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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.

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. 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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. 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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. 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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. 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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. 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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. 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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.

TP53 alteration in chronic lymphocytic leukemia indicates a high-risk disease that is usually refractory to chemotherapy. It may be caused by deletion of 17p involving the loss of TP53 gene, which occurs in low percentage of patients at diagnosis but can be acquired as the disease progresses. Since patients may harbor TP53 mutation without chromosome 17p deletion, consensus recommendations call for both cytogenetic and PCR mutation analysis of TP53 in chronic lymphocytic leukemia. We conducted a single-institution retrospective study to investigate the clinicopathologic features of chronic lymphocytic leukemia with TP53 alterations as well as the utility of different diagnostic modalities to identify p53 alterations. Forty percent of chronic lymphocytic leukemia patients with TP53 alterations demonstrated atypical lymphocytes with cleaved/irregularly shaped nuclei and/or large atypical lymphoid cells with abundant cytoplasm in the peripheral blood. Progression was also observed in lymph node and bone marrow samples (21% with Richter transformation; 33% with findings suggestive of “accelerated phase” of chronic lymphocytic leukemia including prominent proliferation centers and/or increased numbers of prolymphocytes). However, the presence of the morphologic features suggestive of “accelerated phase” had no effect on overall survival within the chronic lymphocytic leukemia group with TP53 abnormalities (p > 0.05). As previously reported by others, a subset of patients with TP53 alterations were only identified by either PCR mutation analysis (12%) or cytogenetic studies (14%). p53 immunostain positivity was only identified in approximately half of the patients with TP53 alterations identified by either method, and it failed to identify any additional patients with p53 abnormalities. In summary, chronic lymphocytic leukemia patients with TP53 alterations frequently show atypical morphologic features. Use of multiple modalities to identify p53 abnormalities is recommended to ensure optimal sensitivity and specificity.

Mutations in the kinase binding domain of BTK at position C481 are associated with resistance to BTK inhibitor (BTKi) therapy in chronic lymphocytic leukemia (CLL). Nearly half of patients manifesting clinical progression with these alterations exhibit a subclonal burden of resistance. Intriguingly, measured BTKC481 variant allelic fractions (VAF) are commonly lower than 10% [Ahn et al, Blood 2017]. This raises the important question of how BTKC481-mutated (MUT) and wildtype (WT) cells differ in their response to therapeutic challenge, and how low-burden MUT subclones facilitate escape from therapy. While the admixture of MUT and WT cells within the same individual presents an opportunity to directly study the downstream effects of subclonal resistance mutations, these cells cannot be separated through sorting. To overcome this limitation, we utilized Genotyping of Transcriptomes (GoT)-a strategy to jointly capture genotyping of a locus of interest together with whole transcriptomes at the single cell level (Fig. 1A). Importantly, GoT eliminates patient-specific and technical confounders, enabling direct linkage of BTK genotypes to transcriptional phenotypes. We applied GoT to 64,099 CD19+ cells across a cohort of seven patients with clinically progressive CLL found to have low-burden BTKC481 subclones (Fig. 1B). Samples were obtained at the time of progression and were screened for mutations in PLCG2. We genotyped 33.3% of cells, consistent with 34.0% of cells expressing BTK in whole transcriptome data. Clustering of the gene expression profiles showed that MUT and WT clones did not segregate by genotype in most (6/7) patients (Fig. 1C), implying a large degree of transcriptional similarity between MUT and WT cells, and further highlighting the need for multi-omics single-cell sequencing to directly link genotype to phenotype in this context. We note that the single exception with distinct genotypic clustering (CLL06, Fig. 1D) was driven by co-occurring large chromosomal aberrations within the MUT cells, including del(8p), which is associated with BTKi resistance [Burger et al, Nat Comm 2016]. CLL cells are known to cycle between the peripheral blood and protective microenvironmental niches, which is a process modulated by BTKi. We applied CXCR4/CD5 expression as a read out to these migration patterns [Chen et al, Leukemia 2016], and observed that MUT cells were comparatively enriched in CXCR4lowCD5hi CLL, which is associated with recent emigration from the stromal niche and increased BCR signaling (Fig. 1E). Conversely, WT cells were the majority of CXCR4hiCD5low CLL, which is associated with a resting peripheral cellular state and BCR downregulation, suggesting WT quiescence with limited stromal support. To explore the phenotypic changes associated with BTK mutations, we first measured the activity of reported BTKi response expression signatures. WT cells showed higher mean response scores compared to MUT (Fig. 1F), demonstrating that the WT cells preserve BTKi responsiveness. To unbiasedly interrogate transcriptional differences, we applied a set of 336 predefined gene modules representing B-cell cellular functions and processes. Enriched modules in MUT cells implicated restoration of B-cell receptor (BCR) signaling and recovery of CLL cell identity (NF-kB, IRF4, CD40, Fig. 1G), a finding also supported by de novo differential gene expression analysis (Fig. 1H), and gene set enrichment of differentially expressed genes (Fig. 1I). In contrast, WT cells showed increases in modules related to quiescence, hypoxia, cellular stress (HIF-1α, XBP1) and terminal B-cell development (Blimp-1). Intriguingly, changes in gene targets associated with restoration of NOTCH1 and IL4 activity were also observed. As these pathways are impaired in patients responding to BTKi and implicated in resistance [Del Papa et al, CCR 2019; Chen et al, ASH 2019], their re-emergence may reflect a cytoprotective strategy. In summary, we utilized multi-omics single-cell sequencing to identify the distinct transcriptional programs of admixed MUT and WT cells in subclonal BTKC481 progression. MUT cells showed robust escape from BTKi inhibition via increased immune receptor signaling and restoration of CLL cell identity program, while WT cells demonstrated a signature of hypoxia and stress response, with NOTCH1 and IL4 activation implicated as mechanisms of clonal persistence. Disclosures Trisal: Celgene: Current Employment, Current equity holder in publicly-traded company. Gandhi:Celgene: Current Employment, Current equity holder in publicly-traded company. Wiestner:Pharmacyclics LLC, an AbbVie Company, Acerta, Merck, Nurix, Verastem, and Genmab: Research Funding; NIH: Patents & Royalties: NIH. Allan:Acerta, Genentech, Abbvie, Sunesis, Ascentage, Pharmacyclics, Janssen, AstraZeneca, BeiGene: Consultancy; Celgene, Genentech, Janssen, TG Therapeutics: Research Funding; Abbvie, Janssen, AstraZeneca, Pharmacyclics: Honoraria. Furman:Genentech: Consultancy; Beigene: Consultancy; AstraZeneca: Consultancy, Research Funding; Acerta: Consultancy; Verastem: Consultancy; Pharmacyclics: Consultancy; TG Therapeutics: Consultancy, Research Funding; Incyte: Consultancy; Janssen: Consultancy, Speakers Bureau; Oncotarget: Consultancy; Loxo Oncology: Consultancy; Abbvie: Consultancy; Sunesis: Consultancy. Landau:Bristol Myers Squibb: Research Funding; Illumina: Research Funding.

Genetic and epigenetic intra-tumoral heterogeneity cooperate to shape the evolutionary course of cancer1. Chronic lymphocytic leukaemia (CLL) is a highly informative model for cancer evolution as it undergoes substantial genetic diversification and evolution after therapy2,3. The CLL epigenome is also an important disease-defining feature4,5, and growing populations of cells in CLL diversify by stochastic changes in DNA methylation known as epimutations6. However, previous studies using bulk sequencing methods to analyse the patterns of DNA methylation were unable to determine whether epimutations affect CLL populations homogeneously. Here, to measure the epimutation rate at single-cell resolution, we applied multiplexed single-cell reduced-representation bisulfite sequencing to B cells from healthy donors and patients with CLL. We observed that the common clonal origin of CLL results in a consistently increased epimutation rate, with low variability in the cell-to-cell epimutation rate. By contrast, variable epimutation rates across healthy B cells reflect diverse evolutionary ages across the trajectory of B cell differentiation, consistent with epimutations serving as a molecular clock. Heritable epimutation information allowed us to reconstruct lineages at high-resolution with single-cell data, and to apply this directly to patient samples. The CLL lineage tree shape revealed earlier branching and longer branch lengths than in normal B cells, reflecting rapid drift after the initial malignant transformation and a greater proliferative history. Integration of single-cell bisulfite sequencing analysis with single-cell transcriptomes and genotyping confirmed that genetic subclones mapped to distinct clades, as inferred solely on the basis of epimutation information. Finally, to examine potential lineage biases during therapy, we profiled serial samples during ibrutinib-associated lymphocytosis, and identified clades of cells that were preferentially expelled from the lymph node after treatment, marked by distinct transcriptional profiles. The single-cell integration of genetic, epigenetic and transcriptional information thus charts the lineage history of CLL and its evolution with therapy. A single-cell approach is used to follow the heritable stochastic changes to DNA methylation that occur in primary chronic lymphocytic leukaemia and healthy B cells, allowing the tracing of cell lineage histories and evolution during treatment with ibrutinib.

