Abstract

Overview: Triple-negative breast cancer (TNBC) carries a poor prognosis. Neoadjuvant chemotherapy (NAC) is standard, and the addition of Pembrolizumab significantly improves pathological complete response (pCR) rates, as shown in the KEYNOTE-522 trial. Our study assessed the efficacy and safety of neoadjuvant TC-AC-Pembrolizumab for TNBC patients at K Hospital.

Methods: This descriptive, prospective cross-sectional study included 49 TNBC patients treated with neoadjuvant Pembrolizumab plus standard chemotherapy at K Hospital. Clinical response was evaluated by RECIST 1.1, pCR after surgery, and adverse events (AEs) by CTCAE v5.0. Data were analyzed using R software.

Results: The pCR rate was 67.3%. A smaller baseline tumor size correlated with higher pCR (median 3.20 mm vs 5.25 mm, p=0.004). Common AEs included fatigue (34.7%), nausea (30.6%), and alopecia (24.5%). Immune-related AEs (irAEs) like thyroiditis (8.2%) and pneumonitis (4.1%) were low-frequency, mostly mild-to-moderate, with no Grade 4 or 5 events.

Conclusion: The neoadjuvant TC-AC-Pembrolizumab regimen demonstrated high efficacy in early-stage TNBC, with impressive clinical and pCR rates and an acceptable safety profile. These findings support its continued clinical use.