Abstract: 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. & lt;6), CLL treatment history, details regarding COVID-19 course, management, and therapy, and vital status were collected. 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 & lt; 1.0 x 109/L; 18% vs. 28%), while others varied between Co1 and Co2 (p & lt;0.0001), including cough (61% vs. 93%), dyspnea (60% vs. 84%), fatigue (13% vs. 77%). 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 & lt;0.0001). Figure 1 depicts OS in each cohort. Univariable analyses demonstrated that age and CIRS ≥6 significantly predicted inferior OS in both cohorts, while only age remained an independent predictor of inferior OS in multivariable analyses (Table 2). Prior treatment for CLL (vs. observation) predicted inferior OS in Co1 but not Co2. 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.

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

Abstract: Introduction Lymphodepletion chemotherapy followed by infusion of T cells engineered to express a CD19-specific chimeric antigen receptor (CAR) has shown remarkable efficacy in patients (pts) with relapsed/refractory (R/R) CD19+ B-cell malignancies, with high response rates reported in non-Hodgkin lymphoma (NHL). Durable responses have been observed in a subset of pts, but the factors associated with these long-term remissions have not been identified. We studied adults with R/R CD19+ B-cell NHL treated with cyclophosphamide and fludarabine lymphodepletion followed by infusion of 2 x 106 CD19 CAR-T cells/kg, and identified factors before and after CAR-T cell infusion that are associated with progression-free survival (PFS). Methods We conducted a phase 1/2 open-label clinical trial (NCT01865617) with the primary objective of evaluating the feasibility and safety of infusing a defined composition of CD4+ and CD8+ CD19 CAR-T cells after lymphodepletion chemotherapy in pts with R/R CD19+ B-cell malignancies. Best responses are reported according to the Lugano criteria (Cheson, JCO 2014). PFS was defined as the time from CAR-T cell infusion until disease progression or death, without censoring for new therapy. Logistic regression and penalized Cox regression multivariable modeling using elastic net were performed for analysis of response and PFS, respectively. Results Characteristics of the 57 pts in the study are shown in Table 1. One patient with incomplete response assessment was excluded. For the 56 remaining pts, the best overall response rate (ORR) without additional therapy was 57% (95% confidence interval [CI], 43-70%), with 48% achieving complete remission (CR; 95% CI, 35-62%). Most pts with partial response (PR) or stable disease (SD) after initial restaging at 4 weeks after CAR-T cell infusion received new therapy (11 of 15, 73%). All pts with PR/SD on initial restaging who did not receive additional therapy after CAR-T cells (n = 4) subsequently achieved CR. The duration of persistence of CAR-T cells was longer in pts who did not receive new therapy (15.7 vs. 5.3 months; P = .06). Eight of 9 pts with indolent histology achieved CR (89%; 95% CI, 51-99%). For the 47 pts with aggressive NHL, the best ORR was 51% (95% CI, 36-66%), with 40% (95% CI, 27-56%) achieving CR. Among aggressive NHL subtypes, pts with DLBCL (n = 28) had best ORR and CR rates of 50% (95% CI, 33-67%) and 43% (95% CI, 25-63%), respectively. In pts with aggressive lymphoma, multivariable analysis showed that the probability of achieving CR was independently associated with a lower pre-lymphodepletion serum LDH concentration (P = .003) and greater increase in serum MCP-1 concentration from a pre-lymphodepletion timepoint to immediately before CAR-T cell infusion (P = .01). Analysis of pts with all histologic subtypes showed that those achieving CR had better PFS and overall survival (OS) compared to those who did not achieve CR (median PFS: CR, not reached; non-CR, 1.35 month; Figure 1). In pts achieving CR, after a median follow-up of 20.2 months (range 2.5-32.4 months), the 24-month probabilities of PFS and OS were 59% (95% CI, 41-84%) and 79% (95% CI, 64-97%), respectively. No pts with indolent NHL who achieved CR (n = 8) have relapsed with a median follow-up of 14.5 months (range, 10.7-30.1 months). For pts with aggressive lymphoma who achieved CR, after a median follow-up of 26.9 months (range, 2.5-32.4 months), the median PFS was 20.0 months (95% CI, 9.2-not reached), and 24-month probabilities of PFS and OS were 46% (95% CI, 28-76%) and 72% (95% CI, 54-96%), respectively. In aggressive NHL, multivariable analysis suggested that, in addition to being associated with the probability of achieving CR, serum LDH and MCP-1 concentration also impacted the probability of longer PFS. The model found that lower pre-lymphodepletion serum LDH (P = .0004) and higher serum MCP-1 peak after CAR-T cell infusion (P = .05), along with higher serum IL-7 (P = .02) and lower serum IL-18 (P = .02) concentrations before lymphodepletion were independently associated with better PFS. Similar findings were obtained after multivariable analysis was performed only in those who had achieved CR. Conclusion CR after CD19 CAR-T cell therapy appears to be a strong predictor of PFS in adult pts with B-cell NHL. Identification of additional factors associated with better PFS might guide future management strategies for pts achieving CR after CD19 CAR-T cell therapy. Disclosures Hirayama: DAVA Oncology: Honoraria. Hay:DAVA Oncology: Honoraria. Li:Juno Therapeutics: Employment, Equity Ownership. Lynch:Incyte: Research Funding; Johnson Graffe Keay Moniz and Wick LLP: Consultancy; Juno Therapeutics: Research Funding; Rhizen Pharmaceuticals: Research Funding; Takeda: Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding. Kiem:Homology Medicine: Consultancy; Rocket Pharmaceuticals: Consultancy; Magenta: Consultancy. Ramos:Seattle Genetics: Employment, Equity Ownership. Shadman:Gilead Sciences: Research Funding; Genentech: Consultancy; Pharmacyclics: Research Funding; Celgene: Research Funding; Mustang Biopharma: Research Funding; Genentech: Research Funding; TG Therapeutics: Research Funding; Acerta Pharma: Research Funding; AbbVie: Consultancy; Verastem: Consultancy; Beigene: Research Funding; AstraZeneca: Consultancy; Qilu Puget Sound Biotherapeutics: Consultancy. Cassaday:Jazz Pharmaceuticals: Consultancy; Amgen: Consultancy, Research Funding; Kite Pharma: Research Funding; Adaptive Biotechnologies: Consultancy; Merck: Research Funding; Pfizer: Consultancy, Research Funding; Seattle Genetics: Other: Spouse Employment, Research Funding; Incyte: Research Funding. Acharya:Juno Therapeutics: Research Funding; Teva: Honoraria. Riddell:Cell Medica: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; NOHLA: Consultancy; Adaptive Biotechnologies: Consultancy. Maloney:GlaxoSmithKline: Research Funding; Juno Therapeutics: Research Funding; Roche/Genentech: Honoraria; Seattle Genetics: Honoraria; Janssen Scientific Affairs: Honoraria. Turtle:Bluebird Bio: Consultancy; Juno Therapeutics / Celgene: Consultancy, Patents & Royalties, Research Funding; Nektar Therapeutics: Consultancy, Research Funding; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Consultancy; Gilead: Consultancy; Adaptive Biotechnologies: Consultancy; Aptevo: Consultancy.

