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We observe previously unknown interactions between clinically important adenovirus vector capsids, platelet factor 4, and CAR.

AbstractThromboses are prevalent in POEMS syndrome, but few risk factors for POEMS‐associated thrombosis have been identified. The objective of this study is to identify novel risk factors for POEMS‐associated thrombosis. In this retrospective cohort of 230 POEMS patients, 27% developed thrombosis. Arterial events were slightly more common than venous. Stroke accounted for 26% of all thromboses and 53% of arterial events. There were differences in baseline features between the thrombosis group and the no thrombosis group, and these were driven by patients with arterial thrombosis. Risk factors for arterial thrombosis included thrombocytosis, elevated hemoglobin/hematocrit, extravascular volume overload, and splenomegaly. Hyperprolactinemia appeared to be a risk factor for venous thrombosis. The risk of thrombosis was most striking among men with elevated hemoglobin (32% vs. 5%, p < .001) and hematocrit (42% vs. 5%, p < .001) compared to men without. Most thromboses occurred prior to POEMS directed therapy, and most that occurred during therapy happened within 3 months of diagnosis. Twenty‐one percent of patients with thrombosis had recurrence. In recognition of high overall rates of thrombosis in this population, all patients with POEMS syndrome should receive prophylactic antiplatelet therapy, and clinicians should consider anticoagulation in patients with risk factors for POEMS‐associated thrombosis.

Abstract Background: There has been a steady improvement in the survival of patients with multiple myeloma (MM) due to better understanding of the pathophysiology, use of novel agents, and risk-adapted therapy. These improvements were largely observed in clinical trials and tertiary center populations and questions remain about the generalizability of these findings to patients in community settings. Here, we compared the experience of patients seen at Mayo Clinic, Rochester (MAYO) and those followed in the Surveillance, Epidemiology, and End Results Program (SEER), to gain a better understanding of current trends in survival. Methods: We studied all patients with MM diagnosed between 01/2004 and 12/2018 seen at MAYO and those followed in SEER (18 registry research data 2000-2018, 11/2020 submission). For comparison with SEER, MAYO patients who were alive at the end of SEER follow-up (12/31/2018) were censored. For the estimation of relative survival, patients alive at the end of 2019 were censored to align with the published United States general population rate tables. Overall survival (OS) estimates were calculated using the method described by Kaplan and Meier. Multivariable-adjusted proportional hazards regression models were used to assess the association between the 5-year interval of diagnosis and overall survival. Expected OS estimates were calculated based on United States general population rate tables from the Human Mortality Database using a conditional approach. Standardized mortality ratios (SMR) were calculated by dividing the number of observed deaths by the number of expected deaths in age- and sex-matched general United States population controls. Linear regression models were fit to test for trends in SMRs over time. Results: The median age at diagnosis was 3 years lower in patients seen at MAYO compared to patients followed in SEER. The proportion of patients 75 years and older at the time of diagnosis was higher in SEER (26.3%) compared to MAYO (15.3%). Median OS was 6.7 years (95% CI 6.3-7.1) for MAYO compared to 4.6 years (95% CI 4.5-4.7) in SEER (Figure 1). When stratifying OS by year of diagnosis (in 5-year-intervals: 2004-2008, 2009-2013, 2014-2018), improvements were seen in both patient populations over time, albeit to a greater extent in patients seen at MAYO (Figures 2 and 3). The results were consistent after adjusting for age and sex in both MAYO and SEER. There were improvements in OS across all three 5-year intervals and age groups in both patient populations. In MAYO, these improvements were most pronounced during the second 5-year interval for younger patients (&lt; 65 years) and more pronounced during the last 5-year interval for older patients (&gt; 65 years). In SEER, the improvements were more gradual across the three 5-year intervals, but it was noted that the relative improvements in younger patients were greater than in older patients during the last 5-year interval. Early mortality decreased over time in both patient populations: from 11% to 6% at MAYO and from 23% to 16% in SEER (Figure 4). To examine the observed improvements in the context of the survival trends of the general population, we stratified the SMRs by patient population, age at diagnosis, and year of diagnosis, and a lack of improvement in excess mortality was observed among older patients (&gt;75 years) in both populations over time (Figure 5). Three- and five-year overall survival estimates were higher in patients seen at MAYO compared to patients followed in SEER, but the survival advantage diminished with increasing follow-up time (Figure 6). On further sub-group analysis within MAYO patients, excess mortality was observed for all International staging system (ISS) stages and patients with high-risk (HR) cytogenetics. Stratifying the SMRs by age and risk group, decreases in excess mortality were most pronounced among older patients, particularly those with indolent disease (Figure 7). Conclusions: Survival outcomes in MM continued to improve in both patient populations. These improvements were more pronounced in MAYO compared to SEER, which may be partially explained by differences in access to specialized care. The most pronounced improvements were observed among younger patients and those with favorable disease characteristics. Future efforts need to focus on improving therapies for patients with unfavorable disease characteristics and on increasing access to specialized care in community settings. Figure 1 Figure 1. Disclosures Kapoor: Glaxo SmithKline: Research Funding; Takeda: Research Funding; Sanofi: Research Funding; Amgen: Research Funding; Sanofi: Consultancy; Pharmacyclics: Consultancy; Ichnos Sciences: Research Funding; BeiGene: Consultancy; Regeneron Pharmaceuticals: Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Karyopharm: Consultancy; Cellectar: Consultancy. Dingli: Alexion: Consultancy; Apellis: Consultancy; Janssen: Consultancy; Novartis: Research Funding; GSK: Consultancy; Sanofi: Consultancy. Gertz: Ionis Pharmaceuticals: Other: Advisory Board; Aurora Biopharma: Other: Stock option; AbbVie Inc, Celgene Corporation: Other: Data Safetly & Monitoring; Akcea Therapeutics, Ambry Genetics, Amgen Inc, Celgene Corporation, Janssen Biotech Inc, Karyopharm Therapeutics, Pfizer Inc (to Institution), Sanofi Genzyme: Honoraria; Akcea Therapeutics, Alnylam Pharmaceuticals Inc, Prothena: Consultancy. Lin: Novartis: Consultancy; Celgene: Consultancy, Research Funding; Juno: Consultancy; Takeda: Research Funding; Gamida Cell: Consultancy; Vineti: Consultancy; Merck: Research Funding; Bluebird Bio: Consultancy, Research Funding; Legend: Consultancy; Sorrento: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Dispenzieri: Sorrento Therapeutics: Consultancy; Janssen: Consultancy, Research Funding; Takeda: Research Funding; Oncopeptides: Consultancy; Alnylam: Research Funding; Pfizer: Research Funding. Kumar: Tenebio: Research Funding; Amgen: Consultancy, Research Funding; Oncopeptides: Consultancy; Bluebird Bio: Consultancy; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche-Genentech: Consultancy, Research Funding; Beigene: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Carsgen: Research Funding; Antengene: Consultancy, Honoraria; BMS: Consultancy, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding.

