Efficacy and Safety of Idecabtagene Vicleucel (ide-cel) in Patients with Clinical High-Risk Newly Diagnosed Multiple Myeloma (NDMM) with an Inadequate Response to Frontline Autologous Stem Cell Transplantation (ASCT): KarMMa-2 Cohort 2c Extended Follow-up

Abstract

Introduction Patients (pts) with multiple myeloma (MM) have a higher risk of progression/death following an inadequate response to frontline ASCT (van de Velde Eur J Haematol 2017). Therapies (Tx) with novel mechanisms of action may further improve response outcomes. Ide-cel previously demonstrated frequent, deep, and durable responses in KarMMa (Munshi N Engl J Med 2021) and significantly improved median progression-free survival (PFS) and overall response rate (ORR) versus standard regimens in KarMMa-3 (Rodríguez-Otero N Engl J Med 2023) in pts with triple-class-exposed relapsed and refractory MM. KarMMa-2 (NCT03601078) is a multicohort, phase 2, multicenter trial evaluating the efficacy and safety of ide-cel in pts with MM; cohort 2c included pts with NDMM who had an inadequate response to frontline Tx with ASCT. In cohort 2c, with a median follow-up of 27.9 months, ide-cel demonstrated deep and durable responses; complete response (CR) rate was 74.2% (ORR, 87.1%), with a 24-month PFS rate of 83.1% (Dhodapkar Blood 2022). Here, we report results with an additional 11.5 months of median follow-up for updated efficacy and safety data, and health-related quality of life (HRQoL) outcomes in cohort 2c. Methods Eligible pts had NDMM, received ≥ 3 cycles of induction Tx (including a proteasome inhibitor, an immunomodulatory agent, and dexamethasone), had < very good partial response (VGPR) 70-110 days after ASCT (single/tandem), and had Eastern Cooperative Oncology Group performance status ≤ 1. Pts received a single infusion of ide-cel (dose range: 150-450 × 10 6 CAR+ T cells) after lymphodepletion and could receive maintenance Tx post-infusion at investigator's discretion. The primary endpoint CR rate and secondary endpoints ORR, duration of response (DOR), PFS, overall survival (OS), safety, and patient-reported outcomes on HRQoL, assessed via European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Core 30 Questionnaire (QLQ-C30) and EORTC Quality of Life Multiple Myeloma Module 20 Questionnaire (QLQ-MY20), are reported. The exploratory endpoint of minimal residual disease (MRD) negativity (sensitivity, 10 -5) is also reported. Results At data cutoff (May 3, 2023), with a median follow-up of 39.4 (range, 31.6-44.7) months, all 31 pts who were infused with ide-cel were alive; 28 (90.3%) remained in follow-up, with 3 (9.7%) having discontinued due to disease progression. The ORR and CR rates were 87.1% and 77.4%, respectively ( Table); best overall response in 1 pt improved from VGPR to stringent CR. The median DOR was not reached (NR; 95% CI, NR-NR), neither was median PFS (95% CI, 38.0-NR) or median OS (95% CI, NR-NR); the 36-month event-free rates were 80.9%, 76.8%, and 100.0%, respectively. In pts who did not receive lenalidomide (LEN) maintenance, 9 (29.0%) had disease progression; of the 8 pts who received LEN maintenance post ide-cel infusion, none experienced disease progression. At 36 months, MRD negativity was confirmed in 9/14 (64.3%) evaluable pts; all 9 achieved ≥ CR. In this extended follow-up, safety results were generally consistent with the previous data cutoff. All pts experienced ≥ 1 any-grade adverse event (AE), most commonly hematologic, including neutropenia (80.6%), anemia (38.7%), leukopenia (32.3%), and thrombocytopenia (29.0%); infection and infestation AEs occurred in 74.2% of pts. No grade 5 AEs were reported. Incidence of any-grade cytokine release syndrome (58.1%; no grade ≥ 3) was unchanged and there were no additional reports of parkinsonism since the previous report. Overall, HRQoL improved ( Figure) and MM disease symptoms were stable over time based on the EORTC QLQ-C30 and QLQ-MY20, respectively, following ide-cel treatment; by month 3, > 75% of pts had improved or stable global health status/QoL. Conclusions Ide-cel continued to demonstrate deep, durable responses in pts with an inadequate response to frontline ASCT, no new safety signals were observed with extended follow-up, and no deaths were reported. No pts who received LEN maintenance post ide-cel experienced disease progression. Ide-cel treatment resulted in stable or improved HRQoL. Overall, ide-cel continued to demonstrate a favorable clinical benefit-risk profile in NDMM after ASCT. Study support 2seventy bio and Celgene, a Bristol-Myers Squibb Company.