Citations

Introduction: Daratumumab (DARA) is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action, and has been approved across lines of therapy for the treatment of multiple myeloma. The addition of DARA to standard-of-care (SoC) regimens, lenalidomide and dexamethasone (D-Rd) and bortezomib, melphalan, and prednisone (D-VMP), in the phase 3 MAIA and ALCYONE clinical studies reduced the risk of disease progression or death by ≥44%, nearly doubled the rate of complete response (CR) or better, and induced a >3-fold increase in MRD-negativity rates (10-5 sensitivity threshold) vs SoC alone in pts with TIE NDMM. In both MAIA and ALCYONE, MRD negativity was associated with longer progression-free survival (PFS), irrespective of trial treatments. MRD negativity provides an index of deep clinical response and may be a more robust evaluation of disease control if sustained over time. Here, we evaluate MRD negativity, including sustained MRD negativity, in pts with TIE NDMM from MAIA and ALCYONE and its association with PFS with longer follow-up. Methods: Pts with NDMM ineligible for high-dose chemotherapy with stem cell transplantation due to age (≥65 years) or unacceptable coexisting conditions in MAIA and ALCYONE were randomized (1:1) to SoC ± DARA. Pts in MAIA received 28-day cycles of Rd (R: 25 mg PO on Days 1-21; d: 40 mg PO QW) ± DARA (16 mg/kg IV QW for Cycles 1-2, Q2W for Cycles 3-6, and Q4W thereafter). ALCYONE pts received up to nine 6-week cycles of VMP (V: 1.3 mg/m2 SC twice weekly during Weeks 1, 2, 4, and 5 of Cycle 1 and QW during Weeks 1, 2, 4, and 5 of Cycles 2-9; M: 9 mg/m2 PO on Days 1-4 of Cycles 1-9; and P: 60 mg/m2 PO on Days 1-4 of Cycles 1-9) ± DARA (16 mg/kg IV QW for Cycle 1, Q3W for Cycles 2-9, and Q4W for Cycles 10+). Study treatments continued until progressive disease or unacceptable toxicity. MRD was assessed in MAIA and ALCYONE in all pts who achieved a CR or stringent CR. For ≥CR pts, additional MRD assessments occurred at 12, 18, 24, and 30 months after the first dose in ALCYONE and at 12, 18, 24, 30, 36, 48, and 60 months in MAIA. MRD was assessed via next-generation sequencing using the clonoSEQ® assay (v.2.0; Adaptive Biotechnologies, Seattle, WA) at the 10-5 sensitivity threshold. Sustained MRD negativity was defined as the maintenance of MRD negativity confirmed ≥6 or ≥12 months apart with no MRD positive test in between and was evaluated in the intention-to-treat (ITT) population. Results: A total of 737 (D-Rd, n=368; Rd, n=369) pts in MAIA and 706 (D-VMP, n=350; VMP, n=356) pts in ALCYONE were randomized; median duration of follow-up was 36.4 months in MAIA and 40.1 months in ALCYONE. In both studies, DARA-based therapy improved MRD negativity vs SoC in the ITT population (D-Rd, 28.8% vs Rd, 9.2%, P<0.0001; D-VMP, 28.3% vs VMP, 7.0%, P<0.0001). MRD-negative pts had improved PFS vs MRD-positive pts in the ITT population, regardless of treatment arm. In a pooled analysis of pts from DARA (D-Rd/D-VMP) and SoC (Rd/VMP) treatment groups, MRD-negative pts had improved PFS vs pts who were MRD positive, irrespective of treatment arm. In general, baseline characteristics were comparable among pts in DARA and control treatment groups with sustained MRD negativity. A higher proportion of pts in the ITT populations of MAIA (D-Rd, n=368; Rd, n=369) and ALCYONE (D-VMP, n=350; VMP, n=356) achieved sustained MRD negativity with DARA-based therapy vs SoC for ≥6-months (D-Rd, 14.9% vs Rd, 4.3%, P<0.0001; D-VMP, 15.7% vs VMP, 4.5%, P<0.0001) and ≥12-months (D-Rd, 10.9% vs Rd, 2.4%; P<0.0001; D-VMP, 14.0% vs VMP, 2.8%, P<0.0001). PFS was prolonged in pts with sustained MRD negativity for ≥6-months and ≥12-months vs pts without sustained MRD negativity in the pooled ITT populations, regardless of treatment arm (Figure). Conclusions: DARA-based combination regimens induce higher rates of MRD-negativity and sustained MRD negativity in pts with TIE NDMM, which are associated with deep responses and improved PFS. Disclosures San-Miguel: Amgen, BMS, Celgene, Janssen, MSD, Novartis, Takeda, Sanofi, Roche, Abbvie, GlaxoSmithKline and Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees. Avet-Loiseau:Celgene and Janssen: Research Funding; Celgene, Amgen, Bristol-Myers Squibb, Sanofi, and Janssen;: Honoraria, Speakers Bureau. Paiva:Takeda: Consultancy, Honoraria, Research Funding; SkylineDx: Consultancy; Kite: Consultancy; Karyopharm: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Honoraria; Adaptive: Honoraria; Roche: Research Funding; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding. Kumar:Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Cellectar: Other; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Kite Pharma: Consultancy, Research Funding; MedImmune: Research Funding; Sanofi: Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Karyopharm: Consultancy; BMS: Consultancy, Research Funding; Carsgen: Other, Research Funding; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genecentrix: Consultancy; Tenebio: Other, Research Funding; Dr. Reddy's Laboratories: Honoraria. Dimopoulos:Beigene: Honoraria; Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Takeda: Honoraria. Facon:Celgene, Janssen, Takeda, Amgen, Roche, Karyopharm, Oncopeptides, BMS, Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mateos:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; Pharmamar: Consultancy; Adaptive: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; EDOMundipharma: Consultancy; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Touzeau:Sanofi: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; GlaxoSmithKline: Honoraria, Research Funding. Jakubowiak:AbbVie, Amgen, BMS/Celgene, GSK, Janssen, Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive, Juno: Consultancy, Honoraria. Usmani:Sanofi: Consultancy, Honoraria, Research Funding; Celgene: Other; Amgen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Abbvie: Consultancy; BMS, Celgene: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; GSK: Consultancy, Research Funding; Array Biopharma: Research Funding; Takeda: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Incyte: Research Funding; SkylineDX: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Research Funding; Merck: Consultancy, Research Funding. Cook:Karyopharm: Honoraria; Celgene, Janssen, Takeda: Research Funding; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Takeda, Roche, Sanofi: Honoraria. Cavo:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Quach:GlaxoSmithKline, Karyopharm, Amgen, Celgene, Janssen Cilag: Consultancy; GlaxoSmithKline, Karyopharm, Amgen, Celgene, Janssen Cilag: Honoraria; Amgen, Celgene, karyopharm, GSK, Janssen Cilag, Sanofi.: Membership on an entity's Board of Directors or advisory committees; Amgen, sanofi, celgene, Karyopharm, GSK: Research Funding. Ukropec:Janssen: Current Employment, Current equity holder in publicly-traded company. Ramaswami:Janssen: Current equity holder in publicly-traded company. Pei:Janssen: Current Employment, Current equity holder in publicly-traded company. Sun:Janssen: Current Employment, Current equity holder in publicly-traded company. Wang:Janssen: Current Employment. Krevvata:Janssen: Current Employment. DeAngelis:Janssen: Current Employment, Current equity holder in publicly-traded company. Heuck:Christoph Heuck: Current Employment, Current equity holder in publicly-traded company. Van Rampelbergh:Janssen: Current Employment. Kudva:Janssen: Current Employment, Current equity holder in publicly-traded company; Memorial Sloan Kettering Cancer Center: Other: non-paid consultancy. Kobos:Janssen: Current Employment, Current equity holder in publicly-traded company. Qi:Janssen: Current Employment, Current equity holder in publicly-traded company; Johnson and Johnson: Current equity holder in publicly-traded company. Bahlis:Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; BMS/Celgene and Janssen: Consultancy, Honoraria, Other: Travel, Accomodations, Research Funding; Sanofi: Consultancy, Honoraria; Karyopharm Therapeutics: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; GSK: Consultancy, Honoraria.

