Neoadjuvant docetaxel with or without carboplatin plus dual HER2 blockade for HER2-positive breast cancer: a retrospective multi-center Chinese study

Background: This study aimed to compare the real-world efficacy and safety of the TCbHP regimen (docetaxel, carboplatin, trastuzumab and pertuzumab) and the THP regimen (docetaxel, trastuzumab and pertuzumab) as neoadjuvant therapy for Chinese patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Methods: We compared efficacy and safety outcomes from 72 Chinese patients with HER2-positive breast cancer who underwent neoadjuvant dual HER2 blockade plus TCb or T chemotherapy and surgery between March 2019 and June 2020. Results: All 72 patients were women (32-76 years old) and the overall pathological complete response (pCR) rate was 70.8% (51/72). The pCR rates were 76.1% (35/46) for the TCbHP regimen and 61.5% (16/26) for the THP regimen (P=0.28). Univariate analyses revealed that pCR was associated with clinical T classification (P=0.024), AJCC stage (P=0.042), estrogen receptor (ER) status (P=0.002), progesterone receptor (PR) status (P=0.035), Ki-67 index (P<0.(X)1), and immunohistochemical HER2 status (P<0.001). Multivariate analyses revealed that pCR was independently predicted by ER status (OR: 0.227, 95% CI: 0.053-0.852; P=0.032) and immunohistochemical HER2 status (OR: 43.673, 95% CI: 6.801-875.86; P<0.001). The common adverse events for both regimens included neutropenia, anemia, thrombocytopenia, nausea, and diarrhea. Relative to the THP group, the TCbHP group had higher frequencies of grade 3-4 thrombmytopenia (17% vs. 0%, P=0.044) and grade 3-4 diarrhea (15% vs. 0%, P=0.044). Both regimens had very good cardiac safety. Conclusions: These results suggest that both TCbHP and THP regimens may be useful neoadjuvant treatments for high-risk early or locally advanced HER2-positive breast cancer. Both regimens had generally gcxxl safety outcomes, although clinicians should be aware of the risks of grade 3-4 thrombocytopenia and diarrhea during TCbHP treatment. Elderly patients who require neoadjuvant therapy may benefit from 6 cycles of THP treatment, based on its good efficacy and mild adverse events.