Ibrutinib demonstrated superior response rates and survival for treatment-naïve chronic lymphocytic leukemia (CLL) patients in a pivotal study that excluded patients younger than 65 (

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

Venetoclax (VEN) is approved for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) as monotherapy (VENmono) or in combination with rituximab. Whether VEN plus anti-CD20 (VENcombo) is superior to VENmono is unknown. We conducted a multicenter, retrospective cohort analysis comparing 321 CLL patients treated with VENmono vs VENcombo across the United States and the United Kingdom. We examined demographics, baseline characteristics, dosing, adverse events, response rates, and outcomes. The primary endpoints were progression-free survival (PFS) and overall survival (OS), estimated by Kaplan-Meier method, in patients treated with VENmono vs VENcombo. Univariate and bivariate analyses were performed with COX regression. Three hundred twenty-one CLL patients were included (3 median prior treatments, 78% prior ibrutinib). The overall response rates (ORRs) were similar (VENmono, 81% ORR, 34% complete remission [CR] vs VENcombo, 84% ORR, 32% CR). With a median follow-up of 13.4 months, no differences in PFS and OS were observed between the groups. In unadjusted analyses, the hazard ratios (HRs) for PFS and OS for VENmono vs VENcombo were HR 1.0 (95% confidence interval [CI], 0.6-1.8; P = .7) and HR 1.2 (95% CI, 0.6-2.3; P = .5), respectively. When adjusting for differences between the cohorts, the addition of an anti-CD20 antibody in combination with VEN did not impact PFS (HR, 1.0; 95% CI, 0.5-2.0; P = .9) or OS (HR, 1.1; 95% CI, 0.4-2.6; P = .8). We demonstrate comparable efficacy between VENmono and VENcombo in a heavily pretreated, high-risk, retrospective cohort, in terms of both response data and survival outcomes. Prospective studies are needed to validate these findings.

Idelalisib is an inhibitor of the PI3Kδ isoform approved for treatment of patients with relapsed chronic lymphocytic leukemia and indolent non-Hodgkin lymphoma. Many patients develop gastrointestinal symptoms during idelalisib therapy; however, the pathologic effects of this drug have not been characterized. We identified 50 patients who received at least 3 months of idelalisib therapy. Clinical findings and symptoms were noted for each patient, and endoscopic findings were recorded for those who underwent colonoscopic examination. Hematoxylin and eosin-stained sections from colonic biopsy samples were evaluated for histologic patterns of injury. Twenty-three (46%) patients experienced diarrhea during treatment with idelalisib, including 8 with severe symptoms (≥7 stools/d above baseline and/or requiring hospitalization). Fourteen patients underwent colonoscopic examination with mucosal biopsy. Twelve (86%) of these had colitis characterized by intraepithelial lymphocytosis, crypt cell apoptosis, and neutrophilic infiltration of crypt epithelium. Eleven patients had symptoms severe enough to warrant drug withdrawal, including 9 who were also treated with corticosteroids. Idelalisib commonly causes diarrheal symptoms in patients undergoing therapy for B-cell neoplasia, which may be severe in nearly 20% of patients. Characteristic histologic features include the combination of intraepithelial lymphocytosis and crypt cell apoptosis, often accompanied by neutrophils. Discontinuation of the drug results in symptomatic improvement and resolution of histologic changes.

SummaryRecurrent mutations in the spliceosome are observed in several human cancers, but their functional and therapeutic significance remains elusive. SF3B1, the most frequently mutated component of the spliceosome in cancer, is involved in the recognition of the branch point sequence (BPS) during selection of the 3′ splice site (ss) in RNA splicing. Here, we report that common and tumor-specific splicing aberrations are induced by SF3B1 mutations and establish aberrant 3′ ss selection as the most frequent splicing defect. Strikingly, mutant SF3B1 utilizes a BPS that differs from that used by wild-type SF3B1 and requires the canonical 3′ ss to enable aberrant splicing during the second step. Approximately 50% of the aberrantly spliced mRNAs are subjected to nonsense-mediated decay resulting in downregulation of gene and protein expression. These findings ascribe functional significance to the consequences of SF3B1 mutations in cancer.

Background The B cell receptor (BCR) is a signaling complex composed of surface immunoglobulin and heterodimer subunits, Igα (CD79a) and Igβ (CD79b) (Sanchez, et al. 1993). Chronic lymphocytic leukemia (CLL) demonstrates dim surface staining of CD79b compared to normal B cells or other B cell malignancies, in part due to overexpression of a splice variant that lacks coding for the extracellular domain (Alfarano, et al. 1999; Cabezudo, et al. 1999). Aggressive lymphomas, like diffuse large B cell lymphomas of non-germinal center origin (DLBCL-ABC), overexpress surface CD79b and can harbor gain of function mutations (Schmitz, et al. 2018). Richter's transformation (RT), a complication of CLL is defined by transformation to a DLBCL-ABC subtype most commonly. Upon transformation outcomes are poor and survival is short with standard therapeutic approaches. Polatuzumab vedotin (Pv), an antibody drug conjugate, targets CD79b on the surface and has obtained FDA approval for relapsed DLBCL in combination with bendamustine and rituximab. Targeting CD79b may represent an attractive therapeutic strategy for patients (pts) with RT. To this end we sought to characterize CD79b expression in RT. Methods Pts with CLL or RT and available paraffin embedded tissue blocks were identified in coordination with Weill Cornell Medicine's (WCM) pathology department. Clone AT107-2 (Bio-Rad, USA) which targets an intracellular epitope was used to stain for CD79b in formalin fixed paraffin embedded (FFPE) tissue sections after optimization following institutional staining procedures. CD79b was classified as either positive (pos) or negative (neg) based on staining pattern and intensity as deemed by a board certified hematopathologist. RT pt derived xenografts (RT-PDXs) were assessed for surface expression of CD79b via flow cytometry. Nonpermabilized cells derived from RT-PDXs were stained using an anti-human CD79b-FITC conjugated antibody (clone CD3-1, Southern Biotech, USA). Mean fluorescence intensity (MFI) was established. RNA seq data was obtained from 2 of 3 RT-PDX models and has been reported previously (Vaisitti, et al. 2018). CD79b transcripts per million (TPM) were analyzed and compared to that of normal lymph node (LN) tissue deposited in the Human Protein Atlas RNA Seq database (HPA-RNA Seq). GraphPad Prism 8.0 was used to perform statistical analysis. Results Nineteen pts with RT and 5 pts with CLL were identified for the study. Median age at diagnosis of the 19 RT pts was 71 years compared to 67 years for the 5 CLL pts. Five RT pts (26%) were treatment naïve (TN) at time of RT. Ten (53%) RT pts transformed on targeted therapy, 6 on BTK inhibitors, 2 on IMiD based therapy, 2 on venetoclax. CD79b stained pos for 16 RT pts (84%) and all 5 (100%) CLL pts. We were not able to identify any correlations between CD79b expression due to low numbers of neg cases. Surface expression of CD79b was evaluated on RT-PDX models from different passages and found to be pos in all 3 models with a median percentage of CD79b+ cells of 45.9% (range 34.6-76%). The median MFI was 2028.5 (range MFI 860-4289). Two of the 3 three models had bimodal populations of cells (pos and neg) whereas the third model was more uniformly pos. RNA seq data from 2 RT-PDX models was available and compared to RNA-seq data from normal LN tissue deposited in the HPA-RNA Seq database. The mean TPM of CD79b for RT-PDX cases was 837.5 compared to 311.5 for normal LN tissue, p=0.028. Conclusion CD79b expression was pos in 84% of FFPE primary RT specimens evaluated. We were able to confirm extracellular CD79b expression with flow cytometry in all 3 RT-PDX models with a median MFI of 2028.5. Surface expression was found to be bimodal in 2 models and uniformly pos in 1 model suggesting tumor heterogeneity. Rna-seq data from RT-PDX models demonstrated higher TPM values in RT-PDX samples compared to normal LN tissue. We conclude that RT expresses CD79b at sufficient levels despite deriving from a CLL cell that historically has demonstrated low surface CD79b expression. Further studies will be undertaken characterizing pos and neg cellular populations focusing on mechanisms of expression and potential differences in splice variant expression. Disclosures Allan: Pharmacyclics LLC, an AbbVie company: Consultancy; Verastem Oncology, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy; Sunesis Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Consultancy; Janssen: Consultancy, Honoraria; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vaisitti:Verastem Inc: Research Funding; VelosBio Inc.: Research Funding. Joyce:Genentech: Employment. Schulz:Genentech, Inc.: Employment; Roche: Equity Ownership. Deaglio:Verastem Inc: Research Funding; iTeos Therapeutics: Research Funding; VelosBio Inc.: Research Funding. Furman:Genentech: Consultancy.

