Breast Cancer Coverage from Every Angle

ESMO Asia 2020: Subgroup Analysis of KEYNOTE-522 Supports Use of Pembrolizumab in Triple-Negative Breast Cancer

By: Julia Fiederlein
Posted: Monday, November 30, 2020

The overall results of the phase III KEYNOTE-522 trial revealed that patients with early triple-negative breast cancer who received neoadjuvant pembrolizumab plus chemotherapy experienced a higher pathologic complete response rate than those who received a placebo plus chemotherapy. According to Rebecca Dent, MD, of the Duke-NUS Medical School, Singapore, and colleagues, this also now seems to hold for the patients recruited from Korea, Japan, Taiwan, and Singapore. The Asian subgroup analysis was presented during the European Society for Medical Oncology (ESMO) Asia Virtual Congress 2020 (Abstract 10).

A total of 1,174 patients with previously untreated, nonmetastatic, centrally confirmed triple-negative breast cancer were enrolled in the trial. The Asian subgroup comprised 215 patients, all of whom were eligible for the safety analysis. They were randomly assigned in a 2:1 ratio to receive either pembrolizumab or placebo plus chemotherapy as neoadjuvant treatment, followed by adjuvant pembrolizumab or placebo. All patients underwent definitive surgery.

Among the first 125 patients, the pathologic complete response rates (primary endpoint: defined as ypT0/Tis ypN0) with pembrolizumab and with the placebo were 59% versus 40%, respectively. These results seemed consistent with those seen across the secondary pathologic complete response definitions; the pathologic complete response rates were higher with pembrolizumab than with the placebo in both the ypT0 ypN0 (51% vs. 30%) and ypT0/Tis (61% vs. 42%) cohorts.

Improvements in the pathologic complete response rates were observed irrespective of the PD-L1 Combined Positive Score and regardless of the definition of pathologic complete response used. Of note, the pathologic complete response rate increased more than 30% in patients who had node-positive disease at baseline.

Treatment-related adverse events of grade 3 or higher occurred in 75% of the pembrolizumab arm and 76% of the placebo arm. No deaths were reported with either treatment.

Disclosure: For full disclosures of the study authors, visit

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