.

Background: Rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) remains standard therapy for previously untreated diffuse large B-cell lymphoma (DLBCL). However, a substantial proportion of patients (pts) will relapse. The anti-PD-1 monoclonal antibody pembrolizumab has shown modest efficacy in previously treated DLBCL. We postulated that the first-line setting, with relatively intact host immunity and coexistence of malignant cells with T-cells in the microenvironment, may represent an opportunity for effective immune checkpoint inhibition. We carried out the first known prospective trial of anti-PD1 therapy with anthracycline chemotherapy in lymphoma, to evaluate the safety of this combination. Methods: Pts age 18 years or older with previously untreated DLBCL, transformed lymphoma and grade 3B follicular lymphoma with a plan for 6-cycle, curative-intent RCHOP were eligible. Steroids within 7 days of treatment, active autoimmune disease, or history of pneumonitis were excluded. This phase I study combined pembrolizumab (200 mg IV q 3 weeks x 6) to RCHOP x 6, with supportive care per standard practice. A 30-pt sample size permitted estimation of the rate of clinically relevant grade 3-5 toxicity, assumed to occur in 40% of pts with RCHOP alone. A stopping rule for more than 3 instances of non-relapse death or inability to complete 6 cycles of RCHOP for any reason was applied. Secondary endpoints included response rates, overall (OS) and progression-free survival (PFS). Baseline PDL1 expression was analyzed centrally (Merck/Qualtek). Peripheral blood flow cytometry for changes in PD1, PDL-1, and PDL-2 subsets were performed. After PET-based response assessment, pts were followed for relapse and survival. Results: Since March 2016, 29 pts were treated on study; 28 have finished all therapy. One is currently on therapy, and 1 remains to be enrolled. Pt characteristics are in Table 1. In 29 pts to date, 18 grade 3-5 clinically significant AE's occurred in 13 unique pts (13/29, 45%). 16 SAE's occurred in 11 pts (11/29, 38%); none qualified as unanticipated events. Two deaths occurred: One in the first accured patient, who had extensive gastric involvement by DLBCL, and died during cycle 1 of bleeding from the responding tumor bed despite maximal inpatient intervention. The other death occurred due to steroid-refractory GVHD after haploidenticial allogeneic transplant for relapsed disease. Four immune-related adverse events (IRAE) occurred: grade 3 rash, resolving with oral steroids and not recurring with further pembrolizumab, grade 1 hyperthyroidism, grade 2 colitis, and 1 episode of grade 3 pneumonitis. This case of pneumonitis was the only immune-related SAE, occurring in a 78 yo with a history of tobacco use and COPD, and resulted in stopping therapy after cycle 3. Among 27 completing treatment (excluding the pt who died during cycle 1), average anthracycline dose was 95% of expected; anthracycline relative dose intensity (RDI: delivered dose intensity/standard dose intensity) was 94%. PET response assessment among 26 evaluable pts showed 18 CR (69%), 7 PR, and 1 primary refractory disease. Among 7 PR, 1 relapsed, 3 had negative biopsies, and 3 remain in remission. Median follow-up of survivors is 13 months and 2 relapses (1 primary progressive disease, 1 after PET PR) occurred. One-year PFS is 87% (Figure 1). Baseline PDL-1 staining available for 19 pts showed a median % tumor cell staining of 30% (moderate 2+ plus strong 3+ staining; range, 0-100%). Tumor PDL1 was ≤5% in 4, 10-29% in 5, 30-49% in 4, and ≥50% in 6 pts. Both EBV+ DLBCL had 60% tumor PDL1 expression. 1 relapsing pt had no detectable tumor PDL1, and the THRLBL failed for technical reasons. Conclusions: RCHOP with pembrolizumab 200 mg q 3 weeks x 6 cycles is safe, with toxicity similar to RCHOP alone and only 4 IRAE's. Anthracycline dose intensity, CR rate, and PFS are favorable. PDL1 tumor cell expression of 10% or more was observed in 15/19 pts. These data support further study of pembrolizumab with chemotherapy in untreated lymphoid malignancies. Final response/progression, correlative studies, and survival data will be presented in December after final accrual. Disclosures Smith: Merck Sharp and Dohme Corp.: Consultancy, Research Funding; Pharmacyclics: Research Funding; Portola Pharmaceuticals: Research Funding; Acerta Pharma BV: Research Funding; Genentech: Research Funding; Seattle Genetics: Research Funding; Incyte Corporation: Research Funding. Lynch:Johnson Graffe Keay Moniz & Wick LLP: Consultancy; Incyte Corporation: Research Funding; Takeda Pharmaceuticals: Research Funding; T.G. Therapeutics: Research Funding; Rhizen Pharmaceuticals S.A.: Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding. Cowan:Sanofi: Research Funding; Juno Therapeutics: Research Funding; Abbvie: Research Funding; Janssen: Research Funding. Shadman:Acerta Pharma: Research Funding; Genentech: Research Funding; Verastem: Consultancy; Gilead Sciences: Research Funding; Qilu Puget Sound Biotherapeutics: Consultancy; Celgene: Research Funding; Genentech: Consultancy; Beigene: Research Funding; Pharmacyclics: Research Funding; AbbVie: Consultancy; Mustang Biopharma: Research Funding; TG Therapeutics: Research Funding; AstraZeneca: Consultancy. Shustov:Seattle Genetics: Research Funding. Cassaday:Amgen: Consultancy, Research Funding; Incyte: Research Funding; Seattle Genetics: Other: Spouse Employment, Research Funding; Merck: Research Funding; Jazz Pharmaceuticals: Consultancy; Adaptive Biotechnologies: Consultancy; Pfizer: Consultancy, Research Funding; Kite Pharma: Research Funding. Gopal:Pfizer: Research Funding; Janssen: Consultancy, Research Funding; BMS: Research Funding; Takeda: Research Funding; Incyte: Consultancy; Spectrum: Research Funding; Gilead: Consultancy, Research Funding; Merck: Research Funding; Aptevo: Consultancy; Asana: Consultancy; Seattle Genetics: Consultancy, Research Funding; Brim: Consultancy; Teva: Research Funding.