Background: While CLL is commonly diagnosed in older patients, there are ~15% of patients diagnosed at ages younger than 50. Several past studies have investigated differences in clinical parameters and treatment outcomes in younger patients with CLL, including a shorter time to first treatment (TTFT) among younger patients (Parikh et al. 2014). However, few studies have reported on the genetic mutational differences between younger and older cohorts. To bridge this gap, we investigated the mutational landscape between younger and older patients and evaluated the clinical outcome TTFT, hypothesizing that our younger cohort of patients would associate with higher risk lesions and behave more aggressively. Methods: We conducted a single center retrospective database review of 557 patients diagnosed with CLL from 1980 to 2019 who underwent whole exome profiling between 2015 to 2019 with a lymphoid specific 75-gene next generation sequencing (NGS) panel (Genoptix Inc). A Pearson's chi-square test was used to compare categorical variables between groups and a Wilcoxon rank sum test was used to compare medians. The TTFT was estimated using Kaplan-Meier methods, and the difference between groups was compared using the log-rank test. Multivariate regression using a Cox proportional hazards model was used to compare TTFT between groups independent of well-accepted clinical risk factors for treatment initiation. Results: Of the 557 patients who underwent NGS testing, 92 (16.5%) were younger than 50 years old with a median age of 44.9 years old compared to a median age of 62.7 years old in the 465 (83.5%) patients older than 50 years old. There was no difference between the two groups with regards to previous treatment prior to NGS testing with 29.2% in the older patients and 26.1% in the younger patients having previously been treated (p=0.63). The median time from CLL diagnosis to initial NGS testing was 5.2 years in the younger cohort vs. 3.2 years in the older cohort (p=0.04). There were no differences in baseline prognostic factors between younger and older patients, including Rai stage, IGVH status, CD38 positivity, ZAP70 expression, and cytogenetic abnormalities. We found a lower frequency of TP53 mutations in younger compared to older patients (6.5% vs 15.7%, p=0.03) but otherwise found no differences in any other genetic mutations between the two groups, including NOTCH1, FAT1, ATM, and SF3B1 (Table 1). There was a longer TTFT in younger patients with a median TTFT of 7.61 years compared to 4.42 years in older patients (p= Conclusions: We found no enrichment of specific genetic mutations in younger versus older patients except a lower prevalence of TP53 mutations in our younger patient population. We found younger patients have a longer TTFT, which is contrary to previous studies that have identified younger age as a negative prognostic marker. Future research is needed to determine why younger patients in our cohort appear to have a more indolent disease course in terms of TTFT despite similar baseline prognostic factors and molecular genetics to older patients. Disclosures Furman: Acerta Pharma: Consultancy; Genentech: Consultancy; Incyte: Consultancy; AstraZeneca: Consultancy; Abbvie: Consultancy; Beigene: Consultancy; TG Therapeutics: Consultancy; Sunesis: Consultancy; Oncotracker: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy; Verastem: Consultancy. Allan:AbbVie, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Consultancy; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics LLC, an AbbVie company: Consultancy; Bayer: Consultancy; Sunesis Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Verastem Oncology, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Introduction: Venetoclax (VEN) based therapy has become a standard of care in front line and relapsed-refractory (R/R) CLL based on favorable efficacy and toxicity. Whereas prospective data regarding activity of therapies following ibrutinib (IBR) or idelalisib (IDE) are available in the settings of progression (VEN, non-covalent BTKi) and intolerance (acalabrutinib), how best to manage patients (pts) who discontinue (dc) VEN remains a key unanswered question. With the increased use of VEN in early lines of therapy (LOT; CLL 14, MURANO), the activity of BTK inhibitors (BTKi) and cellular therapies following VEN becomes a critical issue. No prospective study has addressed this question, and currently reported VEN clinical trials have limited information about subsequent treatments. While recent data describe VEN resistance mechanisms (Guieze 2018, Blombery 2019), the impact of VEN resistance on efficacy of post VEN therapies is unknown. To address this gap, we conducted an international study to identify a large cohort of pts who dc VEN and have been subsequently treated. Methods: We conducted an IRB approved multicenter (31 US, EU, South American sites, in partnership with UK CLL Forum and CORE registry), retrospective cohort study of CLL pts who dc VEN for any reason. We examined demographics, dc reasons, responses, survival, adverse events (AEs) and activity of post VEN therapies. Primary endpoints were overall response rate (ORR) and progression free survival (PFS) for the post VEN treatments stratified by treatment type (BTKi, PI3Ki and cellular therapy: CAR-T or alloHSCT). ORR was defined by iwCLL criteria and PFS was defined from VEN dc to disease progression (PD), death, or last follow up for next treatment. Pts were further stratified by BTKi (resistant / intolerant) and PI3Ki exposure prior to VEN. PFS-2 was defined as time from VEN start to tumor progression on IBR or death from any cause. Results: 326 CLL pts who dc VEN in the front line (4%) and R/R settings (96%) were identified. The cohort was 69% male, 87% white, median (med) age 66 (38-91) at VEN start, 27% treated with VEN based combinations (n=88, med 6 cycles anti-CD20 abs). Pre VEN prognostic features: 82% IGHV unmutated (n tested=166), 47% del17p (n=306), 45% TP53 mut (n=217), 39% complex karyotype (n=273), 23% BTK mut (n=79), 18% NOTCH1 mut (n=103), 10% PLCγ2 mut (n=74). Pts received med 3 therapies (0-11) prior to VEN; 40% were BTKi naïve (n=130), 60% were BTKi exposed (196) and 81% were IDE naïve (n=263). Most common reasons for VEN dc were PD (38%), AE (20%), Richter's transformation (RT, 14%), 8% pt preference, and HSCT 5%. Of 326 pts who dc VEN, 188 (58%) were treated with a subsequent LOT, 61 are alive and untreated and 77 died prior to a subsequent LOT. Post VEN sequencing analyses focused on BTKi, PI3Ki and cellular therapy (CAR-T or alloHSCT) activities following VEN dc (Table1). ORR to BTKi was 84% (n=44) vs. 54% (n=30, p Conclusions: In the largest experience of therapies following VEN dc in CLL, we demonstrated that therapy selection following VEN requires consideration of prior novel agent exposure and reasons for discontinuation. For BTKi naïve pts, selection of a covalently binding BTKi results in high ORR and durable remissions. PFS-2 data provide reassurance for using VEN prior to IBR. For BTKi exposed pts, BTK inhibition is not effective in the setting of BTKi resistance but should be considered if prior BTKi intolerance. PI3K inhibition following VEN does not appear to result in durable remissions even in PI3Ki naïve pts, suggesting possible overlap in resistance mechanisms (BTK or VEN with PI3K). We conclude that BTKi in naïve or previously responsive pts and alloHSCT following VEN appear to be the most effective strategies with durable responses. These data suggest that a number of effective regimens exist for post VEN pts, providing support for VEN use earlier in the course of CLL. Disclosures Mato: Acerta: Consultancy; LOXO: Consultancy, Research Funding; DTRM Biopharma: Research Funding; Janssen: Consultancy; Gilead: Research Funding; Pharmacyclics: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Johnson & Johnson: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB member , Research Funding; AbbVie: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Celgene: Consultancy. Roeker:AbbVie: Equity Ownership; Abbott Laboratories: Equity Ownership. Eyre:Gilead: Consultancy, Other: Research support, Speakers Bureau; Roche: Honoraria; Abbvie: Honoraria, Other: Travel to Conferences; Janssen: Honoraria, Other: Travel to Conferences ; Takeda: Other: Travel to Conferences . Jacobs:Pharmacyclics LLC, an AbbVie Company: Research Funding, Speakers Bureau; AstraZeneca: Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Genentech: Speakers Bureau; JUNO: Consultancy; Gilead: Consultancy; TG Therapeutics: Honoraria, Research Funding. Hill:TG therapeutics: Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Research Funding; Kite: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Takeda: Research Funding; Amgen: Research Funding. Lamanna:Celgene: Consultancy; Infinity/ Verastem: Research Funding; Ming: Research Funding; TG Therapeutics: Research Funding; Oncternal: Research Funding. Brander:Tolero: Research Funding; MEI: Research Funding; BeiGene: Research Funding; DTRM Biopharma: Research Funding; Genentech: Consultancy, Honoraria, Research Funding; Teva: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Research Funding; Novartis: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; AbbVie: Consultancy, Honoraria, Research Funding; Acerta: Research Funding. Shadman:AbbVie: Consultancy, Research Funding; Astra Zeneca: Consultancy; BeiGene: Research Funding; TG Therapeutic: Research Funding; ADC Therapeutics: Consultancy; Atara Biotherapeutics: Consultancy; Verastem: Consultancy; Acerta Pharma: Research Funding; Sunesis: Research Funding; Mustang Bio: Research Funding; Celgene: Research Funding; Pharmacyclics: Consultancy, Research Funding; Sound Biologics: Consultancy; Genentech: Consultancy, Research Funding; Gilead: Consultancy, Research Funding. Ujjani:AstraZeneca: Consultancy; Genentech: Consultancy; Rigel: Consultancy; Gilead: Consultancy; Abbvie: Research Funding; Pharmacyclics: Research Funding. Perini:Janssen: Other: Advisory Board; Abbvie: Other: Advisory Board; AstraZeneca: Other: Advisory Board. Pinilla Ibarz:Sanofi: Speakers Bureau; Bayer: Speakers Bureau; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Takeda: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Teva: Consultancy; TG Therapeutics: Consultancy. Barrientos:Pharmacyclics: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Janssen: Consultancy; Gilead: Consultancy; Genentech: Consultancy. Skarbnik:Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Honoraria, Speakers Bureau; CLL Society: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Speakers Bureau; Novartis: Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Verastem Oncology: Honoraria, Research Funding, Speakers Bureau; Kite Pharma: Honoraria, Speakers Bureau; Gilead Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Acerta: Research Funding. Pagel:AstraZeneca: Consultancy; Gilead Sciences: Consultancy; Pharmacyclics: Consultancy. Choi:Abbvie: Consultancy, Research Funding, Speakers Bureau; Genentech: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Rigel: Consultancy, Research Funding; Gilead: Consultancy, Speakers Bureau; Oncternal: Research Funding. Coombs:H3 Biomedicine: Research Funding. Barr:Janssen: Consultancy; Astra Zeneca: Consultancy, Research Funding; Merck: Consultancy; Verastem: Consultancy; Gilead: Consultancy; Genentech: Consultancy; Pharmacyclics LLC, an AbbVie company: Consultancy, Research Funding; Celgene: Consultancy; TG Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; AbbVie: Consultancy. Portell:Xencor: Research Funding; Roche/Genentech: Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Genentech: Consultancy, Research Funding; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding. Schuster:AstraZeneca: Honoraria; AbbVie: Honoraria, Research Funding; Acerta: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Loxo Oncology: Honoraria; Pfizer: Honoraria; Nordic Nanovector: Honoraria; Pharmacyclics: Honoraria, Research Funding; Novartis: Honoraria, Patents & Royalties: Combination Therapies of CAR and PD-1 Inhibitors with royalties paid to Novartis, Research Funding; Merck: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Gilead: Honoraria, Research Funding. Martinez-Calle:ABBVIE: Other: Travel support. Munir:AbbVie: Honoraria; Alexion: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Roche: Honoraria; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sunesis: Consultancy; Pharmacyclics: Other: TBC; Acerta: Membership on an entity's Board of Directors or advisory committees. Nabhan:Aptitude Health: Employment. King:Astrazeneca: Other: Advisory board; Genentech: Other: Advisory Board ; Incyte: Other: Advisory Board. Zelenetz:Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics/AbbVie: 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; Celgene: 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; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics/AbbVie: 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; Verastem: 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; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: 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; DAVA Oncology: 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; DAVA Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: 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; Genentech/Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cheson:Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Symbios: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trillium: Research Funding; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding; Portola: Research Funding; Kite: Research Funding; Gilead: Research Funding; Epizyme: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding. Fox:Gilead: Consultancy; Janssen: Consultancy; Celgene: Consultancy; AbbVie: Consultancy; Sunesis: Consultancy; Takeda Pharmaceuticals: Consultancy; Atara Biotherapeutics: Consultancy; Adienne: Other: Travel Support. Allan:Sunesis Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy; Janssen: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie company: Consultancy; Verastem Oncology, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Consultancy.

