Abstract PO1-01-04: The optimal neoadjuvant treatment regimen for HR+/HER2+ breast cancer: a network meta-analysis

Abstract Background In patients with the HR+/HER2+ breast cancer (BC) subtype, it can be more challenging to achieve pathological complete response (pCR) after neoadjuvant therapy compared with the HR-/HER2+ subtype. The importance of neoadjuvant therapy and the association of pCR with long-term clinical benefits have been widely demonstrated in HER2+ BC. This network meta-analysis aimed to identify the optimal anti-HER2 regimen, the role of endocrine therapy, and the better chemotherapy choice for the neoadjuvant treatment of HR+/HER2+ BC patients. Methods Literature for neoadjuvant clinical trials in HR+/HER2+ breast cancer was searched in Medline, EMBASE, Cochrane Library, and Web of Science for publications released before June 2023. Single-arm trials, retrospective studies, and observational studies were excluded, as well as studies containing no neoadjuvant phase and/or no anti-HER2 drugs. A network meta-analysis with the fixed-effect model in a Bayesian framework was performed. Odds ratios (ORs) with 95% confidence intervals (CI) for pathological complete response (pCR) analysis and hazard ratios (HRs) with 95% CI for event-free survival (EFS) were calculated. A ranking of treatment patterns was performed using SUCRA. (Registered in PROSPERO: CRD42023385644 Results 2,844 records were identified by the literature search, 60 trials were included after the screening, and valid data were extracted. 19 trials and 2,883 patients were included in the primary analysis of pCR. Compared with trastuzumab + chemotherapy (CT), three treatment regimens showed significantly higher pCR rates, T-DM1 based treatment (T-DM1, OR: 2.83, 95% CI: 1.90, 4.27; which includes T-DM1 alone, T-DM1 + pertuzumab or T-DM1 + endocrine therapy), trastuzumab + pertuzumab + CT (PH, OR: 2.57, 95% CI: 1.70, 3.94), and trastuzumab + tyrosine kinase inhibitor (TKI)+ CT (H+TKI, OR: 1.60, 95% CI: 1.22, 2.09; TKI includes lapatinib, neratinib and pyrotinib). The SUCRA ranking of pCR showed that T-DM1 was ranked first (SUCRA: 0.94), followed by PH (SUCRA: 0.85) and H+TKI (SUCRA: 0.60). PH came first in the SUCRA ranking of EFS (SUCRA: 0.74) as well as cumulative SUCRA combining pCR and EFS (SUCRA: 0.79). For chemotherapy strategies, platinum-containing regimens showed no significant increase in pCR rate compared to no platinum regimens (OR: 1.27, 95% CI: 0.95, 1.69), regimens with anthracycline also had no statistical difference from those without anthracycline (OR: 0.74, 95% CI: 0.51, 1.07). When assessing the impact of endocrine therapy, no significant difference in pCR rate was observed with or without endocrine therapy (OR: 1.18, 95% CI: 0.80, 1.73). Conclusions The PH regimen remains the best neoadjuvant treatment choice for HR+/HER2+ early BC patients considering pCR and EFS outcomes simultaneously. H+TKI did not show significant benefits, so it is not recommended to be given priority in clinical practice. The platinum-containing regimen’s potential benefit compared to the non-platinum regimen is uncertain and needs more clinical investigation. The necessity of adding endocrine therapy is not proven due to limited data availability. Funding: This study was sponsored by Shanghai Roche Pharmaceuticals Ltd. Disclosure: Hao Tang, Shanghai Roche Pharmaceuticals Ltd.: Employee (Ongoing), Salary (Ongoing) Yajing Feng, Shanghai Roche Pharmaceuticals Ltd.: Employee (Ongoing), Salary (Ongoing) Xin Yu, Shanghai Roche Pharmaceuticals Ltd.: Employee (Ongoing), Salary (Ongoing) Citation Format: Hao Wang, Shiwei Liu, Miao Yu, Kun Mi, Exian Mou, Li Xia, Weimin Xie, Hao Tang, Yajing Feng, Xin Yu. The optimal neoadjuvant treatment regimen for HR+/HER2+ breast cancer: a network meta-analysis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-01-04.