Efficacy and safety of PD-1/PD-L1 inhibitors plus chemotherapy for triple-negative breast cancer: a systematic review and meta-analysis.

The results of PD-1/PD-L1 inhibitor combined with chemotherapy for TNBC are controversial. Therefore, a meta-analysis was conducted to evaluate the efficacy and safety after PD-1/PD-L1 inhibitors plus chemotherapy in TNBC patients.We systematically searched seven databases and several mainly oncology conferences for prospective clinical trials of chemotherapy combined with immunotherapy to treat TNBC, and we included pathologic complete response (PCR), progression-free survival (PFS), overall survival (OS) and adverse effects as outcome indicators of the study.We analyzed data from six studies involving 4,187 patients. The efficacy analysis indicated that PD1/PD-L1 inhibitor combined with chemotherapy significantly increased PCR rates in neoadjuvant patients (OR: 1.60; 95% CI: 1.18-2.17; p=0.003). There was no correlation between increases in PCR rates and the expression of PD-L1, but the PCR rate was higher in PD-L1+ patients. Subgroup analysis suggested that the lymph node-positive (OR: 2.52; 95% CI: 1.69-3.77; p<0.001) and ECOG PS 0 (OR: 1.9; 95% CI: 1.42-2.53; p<0.001) subgroups benefited from the combination of PD-1/PD-L1 inhibitor plus chemotherapy. In TNBC receiving advanced rescue treatment, PFS was higher in the group receiving PD-1/PD-L1 inhibitor plus chemotherapy than in the group receiving chemotherapy alone (HR: 0.78; 95% CI: 0.70-0.86; p<0.001). Compared with chemotherapy alone, PD-1/PD-L1 inhibitors combined with chemotherapy did not increase the OS of patients (HR=0.88, 95% CI: 0.76~1.03, p=0.12). In addition, the toxicity analysis showed that more grade 3-4 adverse effects and severe adverse effects occurred in the PD-1/PD-L1 inhibitor combined with chemotherapy group.PD-1/PD-L1 inhibitors combined with chemotherapy can improve the PCR and PFS rate of TNBC patients, but did not improve the OS, and had a higher risk of AEs.