Chronic lymphocytic leukemia (CLL) is the most common leukemia of adults in Western countries. There are approximately 19 000 new cases diagnosed in the United States in 2016 (https://seer.cancer.gov/statfacts/html/clyl.html). MicroRNAs (miRs) have been implicated as one of the key contributors in the pathogenesis of CLL. One of these miRNAs is miR-155, which is probably the best-characterized miRNA involved in B-cell maturation and function. MiR-155 has a critical role in normal immune function,1 including innate response, regulation of the germinal center response and formation of class-switched plasma cells and negative regulation of activation-induced cytidine deaminase. However, miR-155 is also an oncogenic miRNA overexpression of miR-155 in mice or its precursor BIC in chickens led to the development of lymphomas. Furthermore, abnormal expression of miR-155 has been observed in a number of lymphoid malignancies, including diffuse large B-cell lymphoma, classical Hodgkin lymphoma, primary mediastinal B-cell lymphoma and CLL.2 In various studies, miR-155 has been found consistently overexpressed in CLL cells compared with normal B cells. Although there does not appear to be definitive correlations between miR-155 expression levels and individual CLL prognostic factors, high pretreatment levels of miR-155 in CLL cells or in plasma have been demonstrated to be associated with shorter need-for-treatment interval and failure to achieve complete response, respectively.3, 4 The association of adverse clinical outcome in CLL with high miR-155 levels appears to be linked to the capacity of miR-155 to enhance the sensitivity of CLL cells to B-cell receptor ligation.5 Thus it is likely that miR-155 has important roles in the pathobiology of CLL.

Introduction. Recent research in lymphoma has resulted in better outcomes for clinical trial populations. Population studies have suggested that some real-world patients (pts) have not benefited. We hypothesized that one reason for this discrepancy is the difference between trial participants and real-world pts. We aimed to: 1) Compare demographics and baseline clinical characteristics of real-world and clinical trial pts receiving first-line therapy for diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and mantle cell lymphoma (MCL); and 2) Compare demographics and baseline clinical characteristics of real-world DLBCL, FL, and MCL pts with clinical trial eligibility criteria. Methods. Using ClinicalTrials.gov, we identified all phase 2 and 3 clinical trials that opened between 2002-2017 and included pts with DLBCL, FL, MCL. Published trials that included front-line immunotherapy and chemotherapy were selected, and eligibility criteria recorded. We reviewed publications and recorded pt numbers and characteristics. Using the Weill Cornell Medicine (WCM) Lymphoma Database, an IRB-approved, prospective cohort which started in 2010, we identified all pts diagnosed with DLBCL, FL, and MCL and recorded baseline characteristics. Descriptive statistics were used to describe clinical trial eligibility and pt characteristics. Fisher's exact test was used to compare pt characteristics. Results. We identified 642 phase 2 and 3 trials on Clinicaltrials.gov, 37 of which met predefined criteria. The most frequent exclusion criteria were HIV infection (n=33), pregnancy (n=25), HBV infection (n=21), history of non-lymphoma cancer (n=19), ECOG>2 (n=16), HCV infection (n=16), serum creatinine >2 mg/dL or >2x ULN (n=15), active infection (n=12), history of MI (n=11), serum bilirubin >2 mg/dL or >2x ULN (n=7), congestive heart failure (n=4), hemoglobin (Hb) We identified 652 pts in the WCM Database with newly diagnosed DLBCL, FL, and MCL (Table 1). Key differences between clinical trial and Database populations for DLBCL included proportion of pts with stage 3-4 disease (79% vs 60%, p70. Among FL pts, key differences between trial and Database populations included proportion with stage 3-4 disease (98% vs 56%, p70. Clinical trial vs. Database MCL pts differed in proportion with presence of B symptoms (29% vs 18%, p=0.022) or bulky disease (18% vs 5%, p=0.025), and intermediate or high MIPI (63.5% vs 79%, p=0.002); 42% of Database pts were age >70. Of all 652 pts from the Database, 190 (29%) had characteristics that may have excluded them from clinical trial participation. The most common reasons for exclusion included history of cancer (11%), cardiac arrhythmias (7%), MI (6%), active infections (6%) and Hb 2mg/dL (1.4%), serum bilirubin >2 mg/dL (0.9%) and ECOG >2 (0.6%). Conclusions. These data suggest that real-world lymphoma pts are considerably more heterogeneous than clinical trial populations. While the average pt in WCM Database had a lower stage and/or lower prognostic risk score than a typical trial population, over 30% of database pts were > 70, a group that was uncommon in clinical trials. Likewise, almost 30% of Database pts had medical conditions that may have excluded them from clinical trial participation. Future research should focus on better defining the characteristics and outcomes of pts that either are underrepresented on clinical trials, both intentionally due to eligibility criteria and unintentionally for less clear reasons. It is likely that some eligibility criteria have little impact on treatment and outcomes and may be eliminated from prospective trials, while other trials may focus on pts that remain poorly understood. Disclosures Allan: Acerta: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees. Furman:Verastem: Consultancy; Loxo Oncology: Consultancy; Janssen: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; AbbVie: Consultancy; Acerta: Consultancy, Research Funding; TG Therapeutics: Consultancy; Sunesis: Consultancy; Genentech: Consultancy; Incyte: Consultancy, Other: DSMB; Gilead: Consultancy. Leonard:ADC Therapeutics: Consultancy; BMS: Consultancy; Celgene: Consultancy; United Therapeutics: Consultancy; Biotest: Consultancy; Gilead: Consultancy; Novartis: Consultancy; AstraZeneca: Consultancy; Karyopharm: Consultancy; Genentech/Roche: Consultancy; Bayer: Consultancy; Pfizer: Consultancy; MEI Pharma: Consultancy; Juno: Consultancy; Sutro: Consultancy. Martin:AstraZeneca: Consultancy; Janssen: Consultancy; Kite: Consultancy; Bayer: Consultancy; Gilead: Consultancy; Seattle Genetics: Consultancy.

