Breast Cancer Coverage from Every Angle

Pembrolizumab Plus Chemotherapy in Triple-Negative Breast Cancer

By: Celeste L. Dixon
Posted: Monday, November 4, 2019

A statistically significant improvement in pathologic complete response was reported in women with early triple-negative breast cancer who were treated with pembrolizumab in addition to chemotherapy during neoadjuvant treatment prior to definitive tumor-removal surgery. These interim results of KEYNOTE-522, the first phase III trial of immunotherapy in early breast cancer, were reported at the European Society for Medical Oncology (ESMO) Congress 2019 in Barcelona (Abstract LBA8_PR).

“The data suggest that the improved pathologic complete response with pembrolizumab translates into fewer recurrences,” said study author Peter Schmid, MD, PhD, of the United Kingdom’s Centre For Experimental Cancer Medicine at Barts Cancer Institute, Queen Mary University of London, in an ESMO press release. “If we prevent recurrence, we cure more patients.” However, longer-term data for confirmation of these results are necessary, he added.

Initially, 784 patients were randomly assigned to neoadjuvant pembrolizumab plus chemotherapy, followed by adjuvant pembrolizumab, with another 390 patients randomly assigned to neoadjuvant placebo plus chemotherapy, followed by adjuvant placebo. All had nonmetastatic disease that was previously untreated.

With a median follow-up of 15.5 months, and 602 patients in total evaluable for pathologic complete response (one of the co-primary endpoints), the pathologic complete response rate in the pembrolizumab arm was 64.8% vs. 51.2% in the placebo arm (P = .00055). “We found a 13.6% difference, which is a clinically meaningful benefit,” said Dr. Schmid. The pembrolizumab-plus-chemotherapy, surgery, and pembrolizumab sequence showed a favorable trend in event-free survival, which was the other co-primary endpoint (hazard ratio = 0.63; 95% confidence interval, 0.43–0.93). In addition, no new safety signals emerged in the pembrolizumab arm.

Disclosure: For full disclosures of the study authors, visit

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