At data cutoff (Jan 13, 2022, N=46), median follow-up was 4.0 months (range 0.4-16.3), median age was 65 years (range 47-81), and 48% were female. Pts received a median of 5 prior LOT (range 2-16); 83% were triple-class exposed, 61% penta-drug exposed, 37% anti-BCMA non–CAR-T exposed, and 4% anti-BCMA CAR-T exposed. 96% of pts had ≥1 AE (gr 3/4: 67%). The most frequently reported AEs (≥30% across tal + dara cohorts) were CRS (65%; all gr 1/2; median time to onset: 2 days; median duration: 2 days), dysgeusia (57%), thrombocytopenia (35%; gr 3/4: 20%), anemia (39%; gr 3/4: 20%), and dry mouth (44%). Infections occurred in 50% of pts (gr 3/4: 13%). Skin disorders were reported in 72% of pts (gr 3/4: 11%): skin exfoliation in 26% (all gr 1/2) and nail disorders in 11% (all gr 1/2). Two ICANS events were reported in the 800 Q2W group (both gr 1 and resolved within 1 day). 3 pts discontinued due to AEs. Response rates were consistent across both RP2Ds supporting their equivalence (Table). Median time to first response across dosing cohorts was 0.95 months (range 0.9-9.7); median duration of response was not reached. Upregulation of CD38+/CD8+ T cells and proinflammatory cytokines was observed with tal + dara, supporting potential synergy of the combination in pts with prior anti-CD38 exposure.