Real-world efficacy and safety of neoadjuvant pembrolizumab in early-stage triple-negative breast cancer: A systematic review and meta-analysis.

Abstract

e12638 Background: Neoadjuvant chemotherapy (NACT) has become the standard treatment for early-stage triple-negative breast cancer (TNBC), an aggressive form of cancer with poor prognosis. Although addition of the immune checkpoint inhibitor pembrolizumab to NACT regimens has improved response rates in clinical trials, its effectiveness in real-world practice has not been systematically explored. This systematic review and meta-analysis aimed to synthesize evidence regarding the efficacy and safety of adding neoadjuvant pembrolizumab in early-TNBC across real-world settings. Methods: We searched PubMed, Embase, Scopus, and Cochrane from inception to August 14, 2025 for prospective and retrospective cohorts comparing pembrolizumab plus NACT versus NACT alone in early-TNBC. RevMan version 5.4.1 was used to pool outcomes with a random-effects model. Results: Six studies were included (N = 1580, mean ages 34.3-57.8 years). Pembrolizumab significantly improved pathologic complete response (OR 2.30 [1.70–3.12], p < 0.00001) and event-free survival (OR 2.08 [1.24–3.50], p = 0.006), while reducing the odds of axillary lymph node dissection (OR 0.57 [0.42–0.79], p = 0.0008). No significant difference was observed in time to adjuvant therapy (MD -8.36 [-30.08, 13.36], p = 0.45) or overall post-operative complications (OR 0.86 [0.57–1.29], p = 0.47). Similarly, no significant differences were found in specific adverse events, including infection (OR 0.52 [0.17–1.55]), wound dehiscence (OR 0.86 [0.18–4.08]), seroma (OR 1.02 [0.59–1.78]), flap necrosis (OR 1.08 [0.46–2.52]), and bleeding (OR 0.37 [0.04–3.64]). Conclusions: Neoadjuvant pembrolizumab combined with chemotherapy significantly increases pCR rates and reduces axillary lymph-node dissections in early-stage TNBC, without introducing excess perioperative complications. These benefits suggest its potential for real-world use, though careful monitoring for side effects is essential.