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Plasmablastic lymphoma (PBL) is a rare entity, commonly associated with immunosuppressed states such as human immunodeficiency virus (HIV) infection or solid organ transplant. The clinical course is characterized by high relapse rates and a poor prognosis, leading some clinicians to recommend aggressive frontline therapy. However, a specific review of limited stage (LS) PBL patients is not available to evaluate outcomes and justify treatment recommendations. We performed a retrospective review of LS PBL cases to provide insight into this rare disease. Our cohort consisted of 80 stage I or II PBL patients from 13 US academic centers. With a median follow up of 34 months (1-196), the 3-year progression-free survival (PFS) and overall survival (OS) of the entire cohort were 72% (95% CI 62, 83) and 79% (95% CI 70, 89), respectively. The 3-year PFS and OS of patients treated with frontline chemotherapy alone was 65% (95% CI 50, 84) and 71% (95% CI 56, 89), respectively, compared to 85% (95% CI 72, 100) and 96% (95% CI 89, 100), respectively, in patients treated with combined frontline chemotherapy with radiation consolidation. Our data demonstrate favorable outcomes in LS PBL with no improvements in outcome from aggressive frontline treatment including Hyper-CVAD or auto-SCT consolidation. Multivariate regression analysis (MRA) demonstrated improved PFS for patients receiving EPOCH based frontline therapy versus CHOP (HR: 0.23; p = 0.029). Frontline chemotherapy followed by radiation consolidation versus chemotherapy alone appeared to be associated with improved relapse and survival outcomes but did not show statistical significance in MRA.

Purpose:Venetoclax-based therapy is a standard-of-care option in first-line and relapsed/refractory chronic lymphocytic leukemia (CLL). Patient management following venetoclax discontinuation remains nonstandard and poorly understood.Experimental Design:To address this, we conducted a large international study to identify a cohort of 326 patients who discontinued venetoclax and have been subsequently treated. Coprimary endpoints were overall response rate (ORR) and progression-free survival for the post-venetoclax treatments stratified by treatment type [Bruton's tyrosine kinase inhibitor (BTKi), PI3K inhibitor (PI3Ki), and cellular therapies].Results:We identified patients with CLL who discontinued venetoclax in the first-line (4%) and relapsed/refractory settings (96%). Patients received a median of three therapies prior to venetoclax; 40% were BTKi naïve (n = 130), and 81% were idelalisib naïve (n = 263). ORR to BTKi was 84% (n = 44) in BTKi-naïve patients versus 54% (n = 30) in BTKi-exposed patients. We demonstrate therapy selection following venetoclax requires prior novel agent exposure consideration and discontinuation reasons.Conclusions:For BTKi-naïve patients, selection of covalently binding BTKis results in high ORR and durable remissions. For BTKi-exposed patients, covalent BTK inhibition is not effective in the setting of BTKi resistance. PI3Kis following venetoclax do not appear to result in durable remissions. We conclude that BTKi in naïve or previously responsive patients and cellular therapies following venetoclax may be the most effective strategies.See related commentary by Rogers, p. 3501

Supplemental Figure 2: Progression free survival of patients without prior BTKi exposure who had progressed on venetoclax and were then treated with BTKi.

Supplemental Figure 1: Overall survival of entire cohort from initiation of venetoclax.

To report the activity of venetoclax in patients with relapsed mantle cell lymphoma (MCL), we identified 81 patients treated with venetoclax monotherapy (n=50, 62%) or in combination with a BTK inhibitor (n=16, 20%), an anti-CD20 monoclonal antibody (n=11, 14%), or others at 12 US academic medical centers. Patients had high-risk disease features including Ki67 >30% (61%), blastoid/pleomorphic histology (29%), complex karyotype (34%), and TP53 alterations (49%), and received a median of 3 prior treatments including BTK inhibitors in 91%. Venetoclax alone or in combination resulted in an overall response rate (ORR) of 40% and median progression-free (PFS) and overall survival (OS) of 3.7 and 12.5 months, respectively. The receipt of ≤ 3 prior treatments was associated with higher odds of response to venetoclax in a univariable analysis. In a multivariable analysis, having a high-risk MIPI score prior to venetoclax and disease relapse or progression within 24 months of diagnosis were associated with inferior OS whereas the use of venetoclax in combination was associated with superior OS. Although most patients (61%) had low risk for tumor lysis syndrome (TLS), 12.3% of patients developed TLS despite the implementation of several mitigation strategies. In conclusion, venetoclax resulted in good ORR but short PFS in high-risk patients with MCL and may have a better role in earlier lines of treatment and/or in combination with other active agents. TLS remains an important risk in patients with MCL who initiate treatment with venetoclax.

Purpose: Marginal zone lymphoma (MZL) is an uncommon non–Hodgkin lymphoma with malignant cells that exhibit a consistent dependency on B-cell receptor signaling. We evaluated the efficacy and safety of zanubrutinib, a next-generation selective Bruton tyrosine kinase inhibitor, in patients with relapsed/refractory (R/R) MZL. Patients and Methods: Patients with R/R MZL were enrolled in the phase II MAGNOLIA (BGB-3111–214) study. The primary endpoint was overall response rate (ORR) as determined by an independent review committee (IRC) based on the Lugano 2014 classification. Results: Sixty-eight patients were enrolled. After a median follow-up of 15.7 months (range, 1.6 to 21.9 months), the IRC-assessed ORR was 68.2% and complete response (CR) was 25.8%. The ORR by investigator assessment was 74.2%, and the CR rate was 25.8%. The median duration of response (DOR) and median progression-free survival (PFS) by independent review was not reached. The IRC-assessed DOR rate at 12 months was 93.0%, and IRC-assessed PFS rate was 82.5% at both 12 and 15 months. Treatment was well tolerated with the majority of adverse events (AE) being grade 1 or 2. The most common AEs were diarrhea (22.1%), contusion (20.6%), and constipation (14.7%). Atrial fibrillation/flutter was reported in 2 patients; 1 patient had grade 3 hypertension. No patient experienced major hemorrhage. In total, 4 patients discontinued treatment due to AEs, none of which were considered treatment-related by the investigators. Conclusions: Zanubrutinib demonstrated high ORR and CR rate with durable disease control and a favorable safety profile in patients with R/R MZL.

The Bcl-2 inhibitor venetoclax has yielded exceptional clinical responses in chronic lymphocytic leukemia (CLL). However, de novo resistance can result in failure to achieve negative minimal residual disease and predicts poor treatment outcomes. Consequently, additional proapoptotic drugs, such as inhibitors of Mcl-1 and Bcl-xL, are in development. By profiling antiapoptotic proteins using flow cytometry, we find that leukemic B cells that recently emigrated from the lymph node (CD69+/CXCR4Low) in vivo are enriched for cell clusters simultaneously overexpressing multiple antiapoptotic proteins (Mcl-1High/Bcl-xLHigh/Bcl-2High) in both treated and treatment-naive CLL patients. These cells exhibited antiapoptotic resistance to multiple BH-domain antagonists, including inhibitors of Bcl-2, Mcl-1, and Bcl-xL, when tested as single agents in a flow cytometry–based functional assay. Antiapoptotic multidrug resistance declines ex vivo, consistent with resistance being generated in vivo by extrinsic microenvironmental interactions. Surviving “persister” cells in patients undergoing venetoclax treatment are enriched for CLL cells displaying the functional and molecular properties of microenvironmentally induced multidrug resistance. Overcoming this resistance required simultaneous inhibition of multiple antiapoptotic proteins, with potential for unwanted toxicities. Using a drug screen performed using patient peripheral blood mononuclear cells cultured in an ex vivo microenvironment model, we identify novel venetoclax drug combinations that induce selective cytotoxicity in multidrug-resistant CLL cells. Thus, we demonstrate that antiapoptotic multidrug-resistant CLL cells exist in patients de novo and show that these cells persist during proapoptotic treatment, such as venetoclax. We validate clinically actionable approaches to selectively deplete this reservoir in patients.

PURPOSE Burkitt lymphoma (BL) has unique biology and clinical course but lacks a standardized prognostic model. We developed and validated a novel prognostic index specific for BL to aid risk stratification, interpretation of clinical trials, and targeted development of novel treatment approaches. METHODS We derived the BL International Prognostic Index (BL-IPI) from a real-world data set of adult patients with BL treated with immunochemotherapy in the United States between 2009 and 2018, identifying candidate variables that showed the strongest prognostic association with progression-free survival (PFS). The index was validated in an external data set of patients treated in Europe, Canada, and Australia between 2004 and 2019. RESULTS In the derivation cohort of 633 patients with BL, age ≥ 40 years, performance status ≥ 2, serum lactate dehydrogenase > 3× upper limit of normal, and CNS involvement were selected as equally weighted factors with an independent prognostic value. The resulting BL-IPI identified groups with low (zero risk factors, 18% of patients), intermediate (one factor, 36% of patients), and high risk (≥ 2 factors, 46% of patients) with 3-year PFS estimates of 92%, 72%, and 53%, respectively, and 3-year overall survival estimates of 96%, 76%, and 59%, respectively. The index discriminated outcomes regardless of HIV status, stage, or first-line chemotherapy regimen. Patient characteristics, relative size of the BL-IPI groupings, and outcome discrimination were consistent in the validation cohort of 457 patients, with 3-year PFS estimates of 96%, 82%, and 63% for low-, intermediate-, and high-risk BL-IPI, respectively. CONCLUSION The BL-IPI provides robust discrimination of survival in adult BL, suitable for use as prognostication and stratification in trials. The high-risk group has suboptimal outcomes with standard therapy and should be considered for innovative treatment approaches.

Central nervous system (CNS) involvement in Burkitt lymphoma (BL) poses a major therapeutic challenge, and the relative ability of contemporary regimens to treat CNS involvement remains uncertain. We described prognostic significance of CNS involvement and incidence of CNS recurrence/progression after contemporary immunochemotherapy using real-world clinicopathologic data on adults with BL diagnosed between 2009 and 2018 across 30 US institutions. We examined associations between baseline CNS involvement, patient characteristics, complete response (CR) rates, and survival. We also examined risk factors for CNS recurrence. Nineteen percent (120/641) of patients (age 18-88 years) had CNS involvement. It was independently associated with HIV infection, poor performance status, involvement of ≥2 extranodal sites, or bone marrow involvement. First-line regimen selection was unaffected by CNS involvement (P=0.93). Patients with CNS disease had significantly lower rates of CR (59% versus 77% without; P

