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Acalabrutinib has demonstrated significant efficacy and safety in relapsed chronic lymphocytic leukemia (CLL). Efficacy and safety of acalabrutinib monotherapy were evaluated in a treatment-naive CLL cohort of a single-arm phase 1/2 trial (ACE-CL-001). Adults were eligible for enrollment if chemotherapy was declined or deemed inappropriate due to comorbidities (N = 99). Patients had a median age of 64 years and 47% had Rai stage III/IV disease. Acalabrutinib was administered orally 200 mg once daily, or 100 mg twice daily until progression or intolerance. A total of 99 patients were treated; 57 (62%) had unmutated immunoglobulin heavy-chain variable gene, and 12 (18%) had TP53 aberrations. After median follow-up of 53 months, 85 patients remain on treatment; 14 discontinued treatment, mostly because of adverse events (AEs) (n = 6) or disease progression (n = 3). Overall response rate was 97% (90% partial response; 7% complete response), with similar outcomes among all prognostic subgroups. Because of improved trough BTK occupancy with twice-daily dosing, all patients were transitioned to 100 mg twice daily. Median duration of response (DOR) was not reached; 48-month DOR rate was 97% (95% confidence interval, 90-99). Serious AEs were reported in 38 patients (38%). AEs required discontinuation in 6 patients (6%) because of second primary cancers (n = 4) and infection (n = 2). Grade ≥3 events of special interest included infection (15%), hypertension (11%), bleeding events (3%), and atrial fibrillation (2%). Durable efficacy and long-term safety of acalabrutinib in this trial support its use in clinical management of symptomatic, untreated patients with CLL.

Purpose Intolerance is the most common reason for kinase inhibitor (KI) discontinuation in CLL. Umbralisib a novel, highly selective PI3Kδ/CK1e inhibitor, is active and well tolerated in CLL patients. This phase 2 trial evaluated umbralisib in CLL patients who are intolerant to prior BTK or PI3K inhibitor therapy. Patients and methods In this phase 2 trial (NCT02742090), umbralisib was initiated at 800 mg oral daily in CLL patients requiring therapy per investigator discretion who were intolerant to prior BTK or PI3K inhibitor therapy, until progression or toxicity. Primary endpoint was progression-free survival (PFS). Secondary endpoints included time to treatment failure and umbralisib safety profile. DNA isolated from buccal swabs was genotyped for polymorphisms in CYP3A4, CYP3A5 and CYP2D6. Results Fifty-one patients were enrolled (44 BTKi and 7 PI3Kδi intolerant). Median age was 70 years (range 48-96), median of 2 prior lines of therapy (1-7), 24% had del17p and/or TP53 mutation, and 65% were IGHV unmutated. Most common AEs leading to prior KI discontinuation were rash (27%), arthralgia (18%), and atrial fibrillation (16%). Median progression free survival (PFS) was 23.5 months (95% CI 13.1-not estimable). 58% of patients were on umbralisib for a longer duration than prior KI. Most common (≥5%) grade ≥3 AEs on umbralisib (all causality) were neutropenia (18%), leukocytosis (14%), thrombocytopenia (12%), pneumonia (12%), and diarrhea (8%). Six patients (12%) discontinued umbralisib due to an AE. Eight patients (16%) had dose reductions and were successfully re-challenged. Conclusions Umbralisib is safe and effective in this BTK and alternate PI3K inhibitor intolerant CLL population. These are the first prospective data to confirm that switching from a BTK or alternate PI3K inhibitor to umbralisib can result in durable, well tolerated responses.

Standard treatment options in classic HCL (cHCL) result in high response rates and near normal life expectancy. However, the disease itself and the recommended standard treatment are associated with profound and prolonged immunosuppression, increasing susceptibility to infections and the risk for a severe course of COVID-19. The Hairy Cell Leukemia Foundation (HCLF) has recently convened experts and discussed different clinical strategies for the management of these patients. The new recommendations adapt the 2017 consensus for the diagnosis and management with cHCL to the current COVID-19 pandemic. They underline the option of active surveillance in patients with low but stable blood counts, consider the use of targeted and non-immunosuppressive agents as first-line treatment for cHCL, and give recommendations on preventive measures against COVID-19.

The development of highly effective targeted therapies has led to a new treatment paradigm in patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL). Despite these advances, many patients will eventually require alternative treatment strategies due to the emergence of tolerability issues or resistance to these novel agents. Duvelisib is a first-in-class, potent oral agent with dual inhibitor activity against the δ and γ isoforms of phosphoinositide 3-kinase (PI3Kδ and PI3Kγ), which are specific to the hematopoietic system. Dysregulation of the PI3K/PTEN/AKT/mTOR pathway has been implicated in cancer cell growth, survival and metabolism and has been the subject of cancer drug development in recent years. Duvelisib demonstrated activity in CLL/SLL in early trials, leading to further evaluation in the Phase 3 DUO trial that compared duvelisib against ofatumumab in patients with relapsed/refractory CLL/SLL. This trial led to the Food and Drug Administration (FDA) approval for the treatment of adult patients with CLL/SLL after at least two prior lines of therapy. The major reason for therapy discontinuation is the development of serious adverse events, which include severe infections and diarrhea/colitis, precluding its widespread use. Ongoing clinical trials are evaluating duvelisib in combination strategies and with alternate dosing schedules in patients with CLL/SLL. With close monitoring, duvelisib can be a promising drug for the treatment of patients with relapsed or refractory CLL/SLL. This review summarizes the relevant clinical data from recent clinical advances in CLL and aims to interpret the duvelisib trials while exploring strategies to improve its use and adverse event management in the era of novel targeted agents.

A diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) was elicited during acute COVID‐19 infection. COVID‐19 spike proteins trigger the alternative pathway of complement. Acute SARS‐CoV‐2 infection possibly expanded an existing PIG‐A mutation.

BACKGROUND: Treatment of chronic lymphocytic leukemia (CLL) with a fixed-duration venetoclax (Ven)-based regimen is now a standard of care (SOC) option for both frontline and relapsed refractory (R/R) disease based on results of the CLL14 and MURANO trials (Fischer et al NEJM 2019, Seymour et al NEJM 2018). As fixed-duration Ven regimens are now a SOC, it is expected that an increasing number of patients (pts) will ultimately progress after Ven exposure and require additional CLL-directed therapy. While many discuss re-treatment with Ven as a subsequent treatment option, the current literature contains response data on an extremely limited number of evaluable pts (11 pts MURANO, overall response rate (ORR) 55%; 3 pts VEN 365, ORR 100%). Whether re-treatment with Ven is an acceptable option remains an important unanswered clinical question. METHODS: We conducted a multicenter, retrospective study of CLL pts treated with a Ven-based regimen (Ven1) and then re-treated with a second Ven-based regimen (Ven2) in a later line of therapy (LOT). Data were collected from 13 centers and the CLL Collaborative Study of Real-World Evidence database. CLL pts were eligible for inclusion if they were treated with a Ven-based regimen in any LOT and then re-treated with a Ven-based regimen as a later LOT. Collected data included demographics, prognostic disease characteristics, tumor lysis syndrome (TLS) risk and incidence, clinical response and reasons for treatment discontinuation (dc). The primary study endpoint was investigator-assessed ORR (CR: complete response, PR: partial response, SD: stable disease, PD: progression of disease, iwCLL 2018). Kaplan-Meier method was used to estimate progression free survival (PFS). All other analyses were descriptive. RESULTS: We identified 25 pts who were re-treated with Ven. Pt characteristics prior to treatment with Ven1 are summarized in Table 1. In 24% of pts (n=6), Ven1 was administered as part of a clinical trial. Median prior LOT was 2 (range 0-10) with 12.0% treatment naïve and 60% with prior BTKi exposure. The majority of pts had ≥1 high-risk prognostic marker: del17p (39%), TP53 mut (27%), complex karyotype ≥5 abnormalities (30%) and unmutated IGHV (84%). For Ven1, treatment regimens, TLS risk, and dose are summarized in Table 2. With a median duration of exposure of 15 months (mos) (64% pts > 12 mos) for Ven1, the ORR was 88% (CR: 48%, PR: 40%, Figure 1A). Ten pts had minimal residual disease (MRD) assessments by flow cytometry; 8 pts (80%) achieved undetectable MRD (10^-4). Most common reasons for Ven1 dc included: toxicity (28%), completion of planned therapy (24%), MD/pt preference (24%), other (12%), alloHSCT (4%) and cost (4%). There was a median of 8.7 mos (36% > 12 mos) between Ven1 and the initiation of Ven2, and 88% did not receive another LOT between Ven1 and Ven2. Reasons for Ven2 initiation were either CLL progression (87.5%) or MRD-positive relapse (12.5%). For Ven2, TLS risk, TLS incidence and dose information are outlined in Table 2. TLS was a rare event during Ven re-treatment (4.5%, lab only). For Ven2, Ven monotherapy was the most common regimen (52%). Standard Ven dose-escalation was used for re-initiation in 17 of 19 pts with available data, however 1 pt started Ven2 at 400 mg daily (no TLS) and another underwent a prolonged ramp-up period. At the time of this analysis, 18 pts had available response assessments for Ven2: ORR is 72.2% (CR: 4, PR: 9, SD: 4 and PD: 1, Figure 1B). Median time from Ven2 to progression or last follow up is 8 mos (0.2-29 mos). Median PFS has not been reached. Estimated 12-month PFS is 69.1%. For pts with a CR to Ven2, median follow up time is 14.5 mos vs 7 mos for pts with PR or SD. Of 25 pts re-treated with Ven, 68% remain on Ven2 presently and 32% have discontinued Ven2, including due to CLL progression (n=4), completion of planned therapy (n=1), unrelated death (n=1), MD/pt preference (n=1). CONCLUSIONS: To our knowledge, this is the largest reported cohort of CLL pts re-treated with Ven after a prior Ven-based regimen. The high ORR in this pt population (median 2 prior therapies) suggests that re-treatment is a promising strategy and should be considered in treatment sequencing algorithms. Notably, pts with a CR to Ven2 had a longer median follow up than those with a PR or SD, suggesting a likelihood of deeper responses with time. Given the promising ORR, further research to prospectively validate Ven re-treatment is warranted. Updated data will be presented. Disclosures Allan: Celgene, Genentech, Janssen, TG Therapeutics: Research Funding; Abbvie, Janssen, AstraZeneca, Pharmacyclics: Honoraria; Acerta, Genentech, Abbvie, Sunesis, Ascentage, Pharmacyclics, Janssen, AstraZeneca, BeiGene: Consultancy. Sail:AbbVie Inc.: Current Employment, Current equity holder in publicly-traded company. Manzoor:Abbvie: Current Employment, Other: may hold stock or stock options. Pu:Takeda Pharmaceuticals: Consultancy. Barr:Gilead: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy, Research Funding; Abbvie/Pharmacyclics: Consultancy, Research Funding; Verastem: Consultancy; Morphosys: Consultancy; TG therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; Celgene: Consultancy; Merck: Consultancy; Genentech: Consultancy. Coombs:LOXO Oncology: Honoraria; MEI Pharma: Honoraria; Abbvie: Consultancy, Honoraria; Genentech: Honoraria; AstraZeneca: Honoraria; Octapharma: Honoraria; Novartis: Honoraria. Schuster:AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria; Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding. Skarbnik:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Consultancy; Beigene: Speakers Bureau; Verastem: Speakers Bureau; Novartis: Speakers Bureau; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CLL Society: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; 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, Speakers Bureau; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rhodes:Verastem: Consultancy; Abbvie/Genentech: Consultancy; Pharmacyclics: Consultancy; AstraZeneca: Consultancy. Barrientos:Janssen: Honoraria; Sandoz: Consultancy; Oncternal Therapeutics: Research Funding; Bayer: Consultancy; Genentech: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy. Roeker:American Society of Hematology: Research Funding; Abbott Laboratories: Other: spouse with minority ownership interest ; AbbVie: Other: spouse with minority ownership interest . Leslie:Celgene: Speakers Bureau; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; KitePharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Epizyme: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; ADC therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kamdar:Roche: Research Funding. Choi:Pharmacyclics/Abbvie: Research Funding; Genentech: Consultancy. Simkovic:Abbvie: Consultancy, Other: travel expenses. Lansigan:Seattle Genetics: Consultancy; BMS: Consultancy; BMS Steering Committee for MAGNIFY Program: Membership on an entity's Board of Directors or advisory committees; Spectrum Pharma: Consultancy, Research Funding. Zelenetz:Novartis: Consultancy; Gilead: Research Funding; Janssen: Consultancy; Celgene: Consultancy; Gilead: Consultancy; Genentech/Roche: Consultancy; Roche: Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnology: Consultancy; MorphoSys: Research Funding; Amgen: Consultancy; Sandoz: Research Funding; Celgene: Research Funding; MEI Pharma: Research Funding. Moskowitz:Merck: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Miragen Therapeutics: Consultancy; Incyte: Research Funding; Merck: Consultancy; Imbrium Therapeutics, L.P.: Consultancy; Seattle Genetics: Consultancy. Goy:Morphosys: Research Funding; AbbVie: Research Funding; MD Anderson: Research Funding; Regional Cancer Care Associates/OMI: Current Employment; Infinity Verastem: Research Funding; Infinity: Research Funding; Karyopharm: Research Funding; Genentech/Roche: Research Funding; CALBG: Research Funding; Constellation: Research Funding; Bayer: Research Funding; PracticeUpdate Oncology: Consultancy; RCCA/OMI: Current Employment; Acerta: Consultancy, Honoraria, Other: leadership role, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: leadership role, Research Funding; Celgene: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: leadership role, Research Funding; COTA: Consultancy, Current equity holder in publicly-traded company, Other: leadership role; Kite, a Gilead Company: Consultancy, Current equity holder in publicly-traded company, Honoraria, Other: leadership role, Research Funding; Xcenda: Consultancy; Hackensack UMC and University of Nebraska: Research Funding. Feldman:Pfizer: Research Funding; Kyowa Kirin: Consultancy, Research Funding; Eisai: Research Funding; Cell Medica: Research Funding; Amgen: Research Funding; Pharmacyclics: Honoraria, Other, Speakers Bureau; Abbvie: Honoraria; Bayer: Consultancy, Honoraria; Trillium: Research Funding; Portola: Research Funding; Janssen: Speakers Bureau; AstraZeneca: Consultancy; Viracta: Research Funding; Rhizen: Research Funding; Corvus: Research Funding; BMS: Consultancy, Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; Celgene: Honoraria, Research Funding; Takeda: Honoraria, Other: Travel expenses; Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau. Furman:Verastem: Consultancy; Genentech: Consultancy; Beigene: Consultancy; AstraZeneca: Consultancy, Research Funding; Acerta: Consultancy; Abbvie: Consultancy; TG Therapeutics: Consultancy, Research Funding; Sunesis: Consultancy; Pharmacyclics: Consultancy; Oncotarget: Consultancy; Loxo Oncology: Consultancy; Janssen: Consultancy, Speakers Bureau; Incyte: Consultancy. Mato:Genentech: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; BeiGene: Consultancy; LOXO: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Adaptive: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding.

PURPOSE A randomized, double-blind, phase III study of idelalisib (IDELA) plus rituximab versus placebo plus rituximab in patients with relapsed chronic lymphocytic leukemia (CLL) was terminated early because of superior efficacy of the IDELA-plus-rituximab (IDELA/R) arm. Patients in either arm could then enroll in an extension study to receive IDELA monotherapy. Here, we report the long-term efficacy and safety data for IDELA-treated patients across the primary and extension studies. PATIENTS AND METHODS Patients were randomly assigned to receive rituximab in combination with either IDELA 150 mg twice daily (IDELA/R; n = 110) or placebo (placebo/R; n = 110). Key end points were progression-free survival (PFS), overall response rate (ORR), overall survival (OS), and safety. RESULTS The long-term efficacy and safety of treatment with IDELA was assessed in 110 patients who received at least one dose of IDELA in the primary study, 75 of whom enrolled in the extension study. The IDELA/R-to-IDELA group had a median PFS of 20.3 months (95% CI, 17.3 to 26.3 months) after a median follow-up time of 18 months (range, 0.3 to 67.6 months). The ORR was 85.5% (94 of 110 patients; n = 1 complete response). The median OS was 40.6 months (95% CI, 28.5 to 57.3 months) and 34.6 months (95% CI, 16.0 months to not reached) for patients randomly assigned to the IDELA/R and placebo/R groups, respectively. Prolonged exposure to IDELA increased the incidence of all-grade, grade 2, and grade 3 or greater diarrhea (46.4%, 17.3%, and 16.4%, respectively), all-grade and grade 3 or greater colitis (10.9% and 8.2%, respectively) and all-grade and grade 3 or greater pneumonitis (10.0% and 6.4%, respectively) but did not increase the incidence of elevated hepatic aminotransferases. CONCLUSION IDELA improved PFS and OS compared with rituximab alone in patients with relapsed CLL. Long-term IDELA was effective and had an expected safety profile. No new IDELA-related adverse events were identified with longer exposure.

