Efficacy and safety of pembrolizumab based therapies in triple-negative breast cancer: A systematic review of clinical trials.

Breast cancer is the most common cause of cancer-related deaths among women. There are a limited number of targeted therapies available for triple-negative breast cancer (TNBC), and chemotherapy is the mainstay of treatment. Among checkpoint inhibitors, atezolizumab is the only drug approved for PD-L1+ TNBC patients. We performed a systematic review to assess the efficacy and safety of PD-1 inhibitor pembrolizumab in triple-negative breast cancer. We included 15 clinical trials in this review. Pembrolizumab was well tolerated by all patients with triple-negative breast cancer. Pembrolizumab was more effective in the treatment of early-stage TNBC patients as compared to placebo, regardless of PD-L1 status. In advanced-stage breast cancer, pembrolizumab was as effective as single-agent chemotherapy with a better safety profile. Pembrolizumab with chemotherapy showed significantly better median progression free survival as compared to chemotherapy in advanced TNBC.