Introduction: Patients (pts) with CLL may be at particular risk of severe COVID-19 given advanced age and immune dysregulation. Two large series with limited follow-up have reported outcomes for pts with CLL and COVID-19 (Scarfò, et al. Leukemia 2020; Mato, et al. Blood 2020). To provide maximal clarity on outcomes for pts with CLL and COVID-19, we partnered in a worldwide effort to describe the clinical experience and validate predictors of survival, including potential treatment effects. Methods: This international collaboration represents a partnership between investigators at 141 centers. Data are presented in two cohorts. Cohort 1 (Co1) includes pts captured through efforts by European Research Initiative on CLL (ERIC), Italian CAMPUS CLL Program, and Grupo Español de Leucemia Linfática Crónica. The validation cohort, Cohort 2 (Co2), includes pts from US (66%), UK (23%), EU (7%), and other countries (4%). There is no overlap in cases between cohorts. CLL pts were included if COVID-19 was diagnosed by PCR detection of SARS-CoV-2 and they required inpatient hospitalization. Data were collected retrospectively 2/2020 - 5/2020 using standardized case report forms. Baseline characteristics, preexisting comorbidities (including cumulative illness rating scale (CIRS) score ≥6 vs. The primary endpoint of this study was to estimate the case fatality rate (CFR), defined as the proportion of pts who died among all pts hospitalized with COVID-19. Chi-squared test was used to compare frequencies; univariable and multivariable analyses utilized Cox regression. Predictors of inferior OS in both Co1 and Co2 were included in multivariable analyses. Kaplan-Meier method was used to estimate overall survival (OS) from time of COVID-19 diagnosis (dx). Results: 411 hospitalized, COVID-19 positive CLL pts were analyzed (Co1 n=281, Co2 n=130). Table 1 describes baseline characteristics. At COVID-19 dx, median age was 72 in Co1 (range 37-94) and 68 in Co2 (range 41-98); 31% (Co1) and 45% (Co2) had CIRS ≥6. In Co1, 48% were treatment-naïve and 26% were receiving CLL-directed therapy at COVID-19 dx (66% BTKi ± anti-CD20, 19% Venetoclax ± anti-CD20, 9.6% chemo/chemoimmunotherapy (CIT), 1.4% PI3Ki, 4% other). In Co2, 36% were never treated and 49% were receiving CLL-directed therapy (65% BTKi ± anti-CD20, 19% Venetoclax ± anti-CD20, 9.4% multi-novel agent combinations, 1.6% CIT, 1.6% PI3Ki, 1.6% anti-CD20 monotherapy, 1.6% other). Most pts receiving CLL-directed therapy had it held at COVID-19 diagnosis (93% in Co1 and 81% in Co2). Frequency of most COVID-19 symptoms/laboratory abnormalities were similar in the two cohorts including fever (88% in both), lymphocytosis (ALC ≥30 x 109/L; 27% vs. 21%), and lymphocytopenia (ALC < 1.0 x 109/L; 18% vs. 28%), while others varied between Co1 and Co2 (p Median follow-up was 24 days (range 2-86) in Co1 and 17 days (1-43) in Co2. CFRs were similar in Co1 and Co2, 30% and 34% (p=0.45). 54% and 43% were discharged while 16% and 23% remained admitted at last follow-up in Co1 and Co2, respectively. The proportion of pts requiring supplemental oxygen was similar (89% vs. 92%) while rate of ICU admission was higher in Co2 (20% vs. 48%, p Conclusions : In the largest cancer dx-specific cohort reported, pts with CLL hospitalized for COVID-19 had a CFR of 30-34%. Advanced patient age at COVID-19 diagnosis was an independent predictor of OS in two large cohorts. This CFR will serve as a benchmark for mortality for future outcomes studies, including therapeutic interventions for COVID-19 in this population. The effect of CLL treatment on OS was inconsistent across cohorts; COVID-19 may be severe regardless of treatment status. While there were no significant differences in distribution of current lines of therapy between cohorts, prior chemo exposure was more common in Co1 vs. Co2, which may account for difference in OS. Extended follow-up will be presented. Disclosures Roeker: American Society of Hematology: Research Funding; Abbott Laboratories: Other: spouse with minority ownership interest ; AbbVie: Other: spouse with minority ownership interest . Scarfo:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Honoraria; Gilead: Membership on an entity's Board of Directors or advisory committees. Abrisqueta:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau. Eyre:AbbVie: Consultancy, Honoraria, Other: travel support; Gilead: Consultancy, Honoraria, Other: travel support; Janssen: Consultancy, Honoraria, Other: travel support; KITE, AZ, Loxo Oncology at Lilly: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Muntañola Prat:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel grants; participated in advisory boards; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel grants; participated in advisory boards; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel grants; participated in advisory boards. Villacampa:AstraZeneca: Other: advisory role; Merck Sharp & Dohme: Honoraria. Leslie:AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, 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; BeiGene: Speakers Bureau; KitePharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene/BMS: Speakers Bureau; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pharmacyclics/Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Epizyme: Speakers Bureau; Karyopharm: Speakers Bureau; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Allan:Acerta, Genentech, Abbvie, Sunesis, Ascentage, Pharmacyclics, Janssen, AstraZeneca, BeiGene: Consultancy; Celgene, Genentech, Janssen, TG Therapeutics: Research Funding; Abbvie, Janssen, AstraZeneca, Pharmacyclics: Honoraria. Furman:Incyte: Consultancy; Genentech: Consultancy; Sunesis: Consultancy; Pharmacyclics: Consultancy; Loxo Oncology: Consultancy; Oncotarget: Consultancy; Janssen: Consultancy, Speakers Bureau; TG Therapeutics: Consultancy, Research Funding; Abbvie: Consultancy; Beigene: Consultancy; AstraZeneca: Consultancy, Research Funding; Acerta: Consultancy; Verastem: Consultancy. Pagel:BeiGene, Astrazeneca, Loxo Oncology, Gilead: Consultancy. Hernandez-Rivas:Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Rovi: Membership on an entity's Board of Directors or advisory committees. Patel:Genentech: Consultancy, Speakers Bureau; Adaptive Biotechnologies: Consultancy; Janssen: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; BeiGene: Consultancy; Kite: Consultancy; Pharmacyclics: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau. Motta:Roche: Honoraria; Janssen: Honoraria. Lamanna:AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Verastem: Research Funding; Bei-Gene: Research Funding; TG Therapeutics: Research Funding; Acerta: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche-Genentech: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Vitale:Janssen: Honoraria. Kamdar:Roche: Research Funding. Österborg:BeiGene: Research Funding; Kancera: Current equity holder in publicly-traded company, Research Funding; Sanofi: Consultancy; Karolinska Univeristy Hospital, Stockholm, Sweden: Current Employment. Hanson:Janssen-Cilag: Research Funding; Gilead: Research Funding; AbbVie: Honoraria. Eichhorst:ArQule: Consultancy, Honoraria, Other: travel support, Research Funding; BeiGene: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; AstraZeneca: Consultancy, Honoraria, Other: travel support, Research Funding; Oxford Biomedica: Consultancy, Honoraria, Other: travel support, Research Funding; AbbVie: Consultancy, Honoraria, Other: travel support, Research Funding; F. Hoffmann-LaRoche: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen-Cilag: Consultancy, Honoraria, Other: travel support, Research Funding; Celgene: Consultancy, Honoraria, Other: travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: travel support, Research Funding. Reda:Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Varettoni:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel/accommodations/expenses; AbbVie: Other: Travel/accommodations/expenses; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees. Marchetti:Gilead: Consultancy; Novartis: Speakers Bureau; Amgen: Speakers Bureau; AbbVie: Other: Sponsored meetings; Takeda: Other: Sponsored meetings; Pfeizer: Other: Sponsored meetings. Munir:F. Hoffmann-La Roche: Consultancy, Other: Medical writing support, furnished by Scott Battle, PhD, of Health Interactions, was funded by F. Hoffmann-La Roche Ltd, Basel, Switzerland; Alexion: Honoraria. Zabalza:Janssen: Honoraria, Other: travel grants; Roche: Other: travel grants; Novartis: Other: travel grants. Janssens:Amgen: Consultancy, Other: travel grants; speaker fees; Abbvie: Consultancy, Other: travel grants; speaker fees; Celgene: Consultancy, Other: travel grants; speaker fees; Janssen: Consultancy, Other: travel grants; speaker fees; Gilead: Consultancy, Other: travel grants; speaker fees; Novartis: Consultancy, Other: travel grants; speaker fees; Sanofi-Genzyme: Consultancy, Other: travel grants; speaker fees; Roche: Consultancy, Other: travel grants; speaker fees. Niemann:AstraZeneca: Honoraria, Research Funding; CSL Behring: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Sunesis: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Danish Cancer Society: Honoraria, Research Funding; Novo Nordisk Foundation: Honoraria, Research Funding. Perini:Takeda: Honoraria; Janssen: Honoraria, Speakers Bureau; Abbvie: Speakers Bureau. Patten:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Honoraria. Marasca:Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Honoraria. Iyengar:Janssen: Honoraria; Gilead: Honoraria. Ferrari:Abbvie: Honoraria. El-Sharkawi:Roche: Other: Conference fees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Itchaki:Abbvie Inc: Consultancy, Research Funding. Ma:Novartis: Research Funding; Juno: Research Funding; Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Kite: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Bioverativ: Consultancy, Honoraria; BeiGene: Honoraria, Research Funding, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding; TG Therapeutics: Research Funding. Van Der Spek:AMGEN: Other: Teaching activities. Seymour:Seattle Genetics: Research Funding; Merck: Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Genentech: Research Funding; Bristol-Myers Squibb: Research Funding. Rigolin:Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mauro:Roche: Other; Octopharma: Other; Takeda-Shire: Other; Gilead: Other; Janssen: Other; Abbvie: Other. Laurenti:Janssen: Honoraria; Gilead: Honoraria; AbbVie: Honoraria; Roche: Honoraria. Levin:Janssen: Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Abbvie: Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Roche: Membership on an entity's Board of Directors or advisory committees, Other: travel compensation. Špaček:Gilead: Honoraria; Abbvie: Honoraria; Janssen: Honoraria. Walewska:AbbVie: Other: sponsored for educational meetings, Speakers Bureau; Janssen: Other: sponsored for educational meetings, Speakers Bureau; Gilead: Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Wiestner:Pharmacyclics LLC, an AbbVie Company; Acerta, Merck, Nurix, Verastem, and Genmab: Research Funding; National Institutes of Health: Patents & Royalties: and other intellectual property. Broom:Gilead: Other: Travel support, Speakers Bureau. Kater:Abbvie: Research Funding; Roche: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Genentech: Research Funding. Ujjani:AstraZeneca: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Verastem Oncology: Consultancy, Honoraria; Gilead/Kite: Consultancy, Research Funding; Atara: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; MorphoSys: Consultancy. Vandenberghe:Celgene: Other: sponsorship to attend Lugano lymphoma meeting in 2019; Gilead: Other: travel grants, Research Funding; Abbvie: Other: travel grants, Research Funding; Janssen: Other: travel grants; Roche: Other: travel grants, Research Funding. Chong:Novartis: Membership on an entity's Board of Directors or advisory committees; Tessa: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; KITE Pharma: Membership on an entity's Board of Directors or advisory committees. Pu:Takeda Pharmaceuticals: Consultancy. Brown:Janssen, Teva: Speakers Bureau; Gilead, Loxo, Sun, Verastem: Research Funding; Abbvie, Acerta, AstraZeneca, Beigene, Invectys, Juno/Celgene, Kite, Morphosys, Novartis, Octapharma, Pharmacyclics, Sunesis, TG Therapeutics, Verastem: Consultancy. Trentin:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Octapharma: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria. Farina:Abbvie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Sanchez:Abbvie: Other: travel grants; Amgem: Other: travel grants; Janssen: Other: travel grants; Celgene: Other: travel grants; Roche: Other: travel grants. 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. Foglietta:Janssen: Honoraria; Gilead: Honoraria. Jaksic:Roche: Honoraria; Janssen: Honoraria; Abbvie: Honoraria. Sportoletti:AbbVie: Honoraria; Janssen: Honoraria. Barr:Morphosys: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy, Research Funding; Verastem: Consultancy; Seattle Genetics: Consultancy; TG therapeutics: Consultancy, Research Funding; Abbvie/Pharmacyclics: Consultancy, Research Funding; Celgene: Consultancy; Merck: Consultancy; Genentech: Consultancy; Janssen: Consultancy. Ruchlemer:Abbvie Inc: Consultancy, Research Funding. Kersting:Celgene: Other: travel grant; Janssen: Research Funding; Abbvie: Research Funding. Huntington:Pharmacyclics: Honoraria; AbbVie: Consultancy; Novartis: Consultancy; Genentech: Consultancy; DTRM: Research Funding; Celgene: Consultancy, Research Funding; Bayer: Consultancy, Honoraria; Astrazeneca: Honoraria; TG Therapeutics: Research Funding. Herishanu:Roche: Honoraria; Sanofi: Honoraria; Medison: Honoraria; Janssen: Honoraria; Abbvie: Honoraria; AstraZeneca: Honoraria. Jacobs:TG Therapeutics, Inc.: Research Funding; Astra Zeneca: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Pharmacyclics: Research Funding, Speakers Bureau; Seattle Genetics: Consultancy; Verastem: Consultancy; Janssen: Consultancy, Speakers Bureau; Genentech: Speakers Bureau; Sanofi Genzyme: Speakers Bureau. Portell:BeiGene: Consultancy, Research Funding; Pharmacyclics: Consultancy; TG Therapeutics: Research Funding; Infinity: Research Funding; Roche/Genentech: Consultancy, Research Funding; Xencor: Research Funding; Bayer: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding; AbbVie: Research Funding. Rambaldi:Sanofi: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Astellas: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); BMS/Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); University of Milan: Current Employment; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support of parent study and funding of editorial support. Received travel support., Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support from Gilead.; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Research grant from Amgen Inc.; Omeros: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Advisory board and speaker fees from Pfizer.. Brander:Verastem: Consultancy, Honoraria, Other, Research Funding; NCCN: Other; Novartis: Consultancy, Other; Teva: Consultancy, Honoraria; Tolero: Research Funding; NCCN: Other; Novartis: Consultancy, Other; Teva: Consultancy, Honoraria; Tolero: Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ArQule: Consultancy, Other, Research Funding; Ascentage: Other, Research Funding; AstraZeneca: Consultancy, Honoraria, Other, Research Funding; BeiGene: Other, Research Funding; DTRM: Other, Research Funding; Genentech: Consultancy, Honoraria, Other, Research Funding; Juno/Celgene/BMS: Other, Research Funding; MEI Pharma: Other, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Other, Research Funding; Pfizer: Consultancy, Other; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding. Rossi:Abbvie: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Advisory board; Astellas: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees; Alexion: Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Coscia:Karyopharm Therapeutics: Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Coombs:Abbvie: Consultancy, Honoraria; Genentech: Honoraria; AstraZeneca: Honoraria; MEI Pharma: Honoraria; LOXO Oncology: Honoraria; Octapharma: Honoraria; Novartis: Honoraria. Schuster:Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding; AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria. Foà:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Cuneo:Astra Zeneca: Honoraria; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Bosch:Jansen: Honoraria; Abbvie: Honoraria; Novartis: Honoraria; Astra Zeneca: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Roche: Honoraria. Stamatopoulos:AstraZeneca: Honoraria; Janssen, Gilead, Abbvie: Honoraria, Research Funding. Ghia:Adaptive, Dynamo: Consultancy, Honoraria; Novartis: Research Funding; BeiGene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; Celgene/Juno: Consultancy, Honoraria; Lilly: Consultancy, Honoraria; MEI: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; Gilead: Consultancy, Honoraria, Research Funding; ArQule: Consultancy, Honoraria; Acerta/AstraZeneca: Consultancy, Honoraria. Mato:Adaptive: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; BeiGene: Consultancy; LOXO: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding.

Background. BL is a rare, high-grade B-cell lymphoma that is often studied in trials with small sample sizes. Historical definitions of "low-risk BL" vary between studies, use arbitrary cutoffs for lactate dehydrogenase (LDH), and identify a small favorable group, leaving >80-90% of patients (pts) in an undifferentiated "high-risk" category. A validated prognostic index will help compare study cohorts and better define good-prognosis pts for whom reduced treatment would be appropriate vs a poor-prognosis group in need of new approaches. Herein, we constructed and validated a simplified prognostic model for BL applicable to diverse clinical settings across the world. Methods. We derived the BL-IPI from a large real-world evidence cohort of US adults treated for BL in 2009-2018 (Evens A, Blood 2020). Progression-free survival (PFS) from diagnosis until BL recurrence, progression, death, or censoring was the primary outcome. We first determined the best prognostic cutoffs for age, LDH (normalized to local upper limit normal, ULN), hemoglobin (Hgb), and albumin. Independent risk factors were ascertained by forward stepwise selection into Cox regression from candidate variables: age, sex, HIV+ status, ECOG performance status (PS) ≥2, advanced stage (3/4), involvement of >1 extranodal site, bone marrow, central nervous system (CNS), values of LDH, Hgb, and albumin. Derivation models used multiple imputation to mitigate bias from missing data and reported hazard ratios (HR) with 95% confidence interval (CI). BL-IPI groups, defined by inspection of survival curves, were compared using log-rank test for trend. We validated performance of the BL-IPI in an external retrospective dataset of BL pts treated contemporaneously in centers from the United Kingdom, Scandinavia, Canada, and Australia. Results. Characteristics of pts in the derivation (N= 633) and validation (N=457) cohorts are shown in the Table. Age ≥40 years (yr), LDH >3xULN, Hgb 3xULN, low Hgb, and low albumin were associated with inferior PFS in univariate tests. In the multivariable model age ≥40 yr, LDH >3xULN, PS ≥2, and CNS involvement were selected as 4 independent prognostic factors; adding stage did not enhance the model. The model was simplified to 3 groups with 0 (low risk; 18% of pts), 1 (intermediate risk; 36% of pts; HR=3.14; 95%CI, 1.61-6.14), or 2-4 factors (high risk; 46% of pts; HR=6.52; 95%CI, 3.48-12.20; Fig A) with 3 yr PFS of 92%, 72%, and 53%, respectively (P Among pts with stage III/IV (historically classified as "high-risk" and constituting 78% of all pts in the cohort), the BL-IPI further discriminated subgroups with 3 yr PFS of 87%, 71%, and 52%, respectively (P In the international validation cohort, fewer pts had CNS involvement; most received CODOX-M/IVAC+R; and PFS/OS estimates at 3 yr were higher. BL-IPI categories were of similar size (low-risk 15%, intermediate-risk 35%, high-risk 50%), and provided similar risk discrimination (Harrell's C=.65 in both datasets). PFS at 3 yr was 96%, 82%, and 63%, respectively (P Conclusions. BL-IPI is a novel prognostic index specific to BL, which was validated to allow for simplified stratification and comparison of risk distribution in geographically diverse cohorts. The index identified a low-risk group with PFS >90-95%, which could be targeted with future strategies for treatment de-escalation. Conversely, only about 55-60% of pts in the high-risk group achieved cure with currently available immunochemotherapy. Disclosures Olszewski: Spectrum Pharmaceuticals: Research Funding; Genentech, Inc.: Research Funding; TG Therapeutics: Research Funding; Adaptive Biotechnologies: Research Funding. Jakobsen:Takeda: Honoraria. Collins:ADC Therapeutics: Consultancy, Honoraria; Celleron: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Research Funding; BeiGene: Consultancy; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding; Taekda: Consultancy, Honoraria, Other: travel, accommodations, expenses, Speakers Bureau; Roche: Consultancy, Honoraria, Other: travel, accommodations, expenses , Speakers Bureau; Pfizer: Honoraria; Celgene: Research Funding. Cwynarski:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau. Bachanova:Incyte: Research Funding; Karyopharma: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; FATE: Research Funding; Kite: Membership on an entity's Board of Directors or advisory committees; Gamida Cell: Membership on an entity's Board of Directors or advisory committees, Research Funding. Danilov:Abbvie: Consultancy; BeiGene: Consultancy; Nurix: Consultancy; Celgene: Consultancy; Gilead Sciences: Research Funding; Takeda Oncology: Research Funding; Pharmacyclics: Consultancy; Bayer Oncology: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; TG Therapeutics: Consultancy; Astra Zeneca: Consultancy, Research Funding; Verastem Oncology: Consultancy, Research Funding; Karyopharm: Consultancy; Aptose Biosciences: Research Funding; Bristol-Myers Squibb: Research Funding; Rigel Pharmaceuticals: Consultancy. Diefenbach:Trillium: Research Funding; Millenium/Takeda: Research Funding; MEI: Research Funding; Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; Incyte: Research Funding; LAM Therapeutics: Research Funding; Denovo: Research Funding. Epperla:Pharmacyclics: Honoraria; Verastem Oncology: Speakers Bureau. Farooq:Kite, a Gilead Company: Honoraria. Feldman:Pfizer: Research Funding; Portola: Research Funding; Janssen: Speakers Bureau; AstraZeneca: Consultancy; Cell Medica: Research Funding; Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Viracta: Research Funding; Trillium: Research Funding; Rhizen: Research Funding; Corvus: Research Funding; BMS: Consultancy, Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; Celgene: Honoraria, Research Funding; Takeda: Honoraria, Other: Travel expenses; Amgen: Research Funding; Pharmacyclics: Honoraria, Other, Speakers Bureau; Abbvie: Honoraria; Bayer: Consultancy, Honoraria; Eisai: Research Funding; Kyowa Kirin: Consultancy, Research Funding. Gerrie:AbbVie: Consultancy, Honoraria, Research Funding; Astrazeneca: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Roche: Research Funding; Sandoz: Consultancy. Jagadeesh:Regeneron: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Debiopharm Group: Research Funding; MEI Pharma: Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees. Kamdar:BMS: Consultancy; Abbvie: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; AstraZeneca: Consultancy; Pharmacyclics: Consultancy; Seattle Genetics: Speakers Bureau. Karmali:Takeda: Research Funding; AstraZeneca: Speakers Bureau; BeiGene: Speakers Bureau; Karyopharm: Honoraria; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau. Khan:Seattle Genetics: Research Funding; Janssen: Honoraria; Pharmacyclics: Honoraria; Bristol Myers Squibb: Research Funding; Celgene: Research Funding. Klein:Takeda: Membership on an entity's Board of Directors or advisory committees. Lossos:Verastem: Consultancy, Honoraria; Stanford University: Patents & Royalties; Seattle Genetics: Consultancy, Other; Janssen Biotech: Honoraria; NCI: Research Funding; Janssen Scientific: Consultancy, Other. Lunning:ADC Therapeutics: Consultancy; Legend: Consultancy; Acrotech: Consultancy; AstraZeneca: Consultancy, Honoraria; Aeratech: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Verastem: Consultancy, Honoraria; TG Therapeutics: Research Funding; Novartis: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Curis: Research Funding; Bristol Meyers Squibb: Consultancy, Honoraria, Research Funding. Martin:I-MAB: Consultancy; Celgene: Consultancy; Teneobio: Consultancy; Karyopharm: Consultancy, Research Funding; Janssen: Consultancy; Sandoz: Consultancy; Bayer: Consultancy; Beigene: Consultancy; Cellectar: Consultancy; Incyte: Consultancy; Kite: Consultancy; Morphosys: Consultancy; Regeneron: Consultancy. Martinex-Calle:Abbvie: Other: Travel grant. Naik:Celgene: Other: advisory board; Sanofi: Other: advisory board. Palmisiano:Genentech: Research Funding; AbbVie: Research Funding. Phillips:Beigene: Honoraria; Roche: Research Funding. Phillips:Seattle Genetics: Consultancy; Incyte: Consultancy, Other: travel expenses; AstraZeneca: Consultancy; Karyopharm: Consultancy; Beigene: Consultancy; Bayer: Consultancy, Research Funding; BMS: Consultancy; Pharmacyclics: Consultancy; Abbvie: Consultancy, Research Funding; Cardinal Health: Consultancy. Portell:Roche/Genentech: Consultancy, Research Funding; Infinity: Research Funding; Bayer: Consultancy; Amgen: Consultancy; TG Therapeutics: Research Funding; AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding; Xencor: Research Funding; BeiGene: Consultancy, Research Funding. Reddy:Celgene: Consultancy; BMS: Consultancy, Research Funding; Genentech: Research Funding; Abbvie: Consultancy; KITE Pharma: Consultancy. Yazdy:Abbvie: Consultancy; Genentech: Research Funding; Octapharma: Consultancy; Bayer: Honoraria. Smith:Bristol Meyers Squibb: Research Funding; Ayala: Research Funding; Seattle Genetics: Research Funding; Portola: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; De Novo Biopharma: Research Funding; AstraZeneca: Consultancy; Millenium/Takeda: Consultancy; Beigene: Consultancy; Bayer: Research Funding; AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Karyopharm: Consultancy. Cheah:Celgene, F. Hoffmann-La Roche, Abbvie, MSD: Research Funding; Celgene, F. Hoffmann-La Roche, MSD, Janssen, Gilead, Ascentage Pharma, Acerta, Loxo Oncology, TG therapeutics: Honoraria. El-Galaly:F. Hoffmann-La Roche: Current Employment, Other: Support of parent study and funding of editorial support. Evens:Research To Practice: Honoraria, Speakers Bureau; Mylteni: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Merck: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria, Research Funding; MorphoSys: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria.

