KarMMa-2 Cohort 2a: Efficacy and Safety of Idecabtagene Vicleucel in Clinical High-Risk Multiple Myeloma Patients with Early Relapse after Frontline Autologous Stem Cell Transplantation
Ide-cel was successfully manufactured and infused in 37/39 pts. Median age was 57 y; median time since diagnosis was 1.6 y. A total of 62.2% pts had ECOG PS 0, and 70.3% received bridging therapies (corticosteroids, alkylating agents, immunomodulatory agents, proteasome inhibitors [PI], and/or anti-CD38 antibodies) for MM. At study entry, 13.5%/51.4%/5.4% pts had R-ISS stage I/II/III disease, 32.4% had high-risk cytogenetics, 18.9% had bone marrow biopsy-determined high tumor burden (≥50% bone marrow CD138+ plasma cells), and 8.1% had extramedullary disease. Most pts had disease refractory to an immunomodulatory agent (86.5%) or PI (89.2%); 86.5% had double refractory disease.
At data cut-off (14 Mar 2022), median follow-up was 21.5 mo (range 2-31). CRR was 45.9% (95% CI 29.5-63.1), and ORR was 83.8% (95% CI 68.0-93.8) (Table 1). At 6 mo post-ide-cel, MRD− was observed in 11/13 (85%; 95% CI 57.8-95.7) pts. At 12 mo, MRD− was observed in 7/10 (70%; 95% CI 39.7-89.2) pts; of the 7 pts, 1 had PD at 20.8 mo, 5 sustained MRD− at ≥18 mo, and >12 mo data was unavailable for 1 pt. Median TTR was 1 mo (range 0.9-2.9). Median DOR was 15.7 mo (95% CI 7.62-19.81). Median PFS was 11.4 mo (95% CI 5.55-19.58); median OS was not reached. Time to event endpoint results for DOR, PFS, and OS are shown in Table 1.
Grade (Gr) 3-4 AEs on or after ide-cel infusion occurred in all pts, most commonly neutropenia in 35 (94.6%) pts, anemia in 17 (45.9%), and thrombocytopenia in 14 (37.8%). Two pts died due to pneumonia and pseudomonal sepsis. Gr 1/2 cytokine release syndrome (CRS) occurred in 30 (81.1%) pts; 1 (2.7%) pt had a Gr 3 event (Table 1). Gr 1/2 investigator-identified neurotoxicity (NT) occurred in 8 (21.6%) pts; no pts had ≥Gr 3 NT.
Robust cell expansion was seen in 36 evaluable pts (Table 2). Ide-cel cellular expansion levels were higher in pts who had ≥CR vs those who had <CR with ide-cel (Table 2). sBCMA (range 15.0-737.0 ng/mL at infusion, n = 36) was cleared within 2 mo post-ide-cel infusion in 25/37 (67.6%) pts, including all pts who had ≥CR.