Abstract PS4-10-28: Neoadjuvant Chemoimmunotherapy in Early-Stage TNBC: Real-World Analysis of Predictors of pCR and Survival

Abstract Background: Triple-negative breast cancer (TNBC) is one of the most challenging breast cancer subtypes to manage due to its aggressive biology, high recurrence risk, and limited targeted treatment options. Neoadjuvant chemotherapy plus pembrolizumab (NACP) has become a new standard aimed at increasing pathological complete response (pCR) rates and improving long-term survival. This study aims to evaluate pCR and survival outcomes in early-stage TNBC patients receiving NACP based on real-world data, and to identify clinicopathological factors predictive of pCR and survivals. Methods: This multicenter retrospective study included 164 early-stage TNBC patients treated with NACP, followed by surgery. Demographic, clinical, radiological, and pathological data were analyzed. The primary endpoint was the pCR rate; secondary endpoints included disease-free survival (DFS) and overall survival (OS). Predictors of pCR and survivals were evaluated using multivariate logistic and Cox regression analyses, respectively. Results: Among 164 patients with a median follow-up of 49.2 months, the pCR rate was 60.4%. Recurrence and mortality rates were 18.3% and 3.0%, respectively. In the univariate analyses for DFS, radiological T stage at diagnosis (p=0.001), carboplatin administration schedule (p0.001), radiological T response to treatment (p=0.036), overall radiological treatment response (p0.001), and presence of pCR (p0.001) were found to be statistically significant prognostic factors. In addition, ECOG PS (p=0.03), carboplatin administration schedule (p=0.043), radiological T response to treatment (p=0.003), adjuvant capecitabine administration (p=0.003) and radiological N response (p=0.04) were found to be statistically significant prognostic indicators for OS in univariate analysis. In the multivariate Cox regression analysis performed to evaluate variables affecting survival, carboplatin administration schedule (HR=5.137, p=0.001), age (HR=4.301, p=0.026), achievement of pCR (HR=0.138, p0.001), and radiological treatment response (HR=0.197, p0.001) for DFS and only pCR (HR = 0.10, 95% CI: 0.01-1.18, p = 0.004) for OS were found to be significant independent prognostic indicators. To identify predictors of achieving pCR, a multivariate logistic regression analysis was performed, and only carboplatin dosing schedule was significantly associated with pCR (OR=0.308; 95% CI: 0.128-0.740; p=0.008), with weekly dosing favoring higher pCR rates. These findings suggest that carboplatin scheduling may be an independent predictor of pCR, whereas other clinicopathological parameters showed no significant impact in this model. Conclusion: In real-world practice, NACP remains an effective treatment option for early-stage TNBC, yielding high pCR rates and survivals. pCR emerged as a strong predictor of survivals, while weekly carboplatin dosing may enhance treatment efficacy. Integrating clinical, radiological, and pathological factors may support personalized treatment decisions. Prospective studies with larger cohorts and biomarker analyses are warranted to validate these findings. Citation Format: A. Bilici, H. Muglu, O. Ozcan, E. Sunger, T. Sahin, B. Koylu, K. Helvaci, Y. Kemal, U. Demirci, F. Selcukbiricik, G. Basaran, B. Uluc, O. Olmez, S. Aksoy, E. Gokmen. Neoadjuvant Chemoimmunotherapy in Early-Stage TNBC: Real-World Analysis of Predictors of pCR and Survival abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-10-28.