Systematic review and meta-analysis of pathological complete response rate and safety of immunotherapy and chemotherapy in neoadjuvant treatment of triple negative breast cancer

To systematically evaluate the efficacy of adding immune checkpoint inhibitors (ICI) to standard chemotherapy in improving the pathological complete response rate (pCR) compared with chemotherapy alone in the neoadjuvant treatment of patients with early triple-negative breast cancer (TNBC). A comprehensive computer search was conducted in the PubMed, Embase, Web of Science, and Cochrane Library databases to collect relevant English randomized controlled trials (RCTs) published from the inception of the databases to December 2025. Two researchers independently screened the literature, extracted the data, and evaluated the quality using the Cochrane risk-of-bias assessment tool. The primary effect measure for dichotomous outcomes was the odds ratio (OR) with its 95% confidence interval (CI). Statistical analysis was performed using RevMan 5.4 and Stata 17.0 software. The I 2 statistic was used to assess heterogeneity, and the funnel plot was used to evaluate publication bias. A total of 8 randomized controlled trials involving 2860 patients were finally included. The results of the meta-analysis showed that, compared with chemotherapy alone, immunotherapy combined with chemotherapy significantly increased the pCR rate (pooled OR = 2.85, 95% CI [1.80, 4.51], Z = 4.47, P < 0.001; I 2 = 84%, high heterogeneity). The risk of treatment-related grade 3–4 adverse events (AEs) in the immunotherapy combined with chemotherapy group was significantly higher (pooled OR = 1.35, 95% CI [1.12, 1.62], Z = 3.11, P = 0.002; I 2 = 33%, low heterogeneity), with a pooled relative risk (RR) of Further sensitivity analysis was conducted to assess result stability. High heterogeneity was observed in the primary outcome, and exploratory subgroup analysis by different ICIs was performed without direct head-to-head evidence, with a relatively steady risk elevation. 1.09 (95% CI [1.03, 1.16]) and a pooled risk difference (RD) of 0.06 (95% CI [0.02, 0.10]), corresponding to a number needed to harm (NNH) of 17. All comparisons were indirect without direct head-to-head evidence. Neoadjuvant chemotherapy plus ICI is associated with an improved pCR rate in TNBC. Exploratory subgroup analysis indicates varied associations between different ICIs and pCR outcomes, which should be interpreted cautiously due to indirect comparisons and high heterogeneity. Meanwhile, the regimen is associated with a higher risk of treatment-related grade 3–4 AEs, supporting the necessity of individualized toxicity monitoring in clinical practice.