Abstract Background CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don't eat me" signal to suppress macrophage phagocytosis. Overexpression of CD47 can allow tumor cells to escape immune surveillance. TTI-621 (SIRPαFc) is a fusion protein consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1, designed to enhance phagocytosis and antitumor activity by blocking the CD47-SIRPα interaction between malignant cells and macrophages, and engaging Fcγ receptors. Here we report updates from the dose optimization part of the first-in-human study of TTI-621 (NCT02663518), testing dose levels between 0.5-2.0 mg/kg in patients with cutaneous T-cell lymphoma (CTCL). Methods This study has been conducted in 4 parts. Part 1 tested increasing weekly intravenous doses of TTI-621 based on 3+3 escalation. The maximum tolerated dose was initially determined to be 0.2 mg/kg based on dose limiting toxicity (DLT) of thrombocytopenia [defined as Grade (Gr) 4 of any duration]. Expanded testing followed in patients with hematologic malignancies. In Part 2, most patients received 0.2 mg/kg; however, based on investigator discretion, a subset of patients received escalating doses up to 0.5 mg/kg. In Part 3, patients with T-cell lymphomas received stepwise dose escalations from 0.2 to 0.5 mg/kg over the first 5−8 weeks. Part 4 (dose optimization) of this study, is currently ongoing with weekly TTI-621 treatment escalating in a standard 3+3 manner through 5 planned dose levels including 0.5, 0.7, 1, 1.4, and 2 mg/kg. Dose optimization is being assessed in patients with CTCL. The DLT criteria was modified to require Gr 4 thrombocytopenia lasting &gt;72 hours. Safety monitoring includes weekly clinical laboratories and assessments of adverse events (AEs) per CTCAE v 4.03. Blood samples are obtained for pharmacokinetics and disease assessments are performed per Olsen's criteria. Results In Parts 1−3 (n=214), the most common related AEs were infusion-related reaction (IRR, 43%; 3% Gr ≥3), thrombocytopenia (30%; 22% Gr ≥3), chills (22%; 0% Gr ≥3), and fatigue (16%; 1% Gr ≥3). Objective responses to single agent TTI-621 were achieved in 14/71 (20%) NHL pts including CTCL (n=42, 1 CR, 7 PRs), PTCL (n=22, 2 CRs, 2 PRs) and DLBCL (n=7, 1 CR, 1 PR). In Part 4 as of April 12, 2021, 24 patients (17M/7F, median age 65 years) have enrolled into the 5 dose cohorts including 9 patients in the 2.0 mg/kg dose level. CTCL subtypes enrolled include mycosis fungoides (MF, n=18) and Sézary syndrome (SS, n=6). Disease stage was advanced (≥IIB) in 16 (67%) patients and a median of 3 (range 1−12) prior systemic therapies were received. Related AEs occurred in 19 (79%; 33% Gr ≥3) patients including infusion-related reaction (IRR, 50%; 13% Gr ≥3), thrombocytopenia (33%; 25% Gr ≥3), and neutropenia and headache, (13%, 0% Gr ≥3, each). Thrombocytopenia generally occurred on dosing days, and typically recovered within 2-4 days. A total of 15 IRRs have occurred in 12 (50%) patients at all doses levels. Most IRRs occurred during initial infusions only and typically resolved within the day of occurrence. The occurrence of Gr 3 IRRs prompted the addition of corticosteroids to the pre-medication regimen which largely prevent their occurrence. Aside from IRRs and thrombocytopenia which was manageable, AEs were predominantly Gr ≤2. Pharmacokinetic results reveal continued dose-dependent increases in exposure. Objective responses have been observed in 4 of 20 (20%) evaluable patients to date, including 3 partial responses in 14 patients with MF and 1 complete response in 6 patients with SS. Treatment is ongoing in the patient who achieved CR (10+ months) and in 2 of 3 patients who achieved PR (3 and 4 months). A third patient who achieved PR elected to discontinue study treatment at 5 months to pursue allogeneic stem and progenitor cell transplantation. Conclusions Preliminary results from dose optimization testing indicate that weekly infusions of TTI-621 up to 2 mg/kg are generally well tolerated. In Part 4, an overall response rate of 20% has been observed thus far in patients with CTCL. Testing of TTI-621 in alternative dosing schedules is in progress. With demonstrated good tolerability and robust single agent antitumor activity in heavily pre-treated patients, additional testing of TTI-621 beyond relapsed/refractory lymphoma has started. Disclosures Horwitz: Affimed: Research Funding; ADC Therapeutics, Affimed, Aileron, Celgene, Daiichi Sankyo, Forty Seven, Inc., Kyowa Hakko Kirin, Millennium /Takeda, Seattle Genetics, Trillium Therapeutics, and Verastem/SecuraBio.: Consultancy, Research Funding; Acrotech Biopharma, Affimed, ADC Therapeutics, Astex, Merck, Portola Pharma, C4 Therapeutics, Celgene, Janssen, Kura Oncology, Kyowa Hakko Kirin, Myeloid Therapeutics, ONO Pharmaceuticals, Seattle Genetics, Shoreline Biosciences, Inc, Takeda, Trillium Th: Consultancy; Aileron: Research Funding; Celgene: Research Funding; C4 Therapeutics: Consultancy; Crispr Therapeutics: Research Funding; Daiichi Sankyo: Research Funding; Forty Seven, Inc.: Research Funding; Kura Oncology: Consultancy; Kyowa Hakko Kirin: Consultancy, Research Funding; Millennium/Takeda: Research Funding; Myeloid Therapeutics: Consultancy; ONO Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Research Funding; Secura Bio: Consultancy; Shoreline Biosciences, Inc.: Consultancy; Takeda: Consultancy; Trillium