Efficacy and Safety of Immune Checkpoint Inhibitors in Triple-negative Breast Cancer: A Study Based on 41 Cohorts Incorporating 6558 Participants.

The project was designed to investigate the efficacy and safety of immune checkpoint inhibitors (ICIs) in triple-negative breast cancer (TNBC). Electronic databases were screened to identify relevant trials. The primary endpoints were prognostic parameters and adverse events (AEs) through pooled rate, odds ratio, and hazard ratio (HR) with 95% CI. Totally, 6558 TNBC patients from 41 cohorts were included. The pooled pathologic complete response rate (odds ratio=2.03, 95% CI: 1.35-3.06, P =0.0007) and event-free survival (HR=0.84, 95% CI: 0.73-0.96, P =0.0100) of ICIs plus chemotherapy was higher than that of chemotherapy-alone in early-stage TNBC. For metastatic TNBC, compared with chemotherapy-alone, the addition of ICIs prolonged the progression-free survival (PFS) (HR=0.92, 95% CI: 0.88-0.96, P <0.0001); the improvement also existed in the following 3 subgroups: programmed cell death-ligand 1 positive, race of White and Asian, and patients without previous neoadjuvant or adjuvant chemotherapy; however, the benefit of the combined regimen was not observed in overall survival (OS) (HR=0.95; 95% CI: 0.89-1.03, P =0.2127). In addition, the pooled rates of OS, PFS, and objective response rate of ICIs plus chemotherapy were better than those of ICIs plus targeted therapy or ICIs-alone. In the safety analysis, compared with chemotherapy-alone, ICIs plus chemotherapy increased immune-related AEs and several serious AE. The regimen of ICIs plus chemotherapy is promising in both early-stage and metastatic TNBC, while the increased serious AE should not be neglected. Furthermore, the pooled rates of OS, PFS, and objective response rate of ICIs plus chemotherapy were better than those of ICIs plus targeted therapy or ICIs-alone.