The co-occurrence of myeloproliferative (MPN) and lymphoproliferative neoplasms (LPN) is rare and many publications have been limited to small case reports. Others have involved a considerable number of patients, but the coexistence remains underreported and inadequately studied. A recent retrospective review reported that a MPN patients have a 2.8-fold higher relative risk of developing LPN. A database developed at Weill Cornell Medicine (WCM) was queried for patients with ≥3 visits between 1998-2018 with a diagnostic code for a MPN and lymphoma or myeloma subtype. Patients identified were verified to ensure that study inclusion criteria were satisfied. Observed co-occurrence was compared to nation-wide reported prevalence. Demographic and clinical details of 24 patients with a MPN and LPN were recorded (Table 1). The ratio of males to females was 1.7. Essential thrombocythemia and polycythemia vera, and chronic lymphocytic leukemia (CLL) were the leading MPN and LPN subtypes, respectively. Patients were assigned to risk or staging categories at diagnosis based on subtype-specific criteria (Table 2). Median values for diagnostic bone marrow biopsy findings in 14 patients were 2% [0-5] for myeloblasts and 80% [15-100] for cellularity. Additionally, 10 patients had evaluated reticulin fibrosis: 5 (50.0%) presented as MF-0, 4 (40.0%) as MF-1, and 1 (10.0%) as MF-2. Progression to myelofibrosis was confirmed by morphology in 1 (4.2%) patient 10.1 years after a polycythemia vera diagnosis and 5.4 years after a diffuse large B-cell lymphoma (DLBCL) diagnosis. Progression to acute myeloid leukemia was confirmed by morphology in 1 (4.2%) patient 2.4 years after a chronic myelomonocytic leukemia diagnosis and 1.2 years after a smoldering myeloma (SM) diagnosis. Interphase fluorescence in situ hybridization (iFISH) detected cytogenetic abnormalities in 5/8 (62.5%) CLL patients: 2/5 (40.0%) and 5/5 (100.0%) patients harbored deletions in trisomy 12 and 13q14, respectively. Immunoglobulin heavy chain variable region gene (IGVH) status was unmutated in 2 (25.0%) patients. One (12.5%) patient was CD38+ and 2/6 (33.0%) patients were ZAP-70+. At diagnosis, all 8 patients presented with early stage disease (Rai stage 0-II). Based on the CLL-specific international prognostic index (IPI), 3/8 (37.5%) and 5/8 (62.5%) presented as low-risk and intermediate-risk, respectively. Of the 6 lymphoma patients: 5 (83.0%) patients presented with Ann Arbor stage-IV disease at diagnosis. Four (66.7%) patients presented as low/intermediate-risk, and 2 (33.3%) presented as high-risk based on disease-specific IPIs. One patient presented with -17p by iFISH. All 4 patients that were evaluated for Ki-67 had moderate/high expression. Of the 7 multiple myeloma (MM) patients, 6 (85.7%) presented as stage 1 and 1 (14.3%) as stage 3. Of the 3 SM patients, all 3 presented as low risk [12]. In addition, these patients were categorized as IgG-K (4; 40.0%), IgG-L (2; 20.0%), IgA-K (1; 10.0%), IgA-L (1; 10.0%), IgM (1; 10.0%), and biclonal IgG-L/IgA-L (1; 10.0%) [13]. Mutation statuses were identified by commercially tested myeloid or lymphoid molecular panels. As expected in this MPN subtype distribution, 11 (45.8%) are JAK2+, 2 (8.3%) are MPL+, 1 (4.2%) is BCR-ABL+, and 1 (4.2%) is CALR+ (Table 3). The risk of a co-occurrent MPN and LPN is higher than expected if they are mutually exclusive (Table 4A-4B, 5). Of interest, 13 (54.2%) patients were diagnosed with a MPN 11.8±18.8 years prior to a LPN; conversely, 11 (45.9%) were diagnosed with a LPN 6.5±6.2 years prior to a MPN. In addition, MPN therapy was started 2.0±2.3 years after a MPN diagnosis, and LPN therapy was started 2.6±4.0 years after a LPN diagnosis. A review of survival analysis requires larger subtype populations since the degree of survival can vary greatly, but it has been reported that patients with a MPN or LPN have significantly reduced life expectancy when compared to the general population. Median follow-up for our patient is 8.2 years (1.5-28.0) with 17/24 (70.8%) patients still being actively followed at our institution, 6 (25.0%) are been lost to follow-up, and 1 (4.2%) is deceased. The significant prevalence of these hematologic malignancies in combination emphasizes the importance of performing a bone marrow biopsy, which we espouse at our institution, cytogenetic analysis, and myeloid and lymphoid molecular testing to identify mutations. Disclosures Furman: Loxo Oncology: Consultancy; Gilead: Consultancy; Verastem: Consultancy; Acerta: Consultancy, Research Funding; TG Therapeutics: Consultancy; Incyte: Consultancy, Other: DSMB; Pharmacyclics LLC, an AbbVie Company: Consultancy; Genentech: Consultancy; Sunesis: Consultancy; Janssen: Consultancy; AbbVie: Consultancy. Niesvizky:Amgen Inc.: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding. Ritchie:Bristol-Myers Squibb: Research Funding; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Astellas Pharma: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Other: Travel, Accommodations, Expenses, Speakers Bureau; Pfizer: Consultancy, Research Funding; Incyte: Consultancy, Speakers Bureau; ARIAD Pharmaceuticals: Speakers Bureau.

