Atezolizumab and pembrolizumab in triple-negative breast cancer: a meta-analysis

Background: The approval of anti-PD-L1 drugs, including atezolizumab/pembrolizumab in triple-negative breast cancer (TNBC), potentially improveme treatment regimens available for TNBC. Methods: We conducted a meta-analysis to review the efficacy of atezolizumab/pembrolizumab for the treatment of TNBC in both the adjuvant and neoadjuvant settings. We calculated standardized mean difference (SMD) for the associations of progression-free survival (PFS) and overall survival (OS) and odds ratios (ORs) to estimate objective response rate (ORR) and pathological complete response (pCR), using 95% confidence intervals (CIs). Results: Six clinical trials comprising 3612 patients were included. For adjuvant therapies, the ORR (OR = 1.26, P = 0.04) of atezolizumab/pembrolizumab plus chemotherapy was higher in the intention to treat (ITT) arms than the placebo groups in TNBC. A positive effect size was found for PFS in the ITT arms (d = 1.55, P < 0.001). The atezolizumab plus chemotherapy group had a positive effect size for OS compared to control groups (d = 0.52, P < 0.001). In the neoadjuvant setting, patients in ITT arms had higher pCR rates than the control groups (OR = 1.61, P = 0.001). Conclusion: We collate evidence of atezolizumab/pembrolizumab as viable therapeutics among patients with TNBC with PD-L1 subgroups deriving higher benefits.