Safety and efficacy of elranatamab in combination with iberdomide in patients with relapsed or refractory multiple myeloma: Results from the phase 1b MagnetisMM-30 trial
Of the 22 pts in Part 1 (DL1: 13, DL−1: 9), the median age was 68 y (range, 46-83), 10 (45.5%) were male, 4 (18.2%) had extramedullary disease, 9 (40.9%) had high-risk cytogenetics, defined as t(4;14), t(14;16), or del(17p), 1 (4.5%) had R-ISS stage III, and 2 (9.1%) had ≥50% baseline bone marrow plasma cells. Pts had a median of 2.5 prior LOT (range, 2-4), and 11 (50%) had triple-class refractory disease.
At data cutoff (June 23, 2025), the median (range) ELRA treatment duration was 3.1 mo (0.5-7.2) overall and 6.1 mo (0.5-7.2) for DL1 and 1.9 mo (1.5-3.3) for DL−1. IBER treatment duration was 2.6 mo (0.1-6.7) overall and 5.7 mo (0.1-6.7) for DL1 and 1.6 mo (0.7-3.0) for DL−1. ELRA + IBER was ongoing in 77.3% (DL1: 8, DL−1: 9) of pts.
Four pts had DLTs; 2 in DL1 (1 grade [G]3 anorexia; 1 G4 neutropenia) and 2 in DL−1 (1 G3 febrile neutropenia; 1 G4 neutropenia). Treatment-emergent adverse events (TEAEs) were reported in 100% (G3/4 68.2%) of pts. The most frequent TEAEs (any G ≥45% or G3/4 ≥10%) were cytokine release syndrome (68.2%, all ≤G2), fatigue (63.6%, all ≤G2), neutropenia (59.1%, G3/4 59.1%), diarrhea (45.5%, all ≤G2), anemia (31.8%, G3/4 13.6%), and thrombocytopenia (27.3%, G3/4 13.6%). Infections were reported in 40.9% (G3/4 4.5%) of pts and immune effector cell–associated neurotoxicity syndrome events were reported in 2 pts (9.1%, 1 G1 and 1 G2).
At a median follow-up of 6.1 mo (95% CI, 2.8-7.1), estimated by reverse Kaplan-Meier, the unconfirmed ORR was 90.9% (95% CI, 70.8-98.9) in 20/22 pts; 45.5% (10/22) had CR or better and 68.2% (15/22) had very good partial response or better. The confirmed ORR was 77.3% (17/22) with a median time to response of 1.1 mo (range, 0.5-2.4).