Izalontamab brengitecan (iza-bren; BL-B01D1), a first-in-class bispecific antibody-drug conjugate, showed significantly better and more durable outcomes than chemotherapy in patients with recurrent or metastatic nasopharyngeal carcinoma (NPC) who had already undergone multiple treatments.
In the Phase 3 BL-B01D1-301 trial involving 386 patients who had received at least two prior therapies, including platinum-based chemotherapy and a PD-1/PD-L1 inhibitor, iza-bren achieved an overall response rate (ORR) of 54.6%, compared to 27.0% with standard chemotherapy ($P < .0001$). The median progression-free survival (PFS) was 8.38 months with iza-bren versus 4.34 months with chemotherapy, while the median duration of response (DOR) was 8.5 months versus 4.8 months, respectively. Both the primary endpoint (ORR) and key secondary endpoints showed clinically meaningful improvements.
Iza-bren was associated with a higher rate of severe (Grade 3 or higher) treatment-related adverse events—79.9% versus 61.6% with chemotherapy. The most common toxicities included anemia and reduced platelet counts, which were generally manageable with standard supportive care. Dose reductions occurred more often with iza-bren (41.8% vs. 24.3%), but the rate of treatment discontinuation was similar between the two groups. Two treatment-related deaths were reported in the iza-bren arm.
Based on these results, researchers concluded that iza-bren demonstrates superior efficacy and manageable safety, representing a potential new standard of care for heavily pretreated NPC patients.