HIGH RESPONSES RATES WITH SINGLE AGENT BELANTAMAB MAFODOTIN IN RELAPSED SYSTEMIC AL AMYLOIDOSIS

Background: Systemic AL amyloidosis is an incurable relapsing plasma cell disorder. Despite therapeutic advances, there are no approved treatments for relapse disease. Treatment is often challenging due to underlying organ dysfunction. Belantamab mafodotin is an antibody-drug conjugate targeting B-cell maturation antigen with approval for relapsed refractory myeloma. In multiply pre-treated myeloma, the DREAMM-2 phase II trial showed an overall response rate of 32% for those with 2.5 mg/kg dose administered every three weeks with 2/3rd patients reporting keratopathy. A small case series of 6 patients with relapsed AL amyloidosis (Zhang et al , ASH 2021) was recently reported and a phase 2 trial is recruiting for patients with refractory amyloidosis (NCT04617925). Aims: We report our initial results using Belantamab monotherapy for the treatment of patients with AL amyloidosis with relapsed disease. Methods: Data for consecutive patients who were administered Belantamab at a specialist referral centre, National Amyloidosis Centre, University College London, was analysed. Results: Eleven patients were included 8 male, 3 female. Median age at Belantamab initiation was 65 (range 42-74) years. Eight patients had λ AL-type and three κ AL-type. At diagnosis, median involved free light-chain concentration was 534 (range 73-7181) mg/l. A median of two organs involved at baseline (range 1-3): 4 had cardiac involvement (half Mayo stage 2;half Mayo stage 3a) and 8 had renal involvement. The median prior lines of therapy was 3 (range 2-5) with all exposed to prior immunomodulatory drugs, proteasome inhibitors and 73% to anti-CD38 antibody treatments. Thirty-six percent had relapsed after melphalan-conditioned autologous stem cell transplantation. A median of 3 cycles of belantamab were delivered (range 1-8). The most frequent adverse event was ocular toxicity which was experienced in 8 patients (grade 1-3), necessitating dose modification of the three-weekly schedule. One patient developed transient grade 1 dyspnoea and liver dysfunction. No patients developed cytopenias, unlike previous reports (Zhang et al , 2021), nor infections beyond COVID (2 patients mild with no hospital admissions). The majority of the cohort required dose reduction either at initiation (patient 4, due to end stage renal failure;patient 11, post-renal transplant) or during therapy (n=5;three to 1.9mg/kg, two to 1.25mg/kg) due to ocular toxicity. Only one patient remained on the standard dose of 2.5mg/kg for >3 cycles. Ocular toxicity improved after treatment interruption (drug intervals 4-6 weeks) and no patients required complete treatment cessation. One patient is too early to assess response. Haematological responses (PR or better) were seen in 7 patients with 3 complete responses and two very good partial responses (VGPR) which are ongoing. Both renal patients (patients 4 and 11) commenced a dose of 1.25mg/kg and sustained a VGPR with no additional toxicity. Patient 3 had a 42% reduction in sFLC after two doses but then a prolonged gap due to keratopathy and has lost the response. There were no cardiac or renal toxicities observed. Summary/Conclusion: Belantamab mafodotin demonstrates significant activity in patients with heavily pre-treated AL amyloidosis with 70% achieving a ≥PR. Apart from keratopathy requiring dose modification, no other substantial toxicity was observed. Two patients with renal impairment (stage V CKD and ESRD) and one patient post-renal transplant tolerated treatment with no additional toxicity. Belantamab mafodotin shows promise in treatment of relapsed AL and needs further prospective trials.