Therapeutics: Consultancy, Research Funding; Tubulis: Consultancy; Verastem/Securabio: Research Funding. Foran: pfizer: Honoraria; novartis: Honoraria; servier: Honoraria; bms: Honoraria; revolution medicine: Honoraria; taiho: Honoraria; syros: Honoraria; sanofi aventis: Honoraria; certara: Honoraria; gamida: Honoraria; OncLive: Honoraria; abbvie: Research Funding; boehringer ingelheim: Research Funding; takeda: Research Funding; trillium: Research Funding; aptose: Research Funding; actinium: Research Funding; kura: Research Funding; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Lue: Epizyme: Consultancy; TG Therapeutics: Consultancy; Kymera Therapeutics: Research Funding; AstraZeneca: Speakers Bureau; Kura Oncology: Consultancy. Sawas: Affimed: Research Funding; Roche: Current equity holder in publicly-traded company; Flat Iron Health: Current Employment; Seattle Genetics: Honoraria; Acrotech: Honoraria; Daiichi-Sankyo: Speakers Bureau; Seattle Genetics: Speakers Bureau; Gilead: Speakers Bureau. Feldman: Alexion, AstraZeneca Rare Disease: Honoraria, Other: Study investigator. Sokol: Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Mei: Janssen: Honoraria; EUSA: Honoraria; TG Therapeutics: Research Funding; Epizyme: Research Funding; BMS: Research Funding; Morphosys: Research Funding; Beigene: Research Funding. Flinn: AbbVie: Consultancy, Other: All Consultancy and 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; BeiGene: 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; Gilead Sciences: 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; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Janssen: Consultancy, Other: All consultancy and 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; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and 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; Seagen: Consultancy, Other: All consultancy and 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; TG Therapeutics: Consultancy, Other: All consultancy and 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; Verastem: 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; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All 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; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: 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; Curis: Other: All 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; Forty Seven: Other: All 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; Incyte: 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; Karyopharm Therapeutics: Other: All 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; Merck: Other: All 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; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola 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; Teva: Other: All 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. Villa: Janssen: Honoraria; Roche: Honoraria; Lundbeck: Honoraria; Celgene: Honoraria; Seattle Genetics: Honoraria; AbbVie: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria; NanoString Technologies: Honoraria. Percival: Pfizer: Research Funding; Abbvie: Research Funding; Biosight: Research Funding; BMS/Celgene: Research Funding; Cardiff Oncology: Research Funding; Glycomimetics: Research Funding; Nohla Therapeutics: Research Funding; Oscotec: Research Funding; Trillium: Research Funding. Savage: Seattle Genetics: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Other: Institutional clinical trial funding; Merck: Consultancy, Honoraria, Other: Institutional clinical trial funding; AbbVie: Consultancy, Honoraria; Astra-Zeneca: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Roche: Research Funding; Takeda: Other: Institutional clinical trial funding; Beigene: Other: Institutional clinical trial funding; Genentech: Research Funding. Diefenbach: Genentech, Inc./ F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; MEI: Consultancy, Research Funding; Gilead: Current equity holder in publicly-traded company; IMab: Research Funding; Celgene: Research Funding; Trillium: Research Funding; Incyte: Research Funding; AbbVie: Research Funding; Perlmutter Cancer Center at NYU Langone Health: Current Employment; IGM Biosciences: Research Funding. Kim: Kyowa Kirin: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Corvus: Membership on an entity's Board of Directors or advisory committees, Research Funding; Trillium: Research Funding; Galderma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elorac: Research Funding; Portola: Membership on an entity's Board of Directors or advisory committees, Research Funding; Soligenix: Research Funding; Eisai: Research Funding; CRISPR: Research Funding; Regeneron: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Secura Bio: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion, AstraZeneca Rare Disease: Other: Study investigator; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Horizon: Research Funding. Lin: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Catalano: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Petrova: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Uger: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Molloy: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Large: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Bruns: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding.

