Efficacy and safety of neoadjuvant pertuzumab plus trastuzumab in combination with chemotherapy regimen in Chinese patients with HER2-positive early breast cancer: a real-world retrospective multi-center cohort study.

Background: Pertuzumab plus trastuzumab combined with chemotherapy has become a standard neoadjuvant therapy option for patients with high-risk human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC). There is still not enough evidence for the efficacy and safety of neoadjuvant pertuzumab and trastuzumab plus chemotherapy in HER2-positive BC patients in China, both in clinical trials and real-world settings. This study aimed to assess the efficacy and safety of neoadjuvant pertuzumab plus trastuzumab in combination with chemotherapy in Chinese patients with HER2-positive BC in real-world clinical application. Methods: We retrospectively collected the data from the electronic medical records of HER2-positive patients treated with neoadjuvant trastuzumab and pertuzumab plus chemotherapy from December 2018 to May 2021 at 21 hospitals located in Hunan Province, China, including age, American Joint Committee on Cancer (AJCC) stage, clinical tumor size, clinical lymph node status, pathological characteristics (before neoadjuvant systemic therapy), treatment approach, adverse events to neoadjuvant therapy, and achievement of pathological complete response (pCR). The primary endpoint was the total rate of pCR, and the secondary endpoints were the rate of pCR of each subgroup and the safety of dual anti-HER2 therapy. Results: A total of 188 patients met the inclusion criteria and were included in the analysis. Of the 188 patients, 119 (63.3%) were diagnosed at stage II and 64 (34.0%) at stage III; 163 (86.7%) were cT2-3; 149 patients (79.3%) were ≥ cN1; 84 patients (44.7%) were hormone receptor (HR)-positive. pCR was observed in 88 of 188 patients (46.8%). The pCR rate of HR-negative patients (54.8%) was higher (P=0.014) than that of HR-positive patients (36.9%). Patients with Ki-67 <15% achieved a higher (P=0.033) pCR rate (68.2%) than those with Ki-67 ≥15% (44.0%). Anemia was the most common adverse event (63.4%), and the most common grade 3-4 adverse event was nausea and vomiting (8.5%). Conclusions: Our study confirmed the benefit of neoadjuvant pertuzumab plus trastuzumab in combination with chemotherapy on pCR with a tolerable safety profile in routine clinical practice in Chinese patients with HER2-positive BC. HR-negativity and Ki-67 <15% were associated with pCR in these patients.