CILTACABTAGENE AUTOLEUCEL IN LENALIDOMIDE-REFRACTORY PATIENTS WITH PROGRESSIVE MULTIPLE MYELOMA AFTER 1-3 PRIOR LINES OF THERAPY: CARTITUDE-2 BIOLOGICAL CORRELATIVE ANALYSES AND UPDATED CLINICAL DATA

Background: Cohort A of the multicohort phase 2 CARTITUDE-2 (NCT04133636) study is assessing ciltacabtagene autoleucel (cilta-cel), a B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell (CAR-T) therapy, in patients with multiple myeloma (MM) who received 1-3 prior lines of therapy (LOT) and were refractory to lenalidomide (len). This population is difficult to treat and has poor prognosis. Aims: To present updated results from CARTITUDE-2 Cohort A. Methods: All patients provided informed consent. Eligible patients had progressive MM after 1-3 prior LOT that included a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD). Patients were len-refractory and had no prior exposure to BCMA-targeting agents. Patients received a single cilta-cel infusion (target dose: 0.75×106 CAR+ viable T cells/kg) after lymphodepletion. Cilta-cel safety and efficacy were assessed. The primary endpoint was minimal residual disease (MRD) negativity at 10-5 by next generation sequencing. Patient management strategies were used to reduce the risk of movement and neurocognitive adverse events (MNTs). Other assessments included pharmacokinetic (PK) analyses (Cmax and Tmax of CAR+ T-cell transgene levels in blood), levels of cytokine release syndrome (CRS)-related cytokines (e.g., IL-6) over time, peak levels of cytokines by response and CRS, association of cytokine levels with immune effector cell-associated neurotoxicity syndrome (ICANS), and CAR+ T cell CD4/CD8 ratio by response, CRS, and ICANS. Results: As of January 2022 (median follow-up: 17.1 months [range: 3.3-23.1]), cilta-cel was administered to 20 patients (male: 65%;median age: 60 years [range: 38-75]). Median number of prior LOT was 2 (range: 1-3);median time since MM diagnosis was 3.5 years (range: 0.7-8.0). 95% of patients were refractory to their last LOT;40% were triple-class refractory. Overall response rate was 95%, with 90% of patients achieving ≥complete response and 95% achieving ≥very good partial response. Median time to first response was 1.0 month (range: 0.7-3.3);median time to best response was 2.6 months (range: 0.9-13.6). All MRD-evaluable patients (n=16) achieved MRD negativity at 10-5. Median duration of response was not reached. The 12-month progression-free survival rate was 75% and the 12-month event-free rate was 79%. CRS occurred in 95% of patients (grade 3/4: 10%), with a median time to onset of 7 days (range: 5-9) and median duration of 3 days (range: 2-12). 30% of patients had neurotoxicity (5 grade 1/2 and 1 grade 3/4). ICANS occurred in 3 patients (15%;all grade 1/2);1 patient had facial paralysis (grade 2). No MNTs were observed. 1 death due to COVID-19 occurred and was assessed as treatment-related by the investigator;2 deaths due to progressive disease and 1 due to sepsis (not related to treatment) also occurred. Based on preliminary PK analyses of CAR transgene by qPCR, peak expansion of CAR-T cells occurred at day 10.5 (range: 8.7-42.9);median persistence was 153.5 days (range: 57.1-336.8). Summary/Conclusion: A single cilta-cel infusion led to deepening and durable responses at this longer follow-up (median 17.1 months) in patients with MM who had 1-3 prior LOT and were len-refractory. Follow-up is ongoing. We will present updated and detailed PK, cytokine, and CAR-T subset analyses as well as clinical correlation to provide novel insights into biological correlates of efficacy and safety in this difficult-to-treat patient population, which is being further evaluated in the CARTITUDE-4 study (NCT04181827;enrollment concluded).