Abstract: Complete genome sequence analysis of 40 DLBCL tumors and 13 cell lines reveals novel somatic point mutations, rearrangements, and fusions. Recurrence of mutations in genes involved in B-cell homing were identified in germinal center B-cell DLBCLs.

Abstract: Objectives Mantle cell lymphoma (MCL) is an uncommon B-cell non-Hodgkin lymphoma that is incurable with standard therapies. The genetic drivers of this cancer have not been firmly established and the features known to contribute to differences in clinical course remain limited. We sought to extend our understanding of the molecular etiology of this malignancy using an integrative genomic analysis of diagnostic biopsies. Methods We performed exome sequencing on 51 frozen MCL tumors and analyzed these alongside previously published exome cohorts. We sequenced tumour genomes and matched constitutional DNA from 34 frozen MCLs, along with matched constitutional DNA, to more broadly identify the pattern of non-coding mutations. Based on mutations identified in this discovery cohort, we re-sequenced 18 recurrently-mutated genes in 212 archival MCLs, each having clinical follow-up data. We also performed RNA-seq on 110 of these cases and analyzed these data for alternative splicing and differential expression, including the differential splicing of HNRNPH1 in the context of recurrent intronic mutations. We investigated the functional and phenotypic effect of mutations and deregulated HNRNPH1 protein through ectopic expression of full-length HNRNPH1 and a mini-gene containing the exons and introns affected by mutations. Using custom droplet digital PCR (ddPCR) assays, we validated alternative splicing patterns in HNRNPH1 itself and other targets identified through re-analysis of available CLIP-seq data. Results In addition to confirming the prognostic association of TP53 and NOTCH1 mutations in MCL, we identified two additional genes associated with outcome: EWSR1 with poor outcome (HR = 5.6) and MEF2B with good outcome (HR = 0.2). By comparing mutation patterns to diffuse large B-cell lymphoma (DLBCL), we identified an MCL-specific missense hot spot in MEF2B, non-specific truncating mutations in EWSR1, and truncating mutations affecting the DAZAP1 C-terminus in both MCL and DLBCL. The DAZAP1 mutations are predicted to alter protein sub-cellular localization and disrupt protein-protein interactions. We also identified the focal recurrence of non-coding mutations surrounding a single exon of the HNRNPH1 gene that were largely restricted to MCL. These mutations affected a region bound by HNRNPH1 protein and disrupted the preferred binding motif of this protein. Intronic mutations were significantly associated with alternative splicing of the HNRNPH1 mRNA and appear to disrupt a negative regulatory loop that normally limits the level of HNRNPH1. Using cell-based assays, we have evaluated the role of HNRNPH1 in cell survival and proliferation. Our interrogation of alternative splicing events in downstream targets implicate HNRNPH1 as a master splicing regulator which may broadly perturb the transcriptome and proteome to favor lymphomagenesis in MCL. Conclusions We discovered three novel MCL-related genes with roles in RNA trafficking or splicing, namely EWSR1, DAZAP1, and HNRNPH1. Mutations in these RNA-binding proteins were identified in 49 of 291 (17%) samples analyzed. Our results improve the current understanding of the MCL mutational landscape, highlight the similarities and differences between MCL and DLBCL, and strongly implicate a role for aberrant regulation of RNA metabolism in MCL pathobiology. We elucidated a functional role for recurrent non-coding HNRNPH1 mutations specific to MCL and identified multiple downstream targets. We continue to explore putative trans targets of HNRNPH1, a novel oncoprotein in MCL. Disclosures Steidl: Seattle Genetics: Consultancy; Roche: Consultancy; Bristol-Myers Squibb: Research Funding; Bayer: Consultancy; Nanostring: Patents & Royalties: Filed patent on behalf of BC Cancer; Juno Therapeutics: Consultancy; Tioma: Research Funding. Connors:Bristol-Myers Squibb: Consultancy; Seattle Genetics: Honoraria, Research Funding; Takeda Pharmaceuticals: Honoraria. Villa:Roche, Abbvie, Celgene, Seattle Genetics, Lundbeck, AstraZeneca, Nanostring, Janssen, Gilead: Consultancy, Honoraria. Johnson:Roche: Consultancy, Employment, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel fees, gifts, and others, Research Funding; Abbvie: Consultancy, Employment, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria; BMS: Consultancy, Honoraria; BD Biosciences: Other: Provided a significant proportion of the antibodies used in this project free of cost.; Seattle Genetics: Honoraria; Lundbeck: Employment, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel fees, gifts, and others, Research Funding. Scott:Janssen: Consultancy, Research Funding; NanoString: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution], Research Funding; Celgene: Consultancy; Roche/Genentech: Research Funding.