Abstract Introduction: Multiple gene expression profile assays have successfully prognosticated the overall survival (OS) outcomes of patients with Newly Diagnosed Multiple Myeloma (NDMM) and are now available for use in clinical practice. The genes included in these profiles encompass several aspects of cancer biology broadly such as cell-cycle biology, energy metabolism, migration, adhesion, immune evasion etc. Since altered energy metabolism is one of the hallmarks of all cancer cells, our goal was to take a deep-dive into specific genes associated with intracellular central carbon energy metabolism (CCEM) pathways such as oxidative phosphorylation (OxPhos) as well as glycolysis and lactate fermentation (Glyco-Lac) in MM cells to determine their impact on the pathogenesis and prognosis of MM patients. Methods: Gene expression level data via RNA sequencing from the COMMPASS dataset (made available by the Multiple Myeloma Research Foundation (MMRF)) was utilized. The expression levels of all genes associated with the OxPhos (N = 118) and Glyco-Lac (N = 34) pathways were evaluated in CD138+ cells derived from patients with NDMM. Each gene was dichotomized into low and high expression groups -based on their expression level above and below the median fragments per kilobase of transcript per million (FPKM), respectively. The prognostic significance of dichotomizing each of the 152 genes in this NDMM cohort was evaluated by levels of their hazard ratios (HRs) for OS determined by the log-rank method. Genes from the OxPhos and Glyco-Lac pathways were selected based on their significant negative impact on OS, wide representation of their biologic activity throughout the pathway and high independence from each other. This resulted in the selection of 12 distinct genes of interest. A scoring system consisting of assigning a point for every gene where their FPKM was above the median yielded a minimum of 0 and a maximum of 12 for the set of genes in the OxPhos and Glyco-Lac pathways to create an energy metabolism score (EMS). Patients were then categorized into "low" (0-8) or "high" (9-12) EMS groups. In addition, patients were designated as having high-risk cytogenetics if they had any of the following: t(4;14), t(14;16), t(14;20), del17p, and Amp 1q. Survival analysis was performed using the Kaplan-Meier survival analysis and compared via the log-rank method. Finally, the distribution of the EMS score among patients within a spectrum of plasma cell disorders such as, monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma and MM as well as normal plasma cells was assessed using a previously published transcriptome dataset (GSE6477). Results: A total of 766 patients were included in this study. The selected genes included in this scoring system and their biological relevance in the OxPhos and Glyco-Lac pathways are depicted in Figure A. The distribution of low and high EMS groups across ISS stage and cytogenetic risk are depicted in Figure B and C respectively. The median OS (mOS) and PFS for the high (N = 248) vs. low (N = 518) EMS groups was 55 vs. 94 months (HR: 2.41; (95%CI: 1.85-3.14); P &lt;0.0001) (Figure D) and 24 vs. 42 months (HR: 1.74; (95%CI: 1.42-2.13); P &lt;0.0001). Patients with ISS 2 stage disease categorized as having a high or low EMS score had a similar mOS to patients with ISS 3 and ISS 1 stage disease respectively (Figure E). Similarly, the mOS was similar among patients with standard risk and high-risk cytogenetics when categorized by low and high EMS (Figure F). Finally, the relative expression of most of the 12 select CCEM genes (Figure G) and the probability of a high EMS score increased among patients along the spectrum of plasma cell disorders (Normal plasma cell -&gt; MGUS -&gt; SMM -&gt; MM) (Figure H). Conclusions: The expression levels of specific genes associated with the activity of intracellular CCEM pathways such as glycolysis, lactate fermentation and oxidative phosphorylation in plasma cells provides evidence for the impact of cellular energy metabolism on the pathogenesis and survival outcomes of MM. This provides an opportunity for developing future studies aimed at understanding the energy metabolism pathways of plasma cell malignancies in greater detail so as to exploit them for diagnostic and therapeutic purposes in MM. Figure 1 Figure 1. Disclosures Kumar: Novartis: Research Funding; Amgen: Consultancy, Research Funding; Beigene: Consultancy; Carsgen: Research Funding; Merck: Research Funding; Antengene: Consultancy, Honoraria; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Consultancy; Roche-Genentech: Consultancy, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Tenebio: Research Funding; Bluebird Bio: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding. Dispenzieri: Alnylam: Research Funding; Sorrento Therapeutics: Consultancy; Oncopeptides: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Janssen: Consultancy, Research Funding. Kapoor: AbbVie: Research Funding; Takeda: Research Funding; Karyopharm: Consultancy; Cellectar: Consultancy; BeiGene: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Amgen: Research Funding; Ichnos Sciences: Research Funding; Regeneron Pharmaceuticals: Research Funding; Glaxo SmithKline: Research Funding; Karyopharm: Research Funding; Sanofi: Research Funding. Dingli: Apellis: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; GSK: Consultancy; Novartis: Research Funding; Alexion: Consultancy. Lin: Gamida Cell: Consultancy; Takeda: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Juno: Consultancy; Novartis: Consultancy; Legend: Consultancy; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Sorrento: Consultancy; Merck: Research Funding; Vineti: Consultancy. Gertz: Akcea Therapeutics, Ambry Genetics, Amgen Inc, Celgene Corporation, Janssen Biotech Inc, Karyopharm Therapeutics, Pfizer Inc (to Institution), Sanofi Genzyme: Honoraria; Aurora Biopharma: Other: Stock option; AbbVie Inc, Celgene Corporation: Other: Data Safetly & Monitoring; Ionis Pharmaceuticals: Other: Advisory Board; Akcea Therapeutics, Alnylam Pharmaceuticals Inc, Prothena: Consultancy. Fonseca: Aduro: Consultancy; Kite: Consultancy; Juno: Consultancy; Merck: Consultancy; Takeda: Consultancy; Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; AbbVie: Consultancy; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mayo Clinic in Arizona: Current Employment; Amgen: Consultancy; BMS: Consultancy; Celgene: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; GSK: Consultancy.