Ibrutinib, a once-daily oral inhibitor of Bruton tyrosine kinase, has greatly improved outcomes for patients with chronic lymphocytic leukemia (CLL). The phase 3 RESONATE trial, which compared single-agent ibrutinib to ofatumumab in high-risk, relapsed patients with CLL, provided support for approval of ibrutinib in the United States and Europe. We describe long-term follow-up of patients treated in RESONATE, where continued superiority of progression-free survival (PFS) (hazard ratio [HR], 0.133; 95% confidence interval [CI], 0.099-0.178) was observed. Overall survival benefit continues (HR, 0.591; 95% CI, 0.378-0.926), although with decreased magnitude relative to that seen before crossover to ibrutinib was implemented for patients on ofatumumab (HR, 0.426; 95% CI, 0.220-0.823). Notably, overall response to ibrutinib increased over time, with 91% of patients attaining a response. The PFS benefit with ibrutinib was independent of baseline risk factors, although patients with ≥2 prior therapies had shorter PFS than those with

E1912 was a randomized phase 3 trial comparing indefinite ibrutinib plus 6 cycles of rituximab (IR) to 6 cycles of fludarabine, cyclophosphamide, and rituximab (FCR) in untreated younger patients with CLL. We describe measurable residual disease (MRD) levels in E1912 over time and correlate them with clinical outcome. Undetectable MRD rates (

The advent of novel B-cell receptor pathway targeting agents like ibrutinib dramatically changed management of B-cell malignancies. However, with concomitant anticoagulation (AC) and antiplatelet (AP) therapy, ibrutinib is associated with increased bleeding. This post hoc analysis aimed to determine the role of AC/AP therapy in patients with idelalisib-treated B-cell malignancies and to establish if it contributes to increased bleeding events. Data from two idelalisib trials (rituximab ± idelalisib in chronic lymphocytic leukemia [CLL] and idelalisib monotherapy in indolent non-Hodgkin lymphoma [iNHL]) were analyzed. Antithrombotic therapy was common (36%-63%), with comparable bleeding incidence across treatment groups (14%-19%; p = 0.56). Bleeding events of grade ≥3 occurred in 0.9% and 3.2% of the idelalisib-treated CLL and iNHL cohorts, respectively. Our findings demonstrate no increase in bleeding events with simultaneous AC/AP treatment and idelalisib use. Hemorrhagic risk is prevalent in these patients and an important consideration when evaluating available treatment options. ClinicalTrials.gov identifiers: NCT01539512 and NCT01282424.

The treatment of chronic lymphocytic leukemia (CLL) embodies one of the great success stories in translational research, with the development of therapies aimed at disrupting crucial pathways that allow for the survival and proliferation of the malignant clone. The arrival of targeted agents into our armamentarium, along with the advent of novel monoclonal antibodies that can achieve deeper remissions, has steered the field to a new treatment paradigm. Given the panoply of therapeutic options available, the question arises whether chemotherapy still has a role in the management of CLL. The novel targeted agents, which include the Bruton’s tyrosine kinase inhibitors, ibrutinib and acalabrutinib, along with the B-cell lymphoma-2 inhibitor, venetoclax, are highly effective in achieving a response with improved remission duration and survival, particularly in high-risk patients. Despite this major progress, the new agents bring a unique set of toxicities unlike those associated with cytotoxic chemotherapy. There is a paucity of head-to-head comparisons among all of the novel agents, because their approval was based on randomization against traditional chemoimmunotherapeutic regimens. Parallel to the increase in the number of available targeted agents, there has been a significant improvement in quality of life and life expectancy of the patients with a CLL diagnosis over the last decade. Our review will examine whether “chemotherapy-free” frontline treatment approaches are worth the associated risks. Our goal is to help identify optimal treatment strategies tailored to the individual by reviewing available data on monotherapy vs combination strategies, depth of response, treatment duration, and potential toxicities.

Advanced marginal zone lymphoma (MZL) is an incurable B-cell malignancy dependent on B-cell receptor signaling. The phase 2 PCYC-1121 study demonstrated the safety and efficacy of single-agent ibrutinib 560 mg/d in 63 patients with relapsed/refractory MZL treated with prior rituximab (RTX) or rituximab-based chemoimmunotherapy (RTX-CIT). We report the final analysis of PCYC-1121 with median follow-up of 33.1 months (range: 1.4-44.6). Overall response rate (ORR) was 58%; median duration of response (DOR) was 27.6 months (95% confidence interval [CI]: 12.1 to not estimable [NE]); median progression-free survival (PFS) was 15.7 months (95% CI: 12.2-30.4); and median overall survival (OS) was not reached (95% CI: NE to NE). Patients with prior RTX treatment had better outcomes (ORR: 81%; median DOR: not reached [95% CI: 12.2 to NE]; median PFS: 30.4 months [95% CI: 22.1 to NE]; median OS: not reached [95% CI: 30.3 to NE]) vs those with prior RTX-CIT treatment (ORR: 51%; DOR: 12.4 months [95% CI: 2.8 to NE]; PFS: 13.8 months [95% CI: 8.3-22.5]; OS: not reached [95% CI: NE to NE]). ORRs were 63%, 47%, and 62% for extranodal, nodal, and splenic subtypes, respectively. With up to 45 months of ibrutinib treatment, the safety profile remained consistent with prior reports. The most common grade ≥3 event was anemia (16%). Exploratory biomarker analysis showed NF-κB pathway gene mutations correlated with outcomes. Final analysis of PCYC-1121 demonstrated long-term safety and efficacy of ibrutinib in patients with relapsed/refractory MZL, regardless of prior treatment or MZL subtype. This trial was registered at www.clinicaltrials.gov as #NCT01980628.

Ibrutinib positively modulates many T-cell subsets in chronic lymphocytic leukemia (CLL). To understand ibrutinib’s effects on the broader landscape of immune cell populations, we comprehensively characterized changes in circulating counts of 21 immune blood cell subsets throughout the first year of treatment in patients with relapsed/refractory (R/R) CLL (n = 55, RESONATE) and previously untreated CLL (n = 50, RESONATE-2) compared with untreated age-matched healthy donors (n = 20). Ibrutinib normalized abnormal immune cell counts to levels similar to those of age-matched healthy donors. Ibrutinib significantly decreased pathologically high circulating B cells, regulatory T cells, effector/memory CD4+ and CD8+ T cells (including exhausted and chronically activated T cells), natural killer (NK) T cells, and myeloid-derived suppressor cells; preserved naive T cells and NK cells; and increased circulating classical monocytes. T-cell function was assessed in response to T-cell receptor stimulation in patients with R/R CLL (n = 21) compared with age-matched healthy donors (n = 18). Ibrutinib significantly restored T-cell proliferative ability, degranulation, and cytokine secretion. Over the same period, ofatumumab or chlorambucil did not confer the same spectrum of normalization as ibrutinib in multiple immune subsets. These results establish that ibrutinib has a significant and likely positive impact on circulating malignant and nonmalignant immune cells and restores healthy T-cell function.

Therapeutic targeting of Bruton tyrosine kinase (BTK) has dramatically improved survival outcomes for patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Acalabrutinib is an oral, highly selective BTK inhibitor that allows for twice-daily dosing due to its selectivity. In this phase 1b/2 study, 134 patients with relapsed/refractory CLL or SLL (median age, 66 years [range, 42-85 years]; median prior therapies, 2 [range, 1-13]) received acalabrutinib 100 mg twice daily for a median of 41 months (range, 0.2-58 months). Median trough BTK occupancy at steady state was 97%. Most adverse events (AEs) were mild or moderate, and were most commonly diarrhea (52%) and headache (51%). Grade ≥3 AEs (occurring in ≥5% of patients) were neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%), and diarrhea (5%). Atrial fibrillation and major bleeding AEs (all grades) occurred in 7% and 5% of patients, respectively. Most patients (56%) remain on treatment; the primary reasons for discontinuation were progressive disease (21%) and AEs (11%). The overall response rate, including partial response with lymphocytosis, with acalabrutinib was 94%; responses were similar regardless of genomic features (presence of del(11)(q22.3), del(17)(p13.1), complex karyotype, or immunoglobulin variable region heavy chain mutation status). Median duration of response and progression-free survival (PFS) have not been reached; the estimated 45-month PFS was 62% (95% confidence interval, 51% to 71%). BTK mutation was detected in 6 of 9 patients (67%) at relapse. This updated and expanded study confirms the efficacy, durability of response, and long-term safety of acalabrutinib, justifying its further investigation in previously untreated and treated patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443.

Increased absolute lymphocyte count (ALC) is a key feature of chronic lymphocytic leukemia (CLL) but is also observed during treatment with B-cell receptor pathway inhibitors including ibrutinib, a first-in-class inhibitor of Bruton's tyrosine kinase. In patients with CLL treated with single-agent ibrutinib in two multicenter, open-label, randomized, phase 3 studies (RESONATE-2, NCT01722487; RESONATE, NCT01578707), lymphocytosis was observed in 77 of 136 (57%) patients treated in first-line and 133 of 195 (69%) relapsed/refractory patients. On treatment, lymphocytosis resolved in 95% of patients in the first-line and 94% in the relapsed/refractory setting. The median duration of lymphocytosis was 12 and 14 weeks in the first-line and relapsed/refractory settings, respectively. Lymphocytosis is a common and predictable pharmacodynamic effect of ibrutinib treatment, and in the absence of other signs of progression, does not represent disease progression. Lymphocytosis resolves in the majority of patients and does not require interruption or discontinuation of ibrutinib therapy.

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

Phosphatidylinositol 3-kinase-delta (PI3Kδ) signaling is critical for proliferation, survival, homing, and tissue retention of malignant B cells. Idelalisib, a selective oral inhibitor of PI3Kδ, has shown considerable single-agent activity in patients with heavily pretreated chronic lymphocytic leukemia (CLL). This study evaluated the safety and clinical activity of idelalisib in combination with bendamustine (IB) or rituximab (IR) or both (IBR) in patients with relapsed or refractory (R/R) CLL. Idelalisib was given continuously at 100 or 150 mg twice daily in combination with rituximab (375 mg/m2 weekly × 8 doses), bendamustine (70 or 90 mg/m2, days 1 and 2 every 4 weeks × 6 cycles) or BR (rituximab, 375 mg/m2 every 4 weeks and bendamustine, 70 mg/m2, days 1 and 2 every 4 weeks × 6 cycles). The primary endpoint was safety; secondary endpoints included overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS). Fifty-two patients (median age 64 years) with a median of 3 prior therapies were enrolled. ORR was 84.6% (89.5% IR group, 77.8% IB group, and 86.7% IBR group). The overall median PFS was 25.6 months, and median DOR was 26.6 months. The most common grade ≥3 adverse events (≥10% of patients) were pneumonia (19.2%), diarrhea (13.5%), and febrile neutropenia (17.3%). Idelalisib-based combination therapy with bendamustine and/or rituximab was highly active, resulting in durable tumor control in patients with heavily pretreated R/R CLL. However, its tolerability profile suggests that these regimens should be used cautiously in this patient population. ClinicalTrials.gov ID: NCT01088048.

Background In a phase 3 randomized, double-blind, placebo-controlled trial, treatment with idelalisib, a phosphoinositol-3 kinase δ inhibitor, + bendamustine/rituximab improved progression-free survival (PFS) and overall survival (OS) in adult patients with relapsed/refractory chronic lymphocytic leukemia (R/R CLL). Here we report the results of health-related quality of life (HRQL) analyses from this study. Methods From June 15, 2012 to August 21, 2014, 416 patients with R/R CLL were enrolled; 207 patients were randomized to the idelalisib arm and 209 to the placebo arm. In the 416 patients randomized to receive bendamustine/rituximab and either oral idelalisib 150 mg twice-daily or placebo, HRQL was assessed at baseline and throughout the blinded part of the study using the Functional Assessment of Cancer Therapy–Leukemia (FACT-Leu) and EuroQoL Five-Dimension (EQ-5D) visual analogue scale (VAS) questionnaires. The assessments were performed at scheduled patient visits; every 4 weeks for the first 6 months from the initiation of treatment, then every 8 weeks for the next 6 months, and every 12 weeks thereafter until end of study. Least-squares mean changes from baseline were estimated using a mixed-effects model by including treatment, time, and treatment-by-time interaction, and stratification factors as fixed effects. Time to first symptom improvement was assessed by Kaplan-Meier analysis. Results In mixed-effects model analysis, idelalisib + bendamustine/rituximab treatment led to clinically meaningful improvements from baseline in leukemia-associated symptoms. Moreover, per Kaplan-Meier analysis, the proportion of patients with symptom improvement was higher and time to improvement was shorter among patients in the idelalisib-containing arm compared with those who did not receive idelalisib. The physical and social/family FACT-Leu subscale scores, along with the self-rated health assessed by EQ-VAS, showed improvement with idelalisib over placebo, but the difference did not reach statistical significance. The functional and emotional FACT-Leu subscale scores remained similar to placebo. Conclusions Addition of idelalisib to bendamustine/rituximab, apart from improving PFS and OS, had a neutral to beneficial impact on HRQL in patients with R/R CLL, particularly by reducing leukemia-specific disease symptoms. Trial registration Clinicaltrials.gov NCT01569295. Registered April 3, 2012.

Chronic lymphocytic leukemia (CLL) is the most commonly diagnosed adult leukemia in the USA and Western Europe. Kidney disease can present in patients with CLL as a manifestation of the disease process such as acute kidney injury with infiltration or with a paraneoplastic glomerular disease or as a manifestation of extra renal obstruction and tumor lysis syndrome. In the current era of novel targeted therapies, kidney disease can also present as a complication of treatment. Tumor lysis syndrome associated with novel agents such as the B-cell lymphoma 2 inhibitor venetoclax and the monoclonal antibody obinutuzumab are important nephrotoxicities associated with these agents. Here we review the various forms of kidney diseases associated with CLL and its therapies.

Chylothorax, which is defined as the presence of chyle in the pleural space, is often caused by malignancy. However, chylothorax as a result of underlying CLL is exceedingly rare in the literature. Chyle contains fat soluble vitamins and lymphocytes, meaning that its collection into the pleural space may further exacerbate the immunosupressed state of an individual with CLL. Here, we report three cases of patients with CLL who developed chylothorax, and their management. Chylothorax, although rare with CLL, should be considered in the differential diagnosis when patients with CLL present with pleural effusions, especially if recurrent. Discovery of a chylothorax may indicate the need for further treatment of CLL.

Background: The ECOG-ACRIN randomized phase 3 clinical trial E1912 established ibrutinib-rituximab (IR) as the standard of care for CLL patients Methods: Patients enrolled on E1912 completed the Functional Assessment of Cancer Therapy-General (FACT-G) and Leukemia subscale at randomization (baseline), 3, 6, and 12 months post-randomization, and every 6 months for 2 years regardless of disease status. The primary outcome was the 31-item FACT-Leukemia Trial Outcome Index (FACT-Leu TOI), calculated by summing items from the FACT-G physical wellbeing (PWB), functional well-being (FWB), and leukemia subscales (score range: 0-124). The primary endpoint was defined as the difference in FACT-Leu TOI change scores from randomization to 12 months (at response evaluation) between patients treated with continuous therapy Arm A (IR) vs time-limited therapy Arm B (FCR). Mean change scores from baseline to each time point were calculated using all cases with data at baseline and the corresponding time point. Comparisons between treatment arms were performed using two-sample t tests. Linear mixed effects models were used to estimate the trajectories of PRO scores. Results: PRO data was extracted on 3/8/2021. PRO data was provided at baseline and 12 months for 233/354 (65.8%) patients on the IR arm and 118/175 (67.4%) patients on the FCR arm. At enrollment, there were no significant differences in the baseline FACT-Leu TOI scores (mean ± SE) between the two arms: IR (93.27 ± 1.03) vs FCR (92.68 ± 1.38; p=0.73). The FACT-Leu TOI score improved from baseline to 12 months in both arms (Table 1 and Figure 1). The change scores from baseline to 12 months, the primary outcome, were not significantly different between IR (7.59 ± 1.09) vs FCR (8.22 ± 1.44; p=0.73). Change in FACT-Leu TOI from baseline to 3 months was 5.77 ± 0.77 and 4.06 ± 1.18 (p=0.22); and from baseline to 6 months was 6.87 ± 0.87 and 8.01 ± 1.44 (p=0.50) in the IR and FCR arms, respectively. After the first 6 months of treatment, the improvement in FACT-Leu TOI scores was maintained in both treatment arms. There was no significant difference in total FACT-Leu TOI score in the continuous therapy (IR) vs time-limited therapy (FCR) arms over the first 36 months post registration. Analysis of FACT subscales showed PWB improved in the IR arm (0.37 ± 0.22) and declined in the FCR arm (-0.92 ± 0.39) from baseline to 3 months (p=0.004 for difference in PWB change between arms) but there was no significant difference between the two arms for change in PWB scores from baseline to 6 and 12 months. There were no significant differences between the two arms for change in FWB and FACT-Leu subscales from baseline to 3, 6 and 12 months. Conclusions: QOL improves in CLL patients age 70 and younger when treated in the frontline setting with IR or FCR. The improvement in QOL is maintained during continuous therapy with ibrutinib and there is no significant decline in QOL over time. Given the improvement in PFS and OS with IR over FCR seen in E1912, the results of this QOL analysis support the use of frontline ibrutinib in previously untreated younger CLL patients. Acknowledgement: This study was conducted by the ECOG-ACRIN Cancer Research Group (Peter J. O'Dwyer, MD and Mitchell D. Schnall, MD, PhD, Group Co-Chairs) and supported by the National Cancer Institute of the National Institutes of Health under award numbers: U10CA180794, U10CA180820, UG1CA189863, UG1CA190140, UG1CA232760, UG1CA233180, UG1CA233230, UG1CA233253, UG1CA233277, UG1CA233290, UG1CA233339, UG1CA189859, UG1CA233332. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Figure 1 Figure 1. Disclosures Kay: Oncotracker: Membership on an entity's Board of Directors or advisory committees; CytomX Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Research Funding; Acerta Pharma: Research Funding; Behring: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Targeted Oncology: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Research Funding; Sunesis: Research Funding; Genentech: Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding. O'Brien: Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy; Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding. Coutre: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Data Safety Monitoring Committee, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta: Other: Data Safety Monitoring Committee, Research Funding. Barr: AstraZeneca: Consultancy; Gilead: Consultancy; Janssen: Consultancy; Genentech: Consultancy; Beigene: Consultancy; Bristol Meyers Squibb: Consultancy; Seattle Genetics: Consultancy; TG Therapeutics: Consultancy; Morphosys: Consultancy; Abbvie/Pharmacyclics: Consultancy. Cashen: Secura Bio, ADC Therapeutics: Consultancy. Mato: Adaptive Biotechnologies: Consultancy, Research Funding; DTRM BioPharma: Consultancy, Research Funding; Johnson and Johnson: Consultancy, Research Funding; Acerta/AstraZeneca: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; AstraZeneca: Consultancy; BeiGene: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; MSKCC: Current Employment; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Nurix: Research Funding; Janssen: Consultancy, Research Funding; Genmab: Research Funding. Erba: AbbVie Inc; Agios Pharmaceuticals Inc; Astellas; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Daiichi Sankyo Inc; Genentech, a member of the Roche Group; GlycoMimetics Inc; Incyte Corporation; Jazz Pharmaceuticals Inc; Kura Oncology; Nov: Other: Advisory Committee; AbbVie Inc: Other: Independent review committee; AbbVie Inc; Agios Pharmaceuticals Inc; ALX Oncology; Amgen Inc; Daiichi Sankyo Inc; FORMA Therapeutics; Forty Seven Inc; Gilead Sciences Inc; GlycoMimetics Inc; ImmunoGen Inc; Jazz Pharmaceuticals Inc; MacroGenics Inc; Novartis; PTC Therapeutics: Research Funding; AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau. Stone: Onconova: Consultancy; AbbVie: Consultancy; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; Jazz: Consultancy; Syros: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Research Funding; Takeda: Consultancy; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Innate: Consultancy; Janssen: Consultancy; GlaxoSmithKline: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy, Research Funding; Actinium: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Celgene: Consultancy; Macrogenics: Consultancy. Litzow: Actinium: Research Funding; Amgen: Research Funding; AbbVie: Research Funding; Pluristem: Research Funding; Jazz: Other: Advisory Board; Omeros: Other: Advisory Board; Astellas: Research Funding; Biosight: Other: Data monitoring committee. Tallman: NYU Grand Rounds: Honoraria; Kura: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Biosight: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Oncolyze: Membership on an entity's Board of Directors or advisory committees; KAHR: Membership on an entity's Board of Directors or advisory committees; Orsenix: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Rafael Pharmaceuticals: Research Funding; Glycomimetics: Research Funding; Biosight: Research Funding; Orsenix: Research Funding; Abbvie: Research Funding; Mayo Clinic: Honoraria; UC DAVIS: Honoraria; Northwell Grand Rounds: Honoraria; NYU Grand Rounds: Honoraria; Danbury Hospital Tumor Board: Honoraria; Acute Leukemia Forum: Honoraria; Miami Leukemia Symposium: Honoraria; New Orleans Cancer Symposium: Honoraria; ASH: Honoraria; NCCN: Honoraria. Shanafelt: Genentech, Pharmacyclics: Research Funding. Wagner: Eli Lilly, Johnson & Johnson: Other: Spouse, previously held individual stocks;; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Athenex Inc: Consultancy.

