Merck & Co. Inc.'s blockbuster immuno-oncology drug Keytruda failed to meet its main goal of improving survival in certain breast cancer patients compared to chemotherapy in a late-stage study.

The study, named Keynote-119, evaluated the anti-PD1 therapy alone in metastatic triple-negative breast cancer after patients had already received prior treatments that did not show benefit.

Secondary goals were not tested because the primary goal was not met, the Kenilworth, N.J.-based company stated in a May 20 press release.

Merck will report the results of the trial at an upcoming medical meeting.

Keytruda, also known as a checkpoint inhibitor that activates T-cells in the body, is approved for multiple cancer indications and is being tested in over 900 clinical trials.