Breast Cancer Coverage from Every Angle

KEYNOTE-522 in Triple-Negative Breast Cancer: Pathologic Complete Response Rates With Pembrolizumab

By: Melissa E. Fryman, MS
Posted: Friday, January 10, 2020

According to the latest results from the ongoing phase III KEYNOTE-522 trial, the combination of pembrolizumab and chemotherapy seems to improve pathologic complete response rates in patients with triple-negative breast cancer, particularly for those with lymph node involvement. Recurrence rates in this patient population are high, but they appear to be curbed among patients with pathologic complete response to neoadjuvant chemotherapy. Peter Schmid, MD, PhD, FCRP, of the Barts Cancer Institute, London, and colleagues, presented these data at the 2019 San Antonio Breast Cancer Symposium (Abstract GS3-03).

“It has been known for some time that involvement of lymph nodes is associated with an even higher risk of recurrence in patients with triple-negative breast cancer,” said Dr. Schmid in an American Association for Cancer Research press release. “Our results suggest that adding pembrolizumab to neoadjuvant chemotherapy is beneficial for patients with the most aggressive disease and the highest unmet need. I think the results have the potential to be practice-changing.”

In this study, a total of 1,174 patients with previously untreated, nonmetastatic, triple-negative breast cancer were randomly assigned to receive pembrolizumab or placebo plus chemotherapy as neoadjuvant treatment, followed by adjuvant pembrolizumab or placebo. All patients then underwent definitive surgery and radiation therapy if indicated.

At the time of data analysis, the trial results showed that of the patients whose cancers had spread to the lymph nodes, 64.8% of those receiving pembrolizumab plus chemotherapy had a pathologic complete response, compared with 44.1% of patients receiving chemotherapy alone. Preliminary analyses for event-free survival showed “a strong favorable trend”; however, the predefined boundaries for statistical significance have not yet been met, and additional analyses are pending.

Disclosure: For full disclosures of the study authors, visit

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