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William J. Gradishar, MD, FACP, FASCO


SABCS 2023: Can Pembrolizumab Plus Olaparib Improve Survival in Advanced Triple-Negative Breast Cancer?

By: Julia Fiederlein Cipriano, MS
Posted: Friday, December 8, 2023

Although maintenance therapy with the PD-1 inhibitor pembrolizumab plus the PARP inhibitor olaparib vs chemotherapy did not appear to significantly improve progression-free or overall survival in an unselected population of patients with locally recurrent inoperable or metastatic triple-negative breast cancer, Hope Rugo, MD, FASCO, of the University of California San Francisco, and colleagues reported directionally favorable improvements for those with BRCA-mutated disease. These findings from the phase II KEYLYNK-009 trial, which were presented during the 2023 San Antonio Breast Cancer Symposium (SABCS; Abstract GS01-05), warrant confirmatory investigation.

“Tolerable and effective maintenance regimens after induction therapy are needed to sustain clinical benefit,” the investigators commented. “Prior data suggest that PARP inhibitors combined with PD-1/PD-L1 inhibitors could provide an improved therapeutic effect.”

A total of 460 patients underwent induction therapy with pembrolizumab plus platinum-based chemotherapy. Those who achieved a complete response, partial response, or stable disease (n = 271) were randomly assigned in a 1:1 ratio to receive maintenance therapy with pembrolizumab plus either olaparib or chemotherapy. Follow-up data were provided for a median of 17.2 months.

The primary endpoints of progression-free (hazard ratio [HR] = 0.98; P = .4556) and overall (HR = 0.95) survival were not met with pembrolizumab plus olaparib vs chemotherapy. The median duration of progression-free survival was prolonged with olaparib in patients with BRCA-mutated disease but not in those whose tumors expressed PD-L1 with a combined positive score of at least 10; a similar trend was reported for overall survival.

The investigators observed fewer treatment-related adverse events with pembrolizumab plus olaparib vs chemotherapy (84.4% vs 96.2%). Treatment-related adverse events of grade 3 or higher were documented in 32.6% of patients treated with olaparib and in 68.4% of those who received chemotherapy. A total of 8.9% and 19.5% of patients who were administered olaparib and chemotherapy, respectively, discontinued treatment because of related adverse events.  

Disclosure: For full disclosures of the study authors, visit

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