Pembrolizumab plus chemotherapy improves pCR in triple-negative breast cancer

A completed trial in 1,174 participants with triple-negative breast cancer tested neoadjuvant pembrolizumab plus chemotherapy against placebo plus chemotherapy, followed by adjuvant pembrolizumab or placebo after definitive surgery. According to the ClinicalTrials.gov posting, Merck Sharp & Dohme LLC posted these results on 22 October 2026.

The primary pathologic complete response (pCR) rate, assessed as ypT0/Tis ypN0 at the time of definitive surgery, was 64.0 percent in the pembrolizumab plus chemotherapy group and 54.7 percent in the placebo plus chemotherapy group (p=0.00221), according to the posting. That represents an absolute difference of 9.3 percentage points. The registry also reports an event-free survival p value of 0.0005943 for all participants, but median event-free survival is listed as not available in both groups.

The posting does not provide median event-free survival times or hazard ratios, so the direction or size of any event-free survival difference cannot be assessed from these data. Pathologic complete response was measured at surgery, while event-free survival was followed for up to approximately 102 months.