Abstract: Follicular lymphoma (FL) accounts for ∼20% of all new lymphoma cases. Increases in cytological grade are a feature of the clinical progression of this malignancy, and eventual histologic transformation (HT) to the aggressive diffuse large B-cell lymphoma (DLBCL) occurs in up to 15% of patients. Clinical or genetic features to predict the risk and timing of HT have not been described comprehensively. In this study, we analyzed whole-genome sequencing data from 423 patients to compare the protein coding and noncoding mutation landscapes of untransformed FL, transformed FL, and de novo DLBCL. This revealed 2 genetically distinct subgroups of FL, which we have named DLBCL-like (dFL) and constrained FL (cFL). Each subgroup has distinguishing mutational patterns, aberrant somatic hypermutation rates, and biological and clinical characteristics. We implemented a machine learning–derived classification approach to stratify patients with FL into cFL and dFL subgroups based on their genomic features. Using separate validation cohorts, we demonstrate that cFL status, whether assigned with this full classifier or a single-gene approximation, is associated with a reduced rate of HT. This implies distinct biological features of cFL that constrain its evolution, and we highlight the potential for this classification to predict HT from genetic features present at diagnosis.

Abstract: Introduction: MAVORIC was an open-label, multicenter, randomized phase 3 study evaluating the safety and efficacy of mogamulizumab (moga) compared to vorinostat (vori) in patients with mycosis fungoides (MF) or Sézary syndrome (SS) who had failed at least one prior course of systemic therapy (NCT01728805). Primary results have been reported (Kim et al. Lancet Oncol 2018) and were based on a data cutoff date of December 31, 2016. The primary endpoint was progression-free survival (PFS); patients in the moga treatment arm experienced significantly longer PFS compared to patients in the vori treatment arm (median 7.7 months vs 3.1 months; p 〈 0.0001). The most common treatment-emergent adverse events (TEAEs) of any cause or grade reported in patients randomized to moga were: infusion-related reaction (33.2%), drug eruption (ie, skin rash attributed to moga [23.9%]), diarrhea (23.4%), and fatigue (23.4%). This report provides the final safety results of MAVORIC as of the data available on January 3, 2019. Methods: Patients were randomized 1:1 to moga 1.0 mg/kg administered intravenously on Days 1, 8, 15, and 22 of the first cycle and on Days 1 and 15 of subsequent cycles or vori 400 mg administered orally once daily. Patients randomized to vori were allowed to cross over to moga upon progression or intolerable toxicity. Safety was assessed by reported adverse events (AEs), changes in physical examinations, vital sign measurements, electrocardiograms, and laboratory analyses. Results: In total, 372 patients were randomized (moga, 186; vori, 186), of whom 370 received study drug and were included in the safety analysis (moga, 184; vori, 186). For the final safety analysis, median duration of follow-up was 34.5 months (range, 0.13-70.0) in the randomized part of the study. Median treatment exposure was 170 days (range, 1-1813) for moga and 84 days (4-1230) for vori, which represent the same median values but broader ranges compared to the primary analysis (primary analysis, 170 days [1-1379] for moga and 84 days [4-1058] for vori). The type and frequency of AEs in either the moga or vori treatment groups (Table) were consistent with those reported in the primary analysis. TEAEs, regardless of causality, that were reported at similar rates in the two treatment groups included constipation, peripheral edema, headache, and anemia. TEAEs (all causality) that occurred at higher frequency in the moga vs vori arm included infusion-related reaction (33.2% vs 0.5%) and drug eruption (25.0% vs 1.1%); the majority of these events were grade 1 or 2 (Table). The types and frequencies of AEs attributable to moga (per Investigator assessment) included infusion-related reaction (33.2% [61/184]), drug eruption (23.9% [44/184] ), and fatigue (18.5% [34/184]), and for vori, diarrhea (55.4% [103/186] ), nausea (38.2% [71/186]), and fatigue (33.3% [62/186] ). In patients who crossed over from the vori to moga arm and received study drug (n=135), the most frequently reported AEs attributable to moga were infusion-related reaction (37.8% [51/135]), drug eruption (24.4% [33/135] ), fatigue (7.4% [10/135]), increased alanine aminotransferase (7.4% [10/135] ), and increased aspartate aminotransferase (7.4% [10/135]). Discontinuation rates due to AEs were similar between treatment arms and in crossover patients (moga, 21.7% [40/184] ; vori, 23.7% [44/186]; crossover, 25.9% [35/135] ). The most common AEs leading to discontinuation were drug eruption in the moga arm (7.1% [13/184] ) and fatigue in the vori arm (4.3% [8/186]). Overall, the rates of drug-related serious TEAEs were similar between treatment arms and in crossover patients (moga, 19.6% [36/184] ; vori, 16.7% [31/186]; crossover, 11.9% [16/135] ). After the data cutoff for the primary analysis, 1 additional patient randomized to moga (decreased appetite, general physical health deterioration, hypoalbuminemia) and 1 crossover patient (cerebral hemorrhage) experienced TEAEs with an outcome of death, all considered unrelated to study treatment per Investigator. Conclusions: This final safety analysis from the MAVORIC study in patients with previously treated MF and SS demonstrates that moga was generally well tolerated. Longer follow-up and treatment exposure did not identify any new safety signals. The type and incidence