Abstract INTRODUCTION POEMS syndrome is a paraneoplastic disorder that results in multi-organ disease, and Vascular endothelial growth factor (VEGF) is associated with disease activity. There is evidence that the cytokine Interleukin- 6 (IL-6) stimulates VEGF production in several cancer cell lines. It has also been suggested that patients with POEMS syndrome experience symptoms improvement when IL-6 levels are low. Our study aims to understand the role of IL-6 and whether it is a contributor to disease activity in POEMS syndrome. METHODS We conducted a retrospective study of patients (pts) seen at Mayo Clinic within 1 year of diagnosis for POEMS syndrome with an IL-6 level within 3 months of diagnosis between 01/01/2011-05/31/2021 were included. Our database comprised 358 pts,7 were excluded because did not have official diagnosis of POEMS syndrome. Two hundred and ninety-nine pts did not have IL-6 testing within 90 days of diagnosis and were excluded. Clinical data was abstracted from our electronic medical record. Descriptive statistics were used for IL-6 levels. The majority of IL-6 laboratory testing for pts utilized the same reference range. A minority of pts had alternate reference ranges; thus, all IL-6 values and reference ranges were fold-corrected to have a unified reference to determine elevation in IL-6. High IL-6 was considered any value above the normal range, also analyzed pts in quartiles and deciles. Hematologic, VEGF and PET response criteria were utilized to group pts into responders or non-responders. Time to progression (TTP) and overall survival (OS) was calculated using the Kaplan Meier method. Differences between curves were by log rank. Statistical analysis was conducted via JMP software package (SAS, Cary, NC, USA). Univariate analysis was done to determine the prognostic value of IL-6. Statistical significance is considered with p-values &lt;0.05. RESULTS 52 patients from among 352 met criteria and were included for analysis. Twenty-one patients (40%) had elevated IL-6 levels (IQR 5.67, 22.6) at the time of diagnosis. The fold elevation about normal was typically not very high, with a median of 3.1-fold elevation (IQR 1.3, 4.4; and range 1.0, 8.3). The percentage of males in the high IL-6 versus the normal Il-6 group were 90% versus 65%, p=0.03. Compared to normal IL-6, those with elevated IL-6 values had more instances of hepatomegaly (43% vs 16%, p=0.03), ascites (28% vs 6%, p=0 .04), abnormal DLCO (26% vs 3%, p=0.03), mixed bone lesions (57% vs 29%, p= 0.04), and lower serum albumin (range 2.3-3.5 vs 2.5-4.5 g/dL, p=0.0008).There was a trend for lower VEGF values among the high IL-6 group, but this did not meet statistical significance (median 250 vs 438 pg/mL). There was no significant difference in the time to progression between pts with high versus normal IL-6 levels (HR 1.36; p=0.456). Overall survival was significantly longer in pts with normal IL-6 compared to pts with high IL-6 levels (Median OS 67.4 vs 47.8 months, p=0.02). Forty-two pts were evaluated for VEGF response after treatment; there was a significant improvement in time to progression (85.5 vs 14.9 months, p=0.03) in pts who were VEGF responders. Among pts evaluable for a hematologic response (n=15), time to progression in pts with baseline high IL6 was longer in hematologic responders compared to non-responders (p=0.02). Conclusion Although OS was longer for pts with normal IL-6, elevated IL-6 at the time of diagnosis does not prevent pts from achieving disease remission. The study demonstrates that response to treatment rather than interleukin-6 levels in pts with POEMS syndrome is more prognostic. This study is an important initial step into understanding the utility of IL-6 in POEMS syndrome. Figure 1 Figure 1. Disclosures Gertz: Akcea Therapeutics, Alnylam Pharmaceuticals Inc, Prothena: Consultancy; Aurora Biopharma: Other: Stock option; Ionis Pharmaceuticals: Other: Advisory Board; AbbVie Inc, Celgene Corporation: Other: Data Safetly & Monitoring; Akcea Therapeutics, Ambry Genetics, Amgen Inc, Celgene Corporation, Janssen Biotech Inc, Karyopharm Therapeutics, Pfizer Inc (to Institution), Sanofi Genzyme: Honoraria. Kumar: Oncopeptides: Consultancy; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Beigene: Consultancy; Merck: Research Funding; Antengene: Consultancy, Honoraria; Tenebio: Research Funding; Novartis: Research Funding; Roche-Genentech: Consultancy, Research Funding; Carsgen: Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bluebird Bio: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding. Dingli: GSK: Consultancy; Novartis: Research Funding; Janssen: Consultancy; Sanofi: Consultancy; Apellis: Consultancy; Alexion: Consultancy. Lin: Janssen: Consultancy, Research Funding; Merck: Research Funding; Novartis: Consultancy; Legend: Consultancy; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Vineti: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Sorrento: Consultancy; Gamida Cell: Consultancy; Takeda: Research Funding. Kapoor: Karyopharm: Consultancy; Cellectar: Consultancy; BeiGene: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Amgen: Research Funding; Ichnos Sciences: Research Funding; Regeneron Pharmaceuticals: Research Funding; Glaxo SmithKline: Research Funding; Karyopharm: Research Funding; Sanofi: Research Funding; Takeda: Research Funding; AbbVie: Research Funding. Dispenzieri: Pfizer: Research Funding; Sorrento Therapeutics: Consultancy; Oncopeptides: Consultancy; Alnylam: Research Funding; Takeda: Research Funding; Janssen: Consultancy, Research Funding.

