Background
Phase III multicentre, N=386 (iza-bren n=191, chemotherapy n=195), heavily pretreated recurrent/metastatic nasopharyngeal carcinoma (≥2 prior chemo lines including platinum-based + PD-1/L1 progression), 55 hospitals China, median follow-up 7.66 months iza-bren vs 7.10 months control
Interventions and follow up
Arm A: Izalontamab brengitecan 2.5 mg/kg IV days 1,8 q21d
Arm B: Chemotherapy (gemcitabine-based or investigator choice)
Primary endpoint: Objective response rate (ORR) by masked independent central review (RECIST 1.1); dual primary with overall survival (immature at data cutoff)
mFollow up: Median 7.66 months (iza-bren), 7.10 months (chemo) at first interim; OS data immature
Arm B: Chemotherapy (gemcitabine-based or investigator choice)
Primary endpoint: Objective response rate (ORR) by masked independent central review (RECIST 1.1); dual primary with overall survival (immature at data cutoff)
mFollow up: Median 7.66 months (iza-bren), 7.10 months (chemo) at first interim; OS data immature
Results
Objective response rate: Iza-bren 54.6% [95% CI 45.2-63.8%] vs chemo 27.0% [19.1-36.0%], difference 27.9% [95% CI 15.5-39.4%], P<.0001
Overall survival: Immature; secondary follow-up planned
Overall survival: Immature; secondary follow-up planned
Adverse events
Main adverse events: Grade 3+ AE: 80% (iza-bren) vs 62% (chemo). Hematologic toxicities predominant in iza-bren group: anemia 50% (vs 10% chemo), leukopenia 43%, thrombocytopenia 43%, neutropenia 38%. Non-hematologic Grade 1-2 predominantly. Serious AE: 43% (iza-bren) vs 27% (chemo). Treatment-related deaths: 4 (2%) iza-bren.
Conclusions
Izalontamab brengitecan, a bispecific EGFR/HER3 ADC, significantly improves ORR in heavily pretreated recurrent/metastatic NPC, with 27.9% absolute response benefit. Manageable hematologic safety profile supports potential new therapeutic standard; OS maturation awaited.
Key Limitations
Key Limitations: First interim analysis; OS data immature, preventing definitive OS claim. High hematologic toxicity (50% Grade 3+ anemia) requires intensive monitoring. Heavily pretreated population (post-IO failure) may limit generalizability. China-based trial; global applicability needs confirmation.
Clinical Context
Iza-bren represents first bispecific ADC targeting EGFR/HER3 in NPC; validates dual-antigen targeting in solid tumors. Practice-changing for heavily pretreated R/M NPC with PD-1/L1 progression. Expands ADC armamentarium beyond single-antigen therapies.
References
References: Yang Y et al, Lancet, 2025