INTRODUCTION T-cell prolymphocytic leukemia (T-PLL) is a rare, aggressive malignancy of mature T-cells. Although responses may been seen with initial alemtuzumab-based therapy, relapse is inevitable and relapsed/refractory disease carries a dismal prognosis. T-PLL has shown in vitro sensitivity to venetoclax, and short-lived clinical responses to venetoclax monotherapy (Smith, Blood Advances 2020; Boidol, Blood 2017) or when given in combination with pentostatin (Alfayez, Leukemia & Lymphoma 2020). Given the lack of standard treatment options, we reviewed the outcomes of patients (pts) with relapsed T-PLL on venetoclax-based therapy. METHODS Using an institutional clinical database of pts with T-PLL seen in the Division of Hematology at Mayo Clinic, Rochester, MN, all pts treated with venetoclax or venetoclax-based therapies in a relapsed/refractory setting were identified. Clinical, laboratory, and pathology data, as well as treatment dosing and toxicity were ascertained retrospectively from the medical records. Diagnostic criteria and response definitions were utilized as per the T-PLL International Study Group (Staber, Blood 2019). RESULTS Between 8/2017 and 5/2020, 9 pts with relapsed/refractory T-PLL treated with venetoclax were identified. The median age was 63 years (range 49-75), and one-third were male. Baseline characteristics are detailed in Table 1. Rearrangement of TCL1 family genes was present in all 8 pts evaluated with fluorescence in situ hybridization (FISH). Using conventional cytogenetics, a complex karyotype was present in 4/6 pts tested. The median prior lines of therapy was 3 (range 1-4), including alemtuzumab in 8 of 9 pts (intravenous 7/8); and two pts had undergone prior hematopoietic stem cell transplantation (1 allogeneic; 1 autologous) after achieving a complete remission. Additional individual pt details are included in Table 2. Prior to venetoclax therapy initiation, 2 pts had B-symptoms (2 night sweats; 1 fever) and 6 pts had an ECOG score ≥ 2. Lymphadenopathy and splenomegaly were present in 6 and 9 pts, respectively. Extranodal involvement included 3 pts with cutaneous involvement and 5 pts with effusions (4 ascites; 1 pleural). The target maximum dose of venetoclax (800 mg [n=4]; 400 mg [n=1]) was reached by 5 pts at a median of 12 days (range 7-40 days). The other 4 pts had disease progression after a median of 10 days (range 5-22 days) during the dose ramp-up, including 2 pts undergoing rapid dose escalation. Altogether, 6 of the 9 pts initiated venetoclax with a rapid dose escalation. Bendamustine was given with venetoclax in 5/9 pts; median number of cycles 1 (range 1-4) with variable starting dosing (range 60-100 mg/m2). The disease control rate was 56%; best response was partial remission (PR) in 4 (44%) pts and stable disease (SD) in 1 (11%) pt. The 1 pt with SD received venetoclax monotherapy; however, the overall response rate among pts who received the combination of venetoclax and bendamustine was 80% (4/5 pts). One pt with a partial remission met all criteria for complete remission but did not have a confirmatory bone marrow biopsy. Cutaneous disease improved in 2 of 3 pts (both with PR as best response), and effusions improved in 2 of 5 pts (1 PR and 1 SD as best response). Among those in PR, the median decrease in absolute lymphocyte count was 67x109/L and the median decrease in lactate dehydrogenase was 1,162 U/L (normal range 122-222 U/L). Median duration of treatment for all pts was 42 days (range 4-201 days). All pts ultimately died during follow-up with a median overall survival of 53 days (range 4-464 days); Figure 1. All pts experienced at least one adverse event and 8 of 9 pts had a grade ≥ 3 toxicity, most commonly edema (n=7) and neutropenia (n=6). Five pts required dose interruptions due to neutropenia (n=3), tumor lysis syndrome (n=1), and edema (n=1). Three pts had dose reductions, all from 800 mg dosing, due to hematologic toxicity (n=2) and nausea (n=1). No pts discontinued venetoclax as a result of adverse events. CONCLUSION Treatment of pts with relapsed/refractory T-PLL remains a significant unmet need. The 9 pts described herein represent the largest cohort of pts treated with venetoclax-based therapy in this setting to the current date. Despite initial reports of clinical efficacy, our results show that venetoclax (with or without bendamustine) has modest efficacy in the treatment of relapsed/refractory T-PLL after prior alemtuzumab exposure. Disclosures Parikh: TG Therapeutics: Research Funding; Verastem Oncology: Honoraria; GlaxoSmithKline: Honoraria; AbbVie: Honoraria, Research Funding; Genentech: Honoraria; Merck: Research Funding; MorphoSys: Research Funding; Pharmacyclics: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Ascentage Pharma: Research Funding; AstraZeneca: Honoraria, Research Funding. Shah:Dren Bio: Consultancy. Bennani:Verastem: Other: Advisory Board; Affimed: Research Funding; Purdue Pharma: Other: Advisory Board; Kite/Gilead: Research Funding. Wang:Incyte: Research Funding; Novartis: Research Funding; Innocare: Research Funding. Kenderian:MorphoSys: Research Funding; Lentigen: Research Funding; Gilead: Research Funding; Juno: Research Funding; BMS: Research Funding; Tolero: Research Funding; Sunesis: Research Funding; Kite: Research Funding; Novartis: Patents & Royalties, Research Funding; Torque: Consultancy; Humanigen: Consultancy, Patents & Royalties, Research Funding; Mettaforge: Patents & Royalties. Kay:MEI Pharma: Research Funding; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Research Funding; Cytomx: Membership on an entity's Board of Directors or advisory committees; Juno Theraputics: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees; Agios Pharma: 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; Sunesis: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Ding:Octapharma: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Research Funding; alexion: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; DTRM: Research Funding; Abbvie: Research Funding. OffLabel Disclosure: Venetoclax: off-label use in treatment of relapsed/refractory T-cell prolymphocytic leukemia

Background: Multiple myeloma (MM) negatively affects health-related quality of life (HRQoL), and with each relapse, patients with MM experience further declines in HRQoL. Patient-reported HRQoL is therefore an important treatment outcome, in addition to clinical response to therapy. CARTITUDE-1 (NCT03548207) is a phase 1b/2 study evaluating the safety and efficacy of ciltacabtagene autoleucel (cilta-cel; JNJ-68284528; LCAR-B38M CAR-T cells), a chimeric antigen receptor T (CAR-T) cell therapy with 2 B-cell maturation antigen-targeting single-domain antibodies, in patients with relapsed/refractory (R/R) MM. We evaluated symptoms, functioning, and overall HRQoL through patient-reported outcome measures, which is a secondary objective of CARTITUDE-1. Methods: Patients were ≥18 years of age with a diagnosis of MM per International Myeloma Working Group criteria, measurable disease, and Eastern Cooperative Oncology Group performance status ≤1. Patients had received ≥3 prior regimens for MM or were double-refractory to a proteasome inhibitor and immunomodulatory drug, and had received an anti-CD38 antibody. Cilta-cel was given as a single infusion on Day 1 (target dose: 0.75×106 [range: 0.5-1.0×106] CAR+ viable T cells/kg) 5-7 days after start of lymphodepletion (cyclophosphamide 300 mg/m2 + fludarabine 30 mg/m2 daily for 3 days). In the phase 2 portion of CARTITUDE-1, HRQoL was assessed at baseline, on Days 7, 28, 56, 78, and 100, and every 28 days thereafter using 3 patient-reported instruments: the European Organization for Research and Treatment of Cancer QoL Questionnaire Core 30 (EORTC QLQ-C30), 4 items from the