Does adding immune checkpoint inhibitors to chemotherapy improve survival for early-stage triple-negative breast cancer?

For early-stage triple-negative breast cancer (TNBC), the standard treatment has been chemotherapy before surgery (neoadjuvant chemotherapy). Recent research shows that adding an immune checkpoint inhibitor (ICI) — a drug that helps the immune system attack cancer cells — to chemotherapy can improve outcomes. Several large trials and meta-analyses have found that this combination leads to higher rates of pathologic complete response (no cancer found at surgery) and better event-free survival (time without cancer returning). Some studies also show an overall survival benefit. The strongest evidence is for pembrolizumab, which is now approved for early-stage TNBC in combination with chemotherapy.

What the research says

A 2025 review notes that pembrolizumab combined with chemotherapy in the neoadjuvant setting has significantly improved pathologic complete response, event-free survival, and overall survival, establishing a new standard of care ⁹. A meta-analysis of 18 trials found that adding an ICI to neoadjuvant chemotherapy improved event-free survival (HR 0.67) compared to chemotherapy alone, though the overall survival difference was not statistically significant in that analysis ². Another meta-analysis reported that adding ICIs to chemotherapy improved pathologic complete response (odds ratio 1.90) and event-free survival (HR 0.65) in the neoadjuvant setting, with benefits seen regardless of PD-L1 status ⁷. A review of immunotherapy innovations highlights that landmark trials such as KEYNOTE-355 and IMpassion130 have demonstrated survival benefits in PD-L1-positive metastatic TNBC, and similar principles apply to early-stage disease ⁵. However, not all trials have been positive: the IMpassion131 trial, which used atezolizumab with paclitaxel, did not show a progression-free survival benefit in the PD-L1-positive population ¹⁰. The IMpassion132 trial, which enrolled patients with early relapsing disease, also did not meet its primary endpoint of overall survival ¹¹. These mixed results underscore the importance of patient selection and the specific chemotherapy backbone used.

What to ask your doctor

• Is pembrolizumab combined with chemotherapy an option for my stage of triple-negative breast cancer?
• What is my PD-L1 status, and how does it affect the potential benefit of adding an immune checkpoint inhibitor?
• What are the possible side effects of adding an immune checkpoint inhibitor to chemotherapy, and how are they managed?
• How does adding an immune checkpoint inhibitor affect my treatment schedule and the timing of surgery?
• Are there any ongoing clinical trials for early-stage triple-negative breast cancer that I might be eligible for?