TALQUETAMAB, A G PROTEIN-COUPLED RECEPTOR FAMILY C GROUP 5 MEMBER D X CD3 BISPECIFIC ANTIBODY, IN PATIENTS WITH RELAPSED/REFRACTORY MULTIPLE MYELOMA (RRMM): UPDATED PHASE 1 RESULTS FROM MONUMENTAL-1

G protein-coupled receptor family C group 5 member D (GPRC5D) has limited expression in healthy human tissue but is highly expressed in malignant plasma cells, making it a promising target for immunotherapy approaches for MM. Talquetamab (JNJ-64407564) is a first-in-class bispecific antibody that binds to both GPRC5D and CD3 receptors to redirect T cells to kill MM cells. Updated and new results of talquetamab at the recommended phase 2 doses (RP2Ds) are reported (NCT03399799). Eligible patients had RRMM or were intolerant to standard therapies. Patients who were previously treated with B-cell maturation antigen (BCMA)-directed therapies were eligible. This analysis focuses on patients who received talquetamab subcutaneously (SC;range: 5.0-800 μg/kg) weekly (QW) or biweekly (Q2W) with step-up dosing. The primary objectives were to identify the RP2D (part 1) and assess talquetamab safety and tolerability at the RP2Ds (part 2). Adverse events (AEs) were graded by CTCAE v4.03;cytokine release syndrome (CRS) was graded per Lee et al 2014 criteria. Responses were investigator-assessed per IMWG criteria. As of July 19, 2021, 95 patients had received SC talquetamab. The original RP2D was 405 μg/kg SC talquetamab QW with step-up doses, and a second RP2D of 800 μg/kg SC talquetamab Q2W with step-up doses was also identified. 30 patients received 405 μg/kg QW (median 61.5 years [range 46-80];63% male;100% triple-class exposed;80% penta-drug exposed;77% triple-class refractory, 20% penta-drug refractory;30% prior BCMA-directed therapy;median follow-up [mF/U]: 7.5 mo [range 0.9-15.2]). 23 patients received 800 μg/kg Q2W (median 60.0 years [range 47-84];48% male;96% triple-class exposed;70% penta-drug exposed;65% triple-class refractory, 22% penta-drug refractory;17% prior BCMA-directed therapy;mF/U: 3.7 mo [range 0.0-12.0]). No treatment discontinuations due to AEs were reported at either RP2Ds. Most common AEs at the 405 μg/kg QW were CRS (73%;1 grade 3 CRS), neutropenia (67%;grade 3/4: 60%), and dysgeusia (60%;grade 2: 29%). Skin-related AEs occurred in 77% of patients and were all grade 1/2 (nail disorders: 30%). Infections occurred in 37% of patients (1 grade 3 COVID-19 pneumonia). Most common AEs at 800 μg/kg Q2W were CRS (78%;all grade 1/2), dry mouth (44%;all grade 1/2), and neutropenia (44%;grade 3/4: 35%). Skin-related AEs occurred in 65% of patients with grade 3 events in 13% (nail disorders: 17%). Infections occurred in 13% of patients (1 grade 3 pneumococcal sepsis). In 30 response-evaluable patients treated at 405 μg/kg QW, the overall response rate (ORR) was 70% (very good partial response or better [≥VGPR]: 57%). In 17 response-evaluable patients treated at 800 μg/ kg Q2W, the ORR was 71% (≥VGPR: 53%). Responses were durable and deepened over time with both RP2Ds (Figure). Median duration of response (DOR) was not reached at either RP2D;6-month DOR rate was 67% (95% CI: 41-84) at 405 μg/kg QW. Serum trough levels of talquetamab were comparable at both RP2Ds. Pharmacodynamic data at both RP2Ds showed peripheral T cell activation and induction of cytokines. SC talquetamab is well tolerated and highly effective at both RP2Ds. Preliminary data suggest that less frequent, higher doses of SC talquetamab do not negatively impact the safety profile. Further evaluation of talquetamab as monotherapy (phase 2;NCT04634552) and in combination with other therapies in patients with RRMM is underway. (Figure Presented) .