Prophylaxis is commonly used to prevent central nervous sy stem (CNS) relapse in diffuse large B-cell lymphoma (DLBCL), with no clear standard of care. We retrospectively evaluated 1162 adult patients across 21 US academic centers with DLBCL or similar histologies who received single-route CNS prophylaxis as part of frontline therapy between 2013 and 2019. Prophylaxis was administered intrathecally(IT) in 894 (77%) and using systemic high-dose methotrexate (HD-MTX) in 236 (20%); 32 patients (3%) switched route due to toxicity and were assessed separately. By CNS-International Prognostic Index (IPI), 18% were considered low-risk, 51% moderate, and 30% high. Double-hit lymphoma (DHL) was confirmed in 243 of 866 evaluable patients (21%). Sixty-four patients (5.7%) had CNS relapse after median 7.1 months from diagnosis, including 15 of 64 (23%) within the first 6 months. There was no significant difference in CNS relapse between IT and HD-MTX recipients (5.4% vs 6.8%, P = .4), including after propensity score matching to account for differences between respective recipient groups. Weighting by CNS-IPI, expected vs observed CNS relapse rates were nearly identical (5.8% vs 5.7%). Testicular involvement was associated with high risk of CNS relapse (11.3%) despite most having lower CNS-IPI scores. DHL did not significantly predict for CNS relapse after single-route prophylaxis, including with adjustment for treatment regimen and other factors. This large study of CNS prophylaxis recipients with DLBCL found no significant difference in CNS relapse rates between routes of administration. Relapse rates among high-risk subgroups remain elevated, and reconsideration of prophylaxis strategies in DLBCL is of critical need.

Relapsed Mantle cell lymphoma (MCL) is often treated with Bruton's tyrosine kinase inhibitors (BTKi); however, post-BTKi relapse can be challenging. Adding venetoclax (VEN) to ibrutinib (IBR) has shown synergy in preclinical MCL models. Prior MCL studies of the combination show promising efficacy but have conducted limited dose finding. We sought to identify the optimal dosing combination, based on efficacy and toxicity, utilizing a continual reassessment method of 6 combinations of IBR (280 mg, 420 mg, and 560 mg by mouth daily) and VEN (max dose of 200 mg and 400 mg by mouth daily). Eligible participants were not previously exposed to BTKi and not high risk for tumor lysis syndrome (TLS). VEN, initiated first at 100 mg, then at 20 mg by mouth daily after a TLS event, was started prior to adding IBR and ramped-up based on the dose level assigned. Combination treatment continued for six 28-day cycles. Thirty-five participants were enrolled and treated. One TLS event occurred with starting dose of 100 mg VEN; no TLS was seen with 20 mg. The optimal dosing combination was considered to be VEN 200 mg and IBR 420 mg with an overall response rate (ORR) of 93.8% (95% CI: 73.6% to 99.7%) and DLT incidence of 6.2% (95% CI: 0.3% to 26.4%). ORR for all arms was 82.3% (28/34; 95% CI: 65.5% to 93.2%) with a complete response (CR) rate of 42.4% (14/33; 95% CI: 25.5% to 60.8%). A participant was not allocated to IBR 560 mg and VEN 400 mg. ORR benefit was not seen with higher dosing combinations and toxicity was higher; a comparison made within the limitations of small cohorts. Resistance was seen in nearly all arms. This trial was registered at www.clinicaltrials.gov #NCT02419560.

This review summarizes the unique presentation and management of the leukemic variant of mantle cell lymphoma (LV-MCL, also referred to as non-nodal MCL) and highlights the biologic and clinical differentiation from classical mantle cell lymphoma (cMCL) in biomarker expression, clinical features, prognosis, disease course, and treatment. Several studies have evaluated the gene expression profile of mantle cell lymphoma, differentiating LV-MCL from cMCL. The typical immunophenotypic profile is CD5-positive, SOX 11-negative, CD23-low, CD200-low, and cyclin D1 overexpressed. LV-MCL commonly has mutated immunoglobulin heavy chain variable region genes. Data on treatment of LV-MCL is limited to retrospective analyses; the ideal treatment for these patients is unknown although many have a clinically indolent, asymptomatic presentation and often may be observed for an extended period without active treatment. LV-MCL is a clinically and biologically distinct entity. Clinically, it must be distinguished from chronic lymphocytic leukemia and cMCL. Future prospective, randomized clinical trials are required to optimize management, define the initial treatment, and appropriately sequence treatment modalities.

Background Limited data are available on the clinical activity of venetoclax (ven) in mantle cell lymphoma (MCL). In 2 small retrospective studies of patients (pts) with MCL previously treated with BTK inhibitors (BTKi), ven resulted in overall response rates (ORRs) of 50-53% and median overall survival (OS) of 9-14 months (Eyre et al, Haematologica 2019; Zhao et al, Am J Hematol 2020). We sought to report the clinical activity of ven and identify factors associated with outcomes in a larger cohort of pts. Methods We included pts with relapsed MCL from 12 US medical centers treated with ven alone or in combination with an antiCD20 monoclonal antibody (mAb) or a BTKi. Response was determined by the local investigator. We defined OS as time from start of ven to death. Pts not experiencing an event were censored at their last known follow up. OS was determined using the Kaplan-Meier method, and univariable (UVA) and multivariable (MVA) models were developed to identify predictors of response and OS. Results Eighty-one pts were included. Pt characteristics (Table) at diagnosis (dx) were: median age 64 years (yrs) (range 38-87), male 79%, stage III/IV 95%, Ki67 >30% in 61% (available n=62), blastoid/pleomorphic histology 29% (available n=75) and ≥3 cytogenetic abnormalities 34% (available n=62). BCL2 expression was present in 93% (available n=40). Frontline treatment (tx) included intensive chemotherapy [defined as including high-dose cytarabine and/or autologous transplant (ASCT) in first remission] in 52% with ASCT in first remission in 32%. Median number of therapies prior to ven was 3 (range 1-8) including antiCD20 mAb 99%, alkylator 93%, BTKi 91%, anthracycline 58%, cytarabine 56%, and lenalidomide 37%. 55% were refractory (defined as stable (SD) or progressive disease (PD)) to last tx prior to ven. ORR to BTKi prior to ven (n=70) was 66% (complete response (CR) 20%) with median duration of tx of 6.4 months (range 0.5-69). BTKi was stopped due to PD 82% and toxicity 18%. Median time from dx to start of ven was 3.9 yrs (range 0.2-17.8). Ven was given as monotherapy in 62% (n=50) and in combination with BTKi 20% (n=16), antiCD20 mAb 14% (n=11), or other 5% (n=4). Ten pts treated with ven in combination with BTKi received prior tx with BTKi with ORR to BTKi of 40% (all PR). Ven highest dose received was 20-100 mg in 12% (n=9), 200 mg 11% (n=8), 400 mg 61% (n=46), and 800 mg 17% (n=13). Median duration of tx with ven was 2.8 months (range 0.1-30). The best response to ven was CR 18%, partial response (PR) 24%, SD 11%, and PD 47% with ORR of 42%; 19 pts (23%) did not have available data for response. ORR was not significantly different with ven monotherapy 36% (13/36) vs ven + antiCD20 mAb 56% (5/9) vs ven + BTKi 43% (6/14) (p=.559), or with ven monotherapy 36% vs combination therapy 50% (13/26) (p=.274). Ven was stopped due to PD 69%, toxicity 9%, allogeneic transplant 3% or other reasons 19%. Laboratory tumor lysis syndrome (TLS) occurred in 10 pts (12%) including 3 (3.7%) with clinical TLS. 38 pts received post-ven tx with median time from stopping ven to next tx of 0.24 months (range 0-2.2); for the 33 pts with available data, the best response to post-ven tx was CR 24%, PR 27%, SD 9% and PD 39% with ORR of 51%. For the 75 pts with available data, median OS was 12.5 months (95% CI 6-17) with 3-year OS of 13.1% (95% CI 1.4-38.0%) (Figure A). Median OS was numerically longer with ven combination (28.7 months, 95% CI 4-not reached) vs monotherapy (8.6 months, 95% CI 4.7-14.4), p=.0825 (Figure B). Median OS did not significantly differ based on response (CR/PR vs SD/PD) to prior tx with BTKi (14.4 vs 9.5 months, p=.53, Figure C) or last tx prior to ven (16.7 vs 12.4 months, p=.14, Figure D). In MVA for response, achieving CR/PR with BTKi prior to ven (vs SD/PD) was associated with response to ven (odds ratio 3.48, 95% CI 1.01-12.05, p=.049). In MVA for OS, ven combination vs monotherapy (HR 0.13, 95% CI 0.03-0.53; p=.006), longer time from dx to start of ven (>4 vs ≤4 yrs) (HR 0.08, 95% CI 0.02-0.36; p=.001), and higher dose of ven (≥400 mg vs 6 vs ≤6 months) (HR 3.47, 95% CI 1.10-10.99; p=.038) was associated with inferior OS. Conclusions In these high-risk and heavily pretreated pts with MCL, ven resulted in low response rate and poor OS. Ven may have a better role in MCL in earlier lines of therapy and when combined with other agents such as BTKi and/or antiCD20 mAbs. Disclosures Kamdar: Roche: Research Funding. Greenwell:Lymphoma Research Foundation: Research Funding; Acrotech Biopharma LLC, Kyowa Kirin: Consultancy. Hess:ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS, AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Portell:Acerta/AstraZeneca: Research Funding; Kite: Consultancy, Research Funding; Amgen: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; AbbVie: Research Funding; TG Therapeutics: Research Funding; Infinity: Research Funding; Roche/Genentech: Consultancy, Research Funding; Xencor: Research Funding. Goldsmith:Wugen Inc.: Consultancy. Grover:Genentech: Research Funding; Tessa: Consultancy. Riedell:Morphosys: Research Funding; Celgene/Bristol-Myers Squibb Company: Honoraria, Research Funding; Verastem Oncology: Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Kite Pharmaceuticals/Gilead: Honoraria, Research Funding; Bayer: Honoraria; Karyopharm Therapeutics: Honoraria. Karmali:BeiGene: Speakers Bureau; AstraZeneca: Speakers Bureau; Karyopharm: Honoraria; Takeda: Research Funding; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau. Kumar:AbbVie: Research Funding; Kite Pharmaceuticals: Honoraria, Other: Honoraria for Advisory Board; Astra Zeneca: Honoraria, Other: Honoraria for Advisory Board; Celgene: Honoraria, Other: Honoraria for Advisory Board; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Adaptive Biotechnologies,: Research Funding. Hill:Abbvie: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding. Kahl:AstraZeneca Pharmaceuticals LP: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy; AbbVie: Consultancy; Genentech: Consultancy; Pharmacyclics LLC: Consultancy; Roche Laboratories Inc: Consultancy; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cohen:Genentech, BMS, Novartis, LAM, BioInvent, LRF, ASH, Astra Zeneca, Seattle Genetics: Research Funding; Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo: Consultancy. OffLabel Disclosure: Venetoclax is not licensed for use in mantle cell lymphoma