Abstract Multiple myeloma (MM) cells are characterized by cell cycle dysregulation, epigenetic heterogeneity, and perturbation of the transcriptional landscape. We have previously shown that chemical and genetic perturbation of transcriptional regulator CDK7 significantly and selectively impacted MM cell growth and viability, supporting it as a pharmacologically relevant target for MM. Indeed, selective CDK7 inhibitor YKL-5-124 was active against a large panel of MM cell lines and primary MM cells, with a significantly lower IC50 compared to PHA-activated normal donor peripheral blood mononuclear cells (PBMCs). The efficacy of YKL-5-124 was confirmed in vivo in several murine models of MM, including disseminated models. Gene expression analysis after CDK7 inhibition in several MM cell lines revealed that transcripts for only a subset of genes were substantially affected by treatment with low dose of YKL-5-124, showing a strong leading-edge enrichment for downregulation of E2F expression program, cell cycle, DNA damage, and MYC targets. We have indeed confirmed a potent reduction in phosphorylation of RB protein, with consequent decrease of E2F activity in MM cells, supporting CDK7 as a central hub in the oncogenic CDK-pRb-E2F pathway in MM cells, with its expression and activity positively correlated with E2F transcriptional output in patient MM cells. Importantly, dual inhibition with low doses of YKL-5-124 and BRD4 inhibitor JQ1, displayed superior activity against a panel of MM cell lines and primary MM cells compared to single perturbation alone by both converging on a subset of key SE-associated dependencies as well as impacting distinct oncogenic expression programs. To identify synthetically lethal targets and mechanisms of resistance to CDK7 inhibition, we performed a genome-wide CRISPR-Cas9 knockout screen in the MM1S cells treated with YKL-5-124 or DMSO. We found that BCL6, NFKBIA and B, TRAF2, TSC1 and CSNK2A1, a subunit of CK2, were top synthetically lethal hits; whereas deletion of RB1, SF3B3 and the DNA-binding transcriptional activator TADA2A that regulates RNA-pol II transcription, led to resistance to YKL-5-124. Molecular mechanisms of intrinsic and acquired resistance to CDK7 inhibition are now under investigation and will be presented. In conclusion, our study demonstrates CDK7 as an attractive molecular vulnerability in MM that can be exploited therapeutically alone or in combination. Disclosures Shirasaki: FIMECS: Consultancy. Chesi: Novartis: Consultancy, Patents & Royalties: human CRBN transgenic mouse; Pfizer: Consultancy; Pi Therapeutics: Patents & Royalties: Genetically engineered mouse model of myeloma; Abcuro: Patents & Royalties: Genetically engineered mouse model of myeloma; Palleon Pharmaceuticals: Patents & Royalties: Genetically engineered mouse model of myeloma. Anderson: Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Pfizer: 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; Celgene: Membership on an entity's Board of Directors or advisory committees; Scientific Founder of Oncopep and C4 Therapeutics: Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mitsiades: Arch Oncology: Research Funding; Karyopharm: Research Funding; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Ionis Pharmaceuticals: Consultancy, Honoraria; Abbvie: Research Funding; FIMECS: Consultancy, Honoraria; Nurix: Research Funding; Sanofi: Research Funding; Novartis: Research Funding; H3 Biomedicine: Research Funding; EMD Serono: Research Funding; Janssen/Johnson & Johnson: Research Funding; Fate Therapeutics: Consultancy, Honoraria; BMS: Research Funding; TEVA: Research Funding. Munshi: Novartis: Consultancy; Legend: Consultancy; Pfizer: Consultancy; Adaptive Biotechnology: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Abbvie: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; Bristol-Myers Squibb: Consultancy.