CARTITUDE-2 UPDATE: CILTACABTAGENE AUTOLEUCEL, A B-CELL MATURATION ANTIGEN-DIRECTED CHIMERIC ANTIGEN RECEPTOR T-CELL THERAPY, IN LENALIDOMIDEREFRACTORY PATIENTS WITH PROGRESSIVE MULTIPLE MYELOMA AFTER 1-3 PRIOR LINES OF THERAPY

Introduction: Ciltacabtagene autoleucel (cilta-cel) is a chimeric antigen receptor T-cell (CAR-T) therapy expressing two B-cell maturation antigen (BCMA)-targeting, single-domain antibodies. The multicohort, open-label, phase 2 CARTITUDE-2 study (NCT04133636) is assessing cilta-cel in patients (pts) with multiple myeloma (MM) under various clinical settings and evaluating the suitability of outpatient administration. Updated results of CARTITUDE-2 cohort A are presented here. Methods: Cohort A pts had progressive MM after 1-3 prior lines of therapy (LOT;included proteasome inhibitor [PI] and immunomodulatory drug [IMiD]), were lenalidomide-refractory, and had no previous exposure to BCMA-targeting agents. A single cilta-cel infusion at a target dose of 0.75×106 CAR+ viable T cells/kg was given 5-7 d after start of lymphodepletion (cyclophosphamide [300 mg/m2] and fludarabine [30 mg/m2] for 3 d). The primary endpoint was minimal residual disease (MRD) negativity at 10-5 at any time point. Secondary endpoints were overall response rate (ORR), duration of response (DOR), time and duration of MRD negativity, and incidence and severity of adverse events (AEs). Response was assessed per International Myeloma Working Group criteria and AEs were graded by Common Terminology Criteria for Adverse Events version 5.0 (cytokine release syndrome [CRS] and immune effector cell-associated neurotoxicity syndrome [ICANS] by American Society for Transplantation and Cellular Therapy). Results: As of April 15, 2021 (median follow-up of 9.7 mo), 20 pts (65% men;median age 60 y [range 38-75]) received cilta-cel, with 1 pt treated in an outpatient setting. Pts had a median of 2 prior LOT (range 1-3);60% had 1-2 prior LOT and 40% had 3 prior LOT. All pts were exposed to a PI, IMiD, and dexamethasone;95% were exposed to alkylating agents and 65% to daratumumab. 95% of pts were refractory to last LOT;40% were triple-class refractory. ORR was 95% (95% CI 75.1-99.9);85% (95% CI 62.1-96.8) had ≥complete response (CR), and 95% (95% CI 75.1-99.9) had ≥very good partial response (Figure). Median time to first response was 1.0 mo (range 0.7-3.3) and median time to ≥CR was 2.6 mo (range 0.9-7.9). Median DOR was not reached;progression-free survival (PFS) at 6 mo was 90% (95% CI 65.6-97.4). Of 13 MRD-evaluable pts, 92.3% (95% CI 64.0-99.8) were MRD-negative at 10-5. Hematologic AEs (≥20% of pts) were neutropenia (95%;grade [gr] 3/4: 95%), thrombocytopenia (80%;gr 3/4: 35%), anemia (75%;gr 3/4: 45%), lymphopenia (65%;gr 3/4: 60%) and leukopenia (55%;gr 3/4: 55%). 95% of pts had CRS (gr 3/4: 10%);median time to onset was 7 d (range 5-9) and median duration was 4 d (range 2-11). Four pts (20%) had CAR-T neurotoxicity (all gr 1/2). Three pts (15%) had ICANS (all gr 1/2);median time to onset was 8 d (range 7-10) and median duration was 3 d (range 1-3). One pt had facial paralysis (gr 2) with time to onset of 29 d and duration of 51 d. No movement and neurocognitive treatment-emergent adverse events (TEAEs) were reported. One death due to COVID-19 was assessed as treatment-related. Safety was manageable in the pt treated in an outpatient setting. Conclusions: A single cilta-cel infusion led to early and deep responses in pts with MM who had 1-3 prior LOT and were lenalidomide-refractory. No movement and neurocognitive TEAEs occurred, suggesting successful implementation of monitoring and pt management strategies across phase 2/3 studies in the CARTITUDE program.