The advent of molecularly targeted therapies has revolutionized the treatment of Non-Hodgkin's Lymphoma (NHL), including Chronic Lymphocytic Leukemia (CLL). Venetoclax (VEN, an inhibitor of Bcl-2) and ibrutinib (IBR, an inhibitor of BTK) generated excellent clinical responses in CLL patients singly and even more effectively in combination (Portell et al. Blood, 2019; Tam et al.NEJM, 2018). Despite its efficacy, the majority of VEN or VEN+IBR responses are partial and resistance usually develops. We previously reported that treatment with microenvironmental agonists ex vivo can generate anti-apoptotic resistance to the VEN+IBR combination in CLL cells via NF-kB-dependent upregulation of multiple anti-apoptotic proteins (Mcl-1 and Bcl-xL) (Jayappa et al. Blood Adv, 2017). Here, we report that circulating CLL cells of lymph node origin (CD69positive) exhibit resistance to several BH-domain antagonists (inhibitors of Bcl-2, Mcl-1, and Bcl-xL) when used as single agents. Apoptosis resistance was shown to occur at a pre-mitochondrial level by insufficient activation of Bax/Bak proteins (Fig. 1A-B). Supportive of these findings, ex vivo treatment of primary CLL cells with agonists (sCD40L, TLR9 agonist CpG-ODN, and IL10) known to be expressed in the cancer microenvironment in vivoalso resulted in apoptosis restriction due to defective Bax/Bak activation. Our molecular studies suggest that this resistance is driven by the upregulation of anti-apoptotic proteins, which generates an intracellular environment in which single-drug treatments allow pro-apoptotic proteins (e.g. Bim) to swap between upregulated anti-apoptotic proteins (Mcl-1/Bcl-xL/Bcl-2), leading to defective Bax/Bak activation. Hence, therapies aimed at depleting this reservoir must block multiple anti-apoptotic proteins simultaneously or bypass Bax/Bak-dependent apoptosis. Several cancers, including NHL, have evolved mechanisms to suppress the activity of Protein Phosphatase 2A (PP2A), a serine/threonine phosphatase known to regulate cell survival/proliferation. In our current study involving various cancer cell lines (~250), a small molecule agonist of PP2A (SMAP, TRC-382) showed broad activity across blood cancer cell lines. A further pharmacologically optimized SMAP compound (DT061), also known to be safe in animal models (Tohmé et al. JCI Insight, 2019), was effective even in blood cancer cell lines and agonist treated CLL samples resistant to several BH-domain antagonists (inhibitors on Mcl-1, Bcl-xL, and Bcl-2), suggesting that PP2A activation could overcome pre-mitochondrial apoptosis restriction. DT061 was able to overcome drug resistance in patient-derived CD69positive CLL cells through the induction of Bax/Bak-independent apoptosis (Fig. 1C). Supportive of this finding, DT061 was also able to induce apoptosis in Bax/Bak double knockout CLL cell line (MEC1) (Fig. 1D). To determine the mechanisms underlying SMAP-induced apoptosis, we examined additional pathways capable of triggering apoptosis such as mitochondrial permeability transition pore (MPTP), calcium channels, and VDAC1 using selected small molecule inhibitors. Only inhibitors blocking MPTP (NIM811 or cyclopsorin-A/CspA) significantly impaired the DT061- but not VEN-induced apoptosis in primary CLL cells (Fig. 2A-B). Additionally, our analysis using the CalceinAM/CoCl2 method revealed that DT061 was able to induce MPTP opening in primary CLL cells, which was inhibited in the presence of NIM811 or CspA, suggesting that DT061 induces apoptosis through MPTP activation (Fig. 2C). In summary, we identify, in the circulation of treatment-naïve and treated CLL patients, microenvironmentally-activated leukemic B cells that exhibit apoptosis resistance at the level of Bax/Bak activation. Therapies aimed at depleting this reservoir of drug-resistant leukemic B cells must trigger a process of Bax/Bak independent apoptosis. We demonstrate that PP2A activation using the SMAP (DT061) induces apoptosis in drug resistant CLL cells bypassing the Bax/Bak pathway. The apoptosis induction was dependent on MPTP activation. Collectively, this work highlights the existence of an anti-apoptotic multi-drug resistant pool of CLL cells in patients, and validates a novel pharmaceutically tractable pathway to deplete this reservoir. Disclosures Williams: Janssen: Research Funding; Pharmacyclics: Research Funding; TG Therapuetics: Research Funding; Celgene: Honoraria; Gilead: Honoraria; TG Therapeutics: Honoraria; Abbvie: Honoraria; Kite: Honoraria; Xian Janssen: Honoraria. Portell:Xencor: Research Funding; Roche/Genentech: Consultancy, Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding. Narla:The Icahn School of Medicine at Mount Sinai: Patents & Royalties: nternational Application Numbers: PCT/US15/19770, PCT/US15/19764; and US Patent: US 9,540,358 B2; Mount Sinai: Other: Mount Sinai is actively seeking commercial partners for the further development of the technology. G.N. has a financial interest in the commercialization of the technology.; RAPPTA Therapeutics: Consultancy, Current equity holder in private company.

Background: Marginal zone lymphoma (MZL) is rare and heterogeneous and it has been difficult to define optimal therapeutic strategies. Like other indolent non-Hodgkin lymphomas, advanced stage disease is considered incurable, with most patients experiencing a continuing pattern of relapse and remission. MZL is typically dependent on B-cell receptor (BCR) signaling suggesting a role for BCR pathway targeting via inhibition of Bruton's tyrosine kinase (BTK). The utility of this approach was confirmed by the pivotal phase 2 study demonstrating a 48% objective response rate (ORR) to ibrutinib in patients with relapsed/refractory (R/R) MZL (Noy et al. Blood. 2017;129:2224-2232). Zanubrutinib (BGB-3111) is a potent, highly specific, and irreversible next-generation BTK inhibitor. It was specifically designed to maximize BTK occupancy and minimize off-target inhibition of TEC- and EGFR-family kinases, which are thought to be related to atrial fibrillation, thrombocytopenia, and bleeding events. In an early-phase study (BGB-3111-AU-003) of 20 patients with R/R MZL treated with zanubrutinib, at a median follow-up of 27.1 months, the ORR was 80%, with a complete response (CR) rate of 15%, and partial response (PR) rate of 65% (Tedeschi et al. EHA 2020, abstract 2804). Presented here are initial efficacy and safety data in patients with R/R MZL enrolled in the MAGNOLIA trial (BGB-3111-214). Methods: MAGNOLIA is a phase 2, multicenter, single-arm study of adult patients requiring systemic treatment for R/R MZL who had previously received one or more lines of therapy including at least one CD20-directed regimen. All patients were treated with zanubrutinib 160 mg twice daily until disease progression or unacceptable toxicity. Use of long-term antiplatelet and anticoagulation agents was permitted. The primary end point was ORR as determined by an independent review committee in accordance with the Lugano classification. Secondary end points include ORR by investigator assessment, duration of response (DOR), progression-free survival (PFS), and safety. Results: In total, 68 patients were enrolled and treated. The median age was 70 years (range, 37-95), with 28% aged ≥75 years. MZL subtypes included extranodal (mucosa-associated lymphoid tissue) in 38%, nodal in 38%, splenic in 18%, and unknown in 6% of patients. The median number of prior therapies was 2 (range, 1-6), and 35% of patients had disease refractory to last therapy. At a median follow-up of 6.8 months (range, 1.6-12.8), 67 patients were evaluable for efficacy. Investigator-assessed ORR (CR + PR) was 60% (CR 15%, PR 45%, stable disease 27%). Responses were observed in all MZL subtypes, with an ORR of 58%, 64%, 58%, and 50% in extranodal, nodal, splenic, and unknown subtypes, respectively. CR rate was 23% for extranodal MZL, 12% for nodal, and 50% for unknown subtype. CR was not observed in patients with splenic MZL. The median DOR and median PFS were not reached. Twenty-one (30.9%) patients discontinued study treatment. Treatment discontinuation was mainly due to disease progression (16 patients; 23.5%); 1 withdrew consent, 2 required prohibited medications, and 2 due to adverse events (AEs) - 1 from pyrexia (later attributed to disease transformation) and 1 from myocardial infarction. The most common treatment-emergent AEs reported in ≥10% of patients were diarrhea (19.1%), bruising (17.6%), constipation (13.2%), pyrexia (10.3%), upper respiratory tract infection (10.3%), and nausea (10.3%). Most AEs were low grade. Neutropenia was the most common grade ≥3 AE (7.3%). Treatment-related serious AEs included atrial flutter, pyrexia, pneumonia, and thrombocytopenia (1 patient each). One patient with pre-existing coronary artery disease died from myocardial infarction, which was assessed as unrelated to zanubrutinib. All-grade AEs of interest included neutropenia (10.3%), thrombocytopenia (10.3%), and atrial flutter (1.5%). To date, no major hemorrhage, serious opportunistic infection, or tumor lysis syndrome have been reported. Conclusion: Preliminary results of this phase 2 study suggest that zanubrutinib is active in R/R MZL, with a favorable safety profile. (NCT03846427) Disclosures Opat: Beigene: Research Funding; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZenca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffman-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding; Epizyme: Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Tedeschi:AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; BeiGene: 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, Speakers Bureau; Janssen spa: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Department of Hematology Niguarda Hospital Milano: Current Employment; Sunesis: Consultancy. Linton:The Christie NHS Foundation Trust and The University of Manchester: Current Employment; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Conference/travel support; Roche: Consultancy, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Patents & Royalties; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Hartley-Taylor: Honoraria. McKay:Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; TAKEDA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Beatson West of Scotland Cancer Centre: Current Employment; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche, Gilead, Takeda, and Janssen: Other: For lectures etc. Hu:Kite: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Cellectar: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Beigene: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Chan:Celgene: Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company); Roche: Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company); AbbVie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding, Speakers Bureau; Amgen: Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company). Jin:The First Affiliated Hospital of Zhejiang University: Current Employment. Zinzani:Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Consultancy, Speakers Bureau; Verastem: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kirin Kyowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics, Inc.: Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eusapharma: Consultancy, Speakers Bureau; Celltrion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Browett:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; University of Auckland: Current Employment; BeiGene: Research Funding. Coleman:BeiGene: Research Funding; Acerta: Research Funding; Innocare: Research Funding. Sobieraj-Teague:Flinders Medical Centre: Current Employment; Janssen: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Ke:Peking University Third Hospital: Current Employment. Sun:Institute of Hematology and Blood Disease Hospital,Chinese Academy of Medical Sciences and Peking Union of Medical College: Current Employment. Marcus:Gilead: Consultancy; Roche: Honoraria; Janssen: Honoraria, Speakers Bureau. Portell:Xencor: Research Funding; Roche/Genentech: Consultancy, Research Funding; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding; Janssen: Consultancy; Pharmacyclics: Consultancy; AbbVie: Research Funding; TG Therapeutics: Research Funding; Infinity: Research Funding. Zhou:Henan Cancer Hospital: Current Employment. Thieblemont:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Bristol-Myers Squibb: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Incyte: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Cellectis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Hospira: Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Bayer: Honoraria; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding. Co:BeiGene: Current Employment, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding. Wang:BeiGene: Current Employment. Tankersley:Clovis Oncology, Inc: Ended employment in the past 24 months; BeiGene: Current Employment, Current equity holder in publicly-traded company, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Zhou:BeiGene: Current Employment, Current equity holder in publicly-traded company; Beth Israel Deaconess Medical Center: Ended employment in the past 24 months. Cappellini:BeiGene Ltd.: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months; BeiGene Aus Pty. Ltd.: Current Employment. Huang:BeiGene: Current Employment, Current equity holder in publicly-traded company, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Trotman:BeiGene: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Takeda: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Roche: Other: Travel/accommodations/expenses, Research Funding. OffLabel Disclosure: Zanubrutinib has not been approved for MZL in the US

BACKGROUND Salvage immunochemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation is the standard-of-care second-line treatment for patients with relapsed/refractory diffuse large B-cell lymphoma after first-line R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Outcomes after receipt of second-line immunochemotherapy in patients with aggressive B-cell lymphomas who relapse or are refractory to intensive first-line immunochemotherapy regimens (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab [R-EPOCH], rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and cytarabine [R-HyperCVAD], rituximab, cyclophosphamide, vincristine, doxorubicin, and high-dose methotrexate alternating with ifosfamide, etoposide, and cytarabine [R-CODOX-M/IVAC]) remain unknown. METHODS Outcomes of patients with non-Burkitt, aggressive B-cell lymphomas and relapsed/refractory disease after first-line treatment with intensive immunochemotherapy regimens who received platinum-based second-line immunochemotherapy were reviewed retrospectively. Analyses were performed to determine progression-free survival (PFS) and overall survival (OS) from the time of receipt of second-line immunochemotherapy. RESULTS In total, 195 patients from 19 academic centers were included in the study. The overall response rate to second-line immunochemotherapy was 44%, with a median PFS of 3 months and a median OS of 8 months. Patients with early treatment failure (primary refractory or relapse

This review summarizes the unique presentation and management of the leukemic variant of mantle cell lymphoma (LV-MCL, also referred to as non-nodal MCL) and highlights the biologic and clinical differentiation from classical mantle cell lymphoma (cMCL) in biomarker expression, clinical features, prognosis, disease course, and treatment.Several studies have evaluated the gene expression profile of mantle cell lymphoma, differentiating LV-MCL from cMCL. The typical immunophenotypic profile is CD5-positive, SOX 11-negative, CD23-low, CD200-low, and cyclin D1 overexpressed. LV-MCL commonly has mutated immunoglobulin heavy chain variable region genes. Data on treatment of LV-MCL is limited to retrospective analyses; the ideal treatment for these patients is unknown although many have a clinically indolent, asymptomatic presentation and often may be observed for an extended period without active treatment. LV-MCL is a clinically and biologically distinct entity. Clinically, it must be distinguished from chronic lymphocytic leukemia and cMCL. Future prospective, randomized clinical trials are required to optimize management, define the initial treatment, and appropriately sequence treatment modalities.

We performed a multicenter retrospective analysis across 10 US academic medical centers to evaluate treatment patterns and outcomes in patients age ≥60 years with classic Hodgkin lymphoma (cHL) from 2010-2018. Among 244 eligible patients, median age was 68, 63% had advanced stage (III/IV), 96% had Eastern Cooperative Oncology Group performance status (PS) 0-2, and 12% had documented loss of ≥1 activity of daily living (ADL). Medical comorbidities were assessed by the Cumulative Illness Rating Scale–Geriatric (CIRS-G), where n = 44 (18%) had total scores ≥10. Using multivariable Cox models, only ADL loss predicted shorter progression-free (PFS; hazard ratio [HR] 2.13, P = .007) and overall survival (OS; HR 2.52, P = .02). Most patients (n = 203, 83%) received conventional chemotherapy regimens, including doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD; 56%), AVD (14%), and AVD with brentuximab vedotin (BV; 9%). Compared to alternative therapies, conventional regimens significantly improved PFS (HR 0.46, P = .0007) and OS (HR 0.31, P = .0003). Survival was similar following conventional chemotherapy in those ages 60-69 vs ≥70: PFS HR 0.88, P = .63; OS HR 0.73, P = .55. Early treatment discontinuation due to toxicity was more common with CIRS-G ≥10 (28% vs 12%, P = .016) or documented geriatric syndrome (28% vs 13%, P = .02). A competing risk analysis demonstrated improved disease-related survival with conventional therapy (HR 0.29, P = .02) and higher mortality from causes other than disease or treatment with high CIRS-G or geriatric syndromes. This study suggests conventional chemotherapy regimens remain a standard of care in fit older patients with cHL, and highlights the importance of geriatric assessments in defining fitness for cHL therapy going forward.

Data addressing prognostication in patients with HIV related Burkitt lymphoma (HIV-BL) currently treated remain scarce. We present an international analysis of 249 (United States: 140; United Kingdom: 109) patients with HIV-BL treated from 2008 to 2019 aiming to identify prognostic factors and outcomes. With a median follow up of 4.5 years, the 3-year progression-free survival (PFS) and overall survival (OS) were 61% (95% confidence interval [CI] 55% to 67%) and 66% (95%CI 59% to 71%), respectively, with similar results in both countries. Patients with baseline central nervous system (CNS) involvement had shorter 3-year PFS (36%) compared to patients without CNS involvement (69%; P < .001) independent of frontline treatment. The incidence of CNS recurrence at 3 years across all treatments was 11% with a higher incidence observed after dose-adjusted infusional etoposide, doxorubicin, vincristine, prednisone, cyclophosphamide (DA-EPOCH) (subdistribution hazard ratio: 2.52; P = .03 vs other regimens) without difference by CD4 count 100/mm3. In multivariate models, factors independently associated with inferior PFS were Eastern Cooperative Oncology Group (ECOG) performance status 2-4 (hazard ratio [HR] 1.87; P = .007), baseline CNS involvement (HR 1.70; P = .023), lactate dehydrogenase >5 upper limit of normal (HR 2.09; P < .001); and >1 extranodal sites (HR 1.58; P = .043). The same variables were significant in multivariate models for OS. Adjusting for these prognostic factors, treatment with cyclophosphamide, vincristine, doxorubicin, and high-dose methotrexate, ifosfamide, etoposide, and high-dose cytarabine (CODOX-M/IVAC) was associated with longer PFS (adjusted HR [aHR] 0.45; P = .005) and OS (aHR 0.44; P = .007). Remarkably, HIV features no longer influence prognosis in contemporaneously treated HIV-BL.