EORTC QLQ-Multiple Myeloma (MY20) module, and the 5-level EuroQol Five Dimension (EQ-5D-5L) measure. Raw EORTC QLQ-C30 and EORTC QLQ-MY20 scores were linearly transformed to a scale ranging from 0 to 100; the EQ-5D-5L visual analog scale (VAS) score ranges from 0 to 100. Clinically meaningful changes in EORTC QLQ-C30 symptoms, physical functioning, and overall HRQoL were based on anchor-based methods using a patient global impression of change item. Repeated-measures mixed-effects models were used to analyze mean changes in HRQoL from baseline to subsequent assessment time points in patients in the modified intent-to-treat population with ≥1 post-baseline assessment. Median time to event of HRQoL scores was calculated descriptively, using a change in score ≥0.5×standard deviation of values prior to cilta-cel infusion as improvement/worsening with death due to progression defined as worsening. Results: For the 68 patients in the phase 2 portion of CARTITUDE-1 (63.2% male; median age: 62.0 years [range: 43-78]), questionnaire completion rates at baseline and Day 100, respectively, were 92.6% and 69.2% for both the EORTC QLQ-C30 and EORTC QLQ-MY20 items and 92.6% and 70.8% for the EQ-5D-5L. For EORTC QLQ-C30 subscales, clinically meaningful improvements at Day 100 were seen for 71.1% of patients for pain, 62.2% for fatigue, 72.1% for physical functioning, and 51.1% for global health status. Mean changes in pain and fatigue showed a reduction in these symptoms over time (following an initial worsening of fatigue at Day 7; Figure). This trend of improvements over time was also observed for overall HRQoL and EORTC QLQ-MY20 single items. Clinically meaningful improvements at Day 100, defined by a literature-based minimal important difference of 10 points in mean score, were observed for the EORTC QLQ-MY20 single items: thinking about illness and worries about dying or future health. Approximately 50% of the population reported an event of improvement or worsening in EORTC QLQ-C30 and EQ-5D-5L scales, with the rest censored in this early data cut; among these patients, median time to improvement was approximately 1-2 months (with median time to worsening occurring less than 1 month after cilta-cel treatment). There was a trend for an improvement in mean EORTC QLQ-C30 global health status, physical functioning, pain, and fatigue, and EQ-5D-5L VAS at Day 100 with increased depth of response. Conclusions: Some patients with heavily pretreated MM showed rapid and clinically meaningful improvements in pain, fatigue, physical functioning, overall HRQoL, and future perspectives, consistent with their clinical outcomes. With additional follow-up, it is possible that these early improvements in symptoms will translate into greater improvement in overall HRQoL in the long term. Disclosures Martin: Janssen: Research Funding; Sanofi: Research Funding; AMGEN: Research Funding; Seattle Genetics: Research Funding; GSK: Consultancy. Lin:Vineti: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Legend BioTech: Consultancy; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy; Merck: Research Funding; Takeda: Research Funding; Gamida Cells: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cohen:Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda,: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Patents/Intellectual property licensed, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees. Htut:City of Hope Medical Center: Current Employment. Stewart:Janssen, BMS, Sanofi-Aventis, GSK: Honoraria; Tempus, Inc., Genomics England LLC: Membership on an entity's Board of Directors or advisory committees. Hari:GSK: Consultancy; BMS: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Incyte Corporation: Consultancy; Janssen: Consultancy. Berdeja:Teva: Research Funding; Cellularity: Research Funding; Kesios: Research Funding; BMS: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; CURIS: Research Funding; EMD Sorono: Research Funding; Genentech, Inc.: Research Funding; Karyopharm: Consultancy; Poseida: Research Funding; Novartis: Research Funding; Lilly: Research Funding; Amgen: Consultancy, Research Funding; Acetylon: Research Funding; Glenmark: Research Funding; Janssen: Consultancy, Research Funding; Vivolux: Research Funding; Takeda: Consultancy, Research Funding; Servier: Consultancy; CRISPR Therapeutics: Consultancy, Research Funding; Constellation: Research Funding; Bluebird: Research Funding; Abbvie: Research Funding; Prothena: Consultancy; Bioclinica: Consultancy; Kite Pharma: Consultancy; Legend: Consultancy. Madduri:Foundation Medicine: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Speaking Engagement, Speakers Bureau; AbbVie: Consultancy, Honoraria; Legend: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Speaking Engagement, Speakers Bureau; Kinevant: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Speaking Engagement, Speakers Bureau; Celgene: Consultancy, Honoraria. Usmani:Takeda: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; SkylineDX: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Merck: Consultancy, Research Funding; Incyte: Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; GSK: Consultancy, Research Funding; Abbvie: Consultancy; Array Biopharma: Research Funding; Celgene: Other; Amgen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; BMS, Celgene: Consultancy, Honoraria, Other: Speaking Fees, Research Funding. Yeh:Janssen: Current Employment. Allred:Janssen: Current Employment. Olyslager:Janssen: Current Employment. Banerjee:Janssen: Current Employment. Goldberg:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Schecter:Janssen: Current Employment. Jackson:Janssen: Current Employment; Memorial Sloan Kettering Cancer Center: Consultancy. Deraedt:Janssen: Current Employment, Current equity holder in publicly-traded company. Gries:Janssen: Current Employment, Current equity holder in publicly-traded company. Fastenau:Janssen: Current Employment, Current equity holder in publicly-traded company. Wu:Legend Biotech USA Inc.: Current Employment. Carrasco:Legend Biotech USA Inc.: Current Employment. Akram:Legend Biotech USA Inc.: Current Employment. Hossain:Legend Biotech USA Inc.: Current Employment. Jakubowiak:AbbVie, Amgen, BMS/Celgene, GSK, Janssen, Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive, Juno: Consultancy, Honoraria. Jagannath:BMS, Janssen, Karyopharm, Legend Biotech, Sanofi, Takeda: Consultancy.

Introduction: Daratumumab (DARA) is a human, CD38-targeting, IgG1κ monoclonal antibody approved as monotherapy in relapsed/refractory multiple myeloma (RRMM) and in combination with standard of care for RRMM and NDMM. The addition of DARA to standard-of-care regimens in phase 3 studies has consistently improved progression-free survival (PFS) and led to deep and durable responses, including higher rates of minimal residual disease (MRD) negativity compared with standard of care. In the primary analysis of the phase 3 MAIA study (median follow-up, 28.0 mo), D-Rd vs Rd significantly improved PFS and MRD-negativity rates in transplant-ineligible NDMM (Facon T, N Engl J Med 2019). With longer follow-up (36.4 mo), D-Rd maintained a PFS benefit and deeper and more durable responses vs Rd alone (Bahlis N, Blood 2019. 