Efficacy and Safety of Ciltacabtagene Autoleucel (Cilta-cel), a B-Cell Maturation Antigen (BCMA)-Directed Chimeric Antigen Receptor (CAR) T-Cell Therapy, in Lenalidomide-Refractory Patients with Progressive Multiple Myeloma after 1-3 Prior Lines of Therapy: Updated Results from CARTITUDE-2

Introduction: There are several treatment options for patients (pts) with progressive multiple myeloma (MM) who are refractory to lenalidomide but most pts relapse shortly after receiving salvage treatment. Cilta-cel is a CAR-T therapy expressing 2 BCMA-targeting, single-domain antibodies that demonstrated early, deep, and durable responses in pts with MM who had received ≥3 prior lines of therapy (LOT) in the phase 1b/2 CARTITUDE-1 study (Berdeja, Lancet, 2021). The multicohort, open-label, phase 2 CARTITUDE-2 study (NCT04133636) is evaluating cilta-cel safety and efficacy in various clinical settings for pts with MM and exploring suitability of outpatient administration. Initial analysis (median follow-up 5.8 mo) of pts in CARTITUDE-2 cohort A (lenalidomide-refractory with 1-3 prior LOT) demonstrated an overall response rate (ORR) of 95%, with 75% of pts achieving complete response or better (≥CR) and 85% achieving very good partial response or better (≥VGPR). Here, we present updated results for this population. Methods: Pts had progressive MM after 1-3 prior LOT, including a PI and immunomodulatory drug (IMiD), were lenalidomide-refractory, and had no prior exposure to BCMA-targeting agents. Bridging therapy was allowed after apheresis. A single cilta-cel infusion (target dose 0.75×10 6 CAR+ viable T cells/kg) was given 5-7 d after start of lymphodepletion (daily cyclophosphamide [300 mg/m 2] and fludarabine [30 mg/m 2] for 3 d). The primary endpoint was minimal residual disease (MRD) negativity at 10 -5. Secondary endpoints were ORR, duration of response (DOR), time and duration of MRD negativity, and incidence and severity of AEs. MRD was assessed by next-generation sequencing, response was assessed per IMWG criteria, and adverse events (AEs) were graded using CTCAEv5.0 (CRS and ICANS by ASTCT). Results: Initial results from this cohort were published at ASCO 2021. Here we report data as of the April 15, 2021, data cutoff (median follow-up 9.7 mo: range 3.3-13.4). 20 pts (65% male;median age 60 years [range 38-75]) received cilta-cel;1 pt was treated in an outpatient setting. Pts received a median of 2 prior LOT (range 1-3);60% received 1 or 2 prior LOT and 40% received 3 prior LOT. All pts were exposed to a PI, IMiD, and dexamethasone, 95% to alkylating agents, and 65% to daratumumab. In all, 95% of pts were refractory to the last LOT;40% were triple-class refractory. ORR was 95% (95% CI 75.1-99.9);85% (95% CI 62.1-96.8) of pts had ≥CR, and 95% (95% CI 75.1-99.9) had ≥VGPR (Figure). Median time to first response was 1.0 mo (range 0.7-3.3);median time to best response was 3.3 mo (range 0.9-7.9);median time to ≥CR was 2.6 mo (range 0.9-7.9). Median DOR was not reached;6-mo PFS rate was 90% (95% CI 65.6-97.4). Of MRD-evaluable pts (n=13), 92.3% (95% CI 64.0-99.8) were MRD-negative at 10 -5. Hematologic AEs in ≥20% of pts were neutropenia (95%;grade [gr] 3/4: 95%), thrombocytopenia (80%;gr 3/4: 35%), anemia (75%;gr 3/4: 45%), lymphopenia (65%;gr 3/4: 60%) and leukopenia (55%;gr 3/4: 55%). CRS occurred in 95% of pts (gr 3/4: 10%). Median time to CRS onset was 7 d (range 5-9), with a median duration of 4 d (range 2-11). CRS resolved within 7 d in 90% of pts. CAR T-cell neurotoxicity occurred in 4 pts (20%;all gr 1/2). Three pts (15%) had ICANS (all gr 1/2);median time to onset was 8 d (range 7-10) and median duration was 3 d (range 1-3). One pt had other neurotoxicities (gr 2 facial paralysis);time to onset was 29 d with a duration of 51 d. No movement and neurocognitive TEAEs were observed. One death occurred due to COVID-19 (assessed as treatment-related by the investigator). Safety profile was manageable in the pt treated in an outpatient setting. Conclusions: At a longer median follow-up of 9.7 mo, a single cilta-cel infusion led to early and deep responses in pts with MM who had 1-3 prior LOT and were lenalidomide-refractory. ORR in this cohort was consistent with the CARTITUDE-1 study in heavily pretreated pts;responses deepened over time, with 92% of MRD-evaluable pts achievi g MRD 10 -5 negativity. The safety profile was manageable;CRS was mostly gr 1/2, and no movement and neurocognitive TEAEs occurred, suggesting the efficacy