Background
Phase 3 registrational, multicenter randomized trial (NCT06747338) at 61 hospitals in China. N=521 with stage II-III HER2(ERBB2)-positive breast cancer. Neoadjuvant anbenitamab (a HER2-biparatopic antibody) + HB1801 (solvent-free albumin-bound docetaxel) ± carboplatin vs standard trastuzumab + pertuzumab + docetaxel (THP) ± carboplatin. Primary endpoint total pathologic complete response by blinded review.
Results
Interventions and follow up: Arm A (investigational, n=263): anbenitamab + HB1801 ± carboplatin ×6 cycles
Arm B (control, n=258): trastuzumab + pertuzumab + docetaxel ± carboplatin ×6 cycles
Primary endpoint: total pathologic complete response (tpCR)
Results: tpCR: 62.4% vs 51.2% (absolute difference 11.4 points, 95% CI 3.2-19.6, P=.004)
Subgroups: benefit consistent across HR+/HR-, early vs locally advanced, and ± carboplatin
Arm B (control, n=258): trastuzumab + pertuzumab + docetaxel ± carboplatin ×6 cycles
Primary endpoint: total pathologic complete response (tpCR)
Results: tpCR: 62.4% vs 51.2% (absolute difference 11.4 points, 95% CI 3.2-19.6, P=.004)
Subgroups: benefit consistent across HR+/HR-, early vs locally advanced, and ± carboplatin
Adverse events
Grade 3/4 TRAE: 29.3% vs 28.3%
Treatment-related deaths: none
Treatment-related deaths: none
Conclusions
Neoadjuvant anbenitamab + HB1801 significantly improved total pCR over standard THP without increased toxicity in early HER2-positive breast cancer — a positive registrational phase 3 supporting a novel biparatopic-antibody backbone.
Key Limitations
China-only enrollment; tpCR is a surrogate with no EFS/OS data yet; open-label chemotherapy differences (HB1801 vs docetaxel) may contribute; not compared with T-DM1 or emerging HER2 ADCs; short follow-up (data cutoff Jan 2026).
Clinical Context
Neoadjuvant THP, with pCR-adapted adjuvant escalation to T-DM1 (KATHERINE), is the standard for early HER2-positive breast cancer. This trial positions anbenitamab + HB1801 as a potential new neoadjuvant option; a China regulatory filing is anticipated and survival follow-up is pending.