The phase 3 KEYLYNK-010 trial has been discontinued after a review of an interim analysis of the data showed that treatment with Keytruda (pembrolizumab) plus Lynparza (olaparib) failed to significantly improve survival in patients with metastatic castration-resistant prostate cancer whose disease progressed after treatment with chemotherapy and either Zytiga (abiraterone acetate) or Xtandi (enzalutamide), according to Merck, the manufacturer of Keytruda.

The interim analysis demonstrated that the use of the combination did not result in a significant enough overall survival (percentage of patients alive for a duration of time after diagnosis or the start of treatment) benefit, when compared with Zytiga or Xtandi plus the steroid prednisone.

“There remains a significant unmet need for patients diagnosed with advanced prostate cancer, who have a poor prognosis after not responding to initial therapy,” Dr. Roy Baynes, the senior vice president and head of global clinical development, as well as chief medical officer, at Merck Research Laboratories, said in the release. “Merck continues to evaluate the combination of Keytruda and Lynparza in a range of cancers, and to research other Keytruda-based combinations for patients with advanced prostate cancer. We are grateful to the patients, their families and the investigators who made this study possible.”

In the phase 3 KEYLYNK-010 trial, 793 patients received either Keytruda and Lynparza for up to 35 cycles or Zytiga plus prednisone (patients whose diseased previously failed to respond to Xtandi) or Xtandi (for those who were previously treated with Zytiga) and prednisone.

Improved overall survival was one of the main goals of the study. Other outcomes of interest included objective response rate (percentage of patients whose disease partially or completely responds to treatment) in the patient population, as well as, but not limited to, duration of response (which is the time from treatment response to disease progression or death).

The data, according to Merck, indicated that the safety profile of each study drug was consistent with what had been previously reported in other studies. However, patients who received the Keytruda and Lynparza combination experienced more treatment-related side effects (including severe side effects), compared with the other groups that received either Xtandi or Zytiga plus prednisone.

Merck noted that it plans to inform the study investigators about its decision to discontinue the study. Moreover, patients who are enrolled on the trial have been advised to consult with the health care team to figure out next steps.

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