Neoadjuvant therapy for early human epidermal growth factor receptor 2 positive breast cancer in China: A multicenter real-world study (CSBrS-015)

BACKGROUND: Pertuzumab has been approved for application in China by the National Medical Products Administration, and both national and international guidelines make recommendations for the use of neoadjuvant treatment with trastuzumab or trastuzumab + pertuzumab plus chemotherapy regimens for patients with indications. The goal of this study was to investigate the short-term clinical efficacy of the neoadjuvant therapies trastuzumab and trastuzumab+pertuzumab for patients with early human epidermal growth factor receptor 2 (HER2)-positive breast cancer in China. METHODS: A real-world study was conducted using the clinicopathological data of patients with early HER2-positive breast cancer who were admitted to the member hospitals of the Chinese Society of Breast Surgery, Chinese Surgical Society of Chinese Medical Association between March 2019 and December 2020. This study analyzed the efficacy and tolerance of trastuzumab+chemotherapy and trastuzumab+pertuzumab+chemotherapy in patients with early HER2-positive breast cancer. The Response Evaluation Criteria in Solid Tumors 1.1 was adopted to evaluate clinical efficacy. The pathological efficacy was evaluated using the MillerPayne grade. The Common Terminology Criteria for Adverse Events (version 5.0) was adopted to evaluate adverse events (AEs). The propensity scores were subjected to propensity score matching using the R language (1:1 matching with a maximum allowable difference of 0.05 between the two groups). Efficacy was compared using the chi-square test, and correlation analysis was performed using linear regression. RESULTS: A total of 1032 patients with early HER2-positive breast cancer met the enrollment criteria and were included in this study. Among these patients, 472 received neoadjuvant trastuzumab+chemotherapy (the trastuzumab group), and 560 received neoadjuvant trastuzumab+pertuzumab+chemotherapy (the trastuzumab+pertuzumab group). The overall pathologic complete response (pCR) rate was 47.2% (487/1032), while the pCR rates of the trastuzumab and trastuzumab+pertuzumab groups were 34.5% (163/472) and 57.9% (324/560), respectively, and the difference was significant (P < 0.001). The incidence of grade 4 AEs was 24/321 (7.5%) in the trastuzumab+pertuzumab group, and there were no cases in which the left ventricular ejection fraction decreased by more than 10%. CONCLUSIONS: Patients in the trastuzumab+pertuzumab group had a higher pCR rate than those in the trastuzumab group, and the toxic side effects were tolerable.