134[Suppl 1]:1875). Here, we report updated efficacy and safety findings from MAIA after approximately 4 years of follow-up. Methods: Patients with NDMM ineligible for high-dose chemotherapy and autologous stem cell transplantation due to age ≥65 years or comorbidities were randomly assigned (1:1) to receive Rd ± DARA. Stratification factors included International Staging System stage (ISS [I vs II vs III]), region (North America vs other), and age (<75 vs ≥75 years). All patients received 28-day cycles of Rd (R: 25 mg orally once daily on Days 1-21; d: 40 mg orally on Days 1, 8, 15 and 22). In the D-Rd arm, DARA (16 mg/kg intravenously) was given weekly for Cycles 1-2, every 2 weeks in Cycles 3-6, and every 4 weeks thereafter. Patients were treated until disease progression or unacceptable toxicity in both treatment arms. The primary endpoint was PFS. Key secondary endpoints included overall response rate (ORR), MRD-negativity rate (10‒5 sensitivity, clonoSEQ® version 2.0), and safety. PFS on the next line of therapy (PFS2), defined as the time from randomization to progression on the next subsequent line of therapy or death, was also measured. Results: A total of 737 patients were randomized (D-Rd, n = 368; Rd, n = 369). Patient baseline characteristics were well balanced between the two treatment arms. Median (range) age was 73 (45-90) years, with 44% of patients ≥75 years of age. 27%, 43%, and 29% of all patients were ISS stage I, II, and III, respectively. Among 642 patients evaluable for FISH/karyotyping analysis, 86% had standard and 14% had high cytogenetic risk. After a median follow-up of 47.9 months, 176 (48%) and 273 (75%) patients discontinued study treatment in the D-Rd vs Rd groups, respectively, with 85 (23%) and 113 (31%) patients discontinuing treatment due to progressive disease. PFS remained improved for D-Rd vs Rd (median, not reached [NR] vs 34 mo; HR, 0.54; 95% CI, 0.43-0.67; P<0.0001; Figure). The estimated 48-month PFS rate was 60% with D-Rd vs 38% with Rd. The PFS benefit of D-Rd in prespecified subgroups, including patients with high cytogenetic risk, was generally consistent with overall results. Adding DARA to Rd continued to result in deeper responses with higher rates of ≥CR and ≥very good partial response (VGPR; Table). Median duration of response among responders was NR with D-Rd vs 44 months with Rd. Median PFS2 was NR vs 51 months with D-Rd vs Rd, respectively (HR, 0.65; 95% CI, 0.52-0.83; P=0.0005); follow up is ongoing. 107 (29%) patients in the D-Rd group and 132 (36%) in the Rd group have discontinued the study due to death. Grade 3/4 treatment-emergent adverse events (TEAEs; D-Rd/Rd) occurring in ≥10% of patients were neutropenia (53%/37%), pneumonia (18%/11%), anemia (16%/21%), lymphopenia (16%/11%), hypokalemia (12%/10%), leukopenia (11%/6%), and cataract (11%/10%); grade 3/4 infection rates were 40%/29%. The most common serious TEAE was pneumonia (17%/11%). 11% of patients in the D-Rd arm and 22% in the Rd arm discontinued treatment due to an adverse event. The complete updated data set will be presented at the meeting with additional efficacy endpoints, including MRD-negativity rate. Conclusion : After 48 months follow up, the addition of DARA to Rd continues to demonstrate a superior PFS benefit. More patients continued to have deeper and more durable responses with D-Rd vs Rd alone. No new safety concerns were observed with longer follow-up. These results continue to support the use of D-Rd in the first line of treatment for patients with transplant-ineligible NDMM. Disclosures Kumar: Sanofi: Research Funding; Carsgen: Other, Research Funding; Cellectar: Other; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Karyopharm: Consultancy; Merck: Consultancy, Research Funding; Kite Pharma: Consultancy, Research Funding; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Tenebio: Other, Research Funding; BMS: Consultancy, Research Funding; MedImmune: Research Funding; Genecentrix: Consultancy; Dr. Reddy's Laboratories: Honoraria; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Adaptive Biotechnologies: Consultancy. Facon:Celgene, Janssen, Takeda, Amgen, Roche, Karyopharm, Oncopeptides, BMS, Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Usmani:Abbvie: Consultancy; Janssen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Takeda: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Celgene: Other; GSK: Consultancy, Research Funding; Merck: Consultancy, Research Funding; BMS, Celgene: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Amgen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; SkylineDX: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics: Research Funding; Incyte: Research Funding; Array Biopharma: Research Funding. Plesner:Janssen: Consultancy. Orlowski:Founder of Asylia Therapeutics, Inc., with associated patents and an equity interest, though this technology does not bear on the current submission.: Current equity holder in private company, Patents & Royalties; STATinMED Research: Consultancy; Laboratory research funding from BioTheryX, and clinical research funding from CARsgen Therapeutics, Celgene, Exelixis, Janssen Biotech, Sanofi-Aventis, Takeda Pharmaceuticals North America, Inc.: Research Funding; Amgen, Inc., AstraZeneca, BMS, Celgene, EcoR1 Capital LLC, Forma Therapeutics, Genzyme, GSK Biologicals, Ionis Pharmaceuticals, Inc., Janssen Biotech, Juno Therapeutics, Kite Pharma, Legend Biotech USA, Molecular Partners, Regeneron Pharmaceuticals, Inc.,: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi-Aventis, Servier, Takeda Pharmaceuticals North America, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees. Touzeau:Takeda: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; GlaxoSmithKline: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Research Funding. Bahlis:BMS/Celgene and Janssen: Consultancy, Honoraria, Other: Travel, Accomodations, Research Funding; Genentech: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Karyopharm Therapeutics: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Goldschmidt:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Johns Hopkins University: Other: Grants and/or provision of Investigational Medicinal Product; Incyte: Research Funding; University Hospital Heidelberg, Internal Medicine V and National Center for Tumor Diseases (NCT), Heidelberg, Germany: Current Employment; GlaxoSmithKline (GSK): Honoraria; Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Mundipharma GmbH: Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Novartis: Honoraria, Research Funding; Chugai: Honoraria, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Dietmar-Hopp-Foundation: Other: Grants and/or provision of Investigational Medicinal Product:; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Molecular Partners: Research Funding; Merck Sharp and Dohme (MSD): Research Funding. O'Dwyer:Celgene: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); BMS: Research Funding; Carrick Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Janssen: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); AbbVie: Consultancy; ONK Therapeutics: Consultancy, Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Venner:Celgene, Amgen: Research Funding; Janssen, BMS/Celgene, Sanofi, Takeda, Amgen: Honoraria. Weisel:Adaptive: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria; GlaxoSmithKline: Honoraria; Takeda: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Hulin:Celgene/Bristol-Myers Squibb, Janssen, GlaxoSmithKline, and Takeda: Honoraria. Karlin:GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Celgene: Other: Personal fees; Sanofi: Honoraria; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support. Preis:Janssen: Other: for factor XI inhibitor. Broyl:Janssen, Celgene, Takeda, Amgen: Honoraria. Hansson:Amgen, Celgene, Takeda, Janssen Cilag: Consultancy. Krevvata:Janssen: Current Employment. Wang:Janssen: Current Employment. Van Rampelbergh:Janssen: Current Employment. Ukropec:Janssen: Current Employment, Current equity holder in publicly-traded company. Uhlar:Janssen: Current Employment, Current equity holder in publicly-traded company. Kobos:Janssen: Current Employment, Current equity holder in publicly-traded company. Perrot:Amgen, BMS/Celgene, Janssen, Sanofi, Takeda: Consultancy, Honoraria, Research Funding.

