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

Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.