Weekly carfilzomib, lenalidomide, and dexamethasone in relapsed or refractory multiple myeloma: A phase 1b study

Twice-weekly carfilzomib (27 mg/m² ) with lenalidomide-dexamethasone (KRd) is a standard-of-care in relapsed or refractory multiple myeloma (RRMM). This phase 1b study evaluated KRd with once-weekly carfilzomib in RRMM. Patients received carfilzomib (30-minute infusion; 56 or 70mg/m² ) on days 1, 8, and 15; lenalidomide 25 mg on days 1-21; and dexamethasone 40 mg on days 1, 8, 15, and 22 (day 22 omitted for cycles 9+) of 28-day cycles. Primary objective was safety/tolerability; efficacy was a secondary objective. Fifty-six RRMM patients enrolled: 22 during dose evaluation (56-mg/m² , n = 10; 70-mg/m² , n = 12) and 34 during dose expansion (all initiated dosing at 70 mg/m² ). After 2 fatal adverse events (AEs) during 70-mg/m² dose expansion, dosage reduction to 56 mg/m² was permitted. Results are presented for carfilzomib 56-mg/m² (n = 10) and 70-mg/m² groups (dose evaluation/expansion; n = 46). Median carfilzomib dose was 53.2 mg/m² (56-mg/m² group) and 62.4 mg/m² (70-mg/m² group). Grade ≥3 AE rates were 70.0% (56 mg/m² ) and 69.6% (70 mg/m² ). Overall response rates were 90.0% (56 mg/m² ) and 89.1% (70 mg/m² ); ≥very good partial response rates were 50.0% (56 mg/m² ) and 73.9% (70 mg/m² ). Once-weekly KRd was active with acceptable toxicity in RRMM, supporting further evaluation of this regimen.