Immune-related adverse events as predictors of pathological complete response in early-stage triple-negative breast cancer treated with pembrolizumab

Abstract

Purpose: Neoadjuvant chemoimmunotherapy improved pathological complete response (pCR) rates in early triple-negative breast cancer (TNBC). However, the relationship between immune-related adverse events (irAEs) and treatment response remains unclear. This study evaluated the association between the development of irAEs and pCR in TNBC patients receiving neoadjuvant pembrolizumab-based therapy. Method: In this multicenter retrospective study, early TNBC patients who received neoadjuvant pembrolizumab-based therapy were evaluated. Clinicopathologic features, irAE occurrence, and pCR rates were recorded and analyzed. Results: Among 203 patients who completed neoadjuvant treatment and underwent surgery, 127 (62.6%) achieved pCR. irAEs were more frequent in the pCR group compared with the non-pCR group (35.4% vs 19.7%, respectively; p = 0.01). Both univariate and multivariate analyses confirmed a significant association between irAE development and pCR. Conclusion: In patients with early TNBC treated with neoadjuvant pembrolizumab, irAEs occurred more often in those achieving pCR. These findings suggest that irAEs may reflect enhanced immune activation and could serve as a potential indicator of treatment response. Further prospective studies are needed to validate this observation and clarify its clinical relevance.