Introduction: Novel targeted therapies have revolutionized treatments for both upfront and relapsed CLL. However, effective therapies have not been established for progressive CLL after developing resistance to both BTK inhibitor and BCL-2 inhibitors. Similarly, Richter's transformation (RS) remains an area of unmet clinical need. Hypothesizing that progressive CLL and RS possess significant but differential molecular abnormalities, we aimed to dissect the initial genomic profiles in a clinical cohort of patients seen in our routine clinical practice using targeted DNA sequencing and transcriptome analysis. Methods: Twelve CLL patients who had lymph node biopsies for evaluation of clinical progression at Mayo Clinic were included in this study. RNA sequencing and targeted DNA sequencing on a focused oncology panel of 1,711 genes were performed on Illumina HiSeq through Tempus Labs, Inc. (Chicago, IL). Differentially expressed (DE) genes were identified using edgeR at the cutoff of FDR <=0.05 and fold-change >=2. Somatic mutations and copy number alternations (CNAs) were identified through Mutect2 and PatternCNV, respectively. CN loss was defined to have log2(ratio) <=-0.93 and CN gain to have log2(ratio) >= 0.585. Pathway analysis was done through the Enrichr package. Results: Among the 12 patients, 7 had confirmed RS (large cell lymphoma histology) and 5 had CLL based on pathological findings. The clinical and therapeutic history for each patient is illustrated in Fig 1A. FISH results from 11 of the patients showed chromosomal abnormalities including del(13q), del(11q), del(17p) and tri(12) (Fig 1A). Hierarchical clustering of expression profiles from the top 10,000 most variable genes in expression revealed two major clusters (Fig 1A). Cluster C1 contains five RS cases, of which case S207 did not receive ibrutinib, S256 was on high-dose steroid and anti-CD20 post-ibrutinib therapy for >1 year before biopsy, and case S025 was treated for < 6 months with ibrutinib. These three form a subgroup separate from the other two RS in C1 who had 8 and 42 months of continuous ibrutinib therapy pre-biopsy, respectively. C2 contains two RS and five CLL cases. Within C2, CLL and RS cases showed similar transcriptomic profiles. Over 90% of the DE genes showed an overall increase of expression in C1, particularly within the 3-sample subgroup (Fig 1B). These genes are enriched in pathways known to play key roles in CLL, including PI3K-AKT signaling, NOTCH signaling and RAS/MAPK signaling, while genes up-regulated in C2 are enriched in WNT signaling. The results suggest marked differences in gene expression profiles and indicate molecular heterogeneity among RS and CLL patients. In addition, targeted DNA sequencing data were analyzed to identify somatic mutations and CNAs. The analysis confirmed the FISH results of del(13q), del(11q), del(17p) or tri(12) in 8 of the cases (Fig 1A). The mutation profiles are similar between C1 and C2 for the recurrently mutated genes published in CLL. However, we identified recurrent CNAs that occurred preferentially in C1 (covering 9 genes) or C2 (48 genes) (Fig 1C). Manual inspections of the reads coverage revealed that 5 of the 9 genes are from chr1q21.1 to chr1q22 that showed clear CN gains largely in C1. Of the 48 genes, 6 are from chrXp11 that showed CN losses, and 27 are from chr17q12 to chr17q25 that showed CN gains. Therefore, the majority of the 57 genes are from large-scale CNAs. Notably, for the CNAs mostly occurring in C2, the affected genes are enriched in WNT signaling, Cell cycle/protein kinase activity and chromatin modifying enzymes. Collectively, the results support the variability of transcriptomic signatures and genetic lesions between RS and CLL. Conclusion: This study revealed a noticeable heterogeneity in gene expression and genetic variation between RS and CLL, albeit in a small cohort. The vast majority of the DE genes showed elevated expression in C1 containing only RS cases, and these genes are enriched in PI3K-AKT signaling, NOTCH signaling, and RAS/MAPK signaling. The pattern is more pronounced for a subgroup in C1 who were overall less exposed to ibrutinib. For somatic variation, there is a strong tendency of occurrence of recurrent CNAs towards C2 cohort, mainly involving gains of chr17q and deletions of chrXp11. Given these advances we are encouraged to further pursue the genetic abnormalities with defined roles in aggressive and transformed CLL. Disclosures Liu: Eisal: Research Funding; Genentech: Research Funding; GRAIL: Research Funding; Menarini Silicon Biosystems: Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Tesaro: Research Funding. Parikh:Genentech: Honoraria; Ascentage Pharma: Research Funding; AbbVie: Honoraria, Research Funding; Verastem Oncology: Honoraria; Pharmacyclics: Honoraria, Research Funding; GlaxoSmithKline: Honoraria; Merck: Research Funding; MorphoSys: Research Funding; TG Therapeutics: Research Funding; AstraZeneca: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Wang:Incyte: Research Funding; Innocare: Research Funding; Novartis: Research Funding. Kenderian:Gilead: Research Funding; Humanigen: Consultancy, Patents & Royalties, Research Funding; MorphoSys: Research Funding; Lentigen: Research Funding; Novartis: Patents & Royalties, Research Funding; Torque: Consultancy; Mettaforge: Patents & Royalties; BMS: Research Funding; Tolero: Research Funding; Sunesis: Research Funding; Juno: Research Funding; Kite: Research Funding. Kay:Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Theraputics: Membership on an entity's Board of Directors or advisory committees; Cytomx: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Agios Pharma: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; MEI Pharma: Research Funding; Acerta Pharma: Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: 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. Braggio:DASA: Consultancy; Bayer: Other: Stock Owner; Acerta Pharma: Research Funding. Ding:Astra Zeneca: Research Funding; DTRM: Research Funding; Beigene: Membership on an entity's Board of Directors or advisory committees; alexion: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding.

Introduction: PD-1 inhibits the cytotoxic T-cell functions via the interaction with its ligands (PDL1 and PDL2). Recently, our group showed a selective response (~40%) with PD-1 blocking antibody pembrolizumab in patients with Richter transformation (RT), particularly after prior exposure to ibrutinib (Wei Ding et al, Blood, 2017). Additionally, PD-1 showed an increased expression in tumor B-cells of patients with RT (Rong He et al, AJSP, 2018). Here we investigated the functional implications of the PD-1 signaling axis in lymphoma B-cell pathobiology. Methods: 26 CLL-involved lymph node (LN) and 20 RT-involved LN samples were tested for PD-1 expression by immunohistochemistry (mouse clone NAT105, Abcam). Then, we checked PD-1 expression in 10 lymphoma cell lines and 1 CLL cell line (MEC-1) by both, flow cytometry and Western blot (WB) analysis. Over-expression of PD-1 using pLEX-lentiviral system (Thermo Scientific) was evaluated for in vitro cell cycle regulation and in vivo tumor growth. Overexpression of PD-1 was further examined on the regulation of cell signaling pathways using human phospho kinase array kit (R&D) and WB analysis. Gene expression signatures in CLL and RT patients were also identified by Illumina-based RNA sequencing using Formalin-Fixed Paraffin-embedded (FFPE)-nodal tissue obtained by clinical biopsy (Tempus Labs; Chicago, IL). Results: The expression of PD-1 was significantly increased in RT-LN compared to CLL-LN (mean ± SEM in RT vs. CLL, 30.6% ± 4.7% vs. 11.5% ± 2.8%, p < 0.001) [Fig 1A]. PD-1 expression was highest in patients with RT where the last prior CLL therapy was ibrutinib. To test the role of PD-1 in lymphoma B-cells, its expression was assessed in lymphoma and CLL cell lines. The expression of PD-1 was found to be variable, but at very low-levels in lymphoma lines OCI-LY7 and OCI-LY19 (data not shown). Constitutive lentiviral (pLEX-PD-1)-mediated overexpression of PD-1 in OCI-LY7 and OCI-LY19 cells led to increased cell growth (1.4 and 1.9 fold compared to original lines on day 4, respectively, Fig 1BI-II), which was further confirmed by cell cycle analysis which showed an increase in S phase by 20.4% and 24.53% in OCI-LY7 and OCI-LY19 cells (Fig 1B III), respectively. When the luciferase + PD-1 expressing OCI-LY7 cells were injected intravenously (1X106 cells) into NSG mice, increased tumor growth was observed at 22 days of follow up by bioluminescence imaging (p<0.01, Fig 1C). Using phospho-kinase array, an overall decrease of phosphorylation was detected on multiple sites of p53 (S392, S15, S46) and CHK2 (T68) (data not shown). This finding was further confirmed by WB analyses (Fig1DI). In addition, decreased of total p53 and increased phosphorylation on both SHP-1 and SHP-2 were found in PD-1 overexpressing OCI-LY19 and OCI-LY17 cell lines (Fig 1DI). Immunoprecipitation experiments with anti-PD1 antibody showed that PD-1 was in the same complex with SHP-1 and SHP-2 in OCI-LY7 cells but only with SHP-2 in OCI-LY19 cells (Fig 1DII). In parallel, mRNA sequencing was performed on 11 nodal tissues from either RT (n=8) or progressive CLL (n=3) after they developed clinical progression. The expression of PD-1 (PDCD1) was positively correlated with the expression of SHP-1 (PTPN6, r=0.56) and Cyclin E1 (CCNE1, r=0.62), implicating a direct role of PD-1 in regulating cellular proliferation and the induction in phosphatase expression in RT and CLL. Conclusion: Our data support the notion that PD-1 overexpression in lymphoma cells modifies cell proliferation in vitro and in vivo and regulates the function of phosphatase SHP and p53- pathways. These findings also indicate that aggressive lymphoma or CLL leukemic cells have the ability to hijack the PD-1 pathway and may result in downregulation of the p53 mediated DNA repair. This novel information provide for new strategies to further evaluate the interaction of checkpoint signals with DNA repair pathway, and possibly provide novel targets for Richter's transformation. Disclosures Ding: alexion: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Astra Zeneca: Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; DTRM: Research Funding; MEI Pharma: Membership on an entity's Board of Directors or advisory committees. Sakemura:Humanigen: Patents & Royalties. Parikh:Janssen: Honoraria, Research Funding; Merck: Research Funding; Pharmacyclics: Honoraria, Research Funding; Ascentage Pharma: Research Funding; GlaxoSmithKline: Honoraria; MorphoSys: Research Funding; AstraZeneca: Honoraria, Research Funding; Verastem Oncology: Honoraria; Genentech: Honoraria; AbbVie: Honoraria, Research Funding; TG Therapeutics: Research Funding. Wang:Novartis: Research Funding; Incyte: Research Funding; Innocare: Research Funding. Liu:Eisal: Research Funding; Genentech: Research Funding; GRAIL: Research Funding; Menarini Silicon Biosystems: Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Tesaro: Research Funding. Braggio:DASA: Consultancy; Bayer: Other: Stock Owner; Acerta Pharma: Research Funding. Ansell:Seattle Genetics: Research Funding; Takeda: Research Funding; AI Therapeutics: Research Funding; ADC Therapeutics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Bristol Myers Squibb: Research Funding. Kenderian:Sunesis: Research Funding; Tolero: Research Funding; Torque: Consultancy; BMS: Research Funding; Gilead: Research Funding; Kite: Research Funding; Humanigen: Consultancy, Patents & Royalties, Research Funding; Mettaforge: Patents & Royalties; Novartis: Patents & Royalties, Research Funding; MorphoSys: Research Funding; Lentigen: Research Funding; Juno: Research Funding. Kay:Acerta Pharma: Research Funding; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Juno Theraputics: 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; Abbvie: Research Funding; MEI Pharma: Research Funding; Sunesis: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Agios Pharma: Membership on an entity's Board of Directors or advisory committees; Cytomx: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees.