Introduction: Venetoclax (Ven) is approved for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) as monotherapy (Ven mono) or in combination (Ven paired) with rituximab based on clinical trials with selected patients (pts) and limited ibrutinib exposure. Whether Ven paired is superior to Ven mono, patterns of care, and outcomes following Ven discontinuation are unknown. Further, better delineation of adverse events (AEs) when Ven is used outside of clinical trials is needed. To address these gaps, we conducted a multicenter, international study in partnership with CLL Collaborative Study of Real World Evidence (CORE) and UK CLL Study Forum examining the clinical experience of 348 Ven treated CLL pts, representing the largest series of Ven treated pts reported to date. Methods: We conducted a retrospective cohort analysis of CLL pts treated with Ven across 24 US and 42 UK academic and community centers. We examined demographics, baseline disease characteristics, dosing, AEs, TLS risk and outcomes, response rates, outcomes (overall survival (OS) and progression free survival (PFS)), and tx sequencing. TLS events were defined by Howard criteria. PFS and OS were estimated by the Kaplan Meier method. Comparisons of outcomes used the Log Rank test. Univariate and multivariate analyses were performed with COX regression. All other comparisons were descriptive. Results: Of these 348 CLL pts, 94% were R/R, median age 67 years (range:37-91), 69% male, 85% white, and 73% Rai stage ≥2. 19% received Ven on clinical trial. 79% had Ven mono; Ven was paired most commonly with anti-CD20 (n=51) and ibrutinib (n=10). Pts received a median of 3 tx (range 0-15) before Ven; 78% received ibrutinib, 29% received PI3Ki, 20% had ≥2 prior kinase inhibitors, and 68% had chemoimmunotherapy. Median time from most recent tx to Ven start was 1.1 months (range 0-62). Pre-Ven prognostic markers included 43% del17p, 34% TP53 mutated, 24% del11q, 38% complex karyotype (≥ 3 abnormalities), and 84% IGHV unmutated (Table 1). TLS risk was low in 38%, intermediate in 34% and high in 28%. During ramp up, TLS was observed in 10% (22 lab, 9 clinical TLS events, 3 missing data). Following dose escalation, 70% achieved a stable Ven dose of 400 mg, 33% required ≥ 1 dose interruption and 27% required ≥ 1 dose reduction. AEs included grade 3 neutropenia 39%, grade 3 thrombocytopenia 29%, infections 25%, grade ≥ 2 diarrhea 7.8%, and neutropenic fever 7.7%. AEs were similar whether treated on or off clinical trial. The ORR to Ven mono, Ven paired was 81% (34% CR), 86% (29% CR). With a median follow-up of 14.2 months, median PFS and OS were not reached (12 month PFS 74%, OS 82%). Figure 1 depicts PFS stratified by Ven mono vs. paired, clinical trial vs. clinical practice, del17p status, and complex karyotype. Pts who discontinued Ven due to AEs had better OS compared with those who discontinued due to progression or Richter Transformation (RT) (Median OS 47 vs. 15.1 vs. 8.6 months, respectively). In multivariate analyses, complex karyotype was the only independent predictor of PFS (HR 2.8, p Conclusions: In this heavily pretreated, poor risk group, Ven showed favorable outcomes with comparable toxicity and efficacy on or off clinical trial. Similar outcomes were observed for Ven mono and Ven paired; longer follow up is needed from studies of Ven paired to understand depth and durability of response. Complex karyotype independently predicted inferior PFS and OS. Without complex karyotype, del(17p), multiple lines of prior tx, and prior ibrutinib tx were independent predictors of inferior outcomes. Outcomes of retreatment with KI in Ven-failure previously treated with KI were poor. Data on sequencing cellular therapies post Ven is forthcoming. Disclosures Mato: AbbVie: Consultancy, Research Funding; Pharmacyclics, an AbbVie Company: Consultancy, Research Funding; Regeneron: Research Funding; AstraZeneca: Consultancy; Medscape: Honoraria; TG Therapeutics: Consultancy, Research Funding; Acerta: Research Funding; Prime Oncology: Honoraria; Portola: Research Funding; Celgene: Consultancy; Johnson & Johnson: Consultancy. Eyre:Abbvie: Consultancy, Other: travel support; Janssen: Consultancy, Other: travel support; Roche: Consultancy; Gilead: Consultancy, Other: travel support; Celgene: Other: travel support. Nabhan:Cardinal Health: Employment, Equity Ownership. Lamanna:Acerta: Research Funding; TG Therapeutics: Research Funding; Jannsen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Hill:Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Brander:Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Novartis: Consultancy, Other: DSMB; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Teva: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Barr:AbbVie, Gilead: Consultancy. Cheson:AbbVie, Roche/Genentech, Pharmacyclics, Acerta, TG Therapeutics: Consultancy. Shah:Geron: Equity Ownership; Lentigen Technology: Research Funding; Exelexis: Equity Ownership; Oncosec: Equity Ownership; Miltenyi: Other: Travel funding, Research Funding; Juno Pharmaceuticals: Honoraria. Allan:AbbVie: Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy; Sunesis: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees. Kennard:AbbVie, Gilead, Verastem: Consultancy. Schuster:Gilead: Membership on an entity's Board of Directors or advisory committees; Nordic Nanovector: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Research Funding; Physician's Education Source, LLC: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Honoraria, Research Funding; Dava Oncology: Consultancy, Honoraria; OncLive: Honoraria; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Skarbnik:Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Genentech: Honoraria, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead Sciences: Honoraria, Speakers Bureau. Coombs:AROG: Other: Travel fees; Abbvie: Consultancy; Incyte: Other: Travel fees; DAVA Oncology: Honoraria; H3 Biomedicine: Honoraria. Ujjani:AbbVie: Consultancy, Speakers Bureau. Jacobs:Genentech: Honoraria. Pagel:Pharmacyclics, an AbbVie Company: Consultancy; Gilead: Consultancy. Schuh:Giles, Roche, Janssen, AbbVie: Honoraria. Shadman:Celgene: Research Funding; Gilead Sciences: Research Funding; Mustang Biopharma: Research Funding; TG Therapeutics: Research Funding; AstraZeneca: Consultancy; Pharmacyclics: Research Funding; Genentech: Research Funding; Genentech: Consultancy; Acerta Pharma: Research Funding; Beigene: Research Funding; Verastem: Consultancy; Qilu Puget Sound Biotherapeutics: Consultancy; AbbVie: Consultancy. Fox:Abbvie: Consultancy, Other: travel support, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: travel support, Speakers Bureau; Gilead: Consultancy, Other: travel support, Research Funding, Speakers Bureau; Roche: Consultancy, Other: travel support, Research Funding, Speakers Bureau; Celgene: Consultancy, Other: travel support, Speakers Bureau; Sunesis: Consultancy.

Extracellular adenosine generated from ATP/ADP through the concerted action of the ectoenzymes CD39 and CD73 elicits potent cytoprotective and immunosuppressive effects mediated by type-1 purinergic receptors. Chronic lymphocytic leukemia (CLL) cells expressing the ectoenzymes CD39 and CD73 can actively produce adenosine, activating an autocrine adenosinergic axis that supports engraftment of leukemic cells in a growth-favorable environment. These effects are mediated by the A2A adenosine receptor, which inhibits chemotaxis and limits spontaneous and drug-induced apoptosis of CLL cells. Following the reported cross-talk between hypoxia and adenosine, we tested the hypothesis of a functional interplay between the adenosinergic axis and hypoxic signals in the CLL microenvironment. Results indicate that culture of CLL cells under hypoxic conditions, such as those observed in lymph nodes from CLL patients, boosts adenosine production, mainly because of the significant increase in the mRNA and protein levels of CD73, the rate-limiting enzyme in adenosine synthesis. CLL also underwent a robust up-regulation of CD26, which functions as an adenosine-deaminase scaffold protein, in keeping with the hypothesis that extracellular nucleotides enter a scavenging pathway, with conversion to inosine and re-uptake by the leukemic cells. Confirmation was obtained using HPLC assays, which showed increased inosine generation under hypoxia. Consistently, expression of membrane nucleoside transporters was also significantly up-regulated. However, hypoxic CLL cells also expressed high levels of the A2A adenosine receptor, which delivered cytoprotective signals and which supported CLL proliferation in response to TLR signaling. Attention was then focused on the stromal and T cell compartments, which are critical to the formation and maintenance of the leukemic niche. Hypoxia enhanced differentiation of circulating monocytes into nurse-like cells, macrophages of the M2 type playing an essential role in nurturing leukemic cells. The enhancement of NLC differentiation under hypoxic conditions relied, at least in part, on the activation of A2A: its engagement by a pharmacological agonist favored NLC generation, with overexpression of indoleamine 2,3-dioxygenase (IDO) and of the M2 macrophage markers CD163 and CD206. Moreover, activation of A2A induced secretion of immunomodulatory cytokines, such as IL-6, IL-10 and CCL18, while pharmacological blockade of A2A under hypoxia prevented NLC differentiation, expansion, expression of immunosuppressive molecules and secretion of cytokines and chemokines. In the T cell compartment, hypoxic cultures were followed by the sharp up-regulation of A2A, without significantly affecting the enzymes that generate adenosine, which were anyway restricted to the regulatory T cell (Treg) compartment. Co-cultures of T lymphocytes and CLL cells under hypoxia resulted in a dramatic decrease of T cell proliferation, partially rescued by A2A receptor antagonists. Furthermore, hypoxic T cells underwent a metabolic switch, with increased expression of nucleoside transporters and enzymes involved in glucose metabolism, suggesting a Warburg effect. This was accompanied by the differentiation of a population of Tr1 cells, characterized by the expression of LAG3 and CD49b and by the secretion of high levels of IL-10 and VEGF. Expression of the PD-1 immuno-inhibitory receptor was enhanced in hypoxic T cells, suggesting that multiple inhibitory mechanisms are activated. We also observed expansion of classical Tregs, defined on the basis of a CD4+/CD25high/CD127low/foxp3+ phenotype. Blockade of the A2A receptor prevented this phenotype, partially restoring T cell proliferation and immune competence. Together, these findings indicate that the adenosinergic and hypoxic axes synergize in shaping the CLL niche, suggesting that pharmacological inhibition of the adenosinergic signals may counteract some of the effects mediated by an hypoxic environment, contributing to disrupt the leukemic niche and to restore the immune system. Disclosures Gaidano: Celgene: Research Funding; MorphoSys; Roche; Novartis; GlaxoSmithKline; Amgen; Janssen; Karyopharm: Honoraria, Other: Advisory boards.