There is a Blood Commentary on this article in this issue., Key Points Both watch-and-wait and treated CLL patients have high mortality rates when admitted for COVID-19. Receiving a BTKi for CLL at COVID-19 diagnosis severe enough to require hospitalization did not influence case fatality rate in this study., Given advanced age, comorbidities, and immune dysfunction, chronic lymphocytic leukemia (CLL) patients may be at particularly high risk of infection and poor outcomes related to coronavirus disease 2019 (COVID-19). Robust analysis of outcomes for CLL patients, particularly examining effects of baseline characteristics and CLL-directed therapy, is critical to optimally manage CLL patients through this evolving pandemic. CLL patients diagnosed with symptomatic COVID-19 across 43 international centers (n = 198) were included. Hospital admission occurred in 90%. Median age at COVID-19 diagnosis was 70.5 years. Median Cumulative Illness Rating Scale score was 8 (range, 4-32). Thirty-nine percent were treatment naive (“watch and wait”), while 61% had received ≥1 CLL-directed therapy (median, 2; range, 1-8). Ninety patients (45%) were receiving active CLL therapy at COVID-19 diagnosis, most commonly Bruton tyrosine kinase inhibitors (BTKi’s; n = 68/90 [76%]). At a median follow-up of 16 days, the overall case fatality rate was 33%, though 25% remain admitted. Watch-and-wait and treated cohorts had similar rates of admission (89% vs 90%), intensive care unit admission (35% vs 36%), intubation (33% vs 25%), and mortality (37% vs 32%). CLL-directed treatment with BTKi’s at COVID-19 diagnosis did not impact survival (case fatality rate, 34% vs 35%), though the BTKi was held during the COVID-19 course for most patients. These data suggest that the subgroup of CLL patients admitted with COVID-19, regardless of disease phase or treatment status, are at high risk of death. Future epidemiologic studies are needed to assess severe acute respiratory syndrome coronavirus 2 infection risk, these data should be validated independently, and randomized studies of BTKi’s in COVID-19 are needed to provide definitive evidence of benefit., Visual Abstract

We examined adults with untreated Burkitt lymphoma (BL) from 2009 to 2018 across 30 US cancer centers. Factors associated with progression-free survival (PFS) and overall survival (OS) were evaluated in univariate and multivariate Cox models. Among 641 BL patients, baseline features included the following: median age, 47 years; HIV+, 22%; Eastern Cooperative Oncology Group (ECOG) performance status (PS) 2 to 4, 23%; >1 extranodal site, 43%; advanced stage, 78%; and central nervous system (CNS) involvement, 19%. Treatment-related mortality was 10%, with most common causes being sepsis, gastrointestinal bleed/perforation, and respiratory failure. With 45-month median follow-up, 3-year PFS and OS rates were 64% and 70%, respectively, without differences by HIV status. Survival was better for patients who received rituximab vs not (3-year PFS, 67% vs 38%; OS, 72% vs 44%; P < .001) and without difference based on setting of administration (ie, inpatient vs outpatient). Outcomes were also improved at an academic vs community cancer center (3-year PFS, 67% vs 46%, P = .006; OS, 72% vs 53%, P = .01). In multivariate models, age ≥ 40 years (PFS, hazard ratio [HR] = 1.70, P = .001; OS, HR = 2.09, P < .001), ECOG PS 2 to 4 (PFS, HR = 1.60, P < .001; OS, HR = 1.74, P = .003), lactate dehydrogenase > 3× normal (PFS, HR = 1.83, P < .001; OS, HR = 1.63, P = .009), and CNS involvement (PFS, HR = 1.52, P = .017; OS, HR = 1.67, P = .014) predicted inferior survival. Furthermore, survival varied based on number of factors present (0, 1, 2 to 4 factors) yielding 3-year PFS rates of 91%, 73%, and 50%, respectively; and 3-year OS rates of 95%, 77%, and 56%, respectively. Collectively, outcomes for adult BL in this real-world analysis appeared more modest compared with results of clinical trials and smaller series. In addition, clinical prognostic factors at diagnosis identified patients with divergent survival rates.

Natural killer (NK) cell enteropathy is a lymphoproliferative disorder, initially described by Mansoor and colleagues, that presents in the gastrointestinal tract, and is often mistaken for extranodal NK/T-cell lymphoma on first assessment. This population of cells in this process have an NK-cell phenotype (CD3, CD56, CD2, CD7), lacks evidence of Epstein-Barr virus infection, has germline rearrangement of the T-cell receptor, and a very indolent clinical course. Indeed, many of such patients had been originally diagnosed as having an NK/T-cell lymphoma, and subsequently received chemotherapy. We report a unique case where an indolent lymphoproliferative disorder with features that resemble NK-cell enteropathy is encountered for the first time outside the gastrointestinal tract, specifically in the female genitourinary tract. We provide morphologic, immunophenotypic, and molecular documentation of such, in association with a completely indolent clinical behavior of this type of process.

Chimeric antigen receptor (CAR) T-cell immunotherapy is a rapidly emerging and highly publicized new treatment modality, which has gained significant attention for its effectiveness, side effects, and costs. Early-phase clinical trials have shown dramatic results in patients with often heavily pretreated disease, including those with relapsed/refractory childhood acute lymphoblastic leukemia and adult diffuse large B-cell lymphomas. With recent US Food and Drug Administration approval of two CAR T products in these disease groups and ongoing clinical trials in many other clinical contexts, the number of patients who will receive CAR-based adoptive immunotherapy is expected to grow substantially in the coming years. The criteria by which providers will decide who and when to refer for CAR T therapy will continue to evolve considerably as the field matures, and considerations of referral timing, therapeutic target, and treatment-related toxicity will remain important factors going forward. In this chapter, we propose a series of questions which the referring provider should consider in deciding when to refer a patient for CAR T therapy. These aim to address key factors in this process including which diseases are appropriate for CAR T therapy, what the expected timelines are for treatment, and what organ function criteria are needed to tolerate therapy. Finally, we will review the use of CAR T in special populations, including elderly and human immunodeficiency virus–positive patients, for whom the use of CAR T therapy is less established and will warrant further study as the field continues to grow.

Bendamustine (B) with rituximab (R) is a standard frontline treatment for medically fit follicular lymphoma (FL) patients. The safety and efficacy of maintenance rituximab (MR) after BR induction has not been formally compared to observation for FL, resulting in disparate practice patterns. Prospective trials have shown benefit of MR after R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) or R-CVP (rituximab, cyclophosphamide, vincristine, prednisone), yet recent data from the GALLIUM study comparing outcomes of patients treated with chemotherapy with R or obinutuzumab (G) showed higher than anticipated fatal adverse events with BR/BG. In order to assess the efficacy and tolerability of MR after BR, we retrospectively collected data on 640 newly diagnosed patients treated with FL. We found that patients who achieved partial remission (PR) after ≥4 cycles of BR had improved duration of response (DOR) with MR vs. no maintenance, whereas those in complete remission did not. These findings were confirmed in a validation cohort. In the entire study population, the known fatal adverse event rate after BR was 2·5% and did not significantly differ in those receiving MR versus no maintenance. [Correction added on 14 January 2019, after online publication: The preceding sentence has been corrected in this current version.] Within the limitations inherent to retrospective analysis, these data suggest that FL patients with a PR to BR experience prolongation of remission with MR with an acceptable safety profile.

The Bruton tyrosine kinase inhibitor, ibrutinib, is an effective therapy against mature B-cell malignancies. Although generally well tolerated, serious bleeding emerged during developmental clinical trials as an unexpected, although uncommon, adverse event. As the use of ibrutinib increases outside of the clinical trial setting and in patients with more comorbidities, the rate of major bleeding could be greater.A retrospective analysis the data from all patients at our center and its regional clinics who had been prescribed ibrutinib from January 2012 to May 2016 were reviewed for demographic data, comorbid illnesses, bleeding events, and concurrent medications.We identified 70 patients. Bleeding of any grade occurred in 56% of patients, mostly grade 1 to 2 bruising and epistaxis. Major bleeding, defined as grade ≥ 3, occurred in 19% of patients, greater than previously reported. Anemia (hemoglobin 12 g/dL; hazard ratio [HR], 5.0; 95% confidence interval [CI], 1.4-18.2; P = .02) and an elevated international normalized ratio (1.5; HR, 9.5; 95% CI, 2.7-33.5; P .01) at ibrutinib initiation were associated with an increased risk of major bleeding. Of those with major bleeding, most patients were also taking an antiplatelet agent (70%), an anticoagulant (17%), or a CYP 3A4 inhibitor (7%), with 13% taking both antiplatelet and anticoagulant medications. The use of both antiplatelet and anticoagulant therapy significantly increased the risk of a major bleed event (HR, 19.2; 95% CI, 2.3-166.7; P .01).The results of the present study have demonstrated a greater rate of major bleeding with ibrutinib use in a standard clinical setting than previously reported. Patients with anemia or an elevated international normalized ratio or requiring anticoagulant and/or antiplatelet medications during ibrutinib therapy have a significantly increased risk of major bleeding. Careful consideration of the risks and benefits for this population is needed. The combination of antiplatelet and anticoagulation medications with ibrutinib therapy is of particular concern.

Introduction: Plamotamab (XmAb13676) is a humanized bispecific antibody that binds both CD20 and CD3 to recruit cytotoxic T cells to kill CD20 expressing malignant cells. Interim results of an ongoing first-in-human (FIH), dose-escalation study (XmAb13676-01; NCT02924402) in subjects with relapsed/refractory (R/R) non-Hodgkin's lymphoma (NHL) are reported. Methods: The study is an FIH, multi-center, open-label, phase 1, dose-escalation study in subjects with R/R NHL with a standard 3 + 3 design. The primary objectives are to determine safety, tolerability, and the maximum tolerated dose (MTD) or recommended dose of plamotamab. Secondary objectives include preliminary anti-tumor activity and pharmacokinetics/pharmacodynamics of plamotamab. This study has 3 Parts: Part A, escalating dose cohorts that establish an initial priming dose as part of repeated weekly infusions at a fixed, weight-based dose in a 28-day cycle; Part B, with a dosing schedule consisting of a priming dose on Cycle 1 Day 1, established in Part A, followed by step-up dosing (SUD) on subsequent weeks; and Part C is an SUD regimen with flat and less frequent dosing. Cytokine release syndrome (CRS) prophylaxis with dexamethasone, antihistamine, and acetaminophen was mandated prior to each administration of plamotamab. Treatment was continued for 2 cycles or longer if there was evidence of therapeutic benefit. Results: At data cut-off (01Jul2021), 80 subjects with NHL have been treated. Subjects had a median age of 62 years (range 32-89), a median of 4 prior therapies (range 1-10), and had been diagnosed a median of 28 months (range 6-353) prior to treatment in the study. The most common treatment-related adverse event was CRS. Overall, 50 subjects (62.5%) experienced CRS, with 4 (5.0%) experiencing Grade ≥ 3 CRS. No related neurotoxicity >Grade 2 has been observed. Treatment responses for NHL were assessed by the Lugano criteria or International Working Group criteria for Waldenström Macroglobulinemia. There have been 23 objective responses (43.4% overall response rate [ORR]) and 13 (38.2%) at doses of ≥ 80 µg/kg or flat dosing in all evaluable subjects with NHL and diffuse large cell B-cell lymphoma, respectively. In the efficacy-evaluable, follicular lymphoma population, at doses of 80-360 µg/kg or flat dosing, objective responses were observed in 8/10 (80%) subjects. After implementation of flat dosing, as opposed to weight-based dosing, a 50% ORR (4/8 evaluable subjects) has been observed in NHL subjects in that cohort. An MTD has not been reached, and dose escalation is ongoing. Overall, 4 out of 16 (25%) evaluable subjects with prior CAR-T therapy responded to plamotamab. Conclusions: Plamotamab demonstrated evidence of clinical activity in heavily pretreated subjects with R/R NHL. CRS was generally manageable with premedication. The study is ongoing with further optimization of dose and schedule. Figure 1 Figure 1. Disclosures Patel: Kite Pharma: Consultancy, Speakers Bureau; Genentech: Consultancy; Morphosys: Consultancy; Bristol Myers Squibb: Consultancy, Speakers Bureau; BeiGene: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy; Abbvie: Consultancy; TG Therapeutics: Consultancy, Speakers Bureau; MEI Pharma: Consultancy; ADC Therapeutics: Consultancy; Lilly: Consultancy. Michot: GSK: Honoraria; Celgene: Honoraria; MSD: Consultancy, Honoraria; Innate Pharma: Research Funding; Incyte: Research Funding; H3 biomedecine: Research Funding; GSK: Consultancy, Honoraria, Research Funding; Genentech: Research Funding; Gamamabs: Research Funding; Forma: Research Funding; Exelixis: Research Funding; Eos: Research Funding; Eisai: Research Funding; Debiopharm: Research Funding; Daiichi Sankyo,: Research Funding; Clovis: Research Funding; Chugai: Research Funding; Boeringer Ingelheim: Research Funding; Celgene: Research Funding; Blueprint: Research Funding; Beigene: Research Funding; Bayer: Research Funding; Argen-x: Research Funding; Amgen: Research Funding; Agios: Research Funding; Aduro: Research Funding; Abbvie: Research Funding; ASTEX: Research Funding, Speakers Bureau; Astra Zeneca: Honoraria, Research Funding; Roche: Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding. Chanan-Khan: Alpha2 Pharmaceuticals, NonoDev, Starton: Current holder of stock options in a privately-held company; Ascentage: Research Funding; Cellectar: Current equity holder in publicly-traded company; Alpha2 Pharmaceuticals: Patents & Royalties: Tabi; Ascentage, Starton, Cellectar, NonoDev, Alpha2 Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BeiGene, Jansen, Ascentage: Honoraria; BieGene, Jansen, Ascentage: Consultancy. Ghesquieres: Janssen: Honoraria; Mundipharma: Consultancy, Honoraria; Roche: Consultancy; Celgene: Consultancy, Honoraria; Gilead Science: Consultancy, Honoraria. Byrd: Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria; Newave: Membership on an entity's Board of Directors or advisory committees. Cartron: Roche, Celgene-BMS: Consultancy; Danofi, Gilead, Novartis, Jansen, Roche, Celgene-BMS, Abbvie, Takeda: Honoraria. Portell: Acerta/AstraZeneca: Research Funding; Xencor: Research Funding; SeaGen: Research Funding; Targeted Oncology: Honoraria; Aptitude Health: Honoraria; Abbvie: Research Funding; Pharmacyclics: Honoraria; Kite: Honoraria, Research Funding; Merck: Honoraria, Research Funding; BeiGene: Honoraria, Research Funding; Morphosys: Honoraria; TG Therapeutics: Honoraria, Research Funding; Genentech: Research Funding; VelosBio: Research Funding. Solh: Jazz Pharmaceuticals: Consultancy; Partner Therapeutics: Research Funding; BMS: Consultancy; ADCT Therapeutics: Consultancy, Research Funding. Wierda: Loxo Oncology, Inc.: Research Funding; GSK/Novartis: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Miragen: Research Funding; Sunesis: Research Funding; Gilead Sciences: Research Funding; KITE Pharma: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Juno Therapeutics: Research Funding; Acerta Pharma Inc.: Research Funding; Xencor: Research Funding; AstraZeneca: Research Funding; Cyclacel: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Karyopharm: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding. Johnson: Xencor: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months. Garcha: Xencor: Current Employment, Current equity holder in publicly-traded company, Current holder of stock options in a privately-held company; Promedim: Ended employment in the past 24 months. Ribrag: AstraZeneca: Membership on an entity's Board of Directors or advisory committees; GSK: Research Funding; MSD Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Infinity Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; Argen-X: Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Astex Pharmaceuticals: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees; Nanostring: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; PharmaMar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Epizyme: Honoraria, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees. Liebowitz: Xencor: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Phillips: Incyte: Consultancy, Other: received travel expenses from Incyte, Research Funding; ADCT, BeiGene, Bristol Myers Squibb, Cardinal Health, Incyte, Karyopharm, Morphosys, Pharmacyclics, Seattle Genetics: Consultancy; AbbVie: Consultancy, Research Funding; AstraZeneca: Consultancy; BMS: Consultancy, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Research Funding.

