Neoadjuvant pertuzumab plus trastuzumab in combination with chemotherapy for human epidermal growth factor receptor 2 positive breast cancer: a real-world retrospective single-institutional study in China

Abstract Introduction Real-world studies on neoadjuvant dual anti-HER2 therapy combined with chemotherapy for breast cancer (BC) are scarce in China. This study aimed to evaluate the efficacy and safety of neoadjuvant dual anti-HER2 therapy combined with chemotherapy in a real-world setting. Moreover, differences in estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and proliferation cell nuclear antigen (Ki-67) expression pre- and post-neoadjuvant therapy were analyzed. Methods Clinical and pathological data of patients with HER2-positive BC who received neoadjuvant dual anti-HER2 therapy combined with chemotherapy at Liaoning Cancer Hospital & Institute, China, between September 2021 and September 2023, were retrospectively reviewed. Results Among 179 included patients, a pathologic complete response (pCR) was achieved in 109 patients (60.9%). The univariate analysis results indicated that the hormone receptor (HR) status ( P = 0.013), HER2 status ( P = 0.003), and cycles of targeted treatment ( P = 0.035) were significantly correlated with pCR. Subsequent multivariable analysis showed that HR negative and HER2 status 3 + were independent predictive factors of pCR. Anemia was the most common adverse event (62.0%), and the most common grade 3–4 adverse event was neutropenia (6.1%). The differences in HER2 (34.5%) and Ki-67 (92.7%) expression between core needle biopsy and the residual tumor after neoadjuvant therapy were statistically significant, whereas the differences were insignificant in terms of ER or PR status. Conclusions The combination of neoadjuvant trastuzumab and pertuzumab with chemotherapy showed good efficiency, and the toxic side effects were tolerable in patients with BC. In cases where pCR was not achieved after neoadjuvant therapy, downregulation of HER2 and Ki-67 expressions was observed.