Background: The development of Richter Transformation (RT) in patients (pts) with chronic lymphocytic leukemia (CLL) while on targeted agents has been reported to have a median survival of 2.3-3.5 months (mo). Treatment is usually anthracycline-based combination regimens, though responses are short-lived. Phase 2 trial of combined venetoclax-REPOCH achieved a median progression free survival (PFS) of 16 mo. We studied the use of ibrutinib in combination with obinutuzumab, cyclophosphamide, doxorubicin, vincristine, and prednisone (I-OCHOP) JUN2017-SEP2018 (ClinicalTrials.gov: NCT03145480). During the conduct of the study, ibrutinib plus RCHOP in untreated diffuse large B cell lymphoma (NCT01855750) reported more treatment-emergent serious adverse events when compared to RCHOP, leading to higher rates of treatment discontinuation with toxicity more prominent in elderly pts. Since the majority of pts with CLL are elderly, enrollment was stopped. We report the outcomes of 3 participants. Methods: Informed consent was provided through IRB-approved protocol. Subjects were enrolled in an open-label phase II trial combining ibrutinib with O-CHOP. Ibrutinib 560mg was taken daily starting cycle 1 day 1 (C1D1) continuously until progression or start of new anticancer treatment. Obinutuzumab was given per prescription insert starting on C1D1 with CHOP for up to 6 cycles. Pts were allowed to discontinue study drugs to pursue allogeneic stem cell transplant (allo-SCT). Pts aged 18-80 years old with adequate organ function, Eastern Cooperative Oncology Group performance status ≤ 2, and histologically confirmed evidence of RT from CLL were eligible to participate. Prior targeted agent use was allowed until 24 hours prior to dosing. Chemo- or immuno-therapy was not allowed within 21 and 10 days of C1D1 respectively. The primary endpoint was investigator-assessed overall response rate (ORR) per revised response criteria for malignant lymphoma. Secondary outcomes included hematological improvement, PFS, overall survival (OS), and quality of life. Pts were allowed to pursue allo-SCT after achieving a response and were followed for PFS/OS. Descriptive analyses were utilized, and PFS/OS was calculated from initial treatment to death or last follow-up. Results: Three pts consented and started therapy: two women and one man with a median [range] age of 53 [36-73] years, all had high-risk disease (Figure 1). Median Cumulative Illness Rating Scale at baseline 2 [0-4]. No large cell lymphoma involved the bone marrow. All pts developed RT while on a novel agent (ibrutinib, acalabrutinib, or venetoclax monotherapy respectively). All enrolled immediately after RT diagnosis and received I-OCHOP. Participants had overall good adherence to ibrutinib therapy (mean missed doses per 28-day treatment cycle was 0.88 doses) while on trial. Two pts developed neutropenia (n=1, grade 3 and n=1, grade 4; neither febrile) that resolved by time of withdrawal from study. 2 pts had anemia (grade 1 and 2), and one participant had thrombocytopenia (grade 2), neither requiring transfusion support. All 3 pts reported fatigue (all grade 2 or less) that on average improved during treatment as assessed by FACIT questionnaire (mean Δ from baseline to end of treatment: -5). Figure 1 lists other adverse events. Of 3 enrolled pts, 2 pts achieved remission (1 complete, 1 partial) and undetectable minimal residual disease (detection sensitivity 0.01%) in the bone marrow post 4 cycles I-OCHOP and underwent allo-SCT and were followed for progression. Figures 2 and 3 show the PET responses after 2 cycles of I-OCHOP in 2 participants with bulky lymphadenopathy. Time to allo-SCT for the 2 pts was 3.7 and 3.9 mo from C1D1. After transplant, one pt relapsed with RT in the central nervous system after 20 mo and died from pneumonia 5 mo later; the other pt is alive 49.5 mo later with no evidence of disease. The third pt had rapid progression and came off study. Median PFS for the 3 pts was 23.5 mo [1.9-NR] and OS 29.1 mo [6.7-NR] as of datacut July 30, 2021. Conclusions: Despite historically poor outcomes reported after RT while on a targeted agent, ibrutinib addition to anthracycline-based regimen seemed well tolerated. Two patients achieved a rapid and deep responses irrespective of prior BTK inhibitor use and were able to pursue allo-SCT which correlated with durable PFS/OS. Figure 1 Figure 1. Disclosures Rhodes: Conquer Cancer Foundation Young Investigator Award: Other: Grant/Research Support; AbbVie, Genentech, Pharmacyclics, TG Therapeutics: Other: Consultant.

Background: Cirmtuzumab (Cirm) is a humanized monoclonal antibody that inhibits the tumor promoting activity of ROR1 and has demonstrated additive/synergistic activity with many anticancer agents, including ibrutinib (Ibr). Methods: Patients (Pts) with relapsed or refractory (RR) MCL or treatment-naïve (TN) or RR CLL were enrolled. In Part 1 (Dose Escalation), doses of Cirm IV q2wks x5 then q4wks of 2-16 mg/kg and 300 or 600 mg were examined. Safety of Cirm alone was assessed during the first 28 days, then Ibr was started at approved doses for each indication. Cirm 600 mg IV q2wks x3 then q4wks in combination with Ibr starting day 0 was chosen as the recommended dosing regimen for use in Part 2 (Expansion) and Part 3 (CLL only, Cirm/Ibr vs. Ibr). MCL Part 1 is closed, and Part 2 is open for enrollment. CLL Parts 1, 2 & 3 are closed for enrollment. Results: As of 18Jun2021 data cutoff, 28, 34 and 28 pts were treated in MCL Parts 1 & 2, CLL Parts 1 & 2, and CLL Part 3 (Cirm/Ibr (n=18) or Ibr (n=10)). In Parts 1 & 2 MCL, the median number (#) of prior systemic regimens was 1.5 (1-4) including pts relapsing after Ibr (n=4), auto-SCT (n=6), auto-SCT/allo-SCT (n=1), or auto-SCT/CAR-T (n=1). Ki-67 ≥30% and extra-nodal disease was present in 54% and 68% of pts, respectively. The median # of prior systemic regimens for CLL Parts 1 & 2 and CLL Part 3 (RR), was 2 (1-15) including auto-SCT (n=1), and 2 (1-6). Pts entered with Rai staging ≥ Grade 2 in 71% and 64%. Safety (MCL and CLL): Most frequent treatment emergent (TEAEs) (≥30%) for both MCL and CLL pts treated with Cirm/Ibr (N=80), (all grades; regardless of causality) included contusion & fatigue (both 40.0%), and diarrhea (37.5%). Most frequent (≥5%) Grade ≥3 TEAEs, regardless of causality included hypertension (10.0%), fatigue, neutropenia, pneumonia, and atrial fibrillation (all 6.3%), leukocytosis and anemia (both 5.0%). Grade ≥3 TEAEs of myelosuppression, regardless of causality, include anemia (5.0%), thrombocytopenia (1.3%), and neutropenia (6.3%). Most TEAEs in MCL or CLL pts were considered related by Investigator to Ibr alone 64% or 84% vs. Cirm alone 14.3% or 16%. Efficacy (MCL): The best response of 20 evaluable pts in Parts 1 & 2 included CR 35%, PR 45%, SD 10%, and 10% PD. At a median follow-up of 14.9 mos., the objective response rate (ORR), clinical benefit rate (CBR) and median duration of response (DOR) for overall, ≥30% Ki-67, and >1 prior systemic regimen subgroups, were 80%, 90% and (not reached) NR (95% CI: 11.9, NR), 81.8%, 81.8% and 13.8 (95% CI: 8.7, NR), and 90%, 100% and NR (95% CI: 8.7, NR). Responses occurred in all evaluable pts who received prior SCT+/- CAR-T (4CR, 2PR) or prior Ibr (2CR, 2PR). The median PFS (mPFS) for overall, pts achieving CR, and >1 prior systemic regimen subgroups were all NR with varying 95% CI: (16.5, NR), (0.03, NR), and (0.03, NR). Efficacy (CLL): The best response of 34 evaluable pts in Parts 1 & 2 included 94.1% ORR, 11.8% CR, 82.3% PR/PR-L, and 5.9% SD for a CBR of 100%. In Part 3, evaluable Cirm/Ibr TN (n=8) or RR (n=7) and Ibr TN (n=4) or RR (n=3) arms achieved 100% or 85.7% and 100% or 100% ORR, 12.5% or 0% and 0% or 0% CR, 87.5% or 85.7% and 100% or 100% PR/PR-L, 0% or 14.3% and 0% or 0% SD. No pts had PD as best response. All pts had a CBR of 100%. For Parts 1 & 2, at a median follow-up of 24.8 mos., the DOR for overall and >1 prior systemic regimen subgroups, was NR (8.3, 35.9) and NR (12.0, 29.6). In Part 3, at a median follow-up of 14.7 mos., the DOR for TN or RR Cirm/Ibr and Ibr arms is NR (7.7, 18.6) or NR (9.2, 14.8) and NR (11.2, 18.5) or NR (8.3, 14.2). The mPFS (Parts 1 & 2) for overall, pts achieving CR, and >1 prior systemic regimen subgroups were NR (9.1, 35.8), NR (95% CI: 22.5, NR), and NR (9.1, 35.2). In Part 3, mPFS for TN or RR Cirm/Ibr and Ibr arms is all NR. Conclusions: Cirm/Ibr is well-tolerated. ORR, CR, DOR, and mPFS were similar across all subgroups of MCL and CLL pts regardless of number of prior systemic regimens or poor risk factors. Striking responses were observed in patients with MCL as evidenced by a mPFS that was NR (95% CI: 16.5, NR), CR of 35%, and a DOR of NR (95% CI: 11.9, NR) within the study period. These data compare very favorably to the mPFS of 12.8 mos, CR of 20%, and a DOR of 18.6 mos., reported for Ibr alone (Rule 2017). For CLL pts treated with Cirm/Ibr, results continue to be encouraging as they mature. The study is ongoing, with MCL enrollment expanded to include Cirm + Ibr in pts who have had an inadequate response to an Ibr regimen, or who are refractory to approved BTKi agents. Figure 1 Figure 1. Disclosures Lee: Oncternal: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Seagen: Research Funding; BMS: Honoraria, Research Funding; Aptitude Health: Honoraria; Guidepoint: Honoraria; Century Therapeutics: Consultancy; Pharmacyclics: Research Funding; Janssen: Honoraria. Choi: Abbvie: Other: Institution: Research Grant/Funding; Pharmacyclics: Other: Institution: Research Grant/Funding; Oncternal: Other: Institution: Research Grant/Funding; Velosbio: Other: Institution: Research Grant/Funding; Merck: Other: Institution: Research Grant/Funding; Geron: Other: Institution: Research Grant/Funding. Siddiqi: Celgene: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kite Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Speakers Bureau; Oncternal: Research Funding; TG Therapeutics: Research Funding. Wierda: Acerta Pharma Inc.: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; AstraZeneca: Research Funding; Cyclacel: Research Funding; Karyopharm: Research Funding; Xencor: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; KITE Pharma: Research Funding; Miragen: Research Funding; Janssen: Research Funding; Gilead Sciences: Research Funding; Juno Therapeutics: Research Funding; Genentech: Research Funding; GSK/Novartis: Research Funding; Sunesis: Research Funding; Loxo Oncology, Inc.: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding. Tuscano: BMS: Research Funding; Seattle Genetics: Research Funding; Takeda: Research Funding; Acrotech: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Abbvie: Research Funding. Leslie: Abbvie: Consultancy, Honoraria; PCYC/Janssen: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Speakers Bureau; Karyopharm Therapeutics: Honoraria, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Speakers Bureau; BeiGene: Consultancy, Honoraria, Speakers Bureau; ADC Therapeutics: Consultancy; Celgene/BMS: Consultancy, Honoraria, Speakers Bureau; TG Therapeutics: Consultancy, Honoraria, Speakers Bureau; Kite, a Gilead Company: Consultancy, Honoraria, Speakers Bureau; Epizyme: Consultancy, Honoraria, Speakers Bureau; Seagen: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy. Breitmeyer: Oncternal Therapeutics: Current Employment, Membership on an entity's Board of Directors or advisory committees. Yazji: Oncternal Therapeutics: Current Employment. Wang: Oncternal Therapeutics: Current Employment. Wang: OMI: Honoraria; Moffit Cancer Center: Honoraria; Chinese Medical Association: Honoraria; Newbridge Pharmaceuticals: Honoraria; DTRM Biopharma (Cayman) Limited: Consultancy; InnoCare: Consultancy, Research Funding; Scripps: Honoraria; Mumbai Hematology Group: Honoraria; VelosBio: Consultancy, Research Funding; BioInvent: Research Funding; Hebei Cancer Prevention Federation: Honoraria; Epizyme: Consultancy, Honoraria; Anticancer Association: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Lilly: Research Funding; Physicians Education Resources (PER): Honoraria; Dava Oncology: Honoraria; Clinical Care Options: Honoraria; Molecular Templates: Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Research Funding; Acerta Pharma: Consultancy, Honoraria, Research Funding; Imedex: Honoraria; Juno: Consultancy, Research Funding; Celgene: Research Funding; Genentech: Consultancy; Loxo Oncology: Consultancy, Research Funding; Kite Pharma: Consultancy, Honoraria, Research Funding; Miltenyi Biomedicine GmbH: Consultancy, Honoraria; The First Afflicted Hospital of Zhejiang University: Honoraria; Bayer Healthcare: Consultancy; BGICS: Honoraria; CAHON: Honoraria; Oncternal: Consultancy, Research Funding; CStone: Consultancy. Jamieson: Forty Seven Inc.: Patents & Royalties. Kipps: Genentech-Roche: Consultancy; Gilead Sciences: Consultancy, Honoraria, Other, Speakers Bureau; Janssen: Consultancy, Honoraria, Other, Research Funding, Speakers Bureau; Roche: Honoraria, Other; MD Anderson Cancer Center: Research Funding; Velos: Research Funding; CRIM: Research Funding; Indy Hematology Review: Other; TG Therapeutics: Other; Verstem: Other, Speakers Bureau; University of California, San Diego: Current Employment; Pharmacyclics/AbbVie: Honoraria, Research Funding; Breast Cancer Research Foundation: Research Funding; SCOR - The Leukemia and Lymphoma Society: Research Funding; National Cancer Institute/NIH: Honoraria, Research Funding; Genentech/Roche: Honoraria; European Research Initiative on CLL (ERIC): Honoraria; Genetech: Honoraria, Other; Celgene: Consultancy, Honoraria, Other, Research Funding; Bionest Partner: Other; DAVA Pharmaceuticals: Speakers Bureau; DAVAOncology: Consultancy, Honoraria, Other; AbbVie: Consultancy, Honoraria, Other, Speakers Bureau; Oncternal Therapeutics, Inc.: Current holder of stock options in a privately-held company, Other: Stock or other ownership, Patents & Royalties: Cirmtuzumab was developed by Thomas J. Kipps in the Thomas J. Kipps laboratory and licensed by the University of California to Oncternal Therapeutics, Inc., which provided stock options and research funding to the Thomas J. Kipps laboratory., Research Funding; Moores Cancer Center: Current Employment; MedImmune Inc: Research Funding; GlaxoSmithKline: Research Funding; Gilead Sciences, Inc.: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding, Speakers Bureau; Pharmacyclics LLC, an Abbvie Company: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Celgene Corporation: Consultancy, Honoraria, Research Funding; Abbott Laboratories: Consultancy, Research Funding.