Background: Chemoimmunotherapy is considered standard initial therapy for follicular lymphoma (FL) with high tumor burden (HTB). Obinutuzumab and Bendamustine (OB) with maintenance Obinutuzumab (mO) is considered a standard therapy for the frontline treatment of HTB FL (GALLIUM, Marcus et al, NEJM 2017). Venetoclax (VEN), an oral BCL2 inhibitor, is an attractive target in FL given the high BCL2 expression; though single agent activity has been disappointing (Davids et al. JCO 2017). BCL2 inhibition is thought to be synergistic with chemotherapy. Thus, the PrE0403 study evaluated the OB-VEN combination in frontline HTB FL. Here we present end of induction (EOI) outcomes. Methods: The primary objective of this Phase II study was to estimate the complete remission (CR) rate at EOI. Potential participants must have had a histologically confirmed diagnosis of FL grade 1, 2, or 3a with HTB defined by GELF or high risk defined by FLIPI-1 criteria. They must have had adequate performance status and organ function. Notably, creatinine clearance must have been ≥50 mL/min. Participants must have not had prior treatment for FL. Eligible participants were treated with Bendamustine IV 90 mg/m2 Day (D) 1 & 2, Obinutuzumab IV 100 mg D1, 900 mg D2, 1000 mg D8 and D15 of Cycle (C) 1 then D1 of each cycle, and VEN 800 mg orally daily D1-10 every 28 days for 6 total cycles. Due to a high rate of laboratory tumor lysis syndrome (TLS) during C1 in the first 21 patients, VEN was removed from C1 and given in C2-6 only. Participants with a CR at EOI were treated with mO IV 1000 mg D1 every 8 weeks for 2 years. Those with a partial response (PR) or stable disease (SD) were treated with mO as well as VEN 800 mg orally daily for 2 years. Pneumocystis jiroveci Pneumonia (PJP) and antiviral prophylaxis was required as was G-CSF support. Response was assessed via Lugano Criteria at EOI including PET/CT and bone marrow assessment. Adverse Events (AEs) were evaluated using CTCAE v5.0. To be considered promising, OB-VEN should improve the null hypothesis CR rate of 50% (OB) to 65%. With an 85% power and a one sided 15% type I error, 56 participants would be needed with an estimated 51 eligible. Support for the study was from Genentech, Member of the Roche Group. Results A total of 56 participants were enrolled and treated between 12/2017 and 11/2020; baseline characteristics are listed in Table 1. TLS was closely monitored in C1 and 8/21 participants developed TLS when VEN was administered in C1; 0/35 when it was not. However, monitoring for TLS in C1 became less stringent when VEN was not administered. Treatment related Grade ≥3 toxicities occurred in 47/56 participants (83.9%) with serious adverse events in 31 of 56 (55.5%). Atypical infections were seen; there was one treatment related death on study due to cytomegalovirus (CMV) encephalitis as well as PJP pneumonia which occurred after induction C6. Enrollment was temporarily suspended and CMV monitoring was implemented with no further occurrences. Another participant receiving mO later developed BK virus nephropathy following mO C6 and now requires ongoing hemodialysis. Another was diagnosed with Respiratory Syncytial Virus pneumonia 30 days after C6 and later PJP pneumonia after C2 of mO. Common (incidence >10%) AEs during induction are listed in Table 2. 45 of 56 (80.4%) participants were able to receive all 6 cycles of OB-VEN. CR was seen in 41 of 56 participants (73.2%, 2 sided 95% Confidence Interval (CI) 59.7-84.2%) at the EOI. 30 participants (53.5%) went onto maintenance. With a median follow up of 20.9 months, estimated 2 year Overall Survival (OS) and Progression-Free Survival (PFS) (90% CI) is 94.4% (82.4-98.3%) and 85.8% (68.8-93.9%) respectively. Conclusions This Phase II study of OB-VEN in untreated HTB FL showed high CR rate and met its primary endpoint with early signs of prolonged PFS. Laboratory TLS was identified but it was unclear if attributed solely to VEN, as baseline laboratory TLS rate for OB is unknown. The rate of Grade ≥3 AE of 83.9% (compared to 69% for OB in GALLIUM, Hiddeman JCO 2018) and the observation of opportunistic infections including CMV encephalitis, PJP pneumonia and BK nephropathy, suggests the combination is highly immunosuppressive. Therefore, while the study met its primary outcome, the combination of OB-VEN at 800 mg for 10 days, plus mO, does not have an acceptable risk/benefit profile. Participants will continue to be followed for efficacy and safety during the maintenance phase. Figure 1 Figure 1. Disclosures Portell: Acerta/AstraZeneca: Research Funding; SeaGen: Research Funding; Pharmacyclics: Honoraria; Xencor: Research Funding; Aptitude Health: Honoraria; BeiGene: Honoraria, Research Funding; Abbvie: Research Funding; TG Therapeutics: Honoraria, Research Funding; Kite: Honoraria, Research Funding; Merck: Honoraria, Research Funding; Morphosys: Honoraria; Targeted Oncology: Honoraria; Genentech: Research Funding; VelosBio: Research Funding. Nowakowski: MorphoSys: Consultancy; Incyte: Consultancy; Kymera Therapeutics: Consultancy; TG Therapeutics: Consultancy; Blueprint Medicines: Consultancy; Nanostrings: Research Funding; Roche: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Celgene/Bristol Myers Squibb: Consultancy, Research Funding; Zai Labolatory: Consultancy; Daiichi Sankyo: Consultancy; Bantham Pharmaceutical: Consultancy; Curis: Consultancy; Karyopharm Therapeutics: Consultancy; Selvita: Consultancy; Ryvu Therapeutics: Consultancy; Kyte Pharma: Consultancy. Cohen: Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo, BeiGene, Adaptive: Consultancy; Genentech, BMS/Celgene, LAM, BioINvent, LOXO, Astra Zeneca, Novartis, M2Gen, Takeda: Research Funding. Kahl: AbbVie, Acerta, ADCT, AstraZeneca, BeiGene, Genentech: Research Funding; AbbVie, Adaptive, ADCT, AstraZeneca, Bayer, BeiGene, Bristol-Myers Squibb, Celgene, Genentech, Incyte, Janssen, Karyopharm, Kite, MEI, Pharmacyclics, Roche, TG Therapeutics, and Teva: Consultancy. OffLabel Disclosure: Venetoclax is not approved for follicular lymphoma or in combination with bendamustine and obinutuzumab

Background: Targeted therapies including ibrutinib, acalabrutinib and venetoclax (ven) have fundamentally changed the treatment of patients (pts) with chronic lymphocytic leukemia (CLL) leading to improved outcomes and durable remissions for many pts. However, CLL remains an incurable disease and a subset of pts will ultimately have progressive CLL following treatment with a covalent Bruton's Tyrosine Kinase inhibitor (cBTKi, e.g., ibrutinib, acalabrutinib) and ven. Data on efficacy of therapies for "double exposed" pts (i.e., pts exposed to both a cBTKi and ven) are extremely limited. Available approved options include chemoimmunotherapy (CIT) and phosphatidylinositol 3-kinase inhibitors (PI3Ki). However, the landmark clinical trials leading to the approvals of CIT and PI3Kis did not include pts treated with either cBTKi or ven (Furman et al. NEJM 2014, Flinn et al. Blood 2018). Non-covalent BTKis (ncBTKi) and chimeric antigen receptor (CAR) T-cell therapy have demonstrated promising clinical activity in double exposed CLL pts in clinical trials (Mato et al. Lancet 2021, Siddiqi et al. ASH 2020), but have not yet been compared to other novel agents or CIT in clinical trials or real-world analyses. We sought to describe outcomes of therapies for "double exposed" CLL pts. Methods: A retrospective, international, multicenter study was conducted. CLL pts were included if they received a cBTKi and ven and then a subsequent CLL-directed therapy. Therapies for Richter Transformation were excluded. Investigators identified pts at each site and collected data on demographics, disease characteristics, prior therapies, subsequent therapies and response assessments. Information was collected on up to three subsequent lines of therapy (LOT 1-3) per patient. The primary study endpoint was investigator-assessed overall response rate (ORR) per iwCLL 2018 criteria to therapies (LOT 1-3) following both cBTKi and ven. Kaplan-Meier method was used to estimate progression free survival (PFS). All other analyses were descriptive. Analyses were performed using STATA 17.0. Results: We report outcomes on 125 CLL pts who had prior cBTKi and ven and received a subsequent LOT. Baseline characteristics are presented in Table 1. ORR to prior cBTKi was 84.7% and 69.6% to prior ven. The most common reason for discontinuation of prior cBTKi and ven was CLL progression (71.1% cBTKi, 68.8% ven) followed by toxicity (25.6% cBTKi, 16.8% ven). Most common treatment strategies included ncBTKi (n=45), cBTKi (n=43), CIT (n=23), PI3Ki (n=24), alloSCT (n=17), CAR T-cell therapy (n=9), ven re-treatment (n=6), and other (n=44). ORR for selected agents following cBTKi and ven are presented in Table 2. ORR and PFS estimates were as follows: CAR T-cell therapy (85.7%, median PFS 4 months), alloSCT (76.5%, median PFS 11 months), ncBTKi (75.0%, median PFS not reached), PI3Ki (40.9%, median PFS 5 months), CIT (31.8%, median PFS 3 months) and ven re-treatment (ORR 40%, median PFS 14 months). ORR to cBTKi was 53.7%; however, median PFS for pts who discontinued a previous cBTKi for PD was 1 month versus 7 months for pts who discontinued due to AE. Figure 1 shows Kaplan-Meier estimated PFS for ncBTKi, PI3Ki, alloSCT, and CIT. Conclusions: In the largest series of "double exposed" CLL pts, several key findings warrant further investigation and discussion. Practice patterns are variable and no standard of care exists for CLL pts previously treated with a cBTKi and ven. Additionally, approved standard therapies including CIT combinations and PI3Kis yield poor outcomes with responses which are not durable. The low response rates and short PFS for PI3Ki and CIT call into question the use of these therapies as standard comparator arms in planned randomized trials. At this time, ncBTKi has a high ORR with durable responses (median PFS not reached). There appears to be a promising role for alloSCT in select, fit patients (ORR 76.5%, median PFS 11 months), and CAR T-cell therapy should be further explored in this population (ORR 85.7%, median PFS 4 months). Overall, this study highlights a continued unmet need for therapies for "double exposed" CLL pts. Figure 1 Figure 1. Disclosures Thompson: MJH Life Sciences: Honoraria; VJHemOnc: Honoraria; Curio Science: Honoraria. Roeker: Abbot Laboratories: Current equity holder in publicly-traded company; Pharmacyclics: Consultancy; Loxo Oncology: Consultancy; TG Therapeutics: Consultancy; AbbVie, AstraZeneca, Janssen, LOXO, Pharmacyclics, TG Therapeutics, Vaniam Group, Verastem: Consultancy; Pfizer: Consultancy, Research Funding. Coombs: LOXO: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria; Genentech: Honoraria; MEI Pharma: Honoraria. Kamdar: AbbVie: Consultancy; TG Therapeutics: Research Funding; SeaGen: Speakers Bureau; ADC Therapeutics: Consultancy; Adaptive Biotechnologies: Consultancy; AstraZeneca: Consultancy; Celgene: Other; Celgene (BMS): Consultancy; Kite: Consultancy; KaryoPharm: Consultancy; Genentech: Research Funding; Genetech: Other. Pagel: Epizyme: Consultancy; Incyte/MorphoSys: Consultancy; BeiGene: Consultancy; Pharmacyclics/AbbVie: Consultancy; Actinium Pharmaceuticals: Consultancy; AstraZeneca: Consultancy; Gilead: Consultancy; Kite, a Gilead Company: Consultancy; MEI Pharma: Consultancy. Jacobs: MEI Pharma: Research Funding; Adaptive Biotechnologies: Consultancy; Genentech: Consultancy; TG Therapeutics: Research Funding, Speakers Bureau; Verastem: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; ADC Therapeutics: Consultancy; TeneoBio: Research Funding; AbbVie: Consultancy, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding, Speakers Bureau; Jannsen: Speakers Bureau; SecuraBio: Consultancy, Speakers Bureau. Hill: Gentenech: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Celgene (BMS): Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding. Brander: AbbVie: Consultancy, Other: informCLL registry steering committee, Research Funding; AstraZeneca: Research Funding; BeiGene: Research Funding; ArQule: Research Funding; DTRM: Research Funding; LOXO: Research Funding; Verastem: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Juno Therapeutics/Celgene/Bristol Myers Squibb: Research Funding; Novartis: Research Funding; Ascentage: Research Funding; MEI Pharma: Research Funding; Genentech: Consultancy, Research Funding; NCCN: Other: panel member; Pfizer: Consultancy, Other: Biosimilars outcomes research panel; ArQule/Merck: Consultancy. Shadman: Mustang Bio, Celgene, Bristol Myers Squibb, Pharmacyclics, Gilead, Genentech, Abbvie, TG Therapeutics, Beigene, AstraZeneca, Sunesis, Atara Biotherapeutics, GenMab: Research Funding; Abbvie, Genentech, AstraZeneca, Sound Biologics, Pharmacyclics, Beigene, Bristol Myers Squibb, Morphosys, TG Therapeutics, Innate Pharma, Kite Pharma, Adaptive Biotechnologies, Epizyme, Eli Lilly, Adaptimmune , Mustang Bio and Atara Biotherapeutics: Consultancy. Ujjani: AbbVie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Loxo: Research Funding; Adaptive Biotechnologies: Research Funding; Atara Bio: Consultancy; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; TG Therapeutics: Honoraria; Gilead: Honoraria; ACDT: Honoraria; Kite, a Gilead Company: Honoraria. Battiato: Abbvie: Honoraria; Janssen: Honoraria. Rhodes: AbbVie, Genentech, Pharmacyclics, TG Therapeutics: Other: Consultant; Conquer Cancer Foundation Young Investigator Award: Other: Grant/Research Support. Fakhri: Loxo/Lilly: Research Funding. Barr: Morphosys: Consultancy; Gilead: Consultancy; Seattle Genetics: Consultancy; TG Therapeutics: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy; Beigene: Consultancy; Bristol Meyers Squibb: Consultancy; Abbvie/Pharmacyclics: Consultancy; Genentech: Consultancy. Portell: TG Therapeutics: Honoraria, Research Funding; SeaGen: Research Funding; Kite: Honoraria, Research Funding; Xencor: Research Funding; Abbvie: Research Funding; Pharmacyclics: Honoraria; Merck: Honoraria, Research Funding; BeiGene: Honoraria, Research Funding; Acerta/AstraZeneca: Research Funding; Aptitude Health: Honoraria; Targeted Oncology: Honoraria; Morphosys: Honoraria; Genentech: Research Funding; VelosBio: Research Funding. Lamanna: AbbVie: Consultancy, Research Funding; Verastem Oncology: Research Funding; BeiGene: Consultancy; Pharmacyclics: Consultancy; Celgene Corporation: Consultancy; Oncternal Therapeutics: Research Funding; Janssen Pharmaceuticals, Inc.: Consultancy; Gilead Sciences, Inc.: Consultancy; MingSight Pharmaceuticals, Inc.: Research Funding; Genentech, Inc.: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; TG Therapeutics, Inc: Research Funding; Juno Therapeutics, Inc.: Research Funding. Zelenetz: MorphoSys: Honoraria; Verastem: Honoraria; LFR: Other; Gilead: Honoraria, Research Funding; NCCN: Other; AstraZeneca: Honoraria; MEI Pharma: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Janssen: Honoraria; Gilead: Honoraria; Pharmacyclics: Honoraria; BMS/Celgene/JUNO: Honoraria, Other; Novartis: Honoraria; SecuraBio: Honoraria; Genentech/Roche: Honoraria, Research Funding; MethylGene: Research Funding; Amgen: Honoraria; Beigene: Honoraria, Other, Research Funding. Schuster: Abbvie: Consultancy, Research Funding; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; Adaptive Biotechnologies: Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; DTRM: Research Funding; Genetech: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Incyte: Research Funding; Juno Theraputics: Consultancy, Research Funding; Loxo Oncology: Consultancy; Merck: Research Funding; Nordic Nanovector: Consultancy; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Pharmaclcyclics: Research Funding; Tessa Theraputics: Consultancy; TG Theraputics: Research Funding. Eyre: Secura Bio: Consultancy, Honoraria; Loxo Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Research Funding; Incyte: Consultancy; Beigene: Honoraria, Research Funding; Roche: Consultancy, Honoraria; Gilead/KITE: Honoraria, Other: Travel support for conferences, Research Funding, Speakers Bureau; Janssen: Honoraria; Abbvie: Consultancy, Honoraria, Other: Travel to conferences. Mato: MSKCC: Current Employment; AstraZeneca: Consultancy; Genmab: Research Funding; LOXO: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Johnson and Johnson: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; BeiGene: Consultancy, Research Funding; DTRM BioPharma: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Acerta/AstraZeneca: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Nurix: Research Funding.

