As of 3 Feb 2023, 495 pts were randomized (246 to melflufen; 249 to pom); median age was 68 y (range, 39-91) and median prior LoTs was 3. In the intent-to-treat (ITT) melflufen and pom populations, median OS was 20.2 mo vs 24.0 mo (HR, 1.09 [95% CI, 0.88-1.35]), at a median follow-up of 40.3 mo and 38.1 mo, respectively. In the target subgroup of the melflufen and pom groups (pts without a prior ASCT or TTP >36 mo after an ASCT), median OS was 23.6 mo vs 19.1 mo (HR, 0.88 [95% CI, 0.67-1.16]); in the non-target population (pts with TTP <36 mo after ASCT), median OS was 15.7 mo vs 27.5 mo (HR, 1.60 [95% CI, 1.15-2.21]), respectively.

While any grade hematologic toxicities were more common with melflufen, the occurrence of non-hematologic toxicities was similar in the 2 groups. Grade 3/4 (G3/4) treatment-emergent adverse events (TEAEs) in the safety population (melflufen [n=228] and pom [n=246]) occurred in 90% vs 76% of pts, respectively; most commonly thrombocytopenia (78% vs 13%; occurring with G3/4 hemorrhage in 1% vs 0%), neutropenia (64% vs 50%; occurring with G3/4 infections in 4% vs 7%), anemia (43% vs 19%), and infection and infestations (14% vs 24%). Serious AEs occurred in 43% vs 50% of pts (including pneumonia [6% vs 9%], COVID-19 pneumonia [5% vs 6%], and anemia [4% vs 2%]), and fatal AEs in 14% vs 15% (including COVID-19 pneumonia [4% vs 2%] and pneumonia [2% vs 2%]) in the melflufen and pom groups, respectively. With melflufen and pom, TEAEs led to dose reductions in 52% vs 28% of pts (most frequently thrombocytopenia [32% vs 2%] and neutropenia [12% vs 8%]), and discontinuations in 30% vs 24% of pts, respectively. Deaths occurred in 74% vs 68% of pts in the melflufen and pom groups, with AEs being the primary cause of death ≤30 d after last dose in 8% and 11%, respectively.