Richter's transformation (RT) is a complication of chronic lymphocytic leukemia (CLL) characterized by the development of an aggressive lymphoma, typically diffuse large B cell lymphoma (DLBCL). RT is associated with high expression of activation-induced cytidine deaminase (AID) and aberrant somatic hypermutation of non-immunoglobulin genes. Current frontline therapy of CLL, ibrutinib, eliminates AID + CLL cells and alters tissue microenvironment to Th1-biased niches; however approximately 10-20% of CLL patients develop RT upon ibrutinib treatment. In addition, ibrutinib leads to a clinical response in only ~40% of RT patients. Thus, RT remains an important unmet challenge for CLL patients and the mechanism of RT development during ibrutinib treatment is poorly understood. To determine the contributions of AID and T cells in RT development, and to understand the efficacy of ibrutinib in the treatment of RT, we first created patient-derived xenografts (PDXs) with samples from three RT patients who were refractory to (immuno)chemotherapy but had not previously received ibrutinib. In each case, the B-lymphocytes were larger in size and expressed lower levels of CD5 but higher levels of activation markers compared with the CLL cell counterpart. In PDXs, ibrutinib treatment led to significantly less RT cells in spleen with percentage of inhibition ranging from 28-60% for all three cases. Notably, AID levels were similar in RT cells residing in spleen of ibrutinib-treated and control mice. The numbers of T cells were also similar, although Th1:Th2 ratios were significantly increased by ibrutinib (control vs ibrutinib group: 33% vs 42%, P=0.01). Interestingly, the growth and survival of RT cells located in bone marrow (BM) were not affected by ibrutinib. We then investigated the efficacy of ibrutinib in the prevention and treatment of RT in a novel strain of TCL-1 mice, TCL1/Igκ-AID mice, that have AID overexpressed solely in B lymphocytes. These mice develop accelerated CLL disease, have shorter overall survival (OS), and bear increased numbers of AID signature mutations in genes that are drivers in CLL and DLBCL. First we injected primary splenocytes from a TCL1/Igκ-AID mouse (A-31) into wild-type C57BL/6 mice. A week later, mice were treated with vehicle or ibrutinib continuously for 3 weeks (N=5 per group, duplicated experiments). At the end of treatment, RT cells were found in 25% of recipients in the control group and only in 10% of ibrutinib-treated recipients. Ibrutinib-treated animals had overall smaller spleens and lymph nodes (LNs) filled with significantly less CLL or RT cells. Importantly, the balance of Th1/Th2 cytokines was also significantly changed by ibrutinib (Th1/Th2 in control vs ibrutinib: 25% vs 47%, P=0.01). However, again RT cells in BMs of treated and control animals were similar. We then repeated the experiment to determine overall survival by giving the mice vehicle or ibrutinib continuously. Compared to the TCL1/Igκ-AID (A-31) donors, recipients treated with control vehicle developed more aggressive CLL with shorter OS. However, Ibrutinib did not change the OS; both control and ibrutinib treated recipients had similar OS with all the mice developed and died from RT eventually. Finally, to determine the efficacy of ibrutinib in the treatment of RT in TCL1/Igκ-AID mice, we sorted A-31-derived RT cells collected from LNs, and injected these into C57BL/6 mice. Mice then received treatment for 3 weeks. Notably, ibrutinib did not change the numbers or sizes of LNs or spleens. The numbers of RT cells at all sites, including BM, remained the same. In both groups, the number of T cells and the Th1:Th2 were not altered by ibrutinib. In summary, our data suggest that ibrutinib is somewhat effective against primary RT cells in the spleen in PDX models but not at all in the aggressive TCL1/IgK-AID mouse model. This might be because ibrutinib does not reduce AID levels in tissue-resident RT cells. Notably, although RT cells in spleens and LNs respond to ibrutinib, those residing in BM are resistant in both PDX and TCL1/IgK-AID models. This suggests different clones or different ibrutinib-responsiveness of RT cells in primary versus secondary lymphoid tissues. Overall, these results suggest that ibrutinib does not prevent or cure RT. Additionally, TCL1/Igκ-AID mice might provide a model to study the development, prevention, and treatment of RT without the influence of prior chemo- or other therapies. Disclosures Wirtz: Abbvie: Current Employment. Szafer-Glusman: AbbVie: Current Employment, Other: Stock or other ownership.

Background. CLL-like monoclonal B-ceII lymphocytosis (MBL) is considered a requisite precursor of CLL, with 1-2% of subjects annually progressing to CLL requiring therapy. The role of immune alterations leading to and operating in MBL and controlling progression to CLL is not well characterized. Since an increased frequency of immune-related conditions associated with immune dysfunction exists prior to CLL diagnosis (Landgren et al, Br J Haematol 2007 and Blood 2007; Andersen et al, Leukemia 2020), immune alterations likely exist in MBL. We have examined the serum protein profiles of MBL and CLL in search of clues linking immune dysfunction with malignant transformation. Objectives. 1. Characterize the serum proteomic profiles of MBL individuals, IGHV-mutated CLL (M-CLL) and IGHV-unmutated CLL (U-CLL) patients, and age-matched healthy controls (HC). 2. Compare the serum proteomic profiles between the groups. 3. Assess the effect of IGHV mutation status on serum proteomic profiles in CLL. Methods. A total of 12 MBL, 12 M-CLL, 12 U-CLL and 12 age-matched HC were studied. Patients were cared for at Northwell Health, New York (n=25) and Hospital del Mar, Barcelona (n=11). All patients were treatment naive except for one U-CLL patient who was treated one year beforehand. Serum samples were collected, and their protein levels measured employing SOMAmers (modified single-stranded DNA aptamers; SomaLogic) to quantify relative levels of 1,310 proteins. P-values Results. Overall, the levels of 862 proteins differed significantly between groups: MBL vs. HC: 10 downregulated (d) and 24 upregulated (u); M-CLL vs. HC: 206d and 6u; U-CLL vs. HC: 54d and 40u; M-CLL vs. MBL: 384d and 5u; U-CLL vs. MBL: 74d and 24u; and M-CLL vs. U-CLL: 35d and 0u. IPA highlighted a role for the pro-inflammatory HMGB1 pathway in several comparisons. First, an activated HMGB1 pathway was predicted in MBL compared to HC, together with activation of phagocytes, and an inhibition of the systemic immune suppressor TGF-β. Second and consistent with the former, U-CLL patients displayed an activated HMGB1 pathway compared to HC, along with other signs of immune stimulation (activated NFkB and Th1 pathways, maturation of dendritic cells, and inhibition of TGF-β) and leukemic progression (activated progression of tumor, and leukocyte extravasation). Third and contrary to the above, the HMGB1 pathway was inhibited when comparing M-CLL to HC, in line with a global immune suppression signature (inhibited PRR, GM-CSF, FcεRI, IL1, IL8, TNF, Th1, STAT3 and NFkB pathways, in addition to inhibited cell movement, viability and activation). Notably, inhibition of immune pathways was predicted for both M-CLL and U-CLL compared to MBL (diminished TNF and IL6 signaling, and reduced cell movement), although the greatest differences were seen for M-CLL vs. MBL comparison, including blockade of the HMGB1 pathway in M-CLL. Finally, the M-CLL vs. U-CLL comparison suggested inhibited INFγ, IL2, IL3, IL4, NFkB, and decreased T lymphocyte stimulation and movement of tumor cells in M-CLL patients. Conclusions. An increased pro-inflammatory signature with involvement of the HMGB1 pathway was identified in MBL and U-CLL compared with HC, whereas the opposite was seen for M-CLL. Since MBL most often exhibit mutated IGHV (91% of cases in our cohort), these findings suggest immune stimulation as a characteristic feature in the pre-leukemic and U-CLL leukemic stage that surprisingly is not operative in M-CLL. Consistent with this, M-CLL displayed a global immune suppression (HMGB1 pathway inhibition), whereas U-CLL exhibited signs of immune stimulation (HMGB1 pathway activation) compared to HC which may relate to distinct capabilities of the two subtypes to interact with the microenvironment. Lastly, the increased inflammatory signature identified in MBL, which are mainly IGHV-mutated, was lessened in CLL, mainly in M-CLL patients. This is consistent with a decreased influence of immune imbalance and the HMGB1 pathway associated with IGHV-mutated clonal expansions. Acknowledgments. GB is supported by a grant from Fundación Alfonso Martín Escudero. Disclosures Allen: Alexon: Research Funding; Bristol Myers Squibb: Other: Equity Ownership; C4 Therapeutics: Other: Equity Ownership; Sanofi Genzyme: Membership on an entity's Board of Directors or advisory committees. Rhodes: Conquer Cancer Foundation Young Investigator Award: Other: Grant/Research Support; AbbVie, Genentech, Pharmacyclics, TG Therapeutics: Other: Consultant.

Background: Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin lymphoma (NHL) accounting for ~35% of NHL and often have a clinically indolent course. PET/CT max SUV ≥10 and high proliferative index are associated with FL at high risk for transformation to aggressive lymphoma (Schöder, 2005; Rossi, 2020). A subset of patients (pts) with low histologic grade and high proliferation index (LG-HPI) have a more aggressive clinical course with inferior overall survival (OS) compared to low grade, low proliferation index (LG-LPI) FL patients (Wang, 2005). The aim of our study was to identify outcomes for patients with LG-HPI FL at our institution. Methods: We conducted a single center, retrospective study of FL diagnosed from 1/1/2015-1/1/2021. Demographic information, diagnoses, laboratory results, medications, pathology, and radiology reports were collected from pts' electronic medical records. Pathology specimens were de-identified and retrospectively reviewed by two pathologists. Review included comprehensive evaluation of histologic grade, proliferation index by Ki-67 percentage (Ki-67%), immunohistochemical staining, and c-MYC immunohistochemical staining. Biopsies were classified as LG-LPI if Grade 1-2 and Ki-67 was Results: 152 pts were diagnosed with FL and included for analysis. Patient characteristics are summarized in Table 1. Median age at diagnosis for all pts was 65.9 years. Sixty-three pts had LG-LPI, 61 LG-HPI, and 28 HG pts. Ten pts transformed to DLBCL (2 LG-LPI, 5 LG-HPI, 3 HG). Treatment regimens included initial observation (n = 44), anti-CD20 therapy alone (n = 24), chemo-immunotherapy (n = 53), and other (n = 31). Median TTFT was 1.27 mo (range 0-115.2 mo). There was moderate correlation between SUV of biopsied lesion ≥10 and Ki-67 percentage (ROC Area 0.6175). Median PFS was longer for LG-LPI compared to LG-HPI (78.6 vs 57.8 mo, p = 0.04, HR 2.37) but not between LG-HPI and HG (57.8 vs 61.3 mo respectively, p = 0.32) (Figure 1A). Median OS was not reached in any cohort with median follow up of 29.5 mo. There was no difference in OS between LG-LPI vs LG-HPI (p = 0.53) (Figure 1B). Histologic grade, proliferation index, Ann Arbor Staging, FLIPI score, PET/CT SUV intensity (max or of biopsied lesion), presence of c-Myc staining, or initial treatment regimen were not associated with median PFS or OS in either subgroup on univariate analysis. Conclusions: In our cohort, PFS was shorter for LG-HPI compared to LG-LPI but with a similar trajectory to that of HG FL, consistent with prior reports. No differences were seen in OS between LG-HPI and LG-LPI, and no covariates of interest including histologic grade, proliferation index, Ann Arbor Staging, FLIPI score, PET/CT SUV intensity, presence of c-Myc staining, or initial treatment regimen were associated with differences in PFS or OS. Our study is limited by a short follow up time compared to prior published cohorts (29.5 vs 98.4 mo). PET/CT SUV values of ≥10 have moderate predictive value for higher proliferative disease and can aid in identifying patients with higher proliferative disease. Longer follow up is needed to determine if LG-HPI impacts OS. References: 1. SchöderH, et al. Intensity of 18fluorodeoxyglucose uptake in positron emission tomography distinguishes between indolent and aggressive non-Hodgkin's lymphoma. J Clin Oncol 2005;23:4643-51. 2. Rossi C, et al. Baseline SUVmaxis related to tumor cell proliferation and patient outcome in follicular lymphoma. Haematologica 2020;Online ahead of print. 3. Wang SA, et al. Low histologic grade follicular lymphoma with high proliferation index: morphologic and clinical features. Am J Surg Pathol2005;29:1490-6. Figure 1 Figure 1. Disclosures Allen: Sanofi Genzyme: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Other: Equity Ownership; Bristol Myers Squibb: Other: Equity Ownership; Alexon: Research Funding. Rhodes: Conquer Cancer Foundation Young Investigator Award: Other: Grant/Research Support; AbbVie, Genentech, Pharmacyclics, TG Therapeutics: Other: Consultant.