Background Primary bone diffuse large B cell lymphoma (DLBCL) is a variant of extranodal non-Hodgkin lymphoma (NHL) that is relatively rare, accounting for 3-15% of extranodal NHL and less than 1% of all NHL. Patients often present with pain and swelling or pathologic fracture of the affected area of the skeleton, and B symptoms are often less prevalent. Many cases are limited stage at presentation. Patients are usually treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) or similar induction therapy. Based on older studies showing improved outcomes associated with the addition of radiation (many completed prior to the rituximab era), patients often still receive combined-modality therapy today. However, it remains unknown whether consolidative radiation therapy (RT) confers additional benefit following rituximab-based chemoimmunotherapy (CIT) induction. We sought to address this question in a multicenter retrospective study. Methods We conducted a retrospective analysis of outcomes in a modern cohort of patients who underwent treatment for primary bone DLBCL using chemotherapy regimens in the rituximab era either with or without consolidative RT. Data was collected from 13 academic medical centers in the U.S., with patients treated between 2005 and 2019. Patients were identified using each institution's hematologic malignancy registries. Analysis was limited to patients with primary bone DLBCL, with stage I-II disease (primary site +/- locoregional lymph nodes) that could be encompassed in a radiation field. Patients who received CIT alone or CIT followed by RT were included. Treatment selection was at the treating physician's discretion. Electronic medical records were reviewed for: demographics, chemotherapy regimens, radiation treatments, and PET scan data. Local IRB approval was obtained at sites. All data was distributed in a de-identified fashion. The primary outcomes were overall survival (OS), and relapse-free survival (RFS). Secondary outcomes included: response after induction CIT induction and the need for additional therapies. Chi-square test analysis was used to compare categorical variables and the Wilcoxon rank-sum test was used for continuous and ordinal measures. Survival curves were estimated using the Kaplan-Meier method and compared between groups via the log-rank test. Multi-variable analysis (MVA) for OS and RFS was performed using RT vs no RT, PET status post CIT (negative vs positive) and rituximab in induction (Y/N) as variables. Results A total of 127 patients were included: 91 who received CIT and radiation (RT group), and 36 who received CIT alone (no RT group). The median age of patients at diagnosis in the RT group and no RT group was 58.5 and 57.0, respectively. For CIT, the majority of patients received R-CHOP (84%). Despite focusing on 2005-2019, a small percentage of patients (5 - 14%) in each group (RT and no RT) did not receive rituximab with their induction therapy. The OS at 10 years was 74.5% in the RT group and 86.5% in the no RT group (p = 0.29). The RFS at 10 years was 70.9% in the RT group and 78.2% in the no RT group (p = 0.85). Among the 91 patients who received RT, 67 (77.0%) received a dose of 36 Gy or higher. There was no difference in OS (p = 0.63) or RFS (p = 0.90) in patients who received > 36 Gy vs < 36 Gy of radiation. On MVA for OS, RT was not associated with improved OS, although rituximab as part of induction was (p = 0.048). On MVA for RFS, neither RT nor rituximab were associated with improved RFS. For rituximab the trend was in the direction of rituximab benefit (p = 0.11). Conclusion Our results demonstrate that, in the rituximab era, patients with limited stage primary bone DLBCL have excellent outcomes overall. In this study, neither RFS or OS appeared to be improved with the addition of consolidative RT. Rituximab, however, was associated with improved OS on MVA. Outcomes do not appear to differ based on the dose of RT (> 36 Gy vs < 36 Gy). Our data suggests that RT may have less benefit for primary bone DLBCL in the rituximab era, although it is possible that a subset of patients may benefit from consolidative radiation therapy. A larger data set would likely be needed to evaluate this. We plan to present data regarding PET responses at the meeting. Figure 1 Figure 1. Disclosures Lunning: Acrotech: Consultancy; AstraZeneca: Consultancy; Myeloid Therapeutics: Consultancy; Janssen: Consultancy; Morphosys: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Kyowa Kirin: Consultancy; Verastem: Consultancy; Kite, a Gilead Company: Consultancy; Celgene, a Bristol Myers Squibb Co.: Consultancy; Spectrum: Consultancy; Daiichi-Sankyo: Consultancy; Beigene: Consultancy; Legend: Consultancy; ADC Therapeutics: Consultancy; TG Therapeutics: Consultancy; AbbVie: Consultancy. Cashen: Secura Bio, ADC Therapeutics: Consultancy. Bartlett: Autolus: Research Funding; Bristol Myers Squibb: Research Funding; Celgene: Research Funding; Forty Seven: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Merck: Research Funding; Millennium: Research Funding; Pharmacyclics: Research Funding; Seagen: Consultancy, Research Funding; Roche/Genentech: Consultancy; ADC Therapeutics: Consultancy, Research Funding. Caimi: XaTek: Patents & Royalties: Royalties from patents (wife); Amgen Therapeutics.: Consultancy; ADC Theraputics: Consultancy, Research Funding; Genentech: Research Funding; TG Therapeutics: Honoraria; Seattle Genetics: Consultancy; Verastem: Consultancy; Kite Pharmaceuticals: Consultancy. Rodgers: MJH Lifesciences: Consultancy. Barr: Morphosys: Consultancy; Gilead: Consultancy; Genentech: Consultancy; TG Therapeutics: Consultancy; Janssen: Consultancy; Beigene: Consultancy; Bristol Meyers Squibb: Consultancy; Seattle Genetics: Consultancy; AstraZeneca: Consultancy; Abbvie/Pharmacyclics: Consultancy. Epperla: Verastem: Speakers Bureau; Beigene: Speakers Bureau; Karyopharm: Other: Ad Board; Genzyme: Honoraria. Hill: AstraZenica: Consultancy, Honoraria; Celgene (BMS): Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Pfizer: Consultancy, Honoraria; Gentenech: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding. Karmali: BMS/Celgene/Juno: Consultancy, Research Funding; Epizyme: Consultancy; Karyopharm: Consultancy; Janssen/Pharmacyclics: Consultancy; Morphosys: Consultancy, Speakers Bureau; AstraZeneca: Speakers Bureau; BeiGene: Consultancy, Speakers Bureau; EUSA: Consultancy; Takeda: Research Funding; Genentech: Consultancy; Roche: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau. Portell: Acerta/AstraZeneca: Research Funding; Xencor: Research Funding; Abbvie: Research Funding; Aptitude Health: Honoraria; Morphosys: Honoraria; Targeted Oncology: Honoraria; SeaGen: Research Funding; BeiGene: Honoraria, Research Funding; Merck: Honoraria, Research Funding; Pharmacyclics: Honoraria; Kite: Honoraria, Research Funding; TG Therapeutics: Honoraria, Research Funding; Genentech: Research Funding; VelosBio: Research Funding. Fenske: Pharmacyclics: Consultancy; AstraZeneca: Speakers Bureau; Servier Pharmaceuticals: Consultancy; MorphoSys: Consultancy; Adaptive Biotechnologies: Consultancy; KaryoPharm: Consultancy; CSL Therapeutics: Consultancy; TG Therapeutics: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Sanofi: Speakers Bureau; Seattle Genetics: Speakers Bureau; Biogen: Consultancy; ADC Therapeutics: Consultancy; Kite (Gilead): Speakers Bureau; Beigene: Consultancy; AbbVie: Consultancy.

The Bcl-2 inhibitor venetoclax (VEN) shows clinical activity in Chronic Lymphocytic Leukemia (CLL), and the response is potentiated when combined with the BTK inhibitor ibrutinib (IBR) (Portell et al. 2019; Tam et al. 2018). However, many VEN or VEN+IBR responses are incomplete and drug resistance develops in most cases. We previously noted that CLL cells exposed to microenvironmental agonists ex vivo exhibit resistance to VEN+IBR due to upregulation of multiple anti-apoptotic proteins (Jayappa et al. 2017). Here, we find in the circulation of CLL patients that activated (CD69Pos) leukemic B cells recently emigrated from the lymph node exhibit resistance to inhibitors of Bcl-2, Mcl-1, or Bcl-xL due to impaired activation of Bax/Bak proteins. Our molecular analysis suggests that multiple upregulated anti-apoptotic proteins (Mcl-1, Bcl-xL, and Bcl-2) swap for pro-apoptotic proteins (e.g. Bim) in these cells when subjected to single-drug treatments, leading to defective Bax/Bak activation resulting in resistance to drug induced apoptosis. A large-scale cell-based screen using small molecule agonist of Protein Phosphatase 2A (PP2A) (SMAP, TRC-382) revealed that blood cancer cell lines are highly sensitive to SMAP mediated activation of PP2A, a serine/threonine phosphatase known to regulate cell survival. A further pharmacologically optimized SMAP compound (DT061) showed activity even in leukemia cell lines or patient-derived CD69Pos CLL cells resistant to inhibitors of Bcl-2, Mcl-1, or Bcl-xL, suggesting PP2A activation can overcome apoptosis resistance. The PP2A activator DT061 induced apoptosis in these cells in the absence of Bax/Bak activation and was equally effective in an isogenic Bax/Bak double knockout cells, suggesting PP2A activation overcomes multi-drug resistance via induction of Bax/Bak-independent apoptosis. We next examined various Bax/Bak-independent apoptosis mechanisms using inhibitors, and found that inhibitors of mitochondrial permeability transition pores (mPTP) (NIM811 and cyclopsorin-A) blocked the DT061-induced apoptosis in CLL cells. Using the CalceinAM/CoCl2 assay, we noted that DT061 triggers mPTP opening in primary CLL cells, which was blocked by mPTP inhibitors, suggesting DT061 induces apoptosis via mPTP activation. In summary, microenvironmentally activated cancer cells displaying resistance to apoptosis due to defective Bax/Bak activation are found de novo in CLL patients. Reactivation of the tumor suppressive serine/threonine phosphatase by a series of small molecules (SMAPs) overcomes this resistance by inducing mPTP dependent apoptosis. Collectively, these findings demonstrate the existence of an anti-apoptotic multi-drug resistant pool of cancer cells in CLL patients, and validates a novel pharmaceutically tractable pathway to deplete this reservoir. Citation Format: Kallesh D. Jayappa, Caroline Farrington, Vicki L. Gordon, Shekhar Saha, Christopher Morris, Krista M. Isaac, Timothy P. Bender, Michael E. Williams, Craig A. Portell, Goutham Narla, Michael J. Weber. The PP2A activation using a small molecule agonist triggers apoptosis by releasing mitochondrial permeability transition pores in multi-drug resistant leukemic B cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 937.

In recent years, investigators have recognized the rigidity of single-agent, safety-only, traditional designs, rendering them ineffective for conducting contemporary early-phase clinical trials, such as those involving combinations and/or biological agents. Novel approaches are required to address these research questions, such as those posed in trials involving targeted therapies. We describe the implementation of a model-based design for identifying an optimal treatment combination, defined by low toxicity and high efficacy, in an early-phase trial evaluating a combination of two oral targeted inhibitors in relapsed/refractory mantle cell lymphoma. Operating characteristics demonstrate the ability of the method to effectively recommend optimal combinations in a high percentage of trials with reasonable sample sizes. The proposed design is a practical, early-phase, adaptive method for use with combined targeted therapies. This design can be applied more broadly to early-phase combination studies, as it was used in an ongoing study of a melanoma helper peptide vaccine plus novel adjuvant combinations. Clin Cancer Res; 23(23); 7158–64. ©2017 AACR.

De novo resistance and rapid recurrence often characterize responses of B-cell malignancies to ibrutinib (IBR), indicating a need to develop drug combinations that block compensatory survival signaling and give deeper, more durable responses. To identify such combinations, we previously performed a combinatorial drug screen and identified the Bcl-2 inhibitor venetoclax (VEN) as a promising partner for combination with IBR in Mantle Cell Lymphoma (MCL). We have opened a multi-institutional clinical trial to test this combination. However, analysis of primary samples from patients with MCL as well as chronic lymphocytic leukemia (CLL) revealed unexpected heterogeneous de novo resistance even to the IBR+VEN combination. In the current study, we demonstrate that resistance to the combination can be generated by microenvironmental agonists: IL-10, CD40L and, most potently, CpG-oligodeoxynucleotides (CpG-ODN), which is a surrogate for unmethylated DNA and a specific agonist for TLR9 signaling. Incubation with these agonists caused robust activation of NF-κB signaling, especially alternative NF-κB, which led to enhanced expression of the anti-apoptotic proteins Mcl-1, Bcl-xL, and survivin, thus decreasing dependence on Bcl-2. Inhibitors of NF-κB signaling blocked overexpression of these anti-apoptotic proteins and overcame resistance. Inhibitors of Mcl-1, Bcl-xL, or survivin also overcame this resistance, and showed synergistic benefit with the IBR+VEN combination. We conclude that microenvironmental factors, particularly the TLR9 agonist, can generate de novo resistance to the IBR+VEN combination in CLL and MCL cells. This signaling pathway presents targets for overcoming drug resistance induced by extrinsic microenvironmental factors in diverse B-cell malignancies.

Older patients with hematologic malignancies are underrepresented on prospective clinical trials relative to the incidence of disease in this group (Kanapuru et al, 2020). There are few studies in diffuse large B-cell lymphoma (DLBCL) focused specifically on older patients. Rituximab and dose attenuated cyclophosphamide, doxorubicin, vincristine, and prednisone (R-miniCHOP) has been studied on a prospective trial in fit patients aged 80 years and older. Seventy-two percent of patients on this study completed 6 cycles of R-miniCHOP. The overall response rate (ORR) was 73%, and the 2-year progression free survival (PFS) was 47% (Peyrade et al, 2011). Novel regimens are needed to improve upon the efficacy of therapy while preserving tolerability. Brentuximab vedotin (BV) has demonstrated activity in relapsed and refractory DLBCL (Jacobsen et al, 2015) as well as in combination with chemoimmunotherapy (Svoboda, 2020). This study evaluates the feasibility of BV with dose attenuated chemoimmunotherapy. Methods: Patients with both CD30 positive (cut off 1%) and CD30 negative DLBCL aged 75 years and older were enrolled on the study. Patients received six, 3-week cycles of BV 1.8 mg/kg, cyclophosphamide 400 mg/m2, doxorubicin 25 mg/m2, vincristine 1 mg and prednisone 40 mg/m2 days 1-5 (BV R-miniCHP). For the first cycle patients received BV and prednisone as a prephase starting one week prior to cycle 1. All patients received pegfilgrastim. All patients underwent geriatric assessments at screening, following prephase and at the end of treatment. The primary endpoint was feasibility of this regimen in older patients. The regimen was considered feasible if 71% of patients completed 6 cycles of treatment with a 90% confidence interval (CI)=(58.0, 90.6%). Secondary endpoints included toxicity, ORR and complete response (CR) evaluated by positron emission tomography, PFS and overall survival (OS). Response assessments used the Lugano Criteria (Cheson et al, 2014). PFS and OS were estimated using the Kaplan-Meier method. Results: Twenty-two patients were enrolled and started prephase with BV and prednisone. Their baseline characteristics are summarized in the table. Seventy-seven percent (17/22) of patients completed 6 cycles of BV R-miniCHP. Reasons for not completing treatment included progressive disease in 2 patients, myocardial infarction, fatigue, and an unrelated injury in 1 patient each. Twenty-one patients were evaluable for response. ORR was 86% (18/21) in all patients, with 67% (14/21) achieving CR. In CD30 positive patients the ORR was 80% (8/10) and the CR rate was 70% (7/10). In CD30 negative patients the ORR was 91% (10/11) and the CR rate was 64% (7/11). With a median follow up of 23 months, median OS and PFS (figure) were not reached. The 2-year PFS was 60.6%, 90% CI=(40.0%, 76.1%), and the 2-year OS was 73.9%, 90% CI=(52.4%, 86.8%). The most common adverse events (AEs) were fatigue (82%), anemia (50%), diarrhea (50%), dysgeusia (45%) and peripheral sensory neuropathy (45%). Grade ≥3 AEs seen in more than 2 patients included neutropenia (23%), fatigue (18%), pneumonia (18%), hypoxia (14%), thrombocytopenia (9%) and thromboembolism (9%). Grade ≥3 peripheral sensory neuropathy was seen in 9% of patients. There were two deaths in patients receiving study treatment. These included a myocardial infarction related to treatment, and a bowel obstruction secondary to disease progression. Three other patients have died in follow up with 2 secondary to disease progression and 1 due to an unrelated event. Conclusions: The study met its primary feasibility endpoint with 77% of patients completing 6 cycles of therapy. This regimen was delivered safely in this population and toxicities were consistent with those reported in larger prospective studies with R-miniCHOP or ofatumumab and miniCHOP (Peyrade et al, 2011; Peyrade et al 2017). Peripheral neuropathy is a key AE of interest given the inclusion of BV and while nearly half of patients experienced some peripheral neuropathy, it was severe in only 9% of pts. The ORR and CR rate, as well as the 2-year PFS compare favorably to other prospective studies in a population that included patients with high clinical risk, histologic transformation, and double hit lymphoma. BV and R-miniCHP may be a feasible regimen in older patients, and warrants further study based on these preliminary data demonstrating clinical activity and tolerability. Figure 1 Disclosures Reagan: Seattle Genetics: Research Funding; Curis: Consultancy; Kite, a Gilead Company: Consultancy. Portell:Xencor: Research Funding; Roche/Genentech: Consultancy, Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding. Barr:Gilead: Consultancy; Verastem: Consultancy; Abbvie/Pharmacyclics: Consultancy, Research Funding; Genentech: Consultancy; AstraZeneca: Consultancy, Research Funding; Janssen: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; Morphosys: Consultancy; TG therapeutics: Consultancy, Research Funding; Merck: Consultancy. Friedberg:Acerta Pharma - A member of the AstraZeneca Group, Bayer HealthCare Pharmaceuticals.: Other; Roche: Other: Travel expenses; Kite Pharmaceuticals: Research Funding; Seattle Genetics: Research Funding; Portola Pharmaceuticals: Consultancy; Astellas: Consultancy; Bayer: Consultancy.