Abstract Introduction. About 60% of patients with large B-cell lymphoma (LBCL) relapse after standard of care (SOC) anti-CD19 autologous chimeric antigen receptor (CAR) T-cell therapy, CD19 downregulation representing a major mechanism of resistance. Therefore, agents able to target B-cell antigens other than CD19 could be clinically effective for these patients. Polatuzumab vedotin (PV) is an antibody-drug conjugate targeting CD79b, and approved by the FDA in combination with bendamustine and rituximab for patients with relapsed or refractory (r/r) LBCL. Patients who relapsed after CAR T-cell therapy were not included in the registration study, and reports of PV use after CAR T-cells in real world practice are very limited. Methods. This is a multi-center retrospective analysis of patients with LBCL who relapsed after SOC CAR T-cell therapy and subsequently received SOC PV with or without rituximab and bendamustine between 07/2019 and 04/2021. PV was given at the standard dose of 1.8 mg/kg IV every 3 weeks in all patients (except for one patient, who received 1.4 mg/Kg). Response to treatment and progression were defined according to 2014 Lugano criteria. Survival curves were calculated using Kaplan-Meier estimates, and were compared between subgroups using the log-rank test. Cox regression was used for multivariate analysis (MVA). Results. Fifty-four patients were included in the study: median age was 59 (range, 22-79 years), 38 (70%) were male, and 30 (56%) had an internal prognostic index score &gt; 3. Median number of systemic therapies before CAR T-cell therapy was 2 (range, 2-6), 16 (30%) patients previously had autologous stem cell transplant (SCT), and 2 (4%) had allogeneic SCT. Sixteen (30%) patients were primary refractory to CAR T-cell therapy, and median time from CAR T-cell therapy to PV was 5 months (range, 1-40 months). CD19 status at time of relapse after CAR T-cell therapy was assessed by immunohistochemistry and/or flow cytometry in 41 patients, and positive in 34 (83%); CD79b status was assessed in 14 patients, and positive in all cases (100%). Thirty-two (59%) patients received PV-based therapy immediately after CAR T cell therapy, while 22 (41%) had intervening treatments (median 1, range 1-5). At time of PV initiation, median absolute neutrophil count was 2.9 (range 0.5-19 X10 9/L), median platelet count was 87 X10 9/L (range 15-437 X10 9/L), median serum creatinine was 0.9 mg/dL (range 0.4-22 mg/dL), and 44 (81%) patients had elevated serum lactate dehydrogenase (LDH). The median number of PV cycles was 2 (range, 1-16): PV was combined with rituximab in 51 (94%) patients, and administered with bendamustine in 33 (61%). A response was achieved in 24 (45%) patients, including complete remission (CR) in 8 (14%) patients and partial remission in 16 (30%)(Figure A), with a median duration of response of 11 weeks (95%CI, 5-17 weeks). No significant association between baseline characteristics and response was observed. To date, 49 (91%) patients stopped PV: 38 (70%) due to progression, 7 (13%) because of CR/patient decision, 3 (6%) to proceed to allogeneic SCT, and 1 (2%) to proceed to an immunotherapy clinical trial (despite absence of progression). No patients stopped therapy because of toxicity. After a median follow up of 45 weeks (95% CI, 20-70 weeks), 44 (81%) patients progressed/died, and median PFS was 9 weeks (95% CI, 4-14 weeks). To date, 34 (63%) died, and median OS was 16 weeks (95% CI, 13-19 weeks)(Figure B). Causes of death included progression in 31 patients and transplant-related complications in 3. On univariate analysis, a shorter median progression-free survival (PFS) was observed for patients with bone marrow (BM) involvement (3 vs 10 weeks, p=0.002), prior central nervous system involvement (4 vs 10 weeks, p=0.02), and elevated LDH (6 months vs not reached, p=0.004). On MVA, the association was maintained only for BM involvement (hazard ratio [HR] 4.8; 95% confidence interval [CI] 1.6-12.5, p=0.004) and elevated LDH (HR 5; 1.4-16.7, p=0.01)(Figure C). Discussion. PV is safe and effective, but has short duration of response in r/r LBCL after anti-CD19 CAR T-cell therapy, except for patients with normal LDH. Studies aimed at better characterizing intrinsic mechanism of resistance, including upregulation of BCL2 family proteins, to favor the development of more effective PV-based combination strategies for these patients, are warranted. Figure 1 Figure 1. Disclosures Crombie: Roche: Research Funding; Merck: Research Funding; Abbvie: Research Funding; Bayer: Research Funding; Karyopharm: Consultancy; Incyte: Consultancy. Kamdar: Celgene (BMS): Consultancy; Adaptive Biotechnologies: Consultancy; Genentech: Research Funding; Kite: Consultancy; AstraZeneca: Consultancy; ADC Therapeutics: Consultancy; Genetech: Other; TG Therapeutics: Research Funding; SeaGen: Speakers Bureau; Celgene: Other; KaryoPharm: Consultancy; AbbVie: Consultancy. Hess: ADC Therapeutics: Consultancy; BMS: Speakers Bureau. Neelapu: Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees. Lin: Novartis: Consultancy; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Gamida Cell: Consultancy; Sorrento: Consultancy; Legend: Consultancy; Takeda: Research Funding; Merck: Research Funding; Vineti: Consultancy. Strati: Astrazeneca-Acerta: Research Funding; Roche-Genentech: Consultancy.