of monitoring and pt management strategies that were implemented across phase 2/3 studies in the CARTITUDE program. Follow-up is ongoing, including additional enrollment in this cohort;this pt population is being further evaluated in the CARTITUDE-4 study (NCT04181827). [Formula presented] Disclosures: Cohen: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees;Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau;Karyopharm: Research Funding;neopharm / promedico: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau;takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau. Cohen: Janssen: Consultancy;Takeda: Consultancy;AstraZeneca: Consultancy;GlaxoSmithKline: Consultancy, Research Funding;BMS/Celgene: Consultancy;Novartis: Research Funding;Oncopeptides: Consultancy;Genentech/Roche: Consultancy. Delforge: Amgen, Celgene, Janssen, Sanofi: Honoraria, Research Funding. Hillengass: Adaptive: Membership on an entity's Board of Directors or advisory committees;Beijing Medical Award Foundation: Speakers Bureau;Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees;Beijing Life Oasis Public Service Center: Speakers Bureau;Curio Science: Speakers Bureau;Oncopeptides: Membership on an entity's Board of Directors or advisory committees;Oncotracker: Membership on an entity's Board of Directors or advisory committees;Axxess Network: Membership on an entity's Board of Directors or advisory committees;Sanofi: Membership on an entity's Board of Directors or advisory committees;GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees;Skyline: Membership on an entity's Board of Directors or advisory committees. Goldschmidt: GSK: Honoraria;Sanofi: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Adaptive Biotechnology: Consultancy;BMS: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Celgene: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Chugai: Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Incyte: Research Funding;Janssen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Johns Hopkins University: Other: Grant;Molecular Partners: Research Funding;MSD: Research Funding;Mundipharma: Research Funding;Novartis: Honoraria, Research Funding;Dietmar-Hopp-Foundation: Other: Grant;Amgen: Consultancy, Honoraria, Other: Grants and/or Provision of Investigational Medicinal Product, Research Funding;Takeda: Consultancy, Research Funding. Weisel: Adaptive Biotechnologies: 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;Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;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;Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Oncopeptides: 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;Karyopharm: Consultancy Honoraria, Membership on an entity's Board of Directors or advisory committees;Roche: Honoraria;Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Abbvie: Consultancy;Novartis: Honoraria;Pfizer: Honoraria. Raab: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees;Abbvie: Consultancy, Honoraria;Celgene: Membership on an entity's Board of Directors or advisory committees;BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees;Janssen: Membership on an entity's Board of Directors or advisory committees;Roche: Consultancy;Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding;Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding;GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees. Scheid: BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Janssen: 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;Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Abbvie: Honoraria;Roche: Consultancy;Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Schecter: Janssen: Current Employment, Current holder of stock options in a privately-held company. De Braganca: Janssen: Current Employment. Varsos: Janssen: Current Employment. Yeh: Janssen: Current Employment. Vogel: Janssen Global Services, LLC: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock optionsin a privately-held company, Divested equity in a private or publicly-traded company in the past 24 months. Corsale: Janssen: Current Employment. Akram: Legend Biotech USA: Current Employment. Pacaud: Legend Biotech: Current Employment. Nesheiwat: Legend Biotech USA: Current Employment. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. OffLabel Disclosure: At the time of abstract submission, cilta-cel is being investigated for the treatment of multiple myeloma but is not yet approved.