Background : Ibr, an established standard of care in CLL, is a once-daily Bruton tyrosine kinase inhibitor with significant progression-free survival (PFS) and overall survival benefit shown in multiple randomized phase 3 studies in first-line CLL. Ven, an oral BCL-2 inhibitor approved as a single agent or combined with rituximab or obinutuzumab for CLL treatment, achieves high rates of undetectable MRD (uMRD). Ibr and Ven, with distinct and complementary mechanisms of action, work synergistically to mobilize CLL cells from lymph nodes and lymphoid niches, enhance cell killing, and eliminate distinct CLL cell populations. CAPTIVATE (PCYC-1142; NCT02910583) is an international, multicenter phase 2 study evaluating first-line Ibr + Ven in 2 cohorts: MRD and Fixed-Duration (FD). Patients (pts) first received 3 cycles of Ibr followed by 12 cycles of combined Ibr + Ven. In the primary analysis of the MRD cohort, pts with Confirmed uMRD who after fixed duration treatment were randomized to placebo or continued Ibr had similar post-randomization 1-year DFS rates (95% and 100%, respectively) (Wierda, ASH 2020). Two-year post-randomization results are presented. Methods : Pts aged Results : 164 pts were enrolled. Median age was 58 years (range, 28-69). High-risk features included unmutated IGHV (60% of pts), del(17p)/TP53 mutation (20%), complex karyotype (19%), and del(11q) without del(17p) (17%). After 12 cycles of Ibr + Ven, 149 pts were randomized: Confirmed uMRD to placebo (n=43) or Ibr (n=43); without Confirmed uMRD to Ibr (n=31) or Ibr + Ven (n=32). Median overall follow-up was 38.2 mo (range, 15.0-47.9); median post-randomization follow-up was 24.0 mo (range, 5.8-33.1). In pts with Confirmed uMRD randomized to placebo versus Ibr, no new DFS events occurred since the primary analysis; 2-year DFS rates post-randomization remained unchanged at 95% (placebo) vs 100% (Ibr), for a 4.7% difference (95% CI -1.6-10.9) and overall log-rank P=0.1573 (Figure 1). In the placebo and Ibr arms post-randomization, modest improvements were observed in complete response (CR) rates, including CR with incomplete bone marrow recovery (CRi) (Figure 2). Estimated 36-mo PFS rates were 95% with placebo and 100% with Ibr. In pts without Confirmed uMRD randomized to Ibr vs Ibr + Ven, greater improvements in best uMRD rates and CR/CRi rates were observed with Ibr + Ven than with Ibr post-randomization (Figure 2). Estimated 36-mo PFS rates were 97% with both Ibr and Ibr + Ven. Median treatment duration was 36.8 mo (range, 0.5-47.9) in all pts (N=164). Modest differences in AEs were observed across treatment arms post-randomization. During the overall study period across all-treated pts, the most frequent grade 3/4 AEs were neutropenia (36%), hypertension (10%), thrombocytopenia (5%), and diarrhea (5%). With up to 48 mo of treatment, AEs led to discontinuation of Ibr or Ven in 13% of pts; no new safety signals emerged. Conclusions : First-line Ibr + Ven is an all-oral, once-daily, chemotherapy-free regimen that provides deep responses in pts with CLL. With an additional year of follow-up and no new MRD relapses, PDs or deaths in pts with confirmed uMRD, the 2-year DFS rate in the MRD-guided placebo arm remained high at 95% while 3-year PFS rates were ≥95% across all randomized treatment arms. The results in pts with Confirmed uMRD support the potential for treatment-free remission with fixed-duration treatment, including in pts with high-risk features. High rates of uMRD were achieved; the safety profile of Ibr + Ven was consistent with known safety profile for each agent. Figure 1 Figure 1. Disclosures Ghia: Acerta/AstraZeneca: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding; ArQule/MSD: Consultancy, Honoraria; BeiGene: Consultancy, Honoraria; Celgene/Juno/BMS: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Sunesis: Research Funding; Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Research Funding. Allan: Celegene: Research Funding; AstraZeneca Pharmaceuticals LP, Genentech, a member of the Roche Group, Janssen Biotech Inc, TG Therapeutics Inc.: Research Funding; AbbVie: Consultancy, Honoraria; BeiGene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria; Genentech: Consultancy, Research Funding; TG Therapeutics: Research Funding; Epizyme: Consultancy; AbbVie Inc, AstraZeneca Pharmaceuticals LP, BeiGene, Janssen Biotech Inc, Pharmacyclics LLC: Consultancy; AbbVie Inc, Ascentage Pharma, Epizyme, Genentech, a member of the Roche Group, Janssen Biotech Inc, Pharmacyclics LLC: Other: Advisory Committee. Siddiqi: Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Juno therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: 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; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Other: DSM Member, Speakers Bureau; PCYC: Speakers Bureau; Jannsen: Speakers Bureau; Dava Oncology: Honoraria; ResearchToPractice: Honoraria. Kipps: Janssen: Consultancy, Honoraria, Other, Research Funding, Speakers Bureau; Roche: Honoraria, Other; MD Anderson Cancer Center: Research Funding; Velos: Research Funding; CRIM: Research Funding; Indy Hematology Review: Other; TG Therapeutics: Other; Verstem: Other, Speakers Bureau; University of California, San Diego: Current Employment; Pharmacyclics/AbbVie: Honoraria, Research Funding; Breast Cancer Research Foundation: Research Funding; SCOR - The Leukemia and Lymphoma Society: Research Funding; National Cancer Institute/NIH: Honoraria, Research Funding; Genentech/Roche: Honoraria; European Research Initiative on CLL (ERIC): Honoraria; Bionest Partner: Other; Celgene: Consultancy, Honoraria, Other, Research Funding; Genetech: Honoraria, Other; Genentech-Roche: Consultancy; Gilead Sciences: Consultancy, Honoraria, Other, Speakers Bureau; DAVA Pharmaceuticals: Speakers Bureau; DAVAOncology: Consultancy, Honoraria, Other; AbbVie: Consultancy, Honoraria, Other, Speakers Bureau; Oncternal Therapeutics, Inc.: Current holder of stock options in a privately-held company, Other: Stock or other ownership, Patents & Royalties: Cirmtuzumab was developed by Thomas J. Kipps in the Thomas J. Kipps laboratory and licensed by the University of California to Oncternal Therapeutics, Inc., which provided stock options and research funding to the Thomas J. Kipps laboratory., Research Funding; Moores Cancer Center: Current Employment; MedImmune Inc: Research Funding; GlaxoSmithKline: Research Funding; Gilead Sciences, Inc.: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding, Speakers Bureau; Pharmacyclics LLC, an Abbvie Company: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Celgene Corporation: Consultancy, Honoraria, Research Funding; Abbott Laboratories: Consultancy, Research Funding. Kuss: Commonwealth Serum Laboratories: Other: Stock or other ownership; AbbVie: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Kyowa Kirin: Consultancy, Honoraria; Mundipharma: Consultancy, Honoraria; Roche Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Janssen: Speakers Bureau. Opat: AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sandoz: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; CSL: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Monash Health: Current Employment; BeiGene: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GIlead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding. Flinn: Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Badoux: Janssen: Honoraria; AbbVie: Honoraria, Other: Travel, Accommodations, Expenses. Tedeschi: Beigene: Honoraria, Speakers Bureau; AstraZeneca: Honoraria, Speakers Bureau; AbbVie: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau. Gonzalez-Barca: Kiowa: Consultancy, Speakers Bureau; Eusapharma: Consultancy; Janssen: Consultancy, Other: Travel, Accommodations, Expenses, Speakers Bureau; Takeda: Speakers Bureau; Roche: Other: Travel, Accommodations, Expenses; AbbVie: Other: Travel, Accommodations, Expenses, Speakers Bureau. Pagel: Pharmacyclics/AbbVie: Consultancy; Gilead: Consultancy; Actinium Pharmaceuticals: Consultancy; Kite, a Gilead Company: Consultancy; BeiGene: Consultancy; Epizyme: Consultancy; MEI Pharma: Consultancy; AstraZeneca: Consultancy; Incyte/MorphoSys: Consultancy. Jacobs: AstraZeneca: Consultancy, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding, Speakers Bureau; ADC Therapeutics: Consultancy; Adaptive Biotechnologies: Consultancy; MEI Pharma: Research Funding; TeneoBio: Research Funding; SecuraBio: Consultancy, Speakers Bureau; Verastem: Consultancy; TG Therapeutics: Research Funding, Speakers Bureau; Jannsen: Speakers Bureau; Genentech: Consultancy; AbbVie: Consultancy, Speakers Bureau. Szafer-Glusman: AbbVie: Current Employment, Other: Stock or other ownership. Zhou: AbbVie: Current Employment, Other: Stock and other ownership. Ninomoto: AbbVie: Current Employment, Other: Stock or other ownership. Dean: Pharmacyclics: Current Employment, Other: Stock or other ownership; AbbVie: Other: Stock Ownership. Tam: Pharmacyclics: Honoraria; BeiGene: Consultancy, Honoraria; Loxo: Consultancy; AbbVie: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Novartis: Honoraria. Wierda: Janssen: Research Funding; AstraZeneca: Research Funding; GSK/Novartis: Research Funding; Acerta Pharma Inc.: Research Funding; Karyopharm: Research Funding; Xencor: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Loxo Oncology, Inc.: Research Funding; Genentech: Research Funding; Sunesis: Research Funding; Miragen: Research Funding; Cyclacel: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Juno Therapeutics: Research Funding; Gilead Sciences: Research Funding; KITE Pharma: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding. OffLabel Disclosure: Ibrutinib in combination with venetoclax is not approved in any indication.

Introduction: The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a transmembrane protein that is overexpressed in multiple cancers, including hematological malignancies. Zilovertamab vedotin (MK-2140) is an antibody -drug conjugate comprising a humanized IgG1 monoclonal antibody, a proteolytically cleavable linker, and the antimicrotubule cytotoxic agent monomethyl auristatin E (MMAE). Preclinical evidence demonstrated the cytotoxicity of zilovertamab vedotin in hematologic cell lines. This first human phase 1 dose escalation study (NCT03833180) evaluated the safety and efficacy of zilovertamab vedotin at various doses in patients with relapsed/refractory hematologic malignancies. Methods: Eligible patients aged ≥18 years with an Eastern Cooperative Oncology Group Performance Status of 0-2 and histological diagnosis of chronic lymphocytic leukemia/small lymphocytic leukemia, lymphoplasmacytic lymphoma/Waldenström macroglobulinemia, acute lymphoid leukemia, acute myeloid leukemia, or non-Hodgkin lymphoma (NHL; mantle cell lymphoma [MCL], follicular lymphoma, marginal zone lymphoma, diffuse large B-cell lymphoma [DLBCL], Richter transformation, Burkitt lymphoma, and T-cell-NHL) were enrolled. Participants received zilovertamab vedotin intravenously at starting doses of 0.50 mg/kg (up to 2.5 mg/kg) on day 1 every 3 weeks (Q3W) (Schedule 1), 1.0 mg/kg (planned up to 2.25 mg/kg) on day 1 and 8 Q3W (Schedule 2), or 1.0 mg/kg (planned up to 2.25 mg/kg) on days 1, 8, and 15 Q4W (Schedule 3) using an accelerated plus 3+3 dose escalation design. The primary end point was determination of the maximum tolerated dose (MTD). Secondary end points included safety, objective response rate (ORR), and duration of response (DOR). We present data for participants with NHL enrolled in Schedule 1. Results: A total of 51 patients were enrolled in Schedule 1 (starting dose 0.5 [n=1], 1.00 [n=3], 1.50 [n=3], 2.00 [n=3], 2.25 [n=11], or 2.50 [n=30] mg/kg) as of the data cutoff of May 18, 2021. Median (range) age of patients was 70 (44-91) years, 54.9% of patients were male, 49.0% had an ECOG PS of 0, and 41/51 (80%) were diagnosed with NHL; 13/51 (25.5%) were diagnosed with DLBCL and 17/51 (33.3%) were diagnosed with MCL. Enrollment in Schedules 2 and 3 is currently ongoing. The MTD for Schedule 1 was determined to be 2.5 mg/kg. Any-cause adverse events (AEs) occurred in 48 patients (94.1%), most commonly (≥30%) nausea (45.1%), fatigue (45.1%), peripheral neuropathy (41.2%), diarrhea (37.3%), dizziness (35.3%), and neutrophil count decrease (33.3%). Grade ≥3 AEs occurred in 33 (64.7%) patients, most commonly (≥5%) neutrophil count decrease (29.4%), hemoglobin decrease (15.7%), febrile neutropenia (7.8%), peripheral neuropathy (7.8%), platelet count decrease (7.8%), diarrhea (5.9%), lipase increase (5.9%), and pneumonia (5.9%). One patient died due to acute respiratory failure; however, it was not considered treatment-related by the investigator. A total of 7 (13.7%) patients permanently discontinued due to an AE and 18 (35.3%) had treatment interrupted or reduced due to an AE. Treatment-related AEs occurred in 36 patients (70.6%), most commonly (≥20%) peripheral neuropathy (41.2%), fatigue (37.3%), neutrophil count decrease (29.4%), nausea (27.5%), and diarrhea (21.6%); 24 patients (47.1%) experienced a grade ≥3 treatment-related AE. For Schedule 1, ORR was 36.6% (15/41 [95% CI: 22.1%-53.1%]) among all participants with NHL, with 5 having a complete response (CR) and 10 having a partial response (PR). ORR was 38.5% (95% CI: 13.9%-68.4%) for the 13 patients in the NHL group who had DLBCL; 3 patients had a CR and 2 patients had a PR. ORR was 52.9% (95% CI: 27.8%-77.0%) for the 17 patients in the NHL group who had MCL; 2 patients had a CR and 7 patients had a PR. Median (range) DOR was 7.8 months (2.1-17.6+ months) among all participants in Schedule 1 with NHL who achieved a response. Conclusion: These data suggest that targeting the ROR1 pathway with zilovertamab vedotin is associated with a tolerable safety profile and promising antitumor activity in patients with relapsed/refractory NHL. Disclosures Wang: Anticancer Association: Honoraria; Dava Oncology: Honoraria; BioInvent: Research Funding; Bayer Healthcare: Consultancy; Hebei Cancer Prevention Federation: Honoraria; Lilly: Research Funding; Scripps: Honoraria; Kite Pharma: Consultancy, Honoraria, Research Funding; Juno: Consultancy, Research Funding; CAHON: Honoraria; InnoCare: Consultancy, Research Funding; Molecular Templates: Research Funding; Pharmacyclics: Consultancy, Research Funding; Oncternal: Consultancy, Research Funding; Miltenyi Biomedicine GmbH: Consultancy, Honoraria; Genentech: Consultancy; Newbridge Pharmaceuticals: Honoraria; VelosBio: Consultancy, Research Funding; Celgene: Research Funding; Physicians Education Resources (PER): Honoraria; The First Afflicted Hospital of Zhejiang University: Honoraria; OMI: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Loxo Oncology: Consultancy, Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; DTRM Biopharma (Cayman) Limited: Consultancy; Chinese Medical Association: Honoraria; AstraZeneca: Consultancy, Honoraria, Research Funding; Clinical Care Options: Honoraria; Mumbai Hematology Group: Honoraria; Moffit Cancer Center: Honoraria; BGICS: Honoraria; CStone: Consultancy; Imedex: Honoraria; Epizyme: Consultancy, Honoraria; Acerta Pharma: Consultancy, Honoraria, Research Funding. Mei: Janssen: Honoraria; EUSA: Honoraria; Sanofi-Genzyme: Honoraria; Morphosys: Honoraria; TG Therapeutics: Other: Institution: Research Grant/Funding; Epizyme: Other: Institution: Research Grant/Funding; BMS: Other: Institution: Research Grant/Funding; Beigene: Other: Institution: Research Grant/Funding; Incyte: Other: Institution: Research Grant/Funding. Barr: Beigene: Consultancy; Gilead: Consultancy; Morphosys: Consultancy; TG Therapeutics: Consultancy; AstraZeneca: Consultancy; Genentech: Consultancy; Janssen: Consultancy; Abbvie/Pharmacyclics: Consultancy; Bristol Meyers Squibb: Consultancy; Seattle Genetics: Consultancy. Furman: Acerta/AstraZeneca: Consultancy; Janssen: Consultancy, Honoraria; Beigene: Consultancy; Genentech: Consultancy; Incyte: Consultancy; Loxo Oncology: Consultancy; Abbvie: Consultancy, Honoraria, Other: Expert testimony; AstraZeneca: Honoraria; Sunesis: Consultancy; Oncotracker: Consultancy; Pharmacyclics: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy; Morphosys: Consultancy; Sanofi: Consultancy; X4 Pharmaceuticals: Consultancy. Patel: TG Therapeutics: Consultancy, Speakers Bureau; Abbvie: Consultancy; Sunesis Pharmaceuticals: Research Funding; Juno Pharmaceuticals: Consultancy; MEI Pharma: Consultancy, Research Funding; Kite: Consultancy, Research Funding, Speakers Bureau; Millenium/Takeda: Research Funding; Pharmacyclics/Janssen: Consultancy, Research Funding, Speakers Bureau; Morphosys: Consultancy; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Genentech/Roche: Consultancy, Research Funding, Speakers Bureau; Trillium Therapeutics: Research Funding; BeiGene: Consultancy; Aptevo Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Xencor: Research Funding; Velos Bio: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Curis, Inc: Research Funding; Celgene: Consultancy, Research Funding, Speakers Bureau. Thompson: AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Janssen: Consultancy, Honoraria; Gilead: Other: Institution: Advisory/Consultancy, Honoraria; Amgen: Other: Institution: Honoraria, Research Grant/Funding. Choi: Abbvie: Other: Institution: Research Grant/Funding; Pharmacyclics: Other: Institution: Research Grant/Funding; Oncternal: Other: Institution: Research Grant/Funding; Velosbio: Other: Institution: Research Grant/Funding; Merck: Other: Institution: Research Grant/Funding; Geron: Other: Institution: Research Grant/Funding. Zhu: Merck & Co., Inc.: Current Employment. Chakraborty: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Marinello: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Spurgeon: Ionis: Other: Institution: Research Grant/Funding; Gilead Sciences: Other: Institution: Research Grant/Funding; Bristol Myers Squibb: Other: Institution: Research Grant/Funding; BeiGene: Other: Institution: Research Grant/Funding; AstraZeneca: Other: Institution: Research Grant/Funding; Acerta Pharma: Other: Institution: Research Grant/Funding; Pharmacyclics: Consultancy; Janssen: Consultancy, Other: Institution: Research Grant/Funding; Genentech: Consultancy, Other: Institution: Research Grant/Funding; Karyopharm: Consultancy; Velos Bio: Consultancy, Other: Institution: Research Grant/Funding; Merck & Co., Inc.: Other: Institution: Research Grant/Funding; Fred Hutchinson Cancer Research Center: Other: Data Safety Monitoring Board.

Objective: To evaluate how treatment regimens in informCLL aligned with NCCN Guidelines®-recommended regimens for CLL/SLL. Patients: Patients receiving approved CLL treatment were categorized by del(17p)/TP53 mutation status, line of therapy, and age/comorbidity. Significant comorbidities (SC) were defined as Charlson Comorbidity Index (CCI) ≥3. Age/comorbidity groups for patients without del(17p)/TP53mut: frail (≥65 years)+SC; elderly (≥65) without SC or younger ( Results: In informCLL (N=1462; previously untreated [1L], 58%; relapsed/refractory [R/R], 42%), community-based practices enrolled 93%. Median age: 71 years (34–95); median CCI: 1.0 (0–11); CCI ≥3: 16%. 27% of patients (n=389) had del(17p)/TP53mut data available. 59%–64% with del(17p)/TP53mut and 68%–100% without del(17p)/TP53mut received NCCN-recommended regimens. For patients with del(17p)/TP53mut, 62% 1L and 44% R/R received recommended category-2A ibrutinib; 24% 1L and 21% R/R had non-recommended CIT (BR/FCR). For patients without del(17p)/TP53mut and frail+SC, 60% 1L had category-1 ibrutinib or obinutuzumab+chlorambucil, but 24% received non-recommended BR; all R/R patients had category-1 ibrutinib or idelalisib+rituximab. For patients without del(17p)/TP53mut and elderly/younger+SC, 69% 1L and 58% R/R patients had category-1 ibrutinib or category-2A BR. For patients without del(17p)/TP53mut and younger without SC, 87% 1L and 82% R/R had BR (category-2A), FCR (1L: category-1; R/R: category-2A), or ibrutinib (1L: category-2A; R/R: category-1). For patients without del(17p)/TP53mut data available (73%, n=1073), ibrutinib (44%), CIT (32%), and anti-CD20 monotherapy (14%) were the most common regimens. Conclusions: Of patients with del(17p)/TP53mut, one-third received non-NCCN-recommended regimens. Given most patients in informCLL lacked del(17p)/TP53mut data and may have received suboptimal therapy, there is a need for awareness of guidelines recommendations to better inform treatment decisions. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma V.2.2017 - February 21, 2017. © National Comprehensive Cancer Network, Inc. 2017. All rights reserved. Accessed 08/08/2017. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use, or application and disclaims any responsibility for their application or use in any way.

