A prospective, open-label, single-arm phase II clinical study of inetetamab in combination with pyrotinib and albumin-bound paclitaxel for the neoadjuvant treatment of patients with HER2+ early and locally advanced breast cancer.

person Jiang Wu Department of Thyroid, Breast, and Vascular Surgery at Xijing Hospital, Air Force Medical University, Xi'an, China info_outline Jiang Wu, Fengqiang Cui, Yuqing Yang, Jing Yu, Jixin Yang, Lei Wang, Dongdong Xu, Wenyu Hu, Jialing Luo, Wen Ma, Nanlin Li

Authors person Jiang Wu Department of Thyroid, Breast, and Vascular Surgery at Xijing Hospital, Air Force Medical University, Xi'an, China info_outline Jiang Wu, Fengqiang Cui, Yuqing Yang, Jing Yu, Jixin Yang, Lei Wang, Dongdong Xu, Wenyu Hu, Jialing Luo, Wen Ma, Nanlin Li Organizations Department of Thyroid, Breast, and Vascular Surgery at Xijing Hospital, Air Force Medical University, Xi'an, China Abstract Disclosures Research Funding No funding sources reported Background: Chemotherapy combined with dual anti-HER2 target therapy has become the standard neoadjuvant therapy regimen for HER2+ breast cancer. Patients achieving pCR have a relatively better prognosis. Inetetamab (Septin) is an innovative HER2 monoclonal antibody drug developed in China. It has been proven to delay the progression of HER2+ metastatic breast cancer patients and bring survival benefits. The purpose of this study was to explore the efficacy and safety of Inetetamab, Pyrotinib and Albumin-bound Paclitaxel in the neoadjuvant treatment of HER2+ breast cancer. Methods: This phase II trial included patients with HER2+ early or locally advanced breast cancer whose tumor size was>20mm or confirmed axillary lymph node metastasis. Patients receive Inetetamab initial dose of 8 mg/kg over 90 minutes IV infusion, followed 6 mg/kg over 30 to 90 minutes IV infusion q3w, Pyrotinib 400 mg orally every day and Albumin-bound Paclitaxel 125mg/m2, IV, D1/8/15, q3w. Patients receive above treatment every 3 weeks for a total of 4 cycles, followed by surgery. After surgery, EC (90mg/m2 of Epirubicin Hydrochloride, 600mg/m2 of Cyclophosphamide, q21 days, 4 cycles) was administered, followed by maintenance treatment with trastuzumab combined with pertuzumab for 1 year. And provide radiotherapy and endocrine therapy to the patient according to the specific situation. The primary endpoint was pathological complete response (pCR). Results: Until February 4, 2024, 18 patients were enrolled, of which 15 had completed surgical treatment. The median age of enrolled patients was 49 years (35-60 years). 66.7% (10 cases) of patients achieved RCB grade 0 (pCR), 26.7% (4 cases) achieved RCB grade I, 6.7% (1 case) achieved RCB grade II. Of the 15 patients, 73.3% (11 cases) were HR+/HER2+, with 72.7% (8 cases) achieved pCR. Among the 4 HR-/HER2+ patients, 50% (2 case) achieved pCR. HR+/HER2+ patients were more likely to achieve pCR than HR-/HER2+ patients. No severe (grade 3/4) toxicity was observed in any patients. Conclusions: Our current data show that the pCR rate in HER2+ breast cancer patients reaches 66.7%, and even 72.7% in HR+ patients. In the previous Neosphere and PEONY studies of the H+P dual target regimen, the pCR of HR+/HER2+patients increased by only 6% and 8.3%, while in the NeoALTTO and PHEDRA studies of the H+L or H+Py regimen, the pCR increased by 18.9% and 17.7%, indicating that the combination of large and small molecules with dual target neoadjuvant therapy for HR+/HER2+ breast cancer was significantly better than that of the monoclonal antibody dual target therapy. Therefore, Inetetamab, Pyrotinib and albumin-bound paclitaxel is a potential effective new adjuvant treatment for HER2+ breast cancer, especially for HR+ patients. Clinical trial information: NCT054444998.