Assessment of Response to Neoadjuvant Chemotherapy with Single and Dual HER2 Blockade in HER2-Positive Breast Cancers: A Single-Center Experience

Abstract Breast cancer remains the leading cause of morbidity and mortality among women and has now become a molecular spectrum rather than a single disease. The human epidermal growth factor receptor 2 (HER2) overexpressing subtype is a rather aggressive form of breast cancer, and its prognosis is improving at a faster pace in recent times with the advent of multiple strategies with targeted agents. In this study, we planned to compare dual and single HER2 blockades—docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) and trastuzumab, docetaxel, and carboplatin (TCH)—in the neoadjuvant setting and compare the pathological complete response rates for each protocol, and to assess the toxic effect profile of the regimens. We enrolled 30 patients randomized in a 1:2 fashion to TCHP (n = 9) and TCH (n = 21). The patients' age, tumor staging, and N staging were well matched. The completion rates of neoadjuvant therapy were 100% in the TCHP arm and 90% in the TCH arm. Breast conservation surgery rates were 22.2 and 5%, respectively, in the TCHP and TCH arms. The pathological complete response rate was 66.7% (6/9; 95% confidence interval [CI]: 29.9–92.5) in the TCHP arm compared with 15.8% (3/19; 95% CI: 3.4–39.6) in the TCH arm, with an absolute difference of 50.9% (95% CI: 12.8–74.5). No grade 3 or higher treatment-related adverse events were observed. With no added grade 3 adverse events documented in the TCHP arm, we concluded that the addition of pertuzumab would serve as a valuable strategy in the HER2+ subset in the neoadjuvant setting in the population of South Indian origin.