Breast Cancer Coverage from Every Angle

ASCO20: KEYNOTE-355 Trial of Pembrolizumab Plus Chemotherapy in Triple-Negative Breast Cancer

By: Joseph Cupolo
Posted: Saturday, June 20, 2020

Pembrolizumab combined with several chemotherapy partners demonstrated a statistically significant and clinically meaningful improvement in progression-free survival in comparison with chemotherapy alone in patients with previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer with PD-L1 expression. No new safety concerns were noted. Javier Cortes, MD, PhD, of the Hospital Universitario Ramón y Cajal, Madrid, and colleagues, presented their data from the KEYNOTE-355 study during the ASCO20 Virtual Scientific Program (Abstract 1000).

In total, 847 patients who experienced at least a 6-month disease-free interval were randomly assigned 2:1 to pembrolizumab plus chemotherapy (nab-paclitaxel, paclitaxel, or gemcitabine/carboplatin) or placebo plus chemotherapy. Dual primary endpoints were progression-free survival and overall survival.

Assessed by Response Evaluation Criteria in Solid Tumors, version 1.1, blinded independent central review, the median progression-free survival was 9.7 months with pembrolizumab and chemotherapy versus 5.6 months with placebo and chemotherapy in those with a Combined Positive Score (CPS) ≥ 10. “In patients who are PD-L1–positive with a combined positive score of ≥ 10, the primary end point was met, with a hazard ratio of 0.65, which is both statistically significant and of great clinical importance,” noted the investigators. Furthermore, the addition of immunotherapy improved progression-free survival over chemotherapy alone in those with a CPS ≥ 1 (7.6 months vs. 5.6 months; hazard ratio = 0.74).

Disclosure: For full disclosures of the study authors, visit

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