Ide-cel vs standard regimens in triple-class-exposed relapsed and refractory multiple myeloma: updated KarMMa-3 analyses

• With longer follow-up, significantly longer median PFS was maintained with ide-cel vs standard regimens (SRs); safety remained consistent

• OS analysis was confounded by patient crossover from SRs to ide-cel. Crossover adjustment showed a trend of improved OS with ide-cel vs SRs

Outcomes are poor in triple-class-exposed (TCE) relapsed/refractory multiple myeloma (RRMM). In the phase 3 KarMMa-3 (clinicaltrials.gov; NCT03651128) trial, patients with TCE RRMM and 2-4 prior regimens were randomized 2:1 to idecabtagene vicleucel (ide-cel) or standard regimens (SRs). An interim analysis (IA) demonstrated significantly longer median progression-free survival (PFS; primary endpoint; 13.3 vs 4.4 months; P<.0001) and higher overall response rate (ORR) with ide-cel vs SRs. At final PFS analysis (median follow-up, 30.9 months), ide-cel further improved median PFS vs SRs (13.8 vs 4.4 months; hazard ratio (HR), 0.49; 95% confidence interval (CI), 0.38-0.63). PFS benefit with ide-cel vs SRs was observed regardless of number of prior lines of therapy, with greatest benefit after 2 prior lines (16.2 vs 4.8 months, respectively). ORR benefit was maintained with ide-cel vs SRs (71% vs 42%; complete response, 44% vs 5%). Patient-centric design allowed crossover from SRs (56%) to ide-cel upon progressive disease, confounding overall survival (OS) interpretation. At IA of OS, median (95% CI) was 41.4 (30.9-not reached [NR]) vs 37.9 (23.4-NR) months with ide-cel and SRs, respectively (HR, 1.01; 95% CI 0.73-1.40); median OS in both arms was longer than historical data (9-22 months). Two prespecified analyses adjusting for crossover showed OS favoring ide-cel. This trial highlighted the importance of individualized bridging therapy to ensure adequate disease control during ide-cel manufacturing. Ide-cel improved patient-reported outcomes vs SRs. No new safety signals were reported. These results demonstrate the continued favorable benefit-risk profile of ide-cel in early-line and TCE RRMM. NCT03651128