Updated Phase 1 Results from MonumenTAL-1: First-in-Human Study of Talquetamab, a G Protein-Coupled Receptor Family C Group 5 Member D x CD3 Bispecific Antibody, in Patients with Relapsed/Refractory Multiple Myeloma

Introduction: Despite recent advances in treatment, patients with multiple myeloma (MM) continue to relapse. G protein-coupled receptor family C group 5 member D (GPRC5D) is a promising target for immunotherapy in patients with MM due to its high expression in malignant plasma cells and limited expression in normal human tissue;unlike other antigens targeted by MM therapies, there is no indication that GPRC5D sheds into the periphery. Talquetamab (JNJ-64407564) is a first-in-class bispecific IgG4 antibody that redirects T cells to kill MM cells by binding to both GPRC5D and CD3 receptors. Here we report updated and new results of talquetamab at the recommended phase 2 doses (RP2Ds) from a phase 1 trial in relapsed/refractory MM (RRMM;NCT03399799). Methods: Eligible patients with MM had relapsed or refractory disease or were intolerant to standard therapies;patients previously treated with B-cell maturation antigen (BCMA)-directed therapies were eligible. This analysis focuses on patients who received talquetamab subcutaneously (SC;range 5.0-800 µg/kg) weekly or biweekly. Step-up dosing was used as a patient management strategy to minimize the severity of cytokine release syndrome (CRS). The primary objectives were to identify the RP2D (part 1) and assess talquetamab safety and tolerability at the RP2Ds (part 2). Adverse events (AEs) were graded by CTCAE v4.03 with CRS events graded per Lee et al 2014 criteria. Responses were investigator-assessed per International Myeloma Working Group criteria. Results: As of July 19, 2021, 95 patients have received SC talquetamab. The RP2D was originally identified as a weekly SC dose of 405 µg/kg talquetamab with step-up doses. However, alternative dosing schedules that require less frequent administration continue to be investigated. A biweekly RP2D was also identified as an SC dose of 800 µg/kg talquetamab with step-up doses. 30 patients received the 405 µg/kg weekly dosing schedule (median age: 61.5 years [range 46-80];63% male;100% triple-class exposed;80% penta-drug exposed;77% triple-class refractory, 20% penta-drug refractory;30% prior BCMA-directed therapy;median follow-up: 7.5 mo [range 0.9-15.2]). 23 patients received the 800 µg/kg biweekly dosing schedule (median age: 60.0 years [range 47-84];48% male;96% triple-class exposed;70% penta-drug exposed;65% triple-class refractory, 22% penta-drug refractory;17% prior BCMA-directed therapy;median follow-up 3.7 mo [range 0.0-12.0]). There were no treatment discontinuations due to AEs at either of the RP2Ds. The most common AEs at the 405 µg/kg weekly dose were CRS (73%;1 patient had grade 3 CRS), neutropenia (67%;grade 3/4: 60%), and dysgeusia (60%;grade 2: 29%);skin-related AEs occurred in 77% (all grade 1/2;nail disorders: 30%) of patients, and infections occurred in 37% of patients (1 patient had grade 3 COVID-19 pneumonia). The most common AEs at the 800 µg/kg biweekly dose were CRS (78%;all grade 1/2), dry mouth (44%;all grade 1/2), and neutropenia (44%;grade 3/4: 35%);skin-related AEs occurred in 65% of patients (grade 3: 13%;nail disorders: 17%) and infections occurred in 13% of patients (1 patient had grade 3 pneumococcal sepsis). In 30 response-evaluable patients treated with the 405 µg/kg weekly dose, the overall response rate (ORR) was 70% (very good partial response or better [≥VGPR] rate: 57%). In 17 response-evaluable patients treated with the 800 µg/kg biweekly dose, the ORR was 71% (≥VGPR rate: 53%). Responses were durable and deepened over time in both cohorts (Figure). Median duration of response (DOR) was not reached at either RP2D;the 6-month DOR rate for patients who received the 405 µg/kg weekly dose was 67% [95% CI: 41-84]. Serum trough levels of talquetamab were comparable at both RP2Ds. Consistent with the mechanism of action for talquetamab, pharmacodynamic data from cohorts treated at both dose levels showed peripheral T-cell activation and induction of cytokines. Conclusions: These findings indicate that SC talquetamab is well tolerated and highly effective at both RP2Ds. Preliminary data from the 800 µg/kg biweekly cohorts indicate that less frequent, higher doses of SC talquetamab do not have a negative impact on the previously described