INTRODUCTION Nearly 20% of patients (pts) are ≥ 80 years (yrs) of age at the time of CLL diagnosis. Increased medical comorbidities, as well as declining functional status and organ function, often accompany advanced age. However, clinical trials often enroll a disproportionally low number of people from this age demographic due to stringent eligibility parameters, which provides limited evidence to guide decisions. Here, we report clinical characteristics and outcomes of pts ≥ 80 yrs of age at the time of CLL diagnosis. METHODS Between 1/1995 and 3/2020, we identified previously untreated CLL pts from the Mayo Clinic CLL Database who were ≥ 80 yrs of age at the time of CLL diagnosis, and seen within 3 yrs of diagnosis. Baseline characteristics, treatments administered, and time to first treatment (TFT) were analyzed for all pts. Overall survival (OS) was measured from diagnosis date in all pts and separately from treatment date for treated pts. Time to next treatment (TTNT) was measured in treated pts from first treatment date to date of second treatment or last known treatment. TFT and TTNT were analyzed accounting for competing risk of death. Standardized mortality ratio (SMR) compared observed survival to survival in a Minnesota population. Cox multivariable regression models were used to determine which factors were associated with OS (treatment as a time-dependent covariate) and TTNT (accounting for competing risk of death). RESULTS Among the 213 pts identified, the median age was 83 yrs (range 80-97); baseline characteristics are summarized in Table 1. The median number of medical comorbidities among all pts was 4 (range 0-8). At least 1 comorbidity was present in 97% of pts, most commonly hypertension (57%), genitourinary (n=48%), rheumatological (46%), and dyslipidemia (n=43%). Median follow-up was 3.8 yrs. A total of 56 pts received treatment and the median TFT was 6.7 yrs. Over this 25 year interval, the treatment approaches included monoclonal antibody alone (n=17), chemotherapy alone (n=17), or chemoimmunotherapy (n=14), novel agents (n=3), and multi-agent Richter's transformation regimens (n=5). Chlorambucil-based treatments (chlorambucil n=13, chlorambucil, prednisone n=3) were the most frequently used chemotherapy regimens. The most common chemoimmunotherapy regimens included rituximab, cyclophosphamide, prednisone (RCP) with (n=3) or without vincristine (n=6), and chlorambucil with an anti-CD20 monoclonal antibody (n=4; obinutuzumab n=2, rituximab n=2). Among 17 pts who received monoclonal antibody alone, treatments included rituximab alone (n=11), rituximab plus methylprednisolone (n=2), obinutuzumab (n=2), and rituximab with alemtuzumab (n=2). Frontline novel agent treatments included ibrutinib alone (n=1), acalabrutinib alone (n=1), and ibrutinib, obinutuzumab, venetoclax (n=1). Five pts with Richter's transformation (diagnosed concurrent with CLL n=4) received multi-agent chemotherapy. Among the 56 treated pts, 22 pts received second line therapy after a median TTNT of 2.8 yrs from start of first therapy. The most common second line treatments were chlorambucil-based (n=6) and rituximab-based (n=6) regimens. Age, sex, absolute lymphocyte count, del17p, and unmutated IGHV were not predictive of TTNT. The median OS among all 213 pts was 4.6 yrs. SMR was 1.2 (p=0.008) when excluding pts with Richter's transformation. In univariable analyses, receipt of therapy (HR 3.92, 95%CI 2.11-7.28; p<0.001), age (per 5 year increase; HR 1.84, 95%CI 1.43-2.38; p<0.001) and unmutated IGHV (HR 2.03, 95%CI 1.12-3.67; p=0.02) were predictors of shorter OS. The OS among pts who received treatment (Figure 1) was similar when compared across time periods of treatment start year grouped as 1995-2001 (n=10), 2002-2013 (n=32), and 2014-2020 (n=14). Treatment categories by time period are shown in Table 2. CONCLUSIONS In this study of 213 pts ≥ 80 yrs of age at time of CLL diagnosis, the median time to first therapy was ~7 yrs. Although survival outcomes did not differ by era across the 25-year span of this study, pts treated with novel agents were underrepresented and are a patient population which warrants additional evaluation. The finding that pts with CLL in this cohort had a 20% higher risk of death compared to an age- and sex-matched population emphasize the need for ongoing efforts to improve clinical outcomes for CLL pts in this demographic category. Disclosures Kenderian: Torque: Consultancy; Mettaforge: Patents & Royalties; Humanigen: Consultancy, Patents & Royalties, Research Funding; Novartis: Patents & Royalties, Research Funding; Kite: Research Funding; Gilead: Research Funding; Juno: Research Funding; BMS: Research Funding; Tolero: Research Funding; Sunesis: Research Funding; MorphoSys: Research Funding; Lentigen: Research Funding. Wang:Incyte: Research Funding; Innocare: Research Funding; Novartis: Research Funding. Shanafelt:Genentech, Pharmacyclics LLC, an AbbVie Company, AbbVie, GlaxoSmithKline, and Merck: Research Funding; Mayo Clinic: Patents & Royalties: and other intellectual property. Braggio:DASA: Consultancy; Bayer: Other: Stock Owner; Acerta Pharma: Research Funding. Kay:Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Juno Theraputics: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees; Cytomx: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; MEI Pharma: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Agios Pharma: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Research Funding; Dava Oncology: Membership on an entity's Board of Directors or advisory committees. Ding:alexion: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Astra Zeneca: Research Funding; Beigene: Membership on an entity's Board of Directors or advisory committees; DTRM: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding. Parikh:Merck: Research Funding; AstraZeneca: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; MorphoSys: Research Funding; Pharmacyclics: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Ascentage Pharma: Research Funding; Genentech: Honoraria; Verastem Oncology: Honoraria; GlaxoSmithKline: Honoraria; TG Therapeutics: Research Funding.

