Neoadjuvant Anbenitamab and HB1801 in ERBB2 -Positive Breast Cancer: A Phase 3 Randomized Clinical Trial

IMPORTANCE: The combination of neoadjuvant taxanes with trastuzumab and pertuzumab remains the cornerstone treatment strategy in ERBB2-positive breast cancer. Anbenitamab (a ERBB2-biparatopic antibody that induces profound receptor clustering) and HB1801 (a solvent-free albumin-bound docetaxel), have shown promising antitumor activity and an acceptable safety profile in patients with breast cancer. OBJECTIVE: To evaluate whether neoadjuvant anbenitamab combined with HB1801 could improve efficacy without increasing toxic effects for patients with early ERBB2-positive breast cancer. DESIGN, SETTING, AND PARTICIPANTS: This multicenter, phase 3 registrational randomized clinical trial enrolled patients with stage II or III ERBB2-positive breast cancer from 61 hospitals in China between December 19, 2024, and August 29, 2025 (data cutoff: January 28, 2026). Data were analyzed from February 1 to March 20, 2026. INTERVENTIONS: Patients were randomly assigned (1:1) to receive 6 cycles of neoadjuvant anbenitamab plus HB1801, with or without carboplatin (investigational group), or trastuzumab, pertuzumab, and docetaxel, with or without carboplatin (control group). MAIN OUTCOMES AND MEASURES: The primary end point was total pathological complete response (tpCR) assessed by a blinded independent review committee. RESULTS: Among 521 included patients (median [IQR] age, 52.0 [23-79] years), 263 were randomized to the investigational group and 258 to the control group. The tpCR rate was significantly higher in the investigational group than the control group (164 patients [62.4%] vs 132 patients [51.2%]; absolute difference, 11.4 [95% CI, 3.2 to 19.6] percentage points; P =.004). Benefit was consistent across subgroups, including subgroups with hormone receptor-positive disease (77 patients [51.7%] vs 63 patients [44.4%]), hormone receptor-negative disease (87 patients [76.3%] vs 69 patients [59.5%]), early-stage disease (111 patients [63.8%] vs 87 patients [51.8%]), locally advanced disease (53 patients [59.6%] vs 45 patients [50.0%]), with carboplatin treatment (74 patients [66.7%] vs 61 patients [54.5%]), and without carboplatin treatment (90 patients [59.2%] vs 71 patients [48.6%]). Grade 3 or 4 treatment-related adverse events occurred in 77 patients (29.3%) in the investigational group and 73 patients (28.3%) of the control group. No treatment-related deaths occurred. CONCLUSIONS AND RELEVANCE: This randomized clinical trial found that neoadjuvant anbenitamab and HB1801 in patients with breast cancer significantly improved the tpCR rate compared with standard therapy with a highly manageable safety profile. This new combination may offer an improved treatment option, although long-term survival follow-up analyses are warranted.