safety profile. Further investigation of talquetamab as monotherapy (phase 2;NCT04634552) and in combination with other therapies in patients with RRMM is underway. [Formula presented] Disclosures: Krishnan: MAGENTA: Consultancy;BMS: Consultancy, Current equity holder in publicly-traded company, Speakers Bureau;JANSSEN: Consultancy, Research Funding;City of Hope Cancer Center: Current Employment;REGENERON: Consultancy;SANOFI: Consultancy;GSK: Consultancy;Amgen: Speakers Bureau. Minnema: Celgene: Other: Travel expenses;Alnylam: Consultancy;Cilag: Consultancy;BMS: Consultancy;Janssen: Consultancy;Kite/Gilead: Consultancy. Berdeja: Lilly, Novartis: Research Funding;Abbvie, Acetylon, Amgen: Research Funding;Celularity, CRISPR Therapeutics: Research Funding;EMD Sorono, Genentech: Research Funding;Poseida, Sanofi, Teva: Research Funding;Bluebird bio, BMS, Celgene, CRISPR Therapeutics, Janssen, Kite Pharma, Legend Biotech, SecuraBio, Takeda: Consultancy;GSK, Ichnos Sciences, Incyte: Research Funding. Oriol: Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees;Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees;Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees;GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees;BMS/Celgene: 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. van de Donk: Roche: Consultancy;Takeda: Consultancy;Cellectis: Research Funding;Amgen: Consultancy, Research Funding;Janssen: Consultancy, Research Funding;BMS/Celgene: Consultancy, Honoraria;Novartis /bayer/servier: Consultancy. Rodriguez-Otero: Clínica Universidad de Navarra: Current Employment;Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees;Celgene-BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees;GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees;Pfizer: Consultancy;Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees;Kite: Honoraria, Membership on an entity's Board of Directors or advisory committees;Amgen: Honoraria;Regeneron: Honoraria. Askari: Janssen: Research Funding. Mateos: Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees;Sea-Gen: Honoraria, Membership on an entity's Board of Directors or advisory committees;Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees;Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees;Amgen: 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;Celgene - Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees;Takeda: 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;Oncopeptides: Honoraria;Bluebird bio: Honoraria;AbbVie: Honoraria;GSK: Honoraria;Oncopeptides: 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. Costa: BMS: Consultancy, Honoraria, Research Funding;Janssen: Consultancy, Honoraria, Research Funding;Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau;Karyopharm: Consultancy, Honoraria;Pfizer: Consultancy, Honoraria;Sanofi: Consultancy, Honoraria, Speakers Burea . Verona: Janssen: Current Employment. Ma: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Girgis: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Yang: Janssen: Current Employment. Hilder: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Russell: Janssen: Ended employment in the past 24 months. Goldberg: Janssen: Current Employment, Current holder of individual stocks in a privately-held company. Chari: Shattuck Labs: Consultancy, Membership on an entity's Board of Directors or advisory committees;Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding;Millenium/Takeda: Consultancy, Research Funding;Sanofi Genzyme: Consultancy, Membership on an entity's Board of Directors or advisory committees;Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees;BMS/Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Antengene: Consultancy, Membership on an entity's Board of Directors or advisory committees;Takeda: Consultancy, Research Funding;Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Pharmacyclics: Research Funding;Secura Bio: Consultancy, Membership on an entity's Board of Directors or advisory committees;Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees;AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees;GlaxoSmithKline: Consultancy, Membership on an entity's Board of Directors or advisory committees;Novartis: Consultancy, Research Funding;Genentech: Consultancy, Membership on an entity's Board of Directors or advisorycommittees;Janssen Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.