Introduction: Cirmtuzumab (Cirm) is a high-affinity humanized monoclonal antibody designed to inhibit the tumor promoting activity of ROR1. In this study, we examined the safety and efficacy of Cirm in combination with ibrutinib (Ibr) in patients (pts) with MCL or CLL. ROR1 is an onco-embryonic tyrosine kinase-like receptor that is found at high levels on the cell surface of many hematologic and solid cancers. Activation of ROR1 by binding its ligands such as Wnt5a results in increased intracellular signaling, tumor growth and survival, enhanced cancer cell stemness and epithelial mesenchymal transition. Methods: Pts with relapsed or refractory (RR) MCL or treatment naïve (TN) or RR CLL were enrolled and treated in separate groups. In Part 1 Dose Escalation (DE), groups of MCL and CLL pts received Cirm IV q2wks x5 doses then q4wks at assigned doses of 2-16 mg/kg, and in CLL, additional fixed dose levels of 300 or 600 mg were evaluated. The safety and PK of single-agent Cirm was assessed during the first 28 days, and then Ibr was started at 560 mg/day PO for MCL or 420 mg/day PO for CLL. After reviewing the safety and PK data from Part 1, a recommended regimen of fixed dose Cirm 600 mg IV q2wks x3 then q4wks plus Ibr starting D0 was chosen for use in Parts 2 and 3. In Part 3, CLL pts (only) were randomized to either Cirm/Ibr vs. Ibr alone Results: As of April 30, 2020, 12 evaluable MCL pts were enrolled into Part 1 DE. Of these pts, 83% (10) had received ≥ 2 separate prior treatment regimens. In CLL, 34 pts (12 TN and 22 RR pts) enrolled into Part 1 DE (n= 18) or Part 2 Expansion (n= 16). At least 79% of CLL pts in Parts 1 and 2 were high risk as determined by unmutated IGHV, del17p, and/or del11q. Safety: For both MCL and CLL, the most common adverse events (AEs) considered at least possibly related to Cirm alone were grade 1/2 (e.g. fatigue, 6%) with no dose limiting toxicities or discontinuations. The combination of Cirm plus Ibr was well tolerated, with no new or accentuated AEs compared to the known safety profile of Ibr alone. Cirm may be lowering the rates of certain AEs normally seen with Ibr; for example, neutropenic events were 8 mos after stopping all therapy. At a median follow-up of 12.8 mos, 100% of CLL pts were free of disease progression and 82% remained on study. CLL cells collected after the first 28 days of treatment showed a decrease in stemness signature (Choi et al, Cell Stem Cell 2019), with similar reductions seen with single agent Cirm or Cirm + Ibr. Additional pts have been enrolled into Part 2 Expansion MCL and into Part 3 CLL. Early data from these arms are not yet available and will be reported later. Conclusions: Cirmtuzumab in combination with ibrutinib is a well-tolerated and active regimen for RR MCL and TN or RR CLL. The 58% CR/CMR rate for MCL compares favorably to published data with single agent Ibr of 27% (Rule, et al. Haematologica 2019) and it is encouraging that responses occurred in heavily pretreated pts, including those with high Ki-67 expression. In CLL, the high ORR and interim PFS are encouraging; the significance of these observations will be determined with longer follow-up. These data support the continued investigation of this regimen in ROR1-expressing hematologic and solid malignancies. This study is ongoing, and due to the high CR rate in MCL pts, the number of pts to be enrolled in the Part 2 Expansion will be increased to further characterize the safety and efficacy of this combination. Disclosures Lee: Bristol-Myers Squibb: Consultancy, Research Funding; Aptitude Health: Speakers Bureau; Celgene: Research Funding; Guidepoint Blogal: Consultancy; Oncternal Therapeutics: Research Funding; Seattle Genetics: Research Funding; Takeda: Research Funding. Choi:Pharmacyclics/Abbvie: Research Funding; Genentech: Consultancy. Siddiqi:Juno Therapeutics, Pharmacyclics LLC, an AbbVie Company, AstraZeneca, Celgene, Kite Pharma, and BeiGene: Consultancy; Pharmacyclics LLC, an AbbVie Company, Seattle Genetics, Janssen, and AstraZeneca: Speakers Bureau; BeiGene: Other: DMC member; AstraZeneca: Other: Travel/accommodations/expenses; Astrazenca: Membership on an entity's Board of Directors or advisory committees; PCYC: Membership on an entity's Board of Directors or advisory committees; Juno: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics LLC, an AbbVie Company, Juno Therapeutics, KITE Pharma, AstraZeneca, TG Therapeutics, Celgene, Oncternal, and BeiGene: Research Funding. Barrientos:Oncternal Therapeutics: Research Funding; Gilead: Consultancy; AstraZeneca: Consultancy; Bayer: Consultancy; Sandoz: Consultancy; Janssen: Honoraria; Genentech: Consultancy. Lamanna:Octapharma: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bei-Gene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Institutional research grants, Research Funding; Celgene: 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: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Institutional research grants, Research Funding; Juno: Other: Institutional research grants, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; MingSight: Other: Institutional research grants, Research Funding; Oncternal, Verastem, TG Therapeutics: Other: Institutional research grants, Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Institutional research grants, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Institutional research grants, Research Funding; Columbia University Medical Center: Current Employment; Loxo: Research Funding. Tuscano:Abbvie: Research Funding; Pharmacyclics: Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria; Seattle Genetics: Honoraria; Novartis: Research Funding; Spectrum: Research Funding; Takeda: Research Funding; Genentech: Research Funding. Leslie:KitePharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Epizyme: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Speakers Bureau; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; ADC therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; BeiGene: Honoraria, Speakers Bureau; Celgene: Speakers Bureau; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Ianopulos:Oncternal Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Breitmeyer:Oncternal Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Hsu:Oncternal Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company; Immune Design: Ended employment in the past 24 months. Wang:Beijing Medical Award Foundation: Honoraria; Lu Daopei Medical Group: Honoraria; MoreHealth: Consultancy; OMI: Honoraria, Other: Travel, accommodation, expenses; Targeted Oncology: Honoraria; Loxo Oncology: Consultancy, Research Funding; Pulse Biosciences: Consultancy; Kite Pharma: Consultancy, Other: Travel, accommodation, expenses, Research Funding; Juno: Consultancy, Research Funding; BioInvent: Research Funding; VelosBio: Research Funding; Acerta Pharma: Research Funding; InnoCare: Consultancy; Oncternal: Consultancy, Research Funding; Nobel Insights: Consultancy; Guidepoint Global: Consultancy; Dava Oncology: Honoraria; Verastem: Research Funding; Molecular Templates: Research Funding; OncLive: Honoraria; Celgene: Consultancy, Other: Travel, accommodation, expenses, Research Funding; AstraZeneca: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding. Jamieson:Bristol-Myers Squibb: Other; Forty Seven Inc: Patents & Royalties. Kipps:VelosBio: Research Funding; Pharmacyclics/ AbbVie, Breast Cancer Research Foundation, MD Anderson Cancer Center, Oncternal Therapeutics, Inc., Specialized Center of Research (SCOR) - The Leukemia and Lymphoma Society (LLS), California Institute for Regenerative Medicine (CIRM): Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Research Funding; Ascerta/AstraZeneca, Celgene, Genentech/F. Hoffmann-La Roche, Gilead, Janssen, Loxo Oncology, Octernal Therapeutics, Pharmacyclics/AbbVie, TG Therapeutics, VelosBio, and Verastem: Membership on an entity's Board of Directors or advisory committees; Oncternal Therapeutics, Inc.: Other: Cirmtuzumab was developed by Thomas J. Kipps in the Thomas J. Kipps laboratory and licensed by the University of California to Oncternal Therapeutics, Inc., which provided stock options and research funding to the Thomas J. Kipps laboratory, Research Funding.

Background: Treatment options, together with guidelines, for pts with CLL have evolved and expanded with the introduction of novel agents. The informCLLTM registry is the largest US-based prospective, observational registry of pts who received treatment for CLL/SLL in the post-novel agent era. This prospective real-world registry is uniquely positioned to examine the impact of the dynamic treatment landscape, treatment practices, and outcomes in routine clinical setting. Here we present baseline characteristics, prognostic biomarker testing, and treatment patterns for the fully enrolled pt population. Methods: From Oct 2015 to June 2019, informCLL (PCYC-1134; NCT02582879) enrolled eligible pts with CLL/SLL who were ≥18 years (y), initiated FDA-approved treatment for CLL/SLL within ±45 days of enrollment and provided consent. Pts were classified into 5 groups based on treatment received at enrollment (index): ibrutinib (single agent or combination), chemoimmunotherapy (CIT), chemotherapy (CT), immunotherapy (IT), and other novel agents. Descriptive analyses are presented. Results: The registry fully enrolled with 1461 pts: 855 (59%) previously untreated and 606 (41%) relapsed/refractory (R/R) pts. Community-based practices enrolled 93% of pts. The median age was 71 y (33% ≥75 y), the majority were male (64%), and 88% had ECOG performance status of 0/1. For pts with staging performed at enrollment (n=852), 51% had Rai stage III/IV. Median (range) time from diagnosis to initial treatment on study was 18.6 months (mos, FISH testing was performed in 28% (n=415) of pts and was more frequent in previously untreated vs R/R pts (33% vs 21%). TP53 mutation testing was performed in 11% (n=162) of pts (previously untreated: 13%; R/R: 9%). IGHV mutational status testing was performed in 12% (n=171) of pts (previously untreated: 13%; R/R 10%). Of pts with prognostic biomarker testing, 24% (100/415) had del(17p), 27% (43/162) had TP53 mutation, and 71% (121/171) had unmutated IGHV. Prognostic biomarker testing by treatment group is shown in Figure 1. Table 1 shows the distribution of pts receiving different treatments on study. Across lines of therapy, the most common treatment was ibrutinib (46%); the majority (87%) started ibrutinib treatment at the recommended daily dose of 420 mg, and pts continuing ibrutinib therapy largely did not require dose modifications (75%). At 12 or 24 mos, 77% (307/401) and 68% (126/184) of pts continued on ibrutinib treatment, respectively. For pts who completed the most common CIT regimens (bendamustine + rituximab [BR] and fludarabine + cyclophosphamide + rituximab), 80% and 85%, respectively, received Conclusions: The informCLL registry provides an opportunity to prospectively assess CLL treatment patterns in the era of novel agents. The most common index treatment was ibrutinib and the majority of ibrutinib-treated pts remained on therapy at 2 y follow-up; CIT (primarily BR) was also used for one-third of patients. Prognostic biomarker testing rates were poor, especially for TP53 and IGHV mutational status. Data from informCLL also indicate a 'knowledge gap' in terms of prognostic marker testing and selection of therapies for pts with high-risk disease. Data from the now complete pt population and with continued follow up will allow for the ongoing evaluation of real-world treatment decisions and pt care that cannot be addressed by data from randomized clinical trials. Disclosures Mato: Janssen: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Genentech: Consultancy, Research Funding; BeiGene: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; LOXO: Consultancy, Research Funding. Barrientos:Janssen: Honoraria; Oncternal Therapeutics: Research Funding; Sandoz: Consultancy; Gilead: Consultancy; Genentech: Consultancy; Bayer: Consultancy; AstraZeneca: Consultancy. Sharman:AbbVie: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; BeiGene: Research Funding; Bristol Meyers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Acerta: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding. Brander:BeiGene: Other, Research Funding; MEI Pharma: Other, Research Funding; DTRM: Other, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ArQule: Consultancy, Other, Research Funding; Pfizer: Consultancy, Other; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Other, Research Funding; AstraZeneca: Consultancy, Honoraria, Other, Research Funding; Ascentage: Other, Research Funding; Teva: Consultancy, Honoraria; Tolero: Research Funding; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Verastem: Consultancy, Honoraria, Other, Research Funding; NCCN: Other; Novartis: Consultancy, Other; NCCN: Other; Genentech: Consultancy, Honoraria, Other, Research Funding; Juno/Celgene/BMS: Other, Research Funding; Novartis: Consultancy, Other; Teva: Consultancy, Honoraria; Tolero: Research Funding. Kadish:Bluebird Bio: Current equity holder in publicly-traded company; Blueprint Medicines: Current equity holder in publicly-traded company; Teva Pharmaceutical: Current equity holder in publicly-traded company; Bristol-Myers Squibb: Current equity holder in publicly-traded company; Editas Medicine: Current equity holder in publicly-traded company; Johnson & Johnson: Current equity holder in publicly-traded company; Sarepta Therapeutics: Current equity holder in publicly-traded company; AbbVie: Current equity holder in publicly-traded company; Agios: Current equity holder in publicly-traded company; Celgene: Current equity holder in publicly-traded company, Speakers Bureau; Takeda: Speakers Bureau. Arango-Hisijara:Bristol-Myers Squibb: Current equity holder in publicly-traded company; AbbVie: Current equity holder in publicly-traded company; Pharmacyclics LLC, an AbbVie Company: Current Employment. Upasani:AbbVie: Current equity holder in publicly-traded company; Pharmacyclics LLC, an AbbVie Company: Current Employment; Protagonist Therapeutics: Current Employment. Han:Johnson and Johnson: Current equity holder in publicly-traded company; Janssen: Current Employment, Other: Travel expenses. Huang:Janssen Scientific Affairs, LLC: Current Employment; Johnson & Johnson: Current equity holder in publicly-traded company. Iyengar:Express Scripts: Patents & Royalties; AbbVie: Current equity holder in publicly-traded company; Pharmacyclics LLC, an AbbVie Company: Current Employment. Ghosh:Karyopharm: Consultancy; Genmab: Consultancy, Speakers Bureau; SGN: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau; Juno/Celgene/Bristol-Myers Squibb: Consultancy, Research Funding; Janssen: Consultancy, Research Funding, Speakers Bureau; Forty Seven Inc: Consultancy, Other: Research Bureau, Research Funding; Celgene/Bristol-Myers Squibb: Speakers Bureau; AbbVie: Speakers Bureau; AstraZeneca: Speakers Bureau; TG Therapeutics: Consultancy, Research Funding; Roche/Genentech: Research Funding.

