Pembrolizumab-chemotherapy combination appears effective in metastatic triple-negative breast cancer
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The addition of pembrolizumab to first-line chemotherapy significantly extended PFS among patients with metastatic triple-negative breast cancer whose tumors express PD-L1, according to topline data released by the agent’s manufacturer.
The randomized phase 3 KEYNOTE-355 study included 847 patients with locally recurrent inoperable or metastatic triple-negative breast cancer who had not received chemotherapy for metastatic disease.
Researchers randomly assigned patients to receive the anti-PD-1 therapy pembrolizumab (Keytruda, Merck) dosed at 200 mg via IV on day 1 of each 21-day cycle in combination with investigator’s choice of chemotherapy — nab-paclitaxel, paclitaxel (Abraxane, Celgene) or gemcitabine/carboplatin — or placebo plus chemotherapy.
OS and PFS in the entire cohort — as well as the subset of participants whose tumors expressed PD-L1 — served as dual primary endpoints. Secondary endpoints included objective response rate, duration of response, disease control rate and safety.
Results of an interim analysis performed by an independent data monitoring committee showed a significant PFS benefit with pembrolizumab among those whose tumors expressed PD-L1 (combined positive score of 10 or higher).
The committee recommended the trial continue with no changes until OS results can be evaluated.
Pembrolizumab exhibited a safety profile consistent with that observed in prior studies.
Complete data from the trial will be submitted for presentation at an upcoming medical congress.
“Triple-negative breast cancer is an aggressive malignancy. It is very encouraging that Keytruda in combination with chemotherapy has now demonstrated positive results as both a first-line treatment in the metastatic setting with this trial, and as neoadjuvant therapy in the KEYNOTE-522 trial,” Roger M. Perlmutter, MD, PhD, president of Merck Research Laboratories, said in a company-issued press release. “We look forward to sharing these findings with the medical community at an upcoming congress and discussing them with the FDA and other regulatory authorities.”
The FDA approved pembrolizumab for treatment of specific patients with lung cancer, head and neck squamous cell carcinoma, melanoma, hepatocellular carcinoma, classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma, urothelial carcinoma, gastric cancer, cervical cancer, Merkel cell carcinoma and microsatellite instability-high cancers.