Human SLAMF1 (signaling-lymphocytic-activation-molecule-family1, CD150) is a self-ligand adhesion/co-stimulatory molecule wich belongs to a family of 9 receptors. SLAMF1 is also a microbial sensor, as it regulates Gram- bacterial phagosome functions through an ubiquitous cellular autophagic machinery and serves as a receptor for Measles virus. In this work, we investigated expression and function of SLAMF1 in chronic lymphocytic leukemia (CLL) cells. Results indicate that expression of SLAMF1 is lost in a subset of patients with chronic lymphocytic leukemia characterized by an aggressive form of the disease, with shorter time to first treatment (median 2.2 years in SLAMF1- vs 7.6 in SLAMF1+ patients, P=.001) and overall survival (77.5% survival rate at 10 years in SLAMF1- vs 94.7% years in SLAMF1+ patients, P=.036). Consistently, SLAMF1low CLL patients are characterized by clinical or molecular markers of a more aggressive disease. Stable silencing of SLAMF1 in the CLL-like Mec-1 cell line (constitutively SLAMF1+) modulated pathways related to cell migration, cytoskeletal organization and intracellular vesicle formation/recirculation. Decreased expression of CXCR3 and an increased expression of CXCR4, CD38 and CD44 were maintained at the molecular level, likely explaining why SLAMF1- cells show enhanced chemotactic responses to CXCL12. This phenotype was confirmed in primary cells, by comparing a cohorts of SLAMF1high to one of SLAMF1low patients. Gene expression profiling also indicates profound modulation of pathways connected with vesicle formation and recirculation. Consistently, cross-linking of SLAMF1 with an agonisic mAb in primary cells and in the Mec-1 cell line enhanced the generation of autophagic vesicles and their fusion with the lysosomes. Ligation of SLAMF1 with this agonistic monoclonal antibody promoted the autophagic flux, by increasing accumulation of reactive oxygen species (ROS) and inducing phosphorylation of p38, JNK1/2 and bcl-2. The direct consequence was the formation of the autophagy macro-complex containing SLAMF1, the scaffold protein beclin1 and the enzyme Vps34. In agreement with the observation that many drugs used in CLL have autophagy-mediated effects, including fludarabine and the BH3 mimetic ABT-737, SLAMF1-silenced Mec-1 cells or SLAMF1low primary CLL cells were resistant to treatment with both agents. These results indicate that SLAMF1 plays as a critical role in CLL homeostasis. Loss of SLAMF1 expression modulates genetic pathways that regulate chemotaxis and autophagy and that potentially affect drug responses, thus providing a likely explanation for the unfavorable clinical outcome experienced by this patient subset. Restoring SLAMF1 expression in CLL cells would therefore be of therapeutic value for patients with aggressive CLL. Disclosures Gaidano: Morphosys, Roche, Novartis, GlaxoSmith Kline, Amgen, Janssen, Karyopharm: Honoraria, Other: Advisory boards; Celgene: Research Funding.

Introduction: Despite mapping of the mutational landscape in patients (pts) with chronic lymphocytic leukemia (CLL), there remains limited information regarding the functional or clinical impact of less common, recurrently mutated genes. Over the past several years, the influence of high-risk mutations has been reported. With the advent of readily available next generation sequencing (NGS), physicians receive a large amount of genomic data, many times without information regarding the clinical impact of less validated, mutations. Using results from a commercially available NGS platform, we identified a relatively high prevalence of mutations in the gene, FAT1, in treatment naïve (TN) CLL pts. FAT1 encodes a protein in the cadherin superfamily, important in regulating WNT signaling, with a role in tumor suppression. Aberrant mutated FAT1 expression has been associated with acute lymphoblastic leukemias with an intermediate clinical course. Loss of protein, through chromosomal deletions has been implicated in many solid tumors and associated with tumor progression. The majority of mutations arise in the cadherin repeats, previously shown to diminish antagonism of β-catenin, allowing its nuclear localization (Morris Nat Genetics 2013). In CLL, FAT1 mutations have been demonstrated to enrich in fludarabine refractory pts (10.3%) but with a relatively low prevalence in untreated pts (1.1%) (Messina, Blood 2014). Given a high prevalence of FAT1 mutations in our database and evidence suggesting mutated FAT1 contributes to tumor evolution, we investigated the clinical impact of clonal FAT1 mutations in pts with CLL. Methods: Patients were identified for inclusion if mutational analysis was performed prior to, or within 12 months of treatment start date. Only pts treated initially with a signal transduction inhibitor (STI) were included. Treated pts were either on protocol or received their STI as standard of care. All pts underwent whole exome profiling with a lymphoid specific NGS panel, including 75 genes (Genoptix Inc.). Analysis was performed on peripheral blood or bone marrow aspirates. The primary outcome was time to first treatment (TTFT). The log-rank test was used to compare Kaplan-Meir curves. Double-sided P values Results: In total we analyzed 172 pts, 118 (69%) remain on observation, 54 (31%), have been treated at data cutoff. Nineteen (11%) pts were found to be FAT1 mutated (mFAT1) and 153 (89%) were FAT1 wild type (wtFAT1). The median time from diagnosis to mutational profiling for the cohort was 35 months (range 0-301). We identified 21 total mutations, 17 unique (82% cadherin domain, 18% EGF like region). Recurrent mutations were identified, each occurring in 2 pts (p.A636T, p.P1614L, p.R1257Q, p.R2041H). One pt had an indel and 1 pt had an inframe deletion, the remaining were missense. We found no significant differences between groups in regards to age, IGVH mutation status or co-occurrence of high-risk mutations in NOTCH1, SF3B1, TP53 or ATM. Only 17p deletions occurred significantly more in mFAT1 pts (24%) vs. wtFAT1 (7%), p=0.04, other cytogenetic abnormalities were balanced. mFAT1 pts had significantly shorter TTFT, 50 versus 143 months respectively, p=0.02. We investigated if mFAT1 status could stratify IGVH mutated pts but found no differences in TTFT. Eleven mFAT1 pts have received treatment (82% ibrutinib, 18% acalabrutinib), 8 remain on observation. All mFAT1 pts have responded. Conclusions: Given the increasing use of rapidly available NGS testing, physicians receive genomic information with limited data regarding clinical impact. We identified a higher prevalence of FAT1 mutations in TN pts, than that previously reported. FAT1 mutations associated with deletion 17p but not other high-risk genetic mutations. Recurrent FAT1 mutations were identified and commonly found in the cadherin domain. mFAT1 pts have a significantly shorter TTFT than wtFAT1 pts. When treated with novel agents, there was no difference in response rates. These findings suggest FAT1 mutations in TN pts may be more common than previously reported and identify an intermediate risk for progression. Additional studies investigating the influence of recurrent FAT1 mutations and association with 17p deletions in TN pts are warranted. Disclosures Allan: Pharmacyclics: Speakers Bureau.