of treatment-related AEs among patients receiving moga after crossover were similar to those observed for patients initially randomized to moga. Disclosures Kim: Merck: Research Funding; Portola Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Horizon: Research Funding; Corvus: Honoraria, Membership on an entity's Board of Directors or advisory committees; Galderma: Research Funding; Elorac: Research Funding; Soligenix: Research Funding; Kyowa Hakko Kirin: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Forty Seven Inc: Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medivir: Honoraria, Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trillium: Research Funding; Neumedicine: Research Funding; miRagen: Research Funding. Bagot:Innate Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Zinzani:MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eusapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Celltrion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Membership on an entity's Board of Directors or advisory committees; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: 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; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics: Honoraria, Speakers Bureau; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Duvic:Seattle Genetics: Consultancy, Honoraria, Research Funding; Eisai: Research Funding; Shape: Research Funding; UT MD Anderson Cancer Center: Employment; USCLC Registry: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Secretary/treasurer of Item h; Spatz Foundation: Research Funding; Tetralogic: Research Funding; Millennium (formerly Takeda): Research Funding; Mallinckrodt Pharmaceuticals (formeraly Therakos, Inc): Research Funding; Kyowa Hakko Kirin Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Forty Seven Inc: Membership on an entity's Board of Directors or advisory committees; Cutaneous Lymphoma Foundation: Membership on an entity's Board of Directors or advisory committees; PleXus Communications: Speakers Bureau; Guidepoint Global: Consultancy; Evidera, Inc.: Consultancy; Cell Medica Inc.: Consultancy; Allos: Research Funding; Rhizen Pharma: Research Funding; Oncoceuticals: Research Funding; Soligenetics: Research Funding; Cell Medica Ltd.: Honoraria; Therakos: Speakers Bureau; Jonathan Wood & Assoc.: Speakers Bureau; Hawaiian Dermatology Society: Speakers Bureau; Hemedicus: Speakers Bureau; Janssen Pharmaceuticals (div of Johnson & Johnson): Speakers Bureau. Morris:Guys Hospital: Employment. Kim:Medimmune: Research Funding; Soligenix: Research Funding; Kyowa Kirin: Research Funding; Galderma: Consultancy, Research Funding; Actelion: Consultancy, Research Funding. Musiek:Menlo: Other: Investigator; Helsinn: Membership on an entity's Board of Directors or advisory committees; Soligenix: Other: Investigator; Pfizer: Other: Investigator; Elorac: Other: Investigator; Kyowa: Honoraria, Other: Above honoraria: for Ad Board; miRagen: Other: Investigator. Ortiz-Romero:Actelion: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kyowa: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; PLCG1: Patents & Royalties; miRagen: Membership on an entity's Board of Directors or advisory committees; MEDA: Research Funding; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; 4SC: Membership on an entity's Board of Directors or advisory committees. Eradat:Kyowa: Research Funding; Kite: Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Research Funding; Genentech: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Research Funding. Magnolo:University Hospital of Muenster, Center of Innovative Dermatology: Employment. Scarisbrick:Kyowa Kirin: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Recordat: Consultancy; 4SC: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Helsinn: Consultancy, Membership on an entity's Board of Directors or advisory committees. Dalle:Kyowa: Other: Principal Investigator in clinical trials promoted by Kyowa. Fisher:Kyowa Kirin: Consultancy. Poligone:Stemline Therapeutics: Consultancy, Speakers Bureau; Regeneron: Consultancy, Speakers Bureau; Actelion: Consultancy, Speakers Bureau; Astex Pharmaceuticals: Research Funding; Bioniz: Research Funding; Celgene: Consultancy; Helsinn: Research Funding, Speakers Bureau; Innate Pharma: Research Funding; Kyowa Hakko Kirin: Consultancy, Honoraria, Research Funding, Speakers Bureau; miRagen: Research Funding; Soligenix: Research Funding. Pro:Takeda: Consultancy, Honoraria, Other: Travel Expenses; Celgene: Consultancy, Honoraria; Kyowa Hakka Kirin: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Other: Travel Expenses, Research Funding. Quaglino:Actelion: Honoraria, Other: Advisory Board; Innate Pharma: Honoraria, Other: Advisory Board; Takeda: Honoraria, Other: Advisory Board; Kyowa Kirin: Honoraria, Other: Advisory Board; Helsinn: Honoraria, Other: Advisory Board; Therakos: Honoraria, Other: Advisory Board. Reddy:AbbVie: Honoraria; Janssen: Honoraria; KITE: Honoraria; Merck: Research Funding; Celgene: Honoraria, Speakers Bureau. Geskin:Merck: Other: Supported/Contracted Research; UpToDate: Patents & Royalties: Royalty, Receipt of Intellectual Property Rights / Patent Holder; Actelion: Other: Supported/Contracted Research; Helsinn: Consultancy, Honoraria, Other: Supported/Contracted Research; Stratpharma: Other: Supported/Contracted Research; Mallinckrodt: Consultancy, Honoraria, Other: Supported/Contracted Research; Medscape: Speakers Bureau; Medivir: Consultancy, Honoraria. Halwani:Amgen: Other: Investigator; Takeda: Other: PI; Seattle Genetics: Other: PI; Pharmacyclics: Other: Investigator; miRagen: Other: PI; Kyowa Hakko Kirin: Other: PI; Immune Design: Other: PI; Genentech, Inc.: Other: Investigator; Bristol-Myers Squibb: Other: PI; AbbVie: Other: PI. Khot:Peter MacCallum Cancer Centre: Employment; Amgen: Consultancy, Speakers Bureau; Celgene: Consultancy; Janssen: Consultancy; Kyowa Hakko Kirin: Consultancy. Korman:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Dermira: Research Funding; Glaxo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immune Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kyowa: Research Funding; Leo: Research Funding; Menlo: Research Funding; Merck: Research Funding; Novartis: Consultancy, Honoraria, Speakers Bureau; Pfizer: Research Funding; Principia: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Research Funding; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Rhizen: Research Funding; Sun: Honoraria, Membership on an entity's Board of Directors or advisory committees; Syntimmune: Research Funding; UCB: Research Funding; Valeant: Honoraria, Membership on an entity's Board of Directors or advisory committees; Eli Lilly: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Horwitz:Seattle Genetics: Consultancy, Research Funding; Affimed: Consultancy; Astex: Consultancy; Portola: Consultancy; ADCT Therapeutics: Research Funding; Kyowa Hakko Kirin: Consultancy; Infinity/Verastem: Consultancy, Research Funding; Miragen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Forty-Seven: Research Funding; Celgene: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Miragen: Consultancy; Innate Pharma: Consultancy; Kura: Consultancy; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Miragen: Consultancy; Infinity/Verastem: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Portola: Consultancy; Kura: Consultancy; Celgene: Consultancy, Research Funding; Kura: Consultancy; Kyowa Hakko Kirin: Consultancy; Infinity/Verastem: Consultancy, Research Funding; Forty-Seven: Research Funding; Trillium: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Research Funding; Astex: Consultancy; Affimed: Consultancy; ADCT Therapeutics: Research Funding; Aileron: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kyowa Hakko Kirin: Consultancy; Trillium: Research Funding; Millennium/Takeda: Consultancy, Research Funding; Mundipharma: Consultancy; Millennium/Takeda: Consultancy, Research Funding; Kyowa Hakko Kirin: Consultancy; Portola: Consultancy; Aileron: Research Funding; Mundipharma: Consultancy; Celgene: Consultancy, Research Funding; Mundipharma: Consultancy; Seattle Genetics: Consultancy, Research Funding; ADCT Therapeutics: Research Funding; Portola: Consultancy; Kura: Consultancy; ADCT Therapeutics: Research Funding; Corvus Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Aileron: Research Funding; Affimed: Consultancy; Trillium: Research Funding; Innate Pharma: Consultancy; Affimed: Consultancy; Astex: Consultancy; Mundipharma: Consultancy; Aileron: Research Funding; Miragen: Consultancy; Trillium: Research Funding; Innate Pharma: Consultancy; Forty-Seven: Research Funding; Forty-Seven: Research Funding; Innate Pharma: Consultancy; Astex: Consultancy; Seattle Genetics: Consultancy, Research Funding. Lamar:Seattle Genetics: Consultancy; Kyowa: Consultancy, Membership on an entity's Board of Directors or advisory committees. Moskowitz:Cell Medica: Consultancy; ADC Therapeutics: Consultancy; Merck: Research Funding; Erytech Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; Erytech Pharma: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Erytech Pharma: Consultancy; Incyte: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Cell Medica: Consultancy; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Cell Medica: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Merck: Research Funding; Cell Medica: Consultancy; Cell Medica: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Cell Medica: Consultancy; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Cell Medica: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; Incyte: Research Funding; Incyte: Research Funding; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy; Incyte: Research Funding; Cell Medica: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Erytech Pharma: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Merck: Research Funding; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding. Wells:Takeda Pharmaceuticals Australia Pty Limited: Membership on an entity's Board of Directors or advisory committees; MSD Australia: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Akilov:Trillium Therapeutics: Consultancy, Other: PI on the clinical trials, Research Funding; Pfizer: Research Funding. Cowan:Kyowa Kirin: Consultancy. Dummer:Merck Sharp & Dohme: Other: Intermittent, project focused consulting and/or advisory relationships; Novartis: Other: Intermittent, project focused consulting and/or advisory relationships; Bristol-Myers Squibb: Other: Intermittent, project focused consulting and/or advisory relationships; Roche: Other: Intermittent, project focused consulting and/or advisory relationships; Amgen: Other: Intermittent, project focused consulting and/or advisory relationships; Takeda: Other: Intermittent, project focused consulting and/or advisory relationships; Pierre Fabre: Other: Intermittent, project focused consulting and/or advisory relationships; Sun Pharma: Other: Intermittent, project focused consulting and/or advisory relationships; Sanofi: Other: Intermittent, project focused consulting and/or advisory relationships; Catalym: Other: Intermittent, project focused consulting and/or advisory relationships; Second Genome: Other: Intermittent, project focused consulting and/or advisory relationships. Lechowicz:Kyowa Kirin Inc: Consultancy; Spectrum: Consultancy. Foss:Eisai: Consultancy; Seattle Genetics: Consultancy, Other: fees for non-CME/CE services ; miRagen: Consultancy; Acrotech: Consultancy; Mallinckrodt: Consultancy; Spectrum: Other: fees for non-CME/CE services . Wilcox:University of Michigan: Employment. Porcu:Innate Pharma: Honoraria, Other: Scientific Board, Research Funding; Viracta: Honoraria, Other: Scientific Board, Research Funding; BeiGene: Other: Scientific Board, Research Funding; Incyte: Research Funding; Daiichi: Research Funding; Kyowa: Honoraria, Other: Scientific Board, Research Funding; ADCT: Research Funding; Spectrum: Consultancy. Vermeer:Kyowa: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding. Abhyankar:Therakos: Other: Consulting, Speakers Bureau; Incyte: Speakers Bureau. Pacheco:University of Colorado: Employment. William:Techspert: Consultancy; Guidepoint Global: Consultancy; Defined Health: Consultancy; Celgene Corporation: Consultancy; Kyowa Kirin, Inc.: Consultancy. Fukuhara:Kyowa-Hakko Kirin: Honoraria; Bayer: Research Funding; Mundi: Honoraria; Janssen Pharma: Honoraria; Mochida: Honoraria; Ono Pharmaceutical Co., Ltd.: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria; Eisai: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Nippon Shinkyaku: Honoraria; Zenyaku: Honoraria; AbbVie: Research Funding; Gilead: Research Funding; Solasia Pharma: Research Funding. Munoz:Pharmacyclics /Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Merck: Consultancy; Kyowa: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene/Juno: Consultancy, Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau; Fosunkite: Speakers Bureau; AstraZeneca: Speakers Bureau; Portola: Research Funding; Incyte: Research Funding; Kite/Gilead: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy; Alexion: Consultancy; Pfizer: Consultancy. Querfeld:Elorac: Other: Investigator, Research Funding; Trillium: Consultancy, Other: Investigator, Research Funding; Medivir: Consultancy; miRagen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Investigator; Helsinn: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Investigator; Soligenix: Other: Investigator; City of Hope Cancer Center and Beckman Research Institute: Employment; Celgene: Other: Investigator, Research Funding; Kyowa: Membership on an entity's Board of Directors or advisory committees, Other: Investigator; Eisai: Other: Investigator; Bioniz: Membership on an entity's Board of Directors or advisory committees, Other: Investigator. Uhara:Kyowa Kirin Co., Ltd: Honoraria, Research Funding. Huen:Innate Pharmaceuticals: Research Funding; Galderma Inc: Research Funding; Rhizen Pharmaceuticals: Research Funding; Glaxo Smith Kline Inc: Research Funding. Tobinai:Meiji Seika: Honoraria; Takeda Pharmaceutical: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Janssen Pharmaceutical: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Ono Pharmaceutical: Consultancy, Honoraria, Research Funding; Zenyaku Kogyo: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Mundi Pharma: Consultancy, Honoraria, Research Funding; Eisai: Honoraria, Research Funding; HUYA Bioscience: Consultancy, Honoraria; Bristol-Myers Squibb: Honoraria; AbbVie: Research Funding; Verastem: Honoraria; Chugai Pharmaceutical: Honoraria, Research Funding; Yakult: Honoraria; Solasia: Honoraria. Tokura:Kyowa Kirin Pharmaceutical Development, Inc.: Honoraria. Boh:Actelion: Other: Principal Investigator; Tulane University School of Medicine: Employment; Celgene: Other: Principal Investigator, Speaker, Grants; Sun: Other: Speaker; Janssen: Other: Principal Investigator, Speaker, Grants; Novartis: Other: Principal Investigator, Speaker, Grants; Soligenix: Other: Principal Investigator; Incyte: Other: Principal Investigator; Regeneron: Other: Principal Investigator, Grants; Ortho Dermatologics: Other: Speaker, Grants; Pfizer: Other: Principal Investigator; UCB: Other: Speaker, Grants; Elorac: Other: Principal Investigator; Abbvie: Other: Principal Investigator. Nicolay:Teva Pharmaceutical Industries: Honoraria, Other: Conference participation fees; Novartis AG: Consultancy, Honoraria; Biogen GmbH: Consultancy, Honoraria; Almirall Hermal AG: Consultancy, Honoraria; Actelion Pharmaceuticals: Consultancy, Honoraria; Innate Pharma: Consultancy; Kyowa Hakko Kirin: Consultancy, Honoraria; Takeda Pharmaceuticals: Consultancy. Leoni:Kyowa Kirin Pharmaceutical Development, Inc.: Employment. Ito:Kyowa Kirin Pharmaceutical Development, Inc.: Employment. Herr:Kyowa Kirin, Inc.: Employment. Sokol:EUSA: Consultancy.

Abstract: Introduction: Follicular lymphoma (FL) is an indolent disease that undergoes histological transformation (HT) to aggressive diffuse large B-cell lymphoma (DLBCL) in 8-15% of patients. FLs frequently share genetic features with DLBCL, especially those of the germinal center B-cell-like (GCB) cell-of-origin (COO) and the EZB/C3 genetic subgroup, and approximately 80% of transformed FL (tFL) are classified as GCB. Our current understanding of the genetics of FL and tFL is based on a variety of studies, most of which have sequenced tumors in small case numbers or using targeted approaches such that the potential role of non-coding mutations and aberrant somatic hypermutation (aSHM) in predicting HT have not previously been fully explored. Methods: Whole genome sequencing (WGS) data from 212 FL (including 24 from patients that subsequently underwent HT) and 241 de novo DLBCL were analyzed. Simple somatic mutations (SSMs) were called using an ensemble of somatic variant callers, while structural variants (SVs) were called with Manta and copy number variants (CNVs) with Battenberg and GISTIC. Fluorescence in situ hybridization with