Background: Cytogenetic abnormalities detected by fluorescence in situ hybridization (FISH) are known to differentially impact prognosis in patients with chronic lymphocytic leukemia (CLL). Deletion6q23 (del6q23) has been reported in ~2-3% of CLL patients at diagnosis; however, its prognostic significance remains indeterminate. Methods: We identified previously untreated CLL patients from the Mayo Clinic CLL Database seen between 1/1995 - 2/2020 who had FISH performed. The clinical characteristics, concomitant cytogenetic abnormalities, time to first therapy (TTFT), and overall survival (OS) were compared between patients with del6q23 to those without this abnormality. TTFT was analyzed from FISH date until treatment or last known untreated date, accounting for competing risk of death. OS was analyzed using Kaplan-Meier methods from FISH date. In a matched (CLL-IPI risk score and sex) analysis, Cox regression analysis was used to determine the association between TTFT/OS and presence of del6q23. The Mayo Clinic IRB approved this study. Results: A total of 3101 CLL patients were identified; their median age at diagnosis was 64 years and 66% were male. Of these patients, 42 (1.3%) had evidence of del6q23 by FISH. Compared to patients without del6q23, patients with del6q23 carried a more adverse clinical and cytogenetic profile at the time of diagnosis including advanced Rai stage (22% Rai III/IV vs. 9% Rai III/IV; P = 0.002), unmutated IGHV genes (91% vs. 43%; P < 0.001), and high/very high risk CLL-IPI (50% vs. 27%; P < 0.001). Del6q23 was the sole abnormality in 13 patients (31%). Of the remaining patients, del6q23 was concomitantly present with del13q in 8 patients (19%), and with either del11q or del17p in 21 patients (50%). Of the 42 patients with del6q23, 29 received first line therapy: chemoimmunotherapy in 16 patients, BTK inhibitor in 7 patients, and an anti-CD20 monoclonal antibody alone in 6 patients. The median follow-up of the entire cohort was 7.3 years. The median TTFT in patients with del6q23 was 0.7 years while the 5-year OS was 76%. Patients with del6q23 demonstrated significantly shorter TTFT and reduced OS when compared to patients without del6q23 (Figures 1A and 1B). The shorter TTFT was also evident for patients with del6q23 compared to patients without del6q23 divided according to the Dohner risk category (Figure 2A), although there was no difference in OS between these groups of patients (Figure 2B). Because del6q23 patients were enriched for other unfavorable prognostic markers, we identified four control patients without del6q23, matched by CLL-IPI risk score and sex, to each treatment-naïve patient with del6q23. Patients with del6q23 showed a borderline statistically significant shorter TTFT (median 0.7 years versus 3.9 years; P = 0.07) and a nonsignificant association with OS (median 10.9 years versus 10.3 years; P = 0.28). Conclusion: Del6q23 by FISH in previously untreated CLL represents an uncommon abnormality. When compared to patients without del6q23, patients with del6q23 tend to have more adverse clinical and cytogenetic profiles at baseline, which likely confer a worse prognosis as reflected by shorter TTFT compared to patients without this abnormality. Figure Disclosures Ding: Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; DTRM: Research Funding; Beigene: Membership on an entity's Board of Directors or advisory committees; alexion: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Astra Zeneca: Research Funding. Wang:Novartis: Research Funding; Innocare: Research Funding; Incyte: Research Funding. Braggio:DASA: Consultancy; Bayer: Other: Stock Owner; Acerta Pharma: Research Funding. Kay:Sunesis: Research Funding; Abbvie: Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Theraputics: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Cytomx: Membership on an entity's Board of Directors or advisory committees; Agios Pharma: Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Research Funding; MEI Pharma: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Kenderian:Juno: Research Funding; Gilead: Research Funding; Lentigen: Research Funding; MorphoSys: Research Funding; Sunesis: Research Funding; Kite: Research Funding; Novartis: Patents & Royalties, Research Funding; Torque: Consultancy; Humanigen: Consultancy, Patents & Royalties, Research Funding; Mettaforge: Patents & Royalties; Tolero: Research Funding; BMS: Research Funding. Parikh:Ascentage Pharma: Research Funding; Merck: Research Funding; AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; TG Therapeutics: Research Funding; Pharmacyclics: Honoraria, Research Funding; GlaxoSmithKline: Honoraria; Janssen: Honoraria, Research Funding; MorphoSys: Research Funding; Genentech: Honoraria; Verastem Oncology: Honoraria.

Background: Allogeneic HCT continues to be the optimal consolidation strategy for many patients with AML. Cytogenetic and molecular abnormalities are known to influence post-transplant outcomes. We tested the prognostic ability of a modified (mELN) classification system based on available CIBMTR genetic data, to predict post-transplant outcomes. Methods: Adult patients with a diagnosis of AML in first complete remission (CR1) with available pre-transplant cytogenetic and molecular mutational data, receiving a first allogeneic HCT from 2013-2017, were included. Patients were stratified according to mELN genetic classification in three distinct groups: favorable (Fav), intermediate (IM) and adverse (Adv). Clinical outcomes following HCT were compared among groups after adjusting for significant patient, disease, and transplant-related variables. The primary endpoint was disease free survival (DFS). Secondary endpoints were overall survival (OS), non-relapse mortality (NRM), cumulative incidence of relapse, acute GVHD, and chronic GVHD. Cox proportional hazard models were used to compare endpoints among mELN risk groups, age groups and genetic subsets within the adverse-risk group. Results: Demographic characteristics are summarized in Table 1. 2289 patients (Fav, n=181; IM n=1185; and Adv n=923) met the inclusion criteria. Median follow-up for survivors was 35 months. Importantly, 41% of transplant recipients (n=936) were >60 years, 76% (n=1743) had de novo AML and 48% (n=1111) received a myeloablative conditioning regimen. Univariate analysis (UVA) demonstrated significant differences in 2-year OS (Fav: 67.7%, IM: 64.9% and Adv: 53.9%; p<0.001); DFS (Fav: 57.8%, IM: 55.5% and Adv: 45.3; p<0.001) and relapse (Fav: 28%, IM: 27.5% and Adv: 37.5%; p<0.001) There were no significant differences in NRM (p=0.467) or the incidence of acute (p=0.423) and chronic GVHD (p=0.442) among mELN groups. Initial multivariate analysis (MVA) of mELN risk groups indicated that there was no significant difference in clinical outcomes between the Fav and IM risk groups. Thus, these groups were combined for subsequent analyses. Adv risk (vs. Fav/IM) led to significantly worse OS (HR 1.39 [1.24-1.57] p=<0.001), DFS (HR 1.32 [1.18-1.48] p=<0.001), and relapse (HR 1.42 [1.23-1.63] p=<0.001) (Table 2). This mELN classification effectively stratified both younger (<60 y/o) and older (>60 y/o) patients for OS (Adv vs. Fav/IM HR for <60: 1.43 [1.21-1.69] p<0.001; >60: 1.44 [1.21-1.72] p<0.001), DFS (Adv HR for <60: 1.31 [1.12-1.53] p<0.001; >60: 1.41 [1.19-1.66] p<0.001) and relapse (Adv HR for <60: 1.44 [1.20-1.74] p<0.001, >60: 1.42 [1.15-1.76] p=0.001). NRM was higher for older patients (>60 y/o) in both the Fav/IM (HR 1.40 [1.10-1.78] p=0.007) and Adv-risk cohorts (HR 1.59 [1.18-2.13] p=0.002). Genetic subset comparisons within the adverse-risk group showed that patients carrying monosomy 5, del(5q) or monosomy 7 had inferior 2-year OS (42.6%, p<0.001) and DFS (35.2%, p<0.001), as well as higher rates of relapse (45%, p= 0.002) when compared to other patients within the Adv-risk cohort (OS 60%, DFS 50.8%, relapse 33.5%). Conclusion: Stratification using mELN criteria resulted in clear prognostic separation of OS, DFS and relapse in this large cohort of AML patients undergoing allogeneic HCT. While Fav and IM groups had similar OS, DFS and relapse rates; patients in the Adv risk group had the highest risk of relapse and inferior DFS/OS. However, the majority of patients in all cohorts had favorable outcomes for HCT in CR1. Our findings confirm the value of a combined genetic prognostic model in the AML HCT setting and justify the use of this stratification system in future HCT trials. Correlation of genetic subtypes with other important transplant variables, such as conditioning intensity and pre-transplant MRD status deserves further evaluation. There remains a subset of Adv-risk patients for which post-transplant outcomes continue to be poor, even when transplanted in CR1. Novel peri-transplant pre-emptive/therapeutic strategies are urgently needed for this high-risk cohort. Disclosures de Lima: Celgene: Research Funding; Pfizer: Other: Personal fees, advisory board, Research Funding; BMS: Other: Personal Fees, advisory board; Incyte: Other: Personal Fees, advisory board; Kadmon: Other: Personal Fees, Advisory board. Komanduri:Kiadis: Consultancy; Takeda: Consultancy; Celgene: Consultancy; Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees; Adaptimmune: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kebriaei:Ziopharm: Other: Research Support; Jazz: Consultancy; Kite: Other: Served on advisory board; Amgen: Other: Research Support; Novartis: Other: Served on advisory board; Pfizer: Other: Served on advisory board. Bhatt:National Marrow Donor Program: Research Funding; Rigel Pharmaceuticals: Other; Jazz: Research Funding; Agios: Other: Personal Fees; Incyte: Other: Personal Fees, Research Funding; Takeda: Other: Personal Fees; Partner Therapeutics: Other: Personal Fees; Pfizer: Other, Research Funding; CSL Behring: Other; Tolero Pharmaceuticals: Research Funding; Oncoceutics: Other: Drug support for a trial; Partnership for health analytic research, LLC: Other: Personal Fees; Omeros: Other: Personal Fees; Abbvie: Other: Personal Fees, Research Funding. Saad:Orcabio: Other: research support; Kadmon: Other: research support; Amgen: Other: research support; Incyte Pharmaceuticals: Other: Personal Fees; Magenta Therapeutics: Other: Personal Fees. Copelan:Amgen: Membership on an entity's Board of Directors or advisory committees. Defilipp:Incyte: Research Funding; Regimmune: Research Funding; Syndax Pharmaceuticals: Consultancy. Nishihori:Karyopharm: Other: Research support to institution; Novartis: Other: Research support to institution. Weisdorf:Incyte: Research Funding; FATE Therapeutics: Consultancy.