Abstract Background: Patients with relapsed and refractory multiple myeloma (RRMM) who have triple class exposure to immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs) and anti-CD38 monoclonal antibodies (MoABs) have a poor prognosis and high unmet medical need. Ciltacabtagene autoleucel (cilta-cel) is a chimeric antigen receptor T-cell therapy which may offer long-term disease control for these patients. CARTITUDE-1 is an open-label, single arm phase 1b/2 clinical trial conducted to characterize the safety and efficacy of cilta-cel in adult patients with triple-class exposed RRMM. Since CARTITUDE-1 is a single-arm study, adjusted comparisons to other currently available therapies can provide valuable information on relative efficacy and safety benefits of cilta-cel over current real-world clinical practice (RWCP). LocoMMotion is the first prospective study of RWCP efficacy and safety outcomes in triple-class exposed patients with RRMM. It was designed a priori to serve as an external control cohort for CARTITUDE-1, using aligned inclusion criteria and endpoint definitions, to enable robust, high quality indirect comparisons vs. cilta-cel. Objective: To compare patient outcomes of cilta-cel vs. RWCP, including overall response rate (ORR), complete response or better rate (≥CR rate), progression-free survival (PFS) as assessed by a review committee and overall survival (OS) in patients with triple-class exposed RRMM. Methods: Individual patient level data available from both CARTITUDE-1 (clinical cut-off February 2021) and LocoMMotion (clinical cut-off March 2021) were pooled to conduct the comparative analyses. Imbalances between both cohorts on key prognostic baseline characteristics, including refractory status, ISS stage, time to progression on prior line, number of prior lines, average duration of prior lines, age, creatinine clearance, ECOG PS and MM type were adjusted for using inverse probability weighting. Average treatment effect on the treated (ATT) weights derived from propensity scores estimated using multivariable logistic regression modeling were applied to the LocoMMotion patients to have the weighted RWCP cohort reflecting the CARTITUDE-1 patient population. Balance between the ATT weighted RWCP cohort versus the CARTITUDE-1 population was evaluated based on reduction of standardized mean differences and overlap of propensity score distributions. Weighted logistic and Cox proportional hazards regression were used to estimate the relative treatment effects for cilta-cel vs. RWCP on binary endpoints (Odds ratios (OR), transformed into Response-rate Ratios (RR) and time to event endpoints (Hazard ratios (HR)), respectively. The base case analyses included all enrolled (apheresed) patients from CARTITUDE-1, reflecting an intention to treat approach. Additional analyses were conducted including only patients who received cilta-cel infusion compared to an aligned population of LocoMMotion where patients that progressed or died within 52 days were excluded from the LocoMMotion cohort. Results: 113 patients were enrolled in CARTITUDE-1, of which 97 were infused with cilta-cel. 246 patients were enrolled in LocoMMotion receiving RWCP in Italy (24%), Germany (15%), France (14%), UK (11%), Spain (10%), USA (9%), Belgium (5%), Poland (5%), Netherlands (4%) and Russia (3%). Therapies within the RWCP cohort were diverse and &gt;90 unique treatment regimens were used. The most frequent regimens were Kd (13.8%), PCd (12.6%) and Pd (11.0%). The weighted LocoMMotion population was well balanced with the CARTITUDE-1 cohort. Adjusted comparisons (Table 1) showed statistically significant improvements for cilta-cel vs. RWCP for ORR (RR=4.43), ≥CR (RR=568.92), PFS (HR=0.15) and OS (HR=0.38), all comparisons with p&lt;0.001. All additional analyses were consistent with these findings (Table 1). Conclusions: Outcomes for patients with triple-class exposed RRMM treated with RWPC observed in LocoMMotion are poor, illustrating the high unmet medical need. Adjusted comparisons vs. CARTITUDE-1 demonstrate significantly improved ORR, ≥CR, PFS and OS for cilta-cel compared to a diverse set of RWCP. These findings highlight cilta-cel's potential as a highly effective treatment option for patients with triple-class exposed RRMM. Figure 1 Figure 1. Disclosures Mateos: Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria; Sea-Gen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene - Bristol Myers Squibb: 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria; Amgen: 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; Janssen: 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; Bluebird bio: Honoraria; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Weisel: GSK: Consultancy, 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, Research Funding; Adaptive Biotechnologies: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: 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; Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria; Oncopeptides: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy; Novartis: Honoraria; Pfizer: Honoraria. Martin: Sanofi: Research Funding; Oncopeptides: Consultancy; Janssen: Research Funding; GlaxoSmithKline: Consultancy; Amgen: Research Funding. Berdeja: Celularity, CRISPR Therapeutics: Research Funding; Abbvie, Acetylon, Amgen: Research Funding; Bluebird bio, BMS, Celgene, CRISPR Therapeutics, Janssen, Kite Pharma, Legend Biotech, SecuraBio, Takeda: Consultancy; EMD Sorono, Genentech: Research Funding; GSK, Ichnos Sciences, Incyte: Research Funding; Lilly, Novartis: Research Funding; Poseida, Sanofi, Teva: Research Funding. Jakubowiak: Karyopharm: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Gracell: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Stewart: Oncopeptides: Honoraria; Janssen: Honoraria; GSK: Honoraria; BMS: Honoraria; Amgen: Honoraria; Skyline diagnostics: Consultancy; Genomcs England: Membership on an entity's Board of Directors or advisory committees; Tempus Inc.: Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees; PikSci Inc.: Current holder of individual stocks in a privately-held company, Patents & Royalties; Sanofi Aventis: Honoraria. Jagannath: Legend Biotech: Consultancy; Bristol Myers Squibb: Consultancy; Karyopharm Therapeutics: Consultancy; Janssen Pharmaceuticals: Consultancy; Takeda: Consultancy; Sanofi: Consultancy. Lin: Novartis: Consultancy; Bluebird Bio: Consultancy, Research Funding; Legend: Consultancy; Sorrento: Consultancy; Juno: Consultancy; Takeda: Research Funding; Celgene: Consultancy, Research Funding; Gamida Cell: Consultancy; Vineti: Consultancy; Merck: Research Funding; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Diels: Janssen: Current Employment. Ghilotti: Janssen-Cilag SpA, Cologno Monzese, Italy: Current Employment. Perualila: Janssen: Current Employment. Cabrieto: Janssen: Current Employment. Haefliger: Janssen-Cilag AG: Ended employment in the past 24 months; Cilag GmbH International: Current Employment. Erler-Yates: Janssen: Current Employment. Hague: Janssen: Current Employment, Current equity holder in publicly-traded company. Jackson: Janssen: Current Employment; Memorial Sloan Kettering Cancer Center: Consultancy. Strulev: Janssen Pharmaceutica NV: Current Employment. Nesheiwat: Legend Biotech USA: Current Employment. Pacaud: Legend Biotech: Current Employment. Moreau: Janssen: Honoraria; Celgene BMS: Honoraria; Amgen: Honoraria; Sanofi: Honoraria; Abbvie: Honoraria; Oncopeptides: Honoraria. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding.