Safety and efficacy of immune checkpoint inhibitors in patients with triple-negative breast cancer: a systematic review and meta-analysis

BACKGROUND: Immune checkpoint inhibitors (ICIs) are under extensive investigation as a treatment for triple-negative breast cancer (TNBC) in numerous trials. Given the need to evaluate their therapeutic profile, we conducted this systematic review and meta-analysis to comprehensively assess the safety and efficacy of ICI therapy for TNBC. METHODS: We systematically searched PubMed, Embase, and the Cochrane Library for randomized controlled trials (RCTs) published in English from inception to March 10, 2024. Primary endpoints included treatment-related adverse events (trAEs) of any grade and Grade ≥ 3, as well as immune-related adverse events (irAEs). RESULTS: Thirteen RCTs involving 5,890 TNBC patients were included in the meta-analysis. ICI treatment was associated with a significantly increased risk of serious trAEs (risk ratio RR: 1.41; 95% confidence interval CI: 1.12-1.79; p = 0.004) but did not significantly affect the risk of any grade trAEs (RR: 1.00; 95% CI: 0.99-1.02; p = 0.584) or grade ≥ 3 trAEs (RR: 1.01; 95% CI: 0.87-1.18; p = 0.872). In contrast, ICIs markedly elevated the risk of any grade irAEs (RR: 1.54; 95% CI: 1.22-1.95; p < 0.001) and grade ≥ 3 irAEs (RR: 2.82; 95% CI: 1.56-5.11; p = 0.001). Specific irAEs, including hypothyroidism, hyperthyroidism, pneumonitis, adrenal insufficiency, and infusion-related reactions, occurred more frequently with ICI therapy. Network meta-analysis revealed that atezolizumab had the lowest risk of any grade irAEs (surface under the cumulative ranking curve SUCRA: 60%) and grade ≥ 3 irAEs (SUCRA: 66%). Importantly, ICIs significantly improved pathological complete response (pCR) rates (RR: 1.55; 95% CI: 1.25-1.94; p < 0.001) and were associated with enhanced overall survival (hazard ratio HR: 0.84; 95% CI: 0.74-0.96; p = 0.011) and progression-free survival (HR: 0.69; 95% CI: 0.61-0.79; p < 0.001). CONCLUSION: While ICIs demonstrate clinically meaningful benefits in pCR rates and survival outcomes for TNBC patients, they also substantially increase the risk of serious trAEs and irAEs, including hypothyroidism, hyperthyroidism, pneumonitis, adrenal insufficiency, and infusion-related reactions. REGISTRATION: INPLASY202450094.