Introduction: Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal protein that is physiologically expressed during embryogenesis, largely disappears by birth, but can be reexpressed pathologically in transformed tissues of many hematological and solid cancers. VLS-101 is an antibody-drug conjugate (ADC) comprising a rapidly internalizing, humanized monoclonal antibody (UC-961) that recognizes extracellular ROR1, a cleavable linker, and the anti-microtubule cytotoxin, monomethyl auristatin E (MMAE). Methods: This first-in-human, Phase 1 study evaluated the safety, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and efficacy of VLS-101 in patients unselected for tumor ROR1 expression who had previously treated chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), or Richter transformation lymphoma (RTL). VLS-101 was infused over 30 min every 3 wk until cancer progression or intolerable toxicity. After accrual of 1 patient at the first dose level, cohorts were enrolled by 3+3 dose escalation with additional patients accrued and intrapatient dose escalation permitted to refine estimates of maximum tolerated dose and recommended dosing regimen (RDR). Results: 32 patients were enrolled, including 19 males and 13 females with median (range) ages of 70 (54-84) ys; ECOG performance status (n) of 0 (18), 1 (10), or 2 (4); and tumor types (n) of MCL (15), CLL (7), DLBCL (5), FL (3), MZL (1), and RTL (1). Patients had received a median (range) of 4 (1-24) prior systemic therapies including hematopoietic stem cell transplantation (5) and/or chimeric antigen receptor (CAR)-T or -natural killer (NK) cells (6). Among patients with MCL, 15/15 (100%) had received a Bruton tyrosine kinase inhibitor (BTKi), 13/15 (87%) discontinued the BTKi due to progressive disease, and 2/15 (13%) discontinued for atrial fibrillation after 15.6 or 68.5 months of BTKi therapy. Patients (n) by VLS-101 starting dose were 0.5 (1), 1.0 (3), 1.5 (3), 2.25 (11), and 2.5 (14) mg/kg. With intrapatient dose escalation, many patients (n) received a maximum of 2.25 mg/kg (12) or 2.5 mg/kg (17) during VLS-101 therapy (range: 1 to 13 cycles). Cycle 1 DLTs (n/N) by mg/kg dose level were 0.5 (0/1), 1.0 (0/3), 1.5 (0/3), 2.25 (1/11 [9%] Gr 4 neutropenia), and 2.5 (2/14 [14%]; one Gr 4 neutropenia; one Gr 3 diarrhea of uncertain cause). Gr 4 neutropenia occurred in 9/32 (28%) patients; 1/32 (3%) had neutropenic fever. Granulocyte colony-stimulating factor successfully ameliorated neutropenia. Baseline Gr 1 neuropathy was present in 10/32 (31%) patients. On-study reversible Gr 3 neuropathy occurred in 3/32 (9%) patients; no Gr 4 neuropathy occurred. Except for Gr ≤2 alopecia in 3/32 (9%) patients, other adverse events were not obviously drug-related. Considering all 175 infusions administered, drug-related infusion reactions, vomiting, tumor lysis syndrome, rash, hepatic or renal abnormalities, or QT prolongation were not observed. PK showed changes in ADC and MMAE exposures proportional with VLS-101 dose and a mean ADC half-life of ~2.5 d. PD indicated exposure-dependent ROR1 occupancy on circulating CLL cells. No neutralizing anti-drug antibodies were detected. Objective tumor responses were not seen in patients with other tumor types but were observed in 7/15 (47%) of patients with MCL (4 partial; 3 complete) and in 4/5 (80%) of patients with DLBCL (2 partial; 2 complete). From start of therapy, 6/7 patients with responding MCL have responses ongoing at 35, 38, 45, 47, 50, and 58 wk and 2/4 patients with responding DLBCL have responses ongoing at 23 and 47 wk of follow-up. Conclusions: In heavily pretreated patients, VLS-101 infusions were well tolerated and demonstrated a predictable safety profile consistent with an MMAE-containing ADC. Tumor selectivity was confirmed, with no evidence of ROR1-mediated toxicities or non-MMAE toxicities that would suggest normal tissue binding. Considering all data, the VLS-101 RDR was 2.5 mg/kg every 3 wk. Efficacy results provide clinical proof of concept for targeting ROR1 with VLS-101 and demonstrate durable objective responses in patients with advanced MCL or DLBCL, including those with prior BTKi or cellular therapies. Phase 1-2 studies of VLS-101 monotherapy and combination therapy in patients with hematological cancers and solid tumors are planned. Figure Disclosures Wang: Nobel Insights: Consultancy; Lu Daopei Medical Group: Honoraria; Oncternal: Consultancy, Research Funding; MoreHealth: Consultancy; Juno: Consultancy, Research Funding; Loxo Oncology: Consultancy, Research Funding; Acerta Pharma: Research Funding; InnoCare: Consultancy; OncLive: Honoraria; Guidepoint Global: Consultancy; VelosBio: Research Funding; Pulse Biosciences: Consultancy; Kite Pharma: Consultancy, Other: Travel, accommodation, expenses, Research Funding; Beijing Medical Award Foundation: Honoraria; Pharmacyclics: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; OMI: Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Other: Travel, accommodation, expenses, Research Funding; BioInvent: Research Funding; Molecular Templates: Research Funding; Verastem: Research Funding; Dava Oncology: Honoraria; AstraZeneca: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Targeted Oncology: Honoraria. Barrientos:Gilead: Consultancy; Genentech: Consultancy; Bayer: Consultancy; Oncternal Therapeutics: Research Funding; Sandoz: Consultancy; Janssen: Honoraria; AstraZeneca: Consultancy. Furman:Verastem: Consultancy; Incyte: Consultancy; Janssen: Consultancy, Speakers Bureau; Loxo Oncology: Consultancy; Oncotarget: Consultancy; Pharmacyclics: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy, Research Funding; Acerta: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy, Research Funding; Beigene: Consultancy; Genentech: Consultancy. Mei:Sanofi: Consultancy; Morphosys: Membership on an entity's Board of Directors or advisory committees. Barr:AstraZeneca: Consultancy, Research Funding; Verastem: Consultancy; Abbvie/Pharmacyclics: Consultancy, Research Funding; Merck: Consultancy; Morphosys: Consultancy; Gilead: Consultancy; Seattle Genetics: Consultancy; TG therapeutics: Consultancy, Research Funding; Celgene: Consultancy; Janssen: Consultancy; Genentech: Consultancy. Choi:Genentech: Consultancy; Pharmacyclics/Abbvie: Research Funding. de Vos:Bayer: Consultancy; Verastem: Consultancy. Patel:Celgene/BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; BeiGene: Consultancy; Kite: Consultancy; Janssen: Consultancy, Speakers Bureau; Genentech: Consultancy, Speakers Bureau; Adaptive Biotechnologies: Consultancy; Pharmacyclics: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau. Rule:Janssen: Consultancy; Kite: Consultancy; Pharmacyclics: Consultancy. Flanders:VelosBio: Current Employment, Current equity holder in private company. Jessen:VelosBio: Current Employment, Current equity holder in private company; eFFECTOR: Current equity holder in private company. Riebling:VelosBio: Current Employment, Current equity holder in private company. Graham:Ce3: Current Employment. King:Ce3: Current Employment; VelosBio: Consultancy; AI Therapeutics: Consultancy. Schmidt:VelosBio: Current Employment, Current equity holder in private company; Gilead Sciences: Current equity holder in publicly-traded company. Lannutti:VelosBio: Current Employment, Current equity holder in private company; Gilead Sciences: Current equity holder in publicly-traded company. Johnson:Zentalis: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Current equity holder in publicly-traded company; Neoleukin: Current equity holder in publicly-traded company; Oncternal: Divested equity in a private or publicly-traded company in the past 24 months; Appelis: Divested equity in a private or publicly-traded company in the past 24 months; Acerta: Patents & Royalties; VelosBio: Current Employment, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Miller:Cleveland BioLabs: Consultancy, Current equity holder in publicly-traded company; Gilead Sciences: Current equity holder in publicly-traded company; Cancer Genetics: Current equity holder in publicly-traded company; Incuron: Consultancy; Zentalis: Consultancy, Current equity holder in publicly-traded company; AbbVie: Current equity holder in publicly-traded company; EpiThany: Current equity holder in private company; AstraZeneca: Current equity holder in publicly-traded company; VelosBio: Consultancy, Current Employment, Current equity holder in private company; AI Therapeutics: Consultancy, Current equity holder in private company; Catalys Pacific: Consultancy. Spurgeon:Cardinal Health: Honoraria; VelosBio: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy; Bristol-Myers Squibb: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Acerta: Research Funding; AstraZeneca: Research Funding; Genmab: Research Funding; Beigene: Research Funding; Verastem: Research Funding.

7556 Background: Cirmtuzumab (Cirm) is a humanized monoclonal antibody that inhibits the tumor promoting activity of ROR1 and had demonstrated additive/synergistic activity with many anti-cancer agents including ibrutinib (Ibr). Methods: Patients (Pts) with relapsed or refractory (RR) MCL or treatment naïve (TN) or RR CLL were enrolled. In Part 1 (Dose Escalation), doses of Cirm IV q2wks x5 then q4wks of 2-16 mg/kg and 300 or 600 mg were examined. Safety of Cirm alone was assessed during the first 28 days, then Ibr was started at approved doses for each indication. Cirm 600 mg IV q2wks x3 then q4wks in combination with Ibr starting day 0 was chosen as the recommended dosing regimen for use in Part 2 (Expansion) and Part 3 (CLL only, Cirm/Ibr vs. Ibr alone). Results: Twelve evaluable MCL pts were enrolled into Part 1, and 5 into Part 2. Median number of prior regimens was 2 (1-5), including pts relapsing after Ibr (4), auto-SCT (3), auto-SCT/ allo-SCT (1), auto-SCT/CAR-T (1). In CLL, 34 evaluable pts (12 TN and 22 RR) enrolled into Part 1 (18) or Part 2 (16). At least 74% of CLL pts in Parts 1 and 2 were high risk as determined by unmutated IGHV, del17p, and/or del11q. In Part 3, 22 evaluable pts received Cirm/Ibr (15) or Ibr (7). As of the 30OCT2020 safety cut-off for MCL and CLL, common TEAEs (all grades) included diarrhea (41%), contusion (39%), fatigue (39%), URI (31%), hypertension (25%) arthralgia (23%). Grade ≥3 neutropenia was 13% and thrombocytopenia 1%. There were no Cirm dose reductions or discontinuations for toxicity. Overall, Cirm did not appear to negatively impact the safety of Ibr. Efficacy (MCL): As of the 02FEB2021 efficacy cutoff, the best response of 17 evaluable pts in Parts 1 and 2 included an objective response rate (ORR) of 82%, 41% CR/CMR, 41% PR, 12% SD, and 6% PD. CR/CMR remain durable from 8-28+ mos. Most responses occurred rapidly after ̃3 mos of Cirm/Ibr. Notably, responses were achieved in all pts who received prior SCT+/- CAR-T (4CR, 1PR) or prior Ibr (2CR, 2PR). At a median follow-up of 14.6 mos, the median PFS (mPFS) had not been reached (NR) (95% CI: 17.5, NA). Efficacy (CLL): The best response of 34 evaluable pts in Parts 1 and 2 included 91% ORR, 3% CR, 88% PR/PR-L, 9% SD, 0% PD. In Part 3, both arms achieved 100% ORR (all PRs). At a median follow-up of 20.2 mos, the mPFS was NR (95% CI: NA, NA), and the PFS estimate at 24 months was 95% for R/R, and 87% for TN, respectively, for evaluable CLL pts receiving Cirm/Ibr. Conclusions: Cirm/Ibr is a well-tolerated, active regimen in both MCL and CLL. For MCL, the mPFS of NR (95% CI: 17.5, NA) and CRR (41%), with all CRs remaining without PD, compare favorably to mPFS of 12.8 mos (95% CI 8.5-16.6) and CRR (20%) reported for single agent Ibr (Rule 2017). For CLL, the high ORR and PFS are encouraging, particularly for RR CLL. The study is ongoing, with MCL enrollment expanded to study Cirm + Ibr in pts who have had a suboptimal response to an Ibr regimen, or who have failed other approved BTKi agents. Clinical trial information: NCT03088878.

Ibrutinib, an oral inhibitor of Bruton's tyrosine kinase (BTK), at a once-daily dose of 420 mg achieved BTK active-site occupancy in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) that was maintained at 24 hours. It is unknown if intermittent interruption of ibrutinib therapy contributes to altered clinical outcomes. We therefore evaluated the effect of ibrutinib dose adherence on patient outcomes in the phase 3 RESONATE trial. The overall mean dose intensity (DI) was 95% with median treatment duration of similar to 9 months. Pharmacokinetic assessment of ibrutinib exposure at 420-mg dose suggested similar exposure regardless of patient weight or age. As assessed by independent review committee, patients with higher DI experienced longer median progression-free survival (PFS) compared with those with lower DI regardless of del17p and/or TP53 status. Of 79 patients requiring a drug hold, treatment was restarted at the original dose in 73 (92%) patients. Mean duration of a missed-dose event was 18.7 days (range, 8-56). Patients missing >= 8 consecutive days of ibrutinib had a shorter median PFS vs those missing

To the editor: Ibrutinib, approved by the US Food and Drug Administration (FDA), is an inhibitor of Bruton tyrosine kinase (BTK).[1][1][⇓][2][⇓][3][⇓][4]-[5][5] Ibrutinib use is associated with atrial fibrillation (AF), with an incidence of 5% to 6% after 18 months on therapy[4][4][⇓][5]-[6

Marginal zone lymphoma (MZL) is a heterogeneous B-cell malignancy for which no standard treatment exists. MZL is frequently linked to chronic infection, which may induce B-cell receptor (BCR) signaling, resulting in aberrant B-cell survival and proliferation. We conducted a multicenter, open-label, phase 2 study to evaluate the efficacy and safety of ibrutinib in previously treated MZL. Patients with histologically confirmed MZL of all subtypes who received ≥1 prior therapy with an anti-CD20 antibody–containing regimen were treated with 560 mg ibrutinib orally once daily until progression or unacceptable toxicity. The primary end point was independent review committee–assessed overall response rate (ORR) by 2007 International Working Group criteria. Among 63 enrolled patients, median age was 66 years (range, 30-92). Median number of prior systemic therapies was 2 (range, 1-9), and 63% received ≥1 prior chemoimmunotherapy. In 60 evaluable patients, ORR was 48% (95% confidence interval [CI], 35-62). With median follow-up of 19.4 months, median duration of response was not reached (95% CI, 16.7 to not estimable), and median progression-free survival was 14.2 months (95% CI, 8.3 to not estimable). Grade ≥3 adverse events (AEs; >5%) included anemia, pneumonia, and fatigue. Serious AEs of any grade occurred in 44%, with grade 3-4 pneumonia being the most common (8%). Rates of discontinuation and dose reductions due to AEs were 17% and 10%, respectively. Single-agent ibrutinib induced durable responses with a favorable benefit–risk profile in patients with previously treated MZL, confirming the role of BCR signaling in this malignancy. As the only approved therapy, ibrutinib provides a treatment option without chemotherapy for MZL. This study is registered at www.clinicaltrials.gov as #NCT01980628.

Idelalisib, a first-in-class oral inhibitor of phosphatidylinositol-3-kinase δ, has shown considerable antitumor activity as a monotherapy in recurrent indolent non-Hodgkin lymphoma (iNHL). To evaluate the safety and activity of idelalisib in combination with immunotherapy, chemotherapy, or both, 79 patients with relapsed/refractory iNHL were enrolled based on investigator preference in 3 treatment groups. Patients received continuous idelalisib in combination with (1) rituximab (IR; 375 mg/m2 weekly × 8 doses), (2) bendamustine (IB; 90 mg/m2 per day × 2, for 6 cycles), or (3) both bendamustine and rituximab at aforementioned doses (IBR; monthly × 6 cycles). Patients had a median age of 61 years, a median of 3 prior therapies, and 46% had refractory disease. The overall response rate was 75% (22% complete response) for IR, 88% (36%) for IB, and 79% (43%) for IBR. The median progression-free survival was 37.1 months overall: 29.7 months for IR, 32.8 for IB, and 37.1 months for IBR. The median duration of response was 28.6 months in the IR group and has not been reached in the IB and IBR groups. The most common grade ≥3 adverse events and laboratory abnormalities were neutropenia (41%), pneumonia (19%), transaminase elevations (16%), diarrhea/colitis (15%), and rash (9%). The safety and efficacy reflected in these early data, however, stand in contrast with later observations of significant toxicity in subsequent phase 3 trials in frontline chronic lymphocytic leukemia and less heavily pretreated iNHL patients. Our findings highlight the limitations of phase 1 trial data in the assessment of new regimens. This trial was registered at www.clinicaltrials.gov as #NCT01088048 (an extension study was registered at www.clinicaltrials.gov as #NCT01090414).

informCLL is the first United States-based registry of patients with chronic lymphocytic leukemia that initiated enrollment after approval of novel targeted agents. Prognostic/predictive testing rates and chronic lymphocytic leukemia treatment selection with availability of novel agents have not been previously investigated in clinical practice. Results from this interim analysis demonstrate that prognostic/predictive testing was infrequently used to guide treatment selection, potentially inhibiting beneficial outcomes for patients. Introduction: The therapeutic landscape for chronic lymphocytic leukemia (CLL) has significantly shifted with the approval of novel agents. Understanding current prognostic testing and treatment practices in this new era is critical. Beginning enrollment in 2015, informCLL is the first United States-based real-world, prospective, observational registry that initiated enrollment after approval of novel agents. Patients and Methods: Eligible patients were age ≥ 18 years, started CLL treatment within 30 days of enrollment, and provided consent. For this planned interim analysis, treatments were classified into 5 groups: ibrutinib, chemoimmunotherapy, chemotherapy, immunotherapy, and other novel agents. Results: Frequency of prognostic testing and treatment patterns are reported among 840 patients (459 previously untreated; 381 relapsed/refractory), enrolled largely (96%) from community practice settings. Testing for chromosomal abnormalities by fluorescence in situ hybridization, TP53 mutation, or IGHV mutation status occurred infrequently among all patients (31%, 11%, and 11%, respectively). Chemoimmunotherapy was the most common treatment in previously untreated patients (42%), whereas ibrutinib was the most common treatment among relapsed/ refractory patients (51%). Of patients who tested positive for del(17p) or TP53 mutation, 34% and 26% received chemoimmunotherapy, respectively. Among patients who did not have fluorescence in situ hybridization or TP53 mutation testing prior to enrollment, 33% and 32% received chemoimmunotherapy, respectively. Conclusion: Our findings indicate that prognostic testing rates were poor, and approximately one-third of high-risk patients (del[17p] and TP53) received chemoimmunotherapy, which is not aligned with current CLL treatment recommendations. This represents an opportunity to educate and alert health care professionals about the necessity of prognostic testing to guide optimal CLL treatment decisions.

The treatment landscape for chronic lymphocytic leukemia (CLL) is rapidly evolving, with multiple agents recently approved. They include a glycoengineered monoclonal antibody (obinutuzumab), B-cell receptor signaling inhibitors (ibrutinib, idelalisib, and duvelisib), and the BCL-2 inhibitor (venetoclax). These compounds are dramatically changing the natural course of the disease. Nonetheless, despite improved survival rates, particularly in higher-risk disease (older adults, patients with unmutated IGHV, del(11q), and del(17p)/ TP53 mutated), there is still room for progress. Given the panoply of highly effective therapies commercially available, it is important to define a tailored treatment strategy for this heterogeneous condition that considers balance of treatment efficacy versus toxicity or tolerance. This article summarizes the most promising clinical advances by reviewing the data from recent clinical trials and discussing meaningful clinical endpoints, including the role of minimal residual disease assessment. The recent development of therapies targeting dysregulated pathways is revolutionary and may ultimately lead us to not only achieve prolonged remission durations but also envision the possibility of a functional cure for a larger population of patients.

A pooled analysis of 1238 patients with chronic lymphocytic leukemia/small lymphocytic lymphoma from three phase 3 studies found that genomic risk factors were not associated with shorter progression-free survival (PFS) or overall survival for patients treated with ibrutinib. Ibrutinib-treated patients with del(11q) were found to have a longer PFS than those without del(11q). These results suggest less prognostic relevance for certain genomic risk factors with ibrutinib treatment. Background: Certain genomic features, such as del(11q), expression of unmutated immunoglobulin heavy-chain variable region (IGHV) gene, or complex karyotype, predict poorer outcomes to chemotherapy in patients with chronic lymphocytic leukemia (CLL). Patients and Methods: We examined the pooled long-term follow-up data from PCYC-1115 (RESONATE-2), PCYC-1112 (RESONATE), and CLL3001 (HELIOS), comprising a total of 1238 subjects, to determine the prognostic significance of these markers in patients treated with ibrutinib. Results: With a median follow-up of 47 months, ibrutinib-treated patients had longer progression-free survival (PFS) than patients treated in the comparator arm, regardless of genomic risk factors. Among patients treated with ibrutinib, we found that high-risk genomic features were not associated with shorter PFS (63-75% across all subgroups at 42 months) or overall survival (79-83% across all subgroups at 42 months). Surprisingly, we observed that ibrutinib-treated patients with del(11q) actually had a significantly longer PFS than ibrutinib-treated patients without del(11q) (42-month PFS rate 70% vs. 65%, P = .02). Conclusion: These analyses not only demonstrate that genomic risk factors previously associated with poor outcomes lose their adverse prognostic significance but also that del(11q) can be associated with a superior PFS with ibrutinib therapy.

