Since breast cancer is less common in men than in women, data on the use of new therapeutic agents, including cyclin-dependent kinase 4-6 (CDK 4-6) inhibitors, are limited in patients with metastatic hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) male breast cancer. Therefore, we aimed to investigate the treatment responses of metastatic HR+, HER2- male breast cancer patients treated with CDK 4-6 inhibitors in a multicenter real-life cohort.
Male patients with a diagnosis of HR+ and HER2- metastatic breast cancer, treated with any CDK 4-6 inhibitor, were included in the study. Demographic and clinical characteristics of the patients were recorded. We aimed to determine progression-free survival (PFS) time, response rates and drug related side effects.
A total of 25 patients from 14 institutions were recruited. The mean age at diagnosis was 57 years. Median follow-up was 19.53 (95% CI: 14.04-25.02) months. The overall response rate was 60%. While the median PFS was 20.6 months in the whole cohort, it was not reached in those using CDK 4-6 inhibitors in first line and 10 months in the subsequent lines (
In our study, we found that CDK 4-6 inhibitors are effective and safe options in men with HR+ and HER2- metastatic breast cancer, as in women. Our results support the use of CDK 4-6 inhibitor-based combinations in the first-line treatment of HR+ and HER2- metastatic male breast cancer.
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All authors have declared no conflicts of interest.