break-apart probes (BA-FISH) was used to identify MYC, BCL2, and BCL6 translocations, and with IGH /BCL2 dual-fusion probes (DF-FISH) for a subset of FLs. To compare the genetics of FL and DLBCL, 83 significantly mutated genes (SMGs) were identified with dNdS, MutSigCV, HotMaps, and OncoDriveFML, and non-silent mutations were tabulated for their presence in each genome. For 38 hypermutated regions, we used a region-specific threshold to binarize the data to aSHM/no aSHM. Recurrent missense mutations in FOXO1, MYD88L265P, CREBBP lysine acetyltransferase (KAT) domain, EZH2Y646, MEF2B, and STAT6 were tabulated separately from other mutations in these genes. Using only the FL tumors from patients with no evidence of subsequent transformation and all available de novo DLBCLs, we trained a random forest classifier to separate these two entities using this set of 129 features, including MYC and BCL6 translocations. To validate this classifier, we fit a linear model to the number of FL votes from each discovery case, utilizing the 65 features (including 19 aSHM features) that were adequately sequenced in a validation cohort of 127 tFL. Statistical tests were corrected for multiple comparisons where necessary. Results: This large cohort of FL and DLBCL genomes has enabled the curation of an extensive list of novel and established FL driver genes and the identification of distinguishing genetic features among SMGs and CNVs. Loci that are significantly enriched for mutations in FL vs. DLBCL include the CREBBP KAT domain (OR 11.5, P & lt; 0.0001), RRAGC (OR 9.61, P & lt; 0.001), and ATP6V1B2 (OR 11.17, P & lt; 0.001). Deletions of ARID1A (OR 4.74, P & lt; 0.1), PTEN (OR 3.65, P & lt; 0.01), and TNFRSF14 (OR 3.31, P & lt; 0.01) were among the CNVs significantly enriched in FL. Out of 156 FLs, 24 (15%) were negative for BCL2 translocations by BA-FISH, but 4 (17%) of these had BCL2 translocations detected from WGS data. All 4 of these cryptic events were confirmed using IGH /BCL2 DF-FISH. Using a threshold of 0.7, the linear model separated discovery FL cases into a more DLBCL-like subgroup, termed dFL (n = 107), and a genetically homogeneous subgroup enriched for the FL-associated features, which we describe as constrained FL (cFL, n = 105). This separation is supported by more mutations in dFL vs cFL across several aSHM loci, including the transcription start sites for BCL6, BCL7A, DTX1, and ZFP36L1 (Figure 1), consistent with reduced exposure to the germinal center reaction in cFL. Within the targeted capture validation cohort of tFL, 30 (24%) tumors were classified as cFL and 97 (76%) as dFL. The tFL cohort was significantly depleted for mutations in the CREBBP KAT domain (OR 0.59, P & lt; 0.05), and were significantly less frequently classified as cFL (OR 0.30, P & lt; 0.0001) compared to the discovery FLs. Conclusions: The distinction between cFL and dFL is strongly driven by CREBBP KAT domain mutations and different rates of aSHM genome wide. Given the known early clonal nature of CREBBP mutations in FL and its role in regulating germinal center cycling, we speculate that CREBBP KAT mutations may limit the exposure of FL to the dark zone, reducing the opportunity for aSHM and creating an evolutionary constraint that may limit the opportunity for HT. This classification may serve as a useful biomarker to identify FLs at higher risk of HT. Figure 1 Figure 1. Disclosures Coyle: Allakos, Inc.: Consultancy. Grande: Sage Bionetworks: Current Employment. Slack: Seagen: Consultancy, Honoraria. Steidl: Curis Inc.: Consultancy; Trillium Therapeutics: Research Funding; Epizyme: Research Funding; Bayer: Consultancy; Seattle Genetics: Consultancy; AbbVie: Consultancy; Bristol-Myers Squibb: Research Funding. Scott: Janssen: Consultancy, Research Funding; Abbvie: Consultancy; AstraZeneca: Consultancy; NanoString Technologies: Patents & Royalties: Patent describing measuring the proliferation signature in MCL using gene expression profiling.; Incyte: Consultancy; Rich/Genentech: Research Funding; Celgene: Consultancy; BC Cancer: Patents & Royalties: Patent describing assigning DLBCL COO by gene expression profiling--licensed to NanoString Technologies. Patent describing measuring the proliferation signature in MCL using gene expression profiling. . Morin: Epizyme: Patents & Royalties; Foundation for Burkitt Lymphoma Research: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy.

Abstract: Introduction: Inotuzumab ozogamicin (InO) is a CD22-directed antibody-calicheamicin conjugate. Patients (pts) with relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (ALL) treated with InO vs standard of care chemotherapy (SC) had significantly better response, and improved survival in INO-VATE (NCT01564784). Based on central laboratory assessment, this favorable benefit-risk profile of InO was independent of leukemic blast CD22 positivity (≥90% vs & lt;90%) and CD22 receptor density (quantified as Molecules of Equivalent Soluble Fluorochrome, quartile analysis). As CD22 is usually assessed in local labs in clinical practice, this study uses INO-VATE data to investigate the relationship between baseline CD22 positivity assessed by local labs and the efficacy and safety of InO vs SC. Methods: Adult pts (≥18 yrs) with R/R CD22-positive (based on local or central lab results) ALL in salvage 1 or 2 were randomized to InO (n=164) or SC (n=162) (details: NEJM 2016;375:740-53). InO starting dose was 1.8 mg/m2/cycle (0.8 mg/m2 on Day 1; 0.5 mg/m2 on Days 8 & 15 of a 21-28-day cycle for ≤6 cycles) and reduced to 1.5 mg/m2/cycle for pts with complete remission (CR) or CR with incomplete hematologic recovery (CRi). SC included fludarabine/cytarabine [Ara-C]/granulocyte