Real-world evidence of the efficacy of neoadjuvant pembrolizumab in triple-negative breast cancer: A surgeon's point of view

Purpose

Neoadjuvant pembrolizumab has shown efficacy in improving pathologic complete response (pCR) rates and survival outcomes in triple-negative breast cancer (TNBC). However, real-world data on its clinical efficacy, safety, and surgical outcomes remain limited.

Materials and methods

This retrospective observational study included 331 TNBC patients treated at a single institution from July 2022 to December 2023. Patients received weekly paclitaxel with carboplatin followed by doxorubicin and cyclophosphamide (AC), with or without pembrolizumab. Primary outcomes included pCR rates and surgical de-escalation in the breast and axilla. Secondary outcomes included event-free survival (EFS), overall survival (OS), surgical complications, and persistent immune-related adverse events (irAEs).

Results

The pCR rate was higher in the pembrolizumab group (57.7 %) compared to the control group (49.1 %), with an estimated difference of 8.5 % (p = 0.120). Pembrolizumab enabled 32.7 % of patients initially planned for mastectomy to undergo breast-conserving surgery (BCS). Axillary lymph node dissection (ALND) was avoided in 91 % of pembrolizumab-treated patients versus 86.9 % in the control group. Persistent irAEs were observed in 10.9 % of the pembrolizumab group, with thyroid dysfunction being the most common. Surgical complications were similar between groups. Short-term oncologic outcomes, including EFS and OS, did not differ significantly after a median follow-up of 21 months.

Conclusion

Pembrolizumab demonstrated potential benefits in increasing pCR rates and facilitating surgical de-escalation while maintaining comparable safety to conventional regimens. Persistent irAEs underscore the need for preoperative management and vigilant monitoring. Future studies should identify predictive biomarkers to optimize pembrolizumab's use and assess its long-term impact on survival outcomes.