Introduction: There are few data about prognostication and outcomes in patients (pts) with HIV-BL treated in the cART era. Optimal treatment strategies to minimize treatment-related mortality (TRM) remain unclear and current recommendations are based on small studies. We conducted a multicenter international analysis to identify prognostic factors and outcomes in pts with HIV-BL treated in the cART era. Methods: This retrospective analysis included a subcohort from a recent study across 30 US sites (Evens et al. Blood 2020) augmented by data from 5 UK centers treated 2009-2018. Progression-free (PFS) and overall survival (OS) were estimated by Kaplan-Meier & differences assessed by log-rank test. Univariate (UVA) associations were derived via Cox model and multivariable (MVA) models were constructed by forward selection of significant variables with P Results: 249 (US: 140 & UK: 109) pts with newly diagnosed HIV-BL were included. Clinical features included median age 43 (IQR 35-50 years [yrs]); male sex: 84%; ECOG PS: 2-4: 48%; elevated LDH: 85% (> 3x upper limit of normal (ULN) 49% & >5xULN 39%); >1 extranodal (EN) site: 60%; any CNS involvement (CNSinv) 25%; and +bone marrow (BM) 46%. MYC rearrangement was reported in 93% of pts with t(8;14) in 49%, break-apart probe in 41% and MYC-light chain in 3%; the rest had classical BL with negative MYC testing (4%) or missing result (3%) (otherwise classical BL). Median CD4 count was 217 (IQR 90-392 cells/µL) with 68% pts having CD4>100 cells/µL. At BL diagnosis, HIV viral load was detectable in 55%; 39% of pts were on cART. Baseline features were similar between the US & UK cohorts with significant differences only in ECOG PS 2-4 (32% vs 65%; P Tx regimens included: CODOX-M/IVAC (Magrath) 60%, DA-EPOCH 25%, HyperCVAD/MA 13%, & other 1%; most pts (87%) received rituximab (R). Similar regimens were used in pts with baseline CNSinv: Magrath 64%, DA-EPOCH 24% & HyperCVAD 12%. In the US, pts most frequently received DA-EPOCH (42%) followed by Magrath (32%) & HyperCVAD/MA (24%), whereas in the UK, 96% received Magrath. R was more frequently given in the US (94% vs 79%, P With median follow-up of 4.5 yrs, 3-yr PFS & OS were 61% & 66%, respectively, and nearly identical in both countries (Fig A). Pts with CD4>100 cells/µL had better 3-yr PFS (Fig B) & OS (68% vs 57% P=0.03). We observed significantly worse outcomes in pts with baseline CNSinv (3-yr PFS 36% vs 69%, P The incidence of CNS recurrence at 3 yr across all Tx was 11%. Higher incidence was observed with DA-EPOCH (P=0.032 vs other regimens; Fig F) with no difference according to CD4 count. Variables associated with PFS & OS on UVA included: ECOG PS 2-4, >1 EN, +BM, baseline CNSinv, LDH>ULN, CD4 5xULN (HR 2.09, P1 EN sites (HR 1.58 P=0.043). The same variables were significant on MVA for OS. Adjusting for all of the prognostic variables, Tx with Magrath was associated with longer PFS (adjusted HR, 0.45, P=0.005). Conclusions: These data represent the largest analysis of HIV-BL to date. There were favorable tolerance and outcomes with intensive R-containing regimens with Magrath being associated with lower TRM and the highest PFS. In addition, prognostic factors for pt outcomes were associated with lymphoma characteristics rather than with HIV-related features. Pts with baseline CNSinv represent a high-risk group with unmet therapeutic needs. Disclosures Alderuccio: Oncinfo: Honoraria; Puma Biotechnology: Other: Family member; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees; OncLive: Honoraria; Inovio Pharmaceuticals: Other: Family member; Foundation Medicine: Other: Family member; Forma Therapeutics: Other: Family member; Agios Pharmaceuticals: Other: Family member. Olszewski:Spectrum Pharmaceuticals: Research Funding; TG Therapeutics: Research Funding; Adaptive Biotechnologies: Research Funding; Genentech, Inc.: Research Funding. Evens:Epizyme: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria; Merck: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Mylteni: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Research Funding; MorphoSys: Consultancy, Honoraria; Research To Practice: Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria. Collins:Gilead: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding; Taekda: Consultancy, Honoraria, Other: travel, accommodations, expenses, Speakers Bureau; BeiGene: Consultancy; Roche: Consultancy, Honoraria, Other: travel, accommodations, expenses , Speakers Bureau; Celleron: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Speakers Bureau; Celgene: Research Funding; Amgen: Research Funding; Pfizer: Honoraria. Danilov:Astra Zeneca: Consultancy, Research Funding; Verastem Oncology: Consultancy, Research Funding; Takeda Oncology: Research Funding; Gilead Sciences: Research Funding; Bayer Oncology: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; TG Therapeutics: Consultancy; Nurix: Consultancy; Celgene: Consultancy; Aptose Biosciences: Research Funding; Bristol-Myers Squibb: Research Funding; Rigel Pharmaceuticals: Consultancy; Karyopharm: Consultancy; Pharmacyclics: Consultancy; BeiGene: Consultancy; Abbvie: Consultancy. Jagadeesh:Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Debiopharm Group: Research Funding; MEI Pharma: Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees; Regeneron: Research Funding. Reddy:Genentech: Research Funding; Abbvie: Consultancy; BMS: Consultancy, Research Funding; Celgene: Consultancy; KITE Pharma: Consultancy. Farooq:Kite, a Gilead Company: Honoraria. Bond:Seattle Genetics: Honoraria. Khan:Celgene: Research Funding; Janssen: Honoraria; Pharmacyclics: Honoraria; Bristol Myers Squibb: Research Funding; Seattle Genetics: Research Funding. Yazdy:Bayer: Honoraria; Genentech: Research Funding; Octapharma: Consultancy; Abbvie: Consultancy. Karmali:Karyopharm: Honoraria; Takeda: Research Funding; AstraZeneca: Speakers Bureau; BeiGene: Speakers Bureau; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau. Martin:Janssen: Consultancy; Regeneron: Consultancy; Bayer: Consultancy; Sandoz: Consultancy; I-MAB: Consultancy; Beigene: Consultancy; Cellectar: Consultancy; Incyte: Consultancy; Kite: Consultancy; Morphosys: Consultancy; Celgene: Consultancy; Teneobio: Consultancy; Karyopharm: Consultancy, Research Funding. Diefenbach:Bristol-Myers Squibb: Consultancy, Research Funding; Denovo: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Incyte: Research Funding; LAM Therapeutics: Research Funding; MEI: Research Funding; Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Millenium/Takeda: Research Funding; Trillium: Research Funding. Klein:Takeda: Membership on an entity's Board of Directors or advisory committees. Haverkos:Viracta THerapeutics: Consultancy. Epperla:Verastem Oncology: Speakers Bureau; Pharmacyclics: Honoraria. Caimi:Amgen: Other: Advisory Board; Bayer: Other: Advisory Board; Kite Pharma: Other: Advisory Board; ADC Therapeutics: Other: Advisory Board, Research Funding; Celgene: Speakers Bureau; Verastem: Other: Advisory Board. Kamdar:Roche: Research Funding. Feldman:Eisai: Research Funding; Pfizer: Research Funding; Kyowa Kirin: Consultancy, Research Funding; Portola: Research Funding; Janssen: Speakers Bureau; AstraZeneca: Consultancy; Trillium: Research Funding; Cell Medica: Research Funding; Amgen: Research Funding; Pharmacyclics: Honoraria, Other, Speakers Bureau; Abbvie: Honoraria; Bayer: Consultancy, Honoraria; Viracta: Research Funding; Rhizen: Research Funding; Corvus: Research Funding; BMS: Consultancy, Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; Celgene: Honoraria, Research Funding; Takeda: Honoraria, Other: Travel expenses; Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau. Smith:AstraZeneca: Consultancy; Millenium/Takeda: Consultancy; Karyopharm: Consultancy; Beigene: Consultancy; Seattle Genetics: Research Funding; Ayala: Research Funding; Bayer: Research Funding; AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Bristol Meyers Squibb: Research Funding; Portola: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; De Novo Biopharma: Research Funding. Portell:Amgen: Consultancy; Pharmacyclics: Consultancy; AbbVie: Research Funding; Janssen: Consultancy; TG Therapeutics: Research Funding; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Xencor: Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding; Infinity: Research Funding; Roche/Genentech: Consultancy, Research Funding. Naik:Celgene: Other: advisory board; Sanofi: Other: advisory board. Lossos:Janssen Biotech: Honoraria; Verastem: Consultancy, Honoraria; Stanford University: Patents & Royalties; NCI: Research Funding; Seattle Genetics: Consultancy, Other; Janssen Scientific: Consultancy, Other. Cwynarski:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau.

Background: Current standard of care for most patients (pts) with relapsed/refractory (RR) classical Hodgkin lymphoma (cHL) is systemic salvage chemotherapy followed by autologous stem cell transplant (ASCT). Given the treatment-related toxicities associated with ASCT and the expanding novel therapeutic options, it is desirable to identify pts with RR disease who may be cured by less toxic treatment approaches. We aimed to assess outcomes, evaluate treatment-related toxicities, and identify baseline characteristics for pts with RR cHL who were treated with radiation-based therapy as the initial salvage approach. Methods: We conducted a multicenter, retrospective study of pts with RR cHL who did not undergo consolidative ASCT as part of their first salvage therapy and instead were treated with either RT alone or in combination with systemic therapy. Pts who received systemic therapy as first salvage but did not proceed to ASCT and then received a RT-based salvage regimen were also included. We defined relapse as recurrence of disease after achievement of complete response (CR) and primary refractory disease as failure to achieve CR in response to frontline therapy. Responses were based on treating physician assessment using Revised Response Criteria for Malignant Lymphoma (Cheson et al, JCO 2014). Kaplan Meier survival analyses were performed using STATA 15.0 software. Toxicities were recorded using NCI Common Terminology Criteria for Adverse Events (CTCAE) v.5. Results: We identified 22 pts from 5 U.S centers with RR cHL who were treated between January 2009 and August 2019 with salvage RT alone or in combination with systemic therapy without consolidative ASCT. The pts' characteristics are summarized in Table 1. Both pts with relapsed (68%) and refractory (32%) disease were included. All pts with relapsed disease (N = 15) had localized relapse (stage I or II) and 67% had relapsed > 12 months after completion of frontline therapy. Three pts who received frontline RT had relapsed outside their prior RT volumes. The most common reason for not pursuing ASCT was that the relapsed or residual disease was localized (38%). Other reasons cited included age (11%), comorbidities (11%), and pt preference (11%). Pts with relapsed disease were more likely than pts with primary refractory disease to receive RT combined with systemic therapy as a salvage (60% vs 15%, p = 0.01). Out of 13, patients who received combined systemic therapy with RT, 77% (N = 10) received brentuximab vedotin (BV) and 23% received multi-agent chemotherapy. Median duration of BV treatment was 6 cycles. Four pts received multi-agent systemic salvage chemotherapy as first salvage but did not proceed to ASCT and then went on to receive a RT containing salvage regimen Among all 22 RR cHL pts, 82% achieved complete response (CR) and 14% had progressive disease after RT containing salvage regimen (Table 2). Of those achieving CR, 77% (95% CI: 44-92) remained disease free at 5 years. The 5-year PFS for the entire cohort was 68% (95% CI: 41-85). There was no difference in the 5-year PFS among those with primary refractory compared with relapsed disease as shown in Figure 1(c2=0.02, p=0.88). Furthermore, 5-year OS was 95% (95% CI: 69-99). In terms of toxicity, there were no deaths or hospitalizations attributed to complications from salvage therapy. The most common toxicities reported were cytopenias in 32% (N = 7) and peripheral neuropathy in 27% (N = 6). Only 3 pts experienced grade 3/4 adverse events. Systemic salvage therapy was discontinued in 3 pts due to toxicity. No long-term toxicities of RT were reported, but longer follow-up is needed. Conclusions: To the best of our knowledge, this is the first study to evaluate outcomes for patients with RR cHL in the United States who received RT-based salvage regimens without consolidative ASCT. In our study population of pts with localized relapse or refractory disease, 81% of pts achieved CR after this non-transplant approach and 5-year PFS was 68%. Our data provides evidence that RT alone or in combination with systemic therapy can be an effective and potentially less toxic treatment strategy for carefully selected pts. Further evaluation, including with prospective studies and long-term follow-up, is needed to corroborate these findings as well as to examine potential late effects. Disclosures Evens: Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria; Research To Practice: Honoraria, Speakers Bureau; Abbvie: Consultancy, Honoraria; Mylteni: Consultancy, Honoraria. Portell:Xencor: Research Funding; Roche/Genentech: Consultancy, Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding. Epperla:Pharmacyclics: Honoraria; Verastem Oncology: Speakers Bureau. Feldman:Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Takeda: Honoraria, Other: Travel expenses; Celgene: Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding; Corvus: Research Funding; Rhizen: Research Funding; Viracta: Research Funding; Trillium: Research Funding; Bayer: Consultancy, Honoraria; Abbvie: Honoraria; Pharmacyclics: Honoraria, Other, Speakers Bureau; Amgen: Research Funding; Cell Medica: Research Funding; Eisai: Research Funding; Kyowa Kirin: Consultancy, Research Funding; Pfizer: Research Funding; Portola: Research Funding; Janssen: Speakers Bureau; AstraZeneca: Consultancy. Landsburg:Triphase: Research Funding; Seattle Genetics: Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Curis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding. Dwivedy Nasta:Roche: Research Funding; Rafael Pharmaceuticals: Research Funding; Incyte: Research Funding; Debiopharm: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Atara: Research Funding; Forty Seven: Research Funding. Gerson:Loxo: Research Funding; Genentech: Consultancy; Pharmacyclics: Consultancy; Abbvie: Consultancy. Barta:Pfizer: Honoraria; Janssen: Honoraria; Seattle Genetics: Honoraria, Research Funding; Atara: Honoraria; Monsanto: Consultancy. Chong:KITE Pharma: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Tessa: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Schuster:Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding; AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria. Svoboda:Atara: Consultancy; Genmab: Consultancy; TG: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Merck: Research Funding; Incyte: Research Funding; Imbrium: Consultancy; BMS: Consultancy, Research Funding; Astra-Zeneca: Consultancy, Research Funding; Adaptive: Consultancy.