Clinical efficacy of pyrotinib combined with chemotherapy for neoadjuvant treatment in HER2-positive breast cancer: a single-center study

This study aimed to evaluate the efficacy of pyrotinib, an orally administered small molecule tyrosine kinase inhibitor, combined with neoadjuvant chemotherapy in treating patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Pyrotinib works by inhibiting the HER2 signaling pathway, thereby preventing tumor cell growth. This single-arm clinical trial aimed to assess the total pathological complete response (tpCR; ypT0/is and ypN0) rate as the primary endpoint. A total of 27 patients were enrolled, each receiving 4-8 cycles of pyrotinib in combination with neoadjuvant chemotherapy. Pyrotinib combined with neoadjuvant chemotherapy demonstrated notable antitumor activity in patients with HER2-positive breast cancer. Among 26 patients, the tpCR rate was 26% (7/26), while the breast pathological complete response rate was 30% (8/26), indicating complete inhibition of the primary tumor in some cases. Notably, patients with HR-negative breast cancer demonstrated a higher tpCR rate compared with those with HR-positive breast cancer. The treatment regimen was well-tolerated. Diarrhea was the most common adverse event, occurring in 92.3% of patients, with 46.2% experiencing grade 3 or higher diarrhea. No severe adverse events or treatment-related fatalities were reported.