In the phase III study RESONATE, ibrutinib reduced the risk of progression and improved overall survival versus ofatumumab in previously treated patients with CLL/SLL. In this novel analysis of patient well-being including patient-reported outcomes, ibrutinib reduced disease burden while preserving parameters of hematologic and immunologic function in RESONATE. These results suggest that ibrutinib can improve quality of life while prolonging survival. Background: Ibrutinib compared with ofatumumab significantly improves progression-free and overall survival in patients with previously treated chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Patients and Methods: Measures of well-being were assessed in RESONATE, where previously treated patients with CLL/SLL were randomized to receive ibrutinib 420 mg/day (n = 195) or ofatumumab (n = 196) for up to 24 weeks. Endpoints included hematologic function, Functional Assessment of Chronic Illness TherapyeFatigue (FACIT-F), disease-related symptoms, European Organization for Research and Treatment of Cancer Quality of Life Questionnaires Core 30 (EORTC QLQ-C30), and medical resource utilization. Results: With up to 24 months' follow-up (median, 16.4 months), 79% of cytopenic patients showed sustained hematologic improvement (82% with improved platelet count, 69% with improved hemoglobin) on ibrutinib versus 43% on ofatumumab (P = 3 hypertension occurred in 6%, grade >= 3 atrial fibrillation in 4%, major hemorrhage in 2%, and tumor lysis syndrome in 1% of patients. Conclusion: Ibrutinib led to significant improvements in hematologic function and disease symptomatology versus ofatumumab, and can restore quality of life while prolonging survival in relapsed/refractory CLL/SLL. (C) 2018 The Authors. Published by Elsevier Inc.

Context Understanding clinical characteristics and treatment selection for elderly patients is essential in the era of novel agents. informCLL ( NCT02582879 , September 2015 initiation) is an ongoing, US-based, prospective, real-world observational registry of patients with CLL. Objective To characterize overall demographics of previously untreated elderly CLL patients and compare clinical factors and treatment choice of those aged 65-74 years (Group 1) versus ≥75 years (Group 2). Design/Patients An interim analysis (November 2018 data cut) of previously untreated patients from the informCLL registry who were aged ≥65 years and received single-agent ibrutinib, chemoimmunotherapy, or immunotherapy at enrollment. Association between age groups and treatment choice was assessed by multinomial logistic regression after adjusting for comprehensive demographic and clinical factors. Results Analysis included 449 elderly patients (Group 1: 238; Group 2: 211); median age was 74 years. Most patients were male (64.1%), white (92.4%), treated in community settings (94.9%), and Medicare/Medicaid-insured (88.4%). Median time from initial diagnosis to first treatment was 2.0 years. The majority had an Eastern Cooperative Oncology Group (ECOG) score ≤ 1 (87.1%) and Charlson Comorbidity Index (CCI) score ≤ 1 (62.0%). The most common comorbidities were hypertension (69.3%), other cardiovascular disorders (29.2%), non-CLL malignancies (26.3%), and connective tissue diseases (24.5%). Documented cytogenetic/molecular testing rates were low: TP53, 6.01%; IGHV, 5.35%; CLL FISH, 17.8%; any of the three, 18.7%. 202 (45.0%) patients received ibrutinib, 170 (37.9%) received chemoimmunotherapy, and 77 (17.1%) received immunotherapy. Group 2 (vs Group 1) had poorer performance status (ECOG scores ≥2, 12.9% vs 5.7%, p=0.01), more comorbidities (CCI scores ≥2, 45.5% vs 31.1%, p Conclusions Previously untreated real-world CLL patients aged ≥75 years (vs 65-74 years) had poorer performance status, more comorbidities, lower cytogenetic/molecular testing rates, and a higher likelihood of receiving ibrutinib versus chemoimmunotherapy as initial treatment.

8036 Background: ROR1 is an onco-embryonic tyrosine kinase receptor that is re-expressed at high levels on many hematologic and solid cancers but not on normal adult tissues. ROR1 binds Wnt5a, resulting in increased tumor growth and survival, cancer cell stemness and epithelial mesenchymal transition. Cirmtuzumab (Cirm) is a humanized monoclonal antibody designed to inhibit the tumor promoting activity of ROR1. In this study, we examined the safety and efficacy of Cirm in combination with ibrutinib (Ibr) in MCL or CLL. Methods: As of Jan 29, 2020, 12 pts with relapsed refractory (RR) MCL were enrolled into Part 1 Dose Escalation (DE). All MCL pts had stage 3/ 4 at original diagnosis, 25% had bulky tumor at study entry, 58% had intermediate/high risk MIPI scores and the majority (83%) had ≥ 2 prior regimens. 34 pts with CLL [12 treatment naïve (TN) and 22 RR pts] enrolled into Part 1 DE (n = 18) or Part 2 Expansion (n = 16). At least 79% of CLL pts were high risk as determined by unmutated IGHV, 17p/p53 loss, and/or del 11q. DE pts received Cirm IV q2wks x 3-5 doses then q4wks plus Ibr (starting D28). Following DE, Cirm 600mg IV q2wks x3 then q4wks plus Ibr (420mg/day CLL or 560mg/day MCL) was chosen for Expansion. Results: Safety : only grade 1/ 2 AEs were reported as possibly related to Cirm alone, whereas the safety profile attributed to Ibr or Ibr / Cirm was similar to published data, with no new or unexpected events. Efficacy for MCL: 83% ORR, 33% (4) CR, 50% (6) PR, 17% (2) SD. CRs were achieved at a median of 3.6 mos in heavily pretreated pts, including 2 with bulky disease > 5cm. Prior therapy of the 4 CR pts: 2 pts failed R-Ibr (7-10 mos) and R-hyperCVAD, 1 pt, auto-SCT and allo-SCT, 1 pt, auto-SCT and CAR-T. Efficacy for CLL : 88% ORR (92% TN, 86% RR), 3% (1) CR, 85% (22) PR/ (7) PR-L, 12% (4) SD. In addition, 3 PR pts with CLL met criteria for “Clinical CR, bone marrow biopsy not performed”. The pt achieving a CR had RR disease with del 11q; this pt remains in remission > 6 mos after stopping all therapy. At a median follow-up of 9.9 mos, 100% of CLL pts are free of disease progression and > 82% remain on study. Conclusions: Cirm in combination with Ibr is a well-tolerated and active regimen for RR MCL and TN or RR CLL. In this evaluation of 46 pts, the ORR and PFS continue to improve with longer follow-up and additional pts, supporting continued investigation of this regimen in ROR1 expressing tumors. This study is ongoing and enrolling an Expansion arm for MCL pts and an open-label randomized Phase 2 in CLL pts comparing Ibr alone to Cirm /Ibr. Clinical trial information: NCT03088878 .

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

The efficacy of ibrutinib has been demonstrated in patients with chronic lymphocytic leukemia (CLL), including as first‐line therapy. However, outcomes after ibrutinib discontinuation have previously been limited to higher‐risk populations with relapsed/refractory (R/R) disease. The objective of this study was to evaluate outcomes of ibrutinib‐treated patients based on prior lines of therapy, including after ibrutinib discontinuation. Data were analyzed from two multicenter phase 3 studies of single‐agent ibrutinib: RESONATE (PCYC‐1112) in patients with R/R CLL and RESONATE‐2 (PCYC‐1115) in patients with treatment‐naive (TN) CLL without del(17p). This integrated analysis included 271 ibrutinib‐treated non‐del(17p) patients with CLL (136 TN and 135 R/R). Median progression‐free survival (PFS) was not reached for subgroups with 0 and 1/2 prior therapies but was 40.6 months for patients with ≥3 therapies (median follow‐up: TN, 36 months; R/R, 44 months). Median overall survival (OS) was not reached in any subgroup. Overall response rate (ORR) was 92% in TN and 92% in R/R, with depth of response increasing over time. Adverse events (AEs) and ibrutinib discontinuation due to AEs were similar between patient groups. Most patients (64%) remain on treatment. OS following discontinuation was 9.3 months in R/R patients (median follow‐up 18 months, n = 51) and was not reached in TN patients (median follow‐up 10 months, n = 30). In this integrated analysis, ibrutinib was associated with favorable PFS and OS, and high ORR regardless of prior therapies in patients with CLL. The best outcomes following ibrutinib discontinuation were for patients receiving ibrutinib in earlier lines of therapy.

BACKGROUND: Chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab (FCR) has been the standard therapy for younger patients with CLL. FCR therapy is particularly effective in patients with immunoglobulin heavy chain variable region (IGHV) mutated CLL. Approximately half of IGHV mutated patients are progression free 8 years after FCR therapy. At the ASH 2018 meeting, we reported the initial results of the ECOG 1912 (E1912) trial, a phase 3 trial comparing the FCR regimen to the combination of ibrutinib and rituximab (IR) for previously untreated CLL patients age 70 or younger who required therapy. With median follow-up of approximately 34 months, the trial demonstrated both a progression-free survival (PFS) and an overall survival (OS) benefit relative to FCR. On sub-set analysis by IGHV mutation status, the difference in PFS was statistically significant for IGHV unmutated patients but, with current follow-up, not IGHV mutated patients. Here, we present updated results for PFS in the E1912 trial. METHODS: As previously reported, eligible patients were treatment-naive individuals with CLL age 70 or younger. Patients with deletion 17p- were excluded from participating in the E1912 trial given their known poor response to FCR therapy. Patients were randomly assigned in a two-to-one ratio to receive ibrutinib (420 mg/day until disease progression or unacceptable toxicity) and rituximab (50 mg/m2 on day 1 of cycle 2, 325 mg/m2 on day 2 of cycle 2, and then 500 mg/m2 on day 1 of cycles 3-7) or six courses of intravenous fludarabine (25 mg/m2 days 1-3), cyclophosphamide (250 mg/m2 days 1-3) and rituximab (50 mg/m2 on day 1 of cycle 1, 325 mg/m2 on day 2 of cycle 1, and then 500 mg/m2 on day 1 of cycles 2-6) every 28-days. Adverse events (AEs) were graded according to the NCI Common Toxicity Criteria (version 4). Dose adjustments for cytopenias were based on the IWCLL CLL Working Group grading scale. The primary endpoint of the trial was PFS with OS a secondary endpoint. Analysis was by intention to treat. RESULTS: With median follow-up of 45 months, 257 (73%) of 354 patients randomized to IR remain on ibrutinib. With extended follow-up, grade 3 and above treatment-related AEs were observed in 70% of IR and 80% of FCR treated patients (OR=0.56; 95% CI 0.34 - 0.90; p=0.013). Among IR-treated patients, the median time on treatment is currently 43 months (range=0.2-61). Among the 95 patients who have discontinued ibrutinib, the reason for discontinuation was progression or death in 23 (7% of patients who started IR; 24% of those who discontinued treatment), AE or complication in 48 (14% of patients who started IR; 51% of those who discontinued treatment), and withdrawal of consent or other reasons in 24 (7% of patients who started IR; 25% of those who discontinued treatment). On multivariable Cox regression adjusting for Timed Up and Go test score, Cumulative Illness Rating Scale (CIRS) score, age, gender, ECOG performance status, creatinine clearance, and baseline anemia/thrombocytopenia, only CIRS score (range 0 - 14) predicted discontinuation of ibrutinib for a reason other than progression or death (HR=1.13 per unit increase; 95% CI 1.03 - 1.23; p=0.009). Among the 72 patients who discontinued ibrutinib for a reason other than progression or death, the median time on ibrutinib was 15.1 months (range 0.2-58.2 months). The median time from ibrutinib discontinuation to disease progression or death was 23 months. With current follow-up, we observed 110 PFS events. The hazard ratio (HR) for PFS favored IR over FCR (HR=0.39; 95% CI 0.26-0.57; p CONCLUSIONS: Although less than 7% of ibrutinib treated patients progressed while on therapy, roughly 1 in 5 patients have discontinued ibrutinib for a reason other than progression or death. The only parameter significantly associated with discontinuation for a reason other than progression was increased baseline CIRS score. With extended follow-up, the combination of ibrutinib and rituximab continues to provide superior PFS compared to FCR for younger patients with previously untreated CLL. Disclosures Shanafelt: Pharmacyclics: Research Funding; Patent: Patents & Royalties: US14/292,075 on green tea extract epigallocatechin gallate in combination with chemotherapy for chronic lymphocytic leukemia; Polyphenon E International: Research Funding; Merck: Research Funding; Abbvie: Research Funding; Genentech: Research Funding; Celgene: Research Funding; Glaxo-SmithKline: Research Funding; Hospira: Research Funding; Cephalon: Research Funding. Kay:MorphoSys: Other: Data Safety Monitoring Board; Infinity Pharmaceuticals: Other: DSMB; Celgene: Other: Data Safety Monitoring Board; Agios: Other: DSMB. O'Brien:Janssen: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Astellas: Consultancy; Aptose Biosciences, Inc: Consultancy; Amgen: Consultancy; Alexion: Consultancy; Acerta: Research Funding; Eisai: Consultancy; Gilead: Consultancy, Research Funding; GlaxoSmithKline: Consultancy; Verastem: Consultancy; Celgene: Consultancy; Sunesis: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Vaniam Group LLC: Consultancy; Regeneron: Research Funding; Kite: Research Funding. Barrientos:AbbVie: Consultancy, Research Funding; AstraZeneca: Consultancy; Genentech: Consultancy; Bayer: Consultancy; Gilead: Consultancy; Janssen: Honoraria; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Sandoz: Consultancy; Oncternal Therapeutics: Research Funding. Coutre:Astellas: Consultancy, 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, Other: Travel, Accommodations, Expenses; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta: Research Funding; Gilead: Research Funding; BeiGene: Other: Travel, Accommodations, Expenses & Data Safety Monitoring Committee; Genentech: Consultancy. Barr:Pharmacyclics LLC, an AbbVie company: Consultancy, Research Funding; Gilead: Consultancy; Verastem: Consultancy; Genentech: Consultancy; Seattle Genetics: Consultancy; Merck: Consultancy; Celgene: Consultancy; Janssen: Consultancy; AbbVie: Consultancy; Astra Zeneca: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding. Cashen:Celgene: Other: Speaker's Bureau; Seattle Genetics: Other: Speaker's Bureau; Novartis: Other: Speaker's Bureau. Mato:AstraZeneca: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Celgene: Consultancy; Johnson & Johnson: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB member , Research Funding; LOXO: Consultancy, Research Funding; DTRM Biopharma: Research Funding; Genentech: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Gilead: Research Funding; Acerta: Consultancy; Janssen: Consultancy. Erba:Amgen: Consultancy; MacroGenics: Consultancy, Other: Lecture fees, Research Funding; MacroGenics: Consultancy, Other: Lecture fees, Research Funding; Novartis: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; ImmunoGen: Consultancy, Research Funding; Astellas Pharma: Consultancy; Astellas Pharma: Consultancy; Amgen: Consultancy; GlycoMimetics: Consultancy, Other: Chair, data and safety monitoring board, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Celgene: Consultancy, Other: chair, AML Registry Scientific Steering Committee, Speakers Bureau; ImmunoGen: Consultancy, Research Funding; AbbVie: Consultancy, Other: Chair, IRC for phase III studies, Research Funding; GlycoMimetics: Consultancy, Other: Chair, data and safety monitoring board, Research Funding; Covance: Other: Fees for serving as chair on an independent review board for AbbVie Phase III studies; Covance: Other: Fees for serving as chair on an independent review board for AbbVie Phase III studies; AbbVie: Consultancy, Other: Chair, IRC for phase III studies, Research Funding; Celgene: Consultancy, Other: chair, AML Registry Scientific Steering Committee, Speakers Bureau; Pfizer: Consultancy; Pfizer: Consultancy; Seattle Genetics: Consultancy; Seattle Genetics: Consultancy; Daiichi Sankyo: Consultancy, Research Funding. Stone:Arog Pharmaceuticals: Consultancy, Honoraria, Research Funding; Otsuka-Astex Pharmaceuticals: Consultancy; Fujifilm: Consultancy; AstraZeneca: Consultancy; Celator Pharmaceuticals: Consultancy; Abbvie: Consultancy, Research Funding; Ono Pharmaceutical-Theradex Oncology: Consultancy; Cornerstone Pharmaceuticals: Consultancy; Daiichi Sankyo: Consultancy; Takeda: Other: Fees for serving on a data and safety monitoring board ; Orsenix: Consultancy; MacroGenics: Consultancy; Jazz Pharmaceuticals: Consultancy; Agios: Consultancy, Research Funding; Stemline Therapeutics: Consultancy; Pfizer: Consultancy; Celgene: Consultancy, Other: Fees for serving on a steering committee, and fees for serving on a data and safety monitoring board; Novartis: Consultancy, Research Funding; Actinium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Astellas Pharma: Membership on an entity's Board of Directors or advisory committees; Argenx: Other: Fees for serving on a data and safety monitoring board ; Roche: Consultancy. Tallman:Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncolyze: 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.