BACKGROUND: Tumor cell survival critically depends on heterotypic communications with non-malignant cells in the microenvironment. Most of these signals converge on the activation of the transcription factor NF-κB that regulates complex cellular functions, including apoptosis, cell survival and proliferation. Even if NF-kB is constitutively active in most malignancies, including chronic lymphocytic leukemia (CLL), and plays a major role in tumorigenesis, there are no currently approved drugs to target it. IT901 has been recently reported as a novel NF-kB inhibitor, showing efficacy in a non-tumor context1. AIM OF THE WORK: The aim of this work is to test the efficacy of IT901 in CLL and in its more aggressive transformation, Richter syndrome (RS), which represents an unmet therapeutic need. The molecular mechanisms of action of IT901 in leukemic cells are studied, alongside its effects on cells belonging to CLL microenvironment. RESULTS: IT901 induces apoptosis in primary leukemic cells in a dose- and time-dependent manner, showing significant efficacy after 24h of treatment. The apoptotic response is independent of the prognostic subgroup. Conversely, IT901 has minimal impact upon normal B cells. Treatment of CLL cells with IT901 interferes with NF-kB transcriptional activity, resulting in a diminished binding of both p50 and p65 to DNA. Moreover, biochemical analyses indicate a diminished expression of these subunits in the nucleus, as well as of the whole NF-kB complex in the cytoplasm. At the molecular level, compromised expression of NF-kB triggers activation of the Caspase-3 apoptotic pathway, with increased expression of pro-apoptotic proteins (e.g., Bim), paralleled by a diminished expression of the anti-apoptotic ones (e.g., XIAP). Concomitantly, a prominent increase in mitochondrial ROS is evident, providing a link between IT901 effects and induction of apoptosis. Recent data reported the involvement of NF-kB as a transcriptional controller of metabolic pathways promoting oxidative phosphorylation in cancer cells. In line with NF-kB constitutive activation in CLL, dynamic measurement of the energetic profile, indicates a reliance on oxidative phosphorylation, with limited glycolytic capacity. After IT901 treatment, there is a dramatic drop in mitochondrial respiration, with compromised ATP production and a net increase in proton leak, suggesting that primary CLL cells are trying to compensate impaired respiration by shifting to glycolysis. This metabolic response is mediated at the transcriptional levels, as IT901 induces a down-modulation of the genes involved in mitochondrial respiration (e.g., ATP5A1) and a concomitant up-modulation of the ones involved in glucose uptake and lactate transport (e.g., GLUT1). The CLL microenvironment is critical for disease progression and for providing protection from drug-induced apoptosis. Therefore it is important to consider the effects of novel drugs also on non-neoplastic bystander elements. Nurse-like cells (NLC) are a population of monocyte-derived activated macrophages that nurtures CLL cells via soluble and cell contact dependent mechanisms. These interactions are known to activate NF-kB signaling in both partners. Consistently, IT901 inhibited nuclear localization of the p65 subunit in NLC and shifted their polarization towards an M1-phenotype. These results are confirmed using a xenograft model. The Mec-1 cell line was injected into NSG mice and left to engraft for 2 weeks before beginning treatment. Animals treated with IT901 are characterized by decreased tumor growth and leukemic cells diffusion compared to controls, as shown by a diminished number of leukemic cells in kidneys, liver and spleen. Finally, IT901 shows promising effects in a small cohort of leukemic cells obtained from RS patients, inducing significant apoptosis by interfering with the expression and nuclear localization of NF-kB. CONCLUSIONS: Altogether, these results indicate that IT901 blocks NF-kB transcriptional activity. This effect is followed by rapid and marked decrease in genes supporting oxidative phosphorylation, causing mitochondrial damage, ROS release and induction of intrinsic apoptosis. Moreover, IT901 interrupts the support that CLL obtains from the microenvironment. Thus, targeting NF-kB by means of IT901 may be effective for CLL, and possibly even RS patients. 1. Y. Shono et al., Cancer Res76, 377 (Jan 15, 2016). Disclosures Furman: Genentech: Consultancy; Janssen: Consultancy; Abbvie: Consultancy, Honoraria; Gilead Sciences: Consultancy; Pharmacyclics: Consultancy, Speakers Bureau.

Heterozygous mutations in several core members of the spliceosome complex have been reported in Myelodysplastic Syndromes (MDS) and Acute Myeloid Leukemia (AML). In particular high frequency SF3B1 hotspot mutations, a component of the U2 complex involved in the interaction with the branch point (BP) and recognition of the 3' splice sites (ss) during splicing, have been identified in Refractory Anemia with Ringed Sideroblasts (RARS) a subtype of MDS. Using computational analyses of RNAseq from several cancer types including RARS, we identified that SF3B1 hotspot mutations induce aberrant 3'ss selection by recognizing a cryptic AG located between 15 to 24 nucleotides upstream of the canonical AG. Experimental confirmation of these motif features was performed using minigenes in SF3B1 mutant cells. Furthermore, we discovered that SF3B1 mutant utilized a different BP from that used by SF3B1 wild-type providing novel mechanistic insights into changes in function induced by the hotspot mutations. The induction of aberrant splicing can introduce premature termination codons thus targeting mRNA for degradation by Nonsense Mediated Decay (NMD). We predicted that close to 50% of the aberrantly spliced genes would be subject to NMD and showed (using isogenic Nalm-6 cells engineered by AAV homology to express SF3B1K700E or SF3B1K700K) that several of these genes were downregulated at the transcript and protein levels. These downregulated genes/proteins might be involved in the pathogenesis of SF3B1 mutant cancers. Interestingly, pathway analysis of genes differentially expressed or aberrantly spliced in SF3B1 mutant compared to wild-type in RARS samples identified cell differentiation and epigenetics as the primary misregulated pathways. To study the impact of SF3B1 mutations on differentiation, we used the TF-1 differentiation cell model where erythroid differentiation is induced by treatment with erythropoietin (EPO). EPO treatment, as expected, induced erythroid differentiation in TF-1 cells transduced with SF3B1WT, but a block in erythroid differentiation was observed in TF-1 cells transduced with SF3B1K700E (the most common mutation in MDS and chronic lymphocytic leukemia (CLL)). Intriguingly, SF3B1G742D, which is found mutated in CLL but not MDS, did not block differentiation in this myeloid differentiation model, implying that specific SF3B1 mutations and splicing aberrations have important context dependent effects. Pathway analysis comparing SF3B1K700E vs. SF3B1WT or SF3B1G742D identified several genes involved in heme biosynthesis or downstream of GATA1 to be downregulated (such as, AHSP, ALAS2, CCL5, CD36, EPOR, GP1BB, HBB, HBE1, HBG1, PRG2) in SF3B1K700E cells only. This is consistent with the role of SF3B1K700E in RARS. In our analyses, we also identified that ABCB7 is aberrantly spliced and that the aberrant transcript is subject to NMD, causing downregulation of the canonical transcript and protein. ABCB7 is a mitochondrial transporter important in cellular iron metabolism and in heme production; moreover, partial loss of function mutation in ABCB7 has been identified in X-linked sideroblastic anemia and ataxia, demonstrating an iron overload phenotype in cells with defective ABCB7. Interestingly, when ABCB7 was knocked down in TF-1 cells we observed block in differentiation similar to that observed in SF3B1K700E cells suggesting a link between SF3B1 mutation and ABCB7 levels and impaired differentiation. Taken together, these data suggest that SF3B1 mutations induce aberrant splicing and as a consequence downregulation of several genes that contribute to the block in erythroid differentiation, one of the key biological defects observed in MDS. Disclosures Buonamici: H3 Biomedicine: Employment. Darman:H3 Biomedicine: Employment. Perino:H3 Biomedicine: Employment. Agrawal:H3 Biomedicine: Employment. Peng:H3 Biomedicine: Employment. Seiler:H3 Biomedicine: Employment. Feala:H3 Biomedicine: Employment. Bailey:H3 Biomedicine: Employment. Chan:H3 Biomedicine: Employment. Fekkes:H3 Biomedicine: Employment. Keaney:H3 Biomedicine: Employment. Kumar:H3 Biomedicine: Employment. Kunii:H3 Biomedicine: Employment. Lee:H3 Biomedicine: Employment. Mackenzie:Eisai: Employment. Matijevic:Eisai: Employment. Mizui:H3 Biomedicine: Employment. Myint:Eisai: Employment. Park:H3 Biomedicine: Employment. Pazolli:H3 Biomedicine: Employment. Thomas:H3 Biomedicine: Employment. Wang:H3 Biomedicine: Employment. Warmuth:H3 Biomedicine: Employment. Yu:H3 Biomedicine: Employment. Zhu:H3 Biomedicine: Employment. Furman:Acerta Pharma BV: Research Funding; Gilead: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Speakers Bureau. Ebert:Celgene: Consultancy; H3 Biomedicine: Consultancy; Genoptix: Consultancy, Patents & Royalties. Smith:H3 Biomedicine: Employment.