Background
Phase 3, multicenter (China), open-label, randomized (1:1) trial. N=885 with HER2-positive advanced breast cancer, first-line. Anbenitamab is a HER2-targeted bispecific antibody; HB1801 is albumin-bound docetaxel.
Results
Interventions and follow up: Arm A: anbenitamab + HB1801 (n=445)
Arm B: docetaxel + trastuzumab + pertuzumab (THP) (n=440)
Primary endpoint: PFS by BICR
Key secondary: ORR
mFollow up: 21.0 mo (prespecified interim, 401 events)
Results: PFS (24-mo): 58.5% vs 34.4%, HR 0.46 (95% CI 0.37–0.56), P<.001
ORR: 87.6% vs 73.4%
OS: NR (not in abstract)
Arm B: docetaxel + trastuzumab + pertuzumab (THP) (n=440)
Primary endpoint: PFS by BICR
Key secondary: ORR
mFollow up: 21.0 mo (prespecified interim, 401 events)
Results: PFS (24-mo): 58.5% vs 34.4%, HR 0.46 (95% CI 0.37–0.56), P<.001
ORR: 87.6% vs 73.4%
OS: NR (not in abstract)
Adverse events
Grade ≥3 (any): 45.9% vs 34.4%
Hematologic: G≥3 neutropenia 13.1% vs 8.4%
Fatal AEs: 2 vs 2
Hematologic: G≥3 neutropenia 13.1% vs 8.4%
Fatal AEs: 2 vs 2
Conclusions
Anbenitamab plus HB1801 significantly improved PFS over THP in first-line HER2-positive advanced breast cancer, with higher G≥3 toxicity.
Key Limitations
Open-label; interim analysis with OS not reported. Conducted in China only, limiting generalizability. Comparator is THP, with an unclear contribution of nab-docetaxel versus the bispecific antibody. Higher grade ≥3 toxicity. Sponsor-funded.
Clinical Context
THP is the established first-line standard for HER2-positive advanced breast cancer. Regulatory status of anbenitamab and guideline positioning not confirmed here.