colony-stimulating factor, Ara-C plus mitoxantrone, or high-dose Ara-C. CD22 positivity (% of leukemic blasts expressing CD22) was measured at screening by flow cytometry or immunohistochemistry. Efficacy (CR/CRi, minimal residual disease [MRD, assessed in central labs] among responders, overall survival [OS], progression-free survival [PFS] , and duration of remission [DoR]) and safety outcomes were analyzed by CD22 positivity quartiles, Quartil e 1 (Q1) having the lowest and Q4 the highest CD22 positivity. Data cutoff: 04Jan2017. P-values are 1-sided. Results: Baseline CD22 positivity per local lab was available for 152 pts per arm. CD22 positivity (%) was comparable between treatment arms for each quartile; median (range) was 21.9 (1.0-39.4) for InO vs 23.9 (0.0-39.0) for SC in Q1, 55.5 (40.0-68.9) vs 56.3 (40.0-66.0) in Q2, 84.0 (70.0-92.0) vs 84.0 (70.0-92.9) in Q3, and 98.0 (93.0-100.0) for both arms in Q4. CR/CRi rates showed no difference among quartiles in the InO (P=0.5906) or SC arm (P=0.2061), and were significantly higher with InO vs SC for all quartiles (Q1: 81.6% vs 41.2%, P=0.0002; Q2: 68.4% vs 36.8%, P=0.0029; Q3: 73.2% vs 27.0%, P & lt;0.0001; Q4: 77.1% vs 20.9%, P & lt;0.0001) (Figure). MRD negativity rates in responders were also higher with InO vs SC and the differences in the lower quartiles (Q1-Q3) were significant (Q1: 87.1% vs 50.0%, P=0.0121; Q2: 69.2% vs 21.4%, P=0.0048; Q3: 66.7% vs 30.0%, P=0.0486; Q4: 77.8% vs 55.6%, P=0.1930) (Figure). PFS, DoR, and OS were longer with InO vs SC. The benefit of InO over SC was more evident in the higher quartiles (Q2-4); hazard ratio (97.5% Cl) was 0.44 (0.31-0.61) for PFS, 0.53 (0.31-0.88) for DoR, and 0.71 (0.52-0.99) for OS (Table). Cytopenias were the most common ≥grade 3 adverse events in the InO arm, with similar rates across the quartiles (Q1-Q4: neutropenia: 52.6%, 47.4%, 39.0%, and 48.6%; thrombocytopenia: 34.2%, 44.7%, 46.3%, and 31.4%; febrile neutropenia: 15.8%, 28.9%, 29.3%, and 34.3%). Rates of ≥grade 3 infections were 21.1%, 26.3%, 36.6%, and 31.4% for Q1-Q4. In InO-treated pts, rates of ≥grade 3 hyperbilirubinemia were similar for the lower quartiles (Q1-Q3: 5.3%, 7.9%, and 2.4%; 11.4% for Q4); rates of ≥grade 3 veno-occlusive liver disease (VOD)/sinusoidal obstruction syndrome (SOS) within 2 years of randomization regardless of causality were 13.2%, 7.9%, 7.3%, and 17.1% in Q1-Q4, respectively; 3 grade 5 VOD/SOS events occurred in Q1, 2 in Q4, and 0 in Q2 and Q3. Conclusions: In general, the results showed improvement in measures of efficacy for InO over SC that was comparable across all 4 CD22 positivity quartiles per local lab assessments. For DoR, PFS, and OS, there was a suggestion of greater benefit for pts in higher CD22 positivity quartiles treated with InO, though these analyses are limited by the small sample size. These trends are in alignment with those previously presented for central lab CD22 positivity and receptor density (Blood 2017;130[Suppl 1]:1272). Overall, InO demonstrated a favorable benefit/risk profile for pts with R/R B cell precursor ALL independent of local lab CD22 positivity. Disclosures Kantarjian: Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astex: Research Funding; Pfizer: Honoraria, Research Funding; Cyclacel: Research Funding; Ariad: Research Funding; Novartis: Research Funding; Takeda: Honoraria; AbbVie: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; Agios: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Jazz Pharma: Research Funding; BMS: Research Funding; Immunogen: Research Funding. Stock:Astellas: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; UpToDate: Honoraria; Research to Practice: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees; Kite, a Gilead Company: Membership on an entity's Board of Directors or advisory committees; Daiichi: Membership on an entity's Board of Directors or advisory committees. Cassaday:Seattle Genetics: Other: Spouse's disclosure: employment, stock and other ownership interests. DeAngelo:Celgene: Consultancy; Jazz Pharmaceuticals Inc: Consultancy; Takeda Pharmaceuticals: Consultancy; Abbvie: Research Funding; Shire: Consultancy; Amgen: Consultancy; GlycoMimetics: Research Funding; Incyte: Consultancy; Novartis: Consultancy, Research Funding; Blueprint: Consultancy, Research Funding; Pfizer: Consultancy. Jabbour:Pfizer: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Cyclacel LTD: Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding. O'Brien:Sunesis: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; Eisai: Consultancy; Acerta: Research Funding; TG Therapeutics: Consultancy, Research Funding; Alexion: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Aptose Biosciences, Inc: Consultancy; GlaxoSmithKline: Consultancy; Astellas: Consultancy; Kite: Research Funding; Janssen: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Amgen: Consultancy; Regeneron: Research Funding; Verastem: Consultancy; Vaniam Group LLC: Consultancy; Celgene: Consultancy. Stelljes:Novartis: Honoraria; MDS: Consultancy; Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding. Wang:Pfizer: Employment, Equity Ownership. Paccagnella:Pfizer: Employment, Equity Ownership. Nguyen:Navigate BioPharma Services, Inc., a Novartis Subsidiary: Employment; Novartis: Equity Ownership. Sleight:Pfizer: Employment, Equity Ownership. Vandendries:Pfizer: Employment, Equity Ownership. Neuhof:Pfizer: Employment, Equity Ownership. Laird:Pfizer: Employment, Equity Ownership. Advani:Amgen: Research Funding; Abbvie: Research Funding; Macrogenics: Research Funding; Pfizer: Honoraria, Research Funding; Glycomimetics: Consultancy, Research Funding; Kite Pharmaceuticals: Consultancy.