Clinical observation of neoadjuvant chemotherapy with pyrotinib plus trastuzumab in HER2-positive breast cancer: a cohort study

Background: Pyrotinib is a new small-molecule tyrosine kinase inhibitor (TKI). However, the efficacy of pyrotinib in neoadjuvant therapy for HER2-positive breast cancer is unknown. This paper is a populationbased cohort study, and the purpose is to evaluate the efficacy and safety of pyrotinib plus trastuzumab in a neoadjuvant setting for HER2-positive early or locally advanced breast cancers, and to compare it with that of pertuzumab plus trastuzumab. Methods: This cohort study included 166 patients with HER2-positive breast cancer who received neoadjuvant therapy and underwent surgery. Case groups: Group I: 63 patients received pyrotinib + trastuzumab; Group II: 50 patients received pertuzumab + trastuzumab. The control group consisted of 53 patients treated with trastuzumab alone in combination with neoadjuvant chemotherapy. Univariate logistic regression analysis was applied. Enumeration data were processed by Fisher's exact test. Results: The total pathological complete response (tpCR) rate of Group I was 63.49% (40/63); the breast pathological complete response (bpCR) rate was 76.19% (48/63); and the objective response rate (ORR) was 100% (63/63). Compared with the tpCR rate of 54.00% (27/50), bpCR rate of 58.00% (29/50), and ORR 100% (50/50) of Group II, there was no statistical difference. Regarding adverse events (AEs), diarrhea (n=56, 88.89%) was the most frequent in the group I, including 7 participants who developed grade 3 diarrhea (11.11%), followed by leukopenia (n=48, 76.19%). In the meantime, there was only 1 patient experienced grade IV thrombocytopenia. Hormone receptor (HR)-negative patients were more likely to reach tpCR as compared to HR-positive patients (61.54% vs. 37.50%, P=0.002, 95% CI: 1.423 to 4.997), and the tpCR rate of tumor, node, metastasis (TNM) stage III 37.04% (20/54) was significantly lower than that of stage II 54.46% (61/112), which was statistically significant (P=0.048, 95% CI: 1.064 to 4.041). No recurrence or metastasis was found during short-term follow-up. Conclusions: Pyrotinib plus trastuzumab combined with neoadjuvant chemotherapy showed good shortterm efficacy in HER2-positive breast cancer, and the AEs developed were all manageable. More sample data is required to further support the comparison with pertuzumab plus trastuzumab.