Background
Phase 2, open-label, single-arm trial (KarMMa). N=128 patients with relapsed or refractory multiple myeloma after ≥3 prior lines including a PI, IMiD, and anti-CD38 monoclonal antibody. All patients were triple-class exposed; 84% triple-class refractory. Idecabtagene vicleucel (ide-cel; bb2121) is an autologous BCMA-directed CAR-T cell therapy.
Interventions and follow up
Regimen: Idecabtagene vicleucel (ide-cel) 150–450 × 10⁶ CAR-T cells IV (single infusion) after lymphodepleting chemotherapy (fludarabine 30 mg/m² + cyclophosphamide 300 mg/m² daily ×3)
Population: Triple-class–exposed R/R MM, median 6 prior lines
Primary endpoint: Overall response rate (ORR)
mFollow up: 13.3 months
Population: Triple-class–exposed R/R MM, median 6 prior lines
Primary endpoint: Overall response rate (ORR)
mFollow up: 13.3 months
Results
ORR: 73.4% (95% CI 64.8–80.7%)
≥CR rate: 33%
MRD-negativity (10⁻⁵, among ≥CR): 79%
mDOR: 10.7 months
mPFS: 8.8 months
mOS: 19.4 months
≥CR rate: 33%
MRD-negativity (10⁻⁵, among ≥CR): 79%
mDOR: 10.7 months
mPFS: 8.8 months
mOS: 19.4 months
Adverse events
CRS/neurotoxicity: CRS any grade 84%, grade ≥3 5%; ICANS any grade 18%, grade ≥3 3%
Hematologic (grade ≥3): Neutropenia 89%, anemia 60%, thrombocytopenia 52%
Infections: Grade ≥3 22%
Hematologic (grade ≥3): Neutropenia 89%, anemia 60%, thrombocytopenia 52%
Infections: Grade ≥3 22%
Conclusions
Ide-cel achieved a 73% ORR including 33% complete responses in triple-class-exposed RRMM with a manageable CRS profile, marking the first CAR-T cell therapy approval for multiple myeloma and establishing BCMA as a validated target for cellular immunotherapy.
Key Limitations
Single-arm design without a randomized comparator limits efficacy interpretation. Responses, while deep, were not durable (mPFS 8.8 months) at the highest target dose. Manufacturing logistics, vein-to-vein time, and bridging therapy needs limit access for rapidly progressing patients. Prolonged grade ≥3 cytopenias and infection risk require specialized supportive care.
Clinical Context
FDA approved ide-cel (Abecma) in March 2021 for RRMM after ≥4 prior lines; KarMMa-3 later supported a label expansion to earlier lines. It was the first BCMA-directed CAR-T approved in any indication. ESMO-MCBS scoring reflects meaningful benefit in a heavily pretreated, unmet-need population.