IntroductionMany systemic treatment options are available for patients with human epidermal growth factor 2 (HER2)-positive breast cancer brain metastases. However, it is unclear which pharmacological treatment option is the most beneficial.MethodsWe searched databases, such as PubMed, Embase, and Cochrane Library, and conference abstracts according to keywords. We extracted progression-free survival (PFS), overall survival (OS) data, and overall response rate (ORR) from randomized controlled trials and single-arm studies of HER2-positive breast cancer brain metastasis treatment for meta-analysis and analyzed different drug-related adverse events (AEs).ResultsThree randomized controlled trials and seven single-arm clinical studies with 731 patients with HER2-positive brain metastases from breast cancer involving at least seven drugs were included. In randomized controlled trials, our results showed that trastuzumab deruxtecan significantly improved PFS and OS in patients and was superior to other drug regimens. In the single-arm study, the ORR was more pronounced for the trastuzumab deruxtecan and pyrotinib plus capecitabine regimens (ORR, 73.33%; 95% confidence intervals [CI], 44.90%−92.21%; ORR, 74.58%; 95% CI, 61.56%−85.02%, respectively). We found that the main AEs of antibody-drug conjugate (ADC) were nausea and fatigue, while the main AE of small-molecule tyrosine kinase inhibitor (TKI) drugs and large monoclonal antibodies was diarrhea.ConclusionsTrastuzumab deruxtecan was shown to be the most significant in improving survival in patients with HER2-positive breast cancer brain metastases in network meta-analysis, and in single-arm study, patients with HER2-positive breast cancer brain metastases treated with trastuzumab deruxtecan and pyrotinib plus capecitabine regimen had the highest ORR. The main AEs associated with ADC, large monoclonal antibodies, and TKI drugs were nausea, fatigue, and diarrhea, respectively.

Background: The optimal second-line therapy for hormone receptor–positive (HR+)/ human epidermal growth factor receptor 2 negative (HER2−) advanced or metastatic breast cancer is yet to be established. Therefore, we conducted a network meta-analysis (NMA) of marketed drugs to compare their efficacy. Methods: We searched the literature in PubMed, Embase, Web of Science databases, and the main international conferences in the past 5 years to find phase III clinical trials on drugs available in the market. Network meta-analysis of progression-free survival (PFS), overall survival (OS), and the objective response rate (ORR) was performed using R software. The efficiency of treatment options was compared using hazard ratios and 95% credibility intervals. Results: Overall, 12 studies with 6120 patients were included in the analysis. In an indirect comparison of the five regimens, cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) plus 500 mg fulvestrant (Ful500) gave the best PFS results; palbociclib ranked first with a surface under the cumulative ranking (SUCRA) of 94.99%, followed by mammalian target of rapamycin inhibitor (mTORi) plus everolimus (SUCRA=73.07%), phosphoinositide 3–kinase inhibitor (PI3Ki) plus Ful500 (SUCRA=66.73%), Ful500 alone (SUCRA=44.55%), and histone deacetylase inhibitor (HDACi) plus exemestane (SUCRA=43.49%). However, no significant difference was found in the PFS rates of CDK4/6i, mTORi, and PI3Ki. For OS, CDK4/6i plus Ful500 ranked first; the SUCRA of ribociclib, abemaciclib, and palbociclib were 86.20%, 83.98%, and 78.52%, respectively. Alpelisib plus Ful500 (SUCRA=66.91%) ranked second but was not statistically different from CDK4/6i. The mTORi plus everolimus group had the best ORR (SUCRA=88.73%). In terms of safety, 81.56% of patients in the tucidinostat plus exemestane regimen developed neutropenia, suggesting strong hematological toxicity; 13.40% of patients developed grade 3–4 diarrhea after using abemaciclib plus Ful500. Conclusion: For second-line endocrine therapy in HR+/HER2− advanced/metastatic breast cancer, CDK4/6i is a better choice than mTORi, PI3Ki, HDACi, and Ful; it shows good PFS and OS outcomes and a low probability for serious adverse events.

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