Background: Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy approved for pts with R/R LBCL with ≥ 2 prior systemic therapies. With a median follow-up of 27.1 months in ZUMA-1, the objective response rate (ORR) with axi-cel was 83% (58% complete response rate) in pts with refractory LBCL. Grade ≥ 3 cytokine release syndrome (CRS) and neurologic events (NEs) occurred in 11% and 32% of pts, respectively (Locke FL, et al. LancetOncol. 2019). Although CRS can be ameliorated with use of the anti-IL-6 receptor antibody tocilizumab, NEs may be unaffected or worsened by tocilizumab (Gust J, et al. Cancer Discov. 2017; Lee DW, et al. Blood. 2014; Santomasso BD, et al. Cancer Discov. 2018; Locke FL, et al. ASH 2017. #1547). Identification of mitigation strategies for NEs is complicated by a significant association between CAR T cell expansion and both ORR and Grade ≥ 3 NEs, suggesting a correlation between efficacy and adverse events (AEs; Neelapu SS, et al. N EnglJ Med. 2017). ZUMA-1 Cohort 4 suggested that earlier utilization of systemic corticosteroids for broad immune system suppression in pts with mild NEs and low-grade CRS may reduce the incidence of Grade ≥ 2 NEs without significant impact on efficacy (Topp MS, et al. ASH 2019. #243). However, this reactive approach has not fully abrogated NEs; as such, proactive strategies to further improve safety management with CAR T cell therapy without negatively impacting efficacy are needed. Upon tumor challenge, CAR T cells produce granulocyte-macrophage colony-stimulating factor (GM-CSF; Giavridis T, et al. Nat Med. 2018), which acts to promote myeloid activation, expansion, and cytokine production (Spath S, et al. Immunity. 2017). GM-CSF was among the cytokines significantly associated with Grade ≥ 3 NEs in ZUMA-1 (Neelapu SS, et al. N Engl J Med. 2017). Notably, peak GM-CSF levels occurred before those of most other cytokines, and no direct association was observed between GMCSF levels and ORR (Rossi JM, et al. EMA Workshop, 2016). These findings suggest that GM-CSF may initiate inflammatory events that cause NEs and that GM-CSF inhibition has the potential to improve the safety of CAR T cells, without impacting efficacy. GM-CSF depletion with lenzilumab, a humanized monoclonal antibody that neutralizes GM-CSF, prevented CRS and NEs in preclinical models of CAR T cell toxicity (Sterner RM, et al. Blood2019). The Phase 1/2 ZUMA19 study is evaluating sequenced therapy with lenzilumab and axi-cel to prevent axi-cel-related CRS and NEs in pts with R/R LBCL. Methods: Eligible pts are adults (≥ 18 y) with LBCL who relapsed after ≥ 2 systemic lines of therapy or are chemorefractory - defined as i) a best response of progressive disease (PD) or stable disease (SD) to ≥ 4 cycles of first-line systemic therapy (SD duration ≤ 6 months); or ii) a best response of PD or SD after ≥ 2 cycles of the most recent second-or-later line of systemic therapy. Prior therapy must have included an anti-CD20 monoclonal antibody and an anthracycline-containing regimen. Pts will undergo leukapheresis and may receive optional corticosteroid bridging therapy. Pts will then receive lymphodepleting chemotherapy on Days ‒3 to ‒5 followed by Day 0 administration of lenzilumab and, 6 hours later, a single infusion of axi-cel (target dose, 2 × 106 CAR T cells/kg). Phase 1 will initially enroll pts in 2 dose-escalation cohorts; each will receive a single infusion of lenzilumab. Safety data will be reviewed after 3 and 6 (if needed) pts in each cohort have been followed for 28 days. The recommended Phase 2 dose (RP2D) of lenzilumab will be based on the dose-limiting toxicity rate (phase 1 primary endpoint), and, if necessary, translational assessment of GM-CSF axis suppression. Phase 2 will assume a Simon 2-stage design. The primary endpoint for phase 2 is the incidence of Grade ≥ 2 NEs within 28 days of axi-cel administration. Efficacy, safety (including CRS and NEs), and blood levels of CAR T cells and cytokines (including GM-CSF) will be evaluated as secondary endpoints. An interim analysis will be performed when 14 subjects have received the RP2D in Phase 1 or 2 and are followed for ≥ 28 days after axi-cel infusion. If futility criteria are not met, enrollment will continue. Primary analysis will be performed after 30 pts are treated with RP2D of lenzilumab and have ≥ 6 months of follow up. ZUMA-19 is open and actively recruiting pts. Disclosures Kenderian: Mettaforge: Patents & Royalties; Humanigen: Consultancy, Patents & Royalties, Research Funding; Lentigen: Research Funding; MorphoSys: Research Funding; Sunesis: Research Funding; Tolero: Research Funding; BMS: Research Funding; Juno: Research Funding; Gilead: Research Funding; Kite: Research Funding; Novartis: Patents & Royalties, Research Funding; Torque: Consultancy. Oluwole:Bayer: Consultancy; Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Spectrum Pharmaceuticals: Consultancy. McCarthy:Genentech: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Juno Therapeutics, a Bristol-Myers Squibb Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board , Research Funding is to Roswell Park, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Karyopharm: Consultancy, Honoraria; Magenta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Starton: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board. Reshef:Celgene: Consultancy; Pharmacyclics: Research Funding; Shire: Research Funding; Bluebird: Research Funding; Kiadis: Research Funding; Monsanto: Consultancy; Takeda: Research Funding; Atara: Consultancy, Research Funding; Incyte: Research Funding; Bristol-Myers Squibb: Research Funding; Immatics: Research Funding; Gilead: Consultancy, Honoraria, Other: Travel support, Research Funding; Novartis: Honoraria; Magenta: Consultancy. Shiraz:Kite, a Gilead Company: Research Funding; ORCA BioSystems: Research Funding. Ahmed:Humanigen, Inc.: Current Employment, Current equity holder in publicly-traded company. Le Gall:Kite, a Gilead Company: Ended employment in the past 24 months; Gilead Sciences: Current equity holder in publicly-traded company. Nahas:Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Tang:Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company. Neelapu:Takeda Pharmaceuticals: Patents & Royalties; Cellectis: Research Funding; Calibr: Other; Precision Biosciences: Other: personal fees, Research Funding; Bristol-Myers Squibb: Other: personal fees, Research Funding; Merck: Other: personal fees, Research Funding; Kite, a Gilead Company: Other: personal fees, Research Funding; Acerta: Research Funding; Karus Therapeutics: Research Funding; Poseida: Research Funding; Cell Medica/Kuur: Other: personal fees; Incyte: Other: personal fees; Unum Therapeutics: Other, Research Funding; N/A: Other; Adicet Bio: Other; Legend Biotech: Other; Allogene Therapeutics: Other: personal fees, Research Funding; Pfizer: Other: personal fees; Celgene: Other: personal fees, Research Funding; Novartis: Other: personal fees.