MSD has announced plans to start three late-stage studies of Keytruda (pembrolizumab) in combination with other drugs, including the PARP inhibitor Lynparza (olaparib), in patients with metastatic castration-resistant prostate cancer.

The news comes after the drug showed anti-tumour activity in the early-stage Phase Ib/II KEYNOTE-365 umbrella trial investigating the anti-PD-1 therapy in combination with various agents in this indication.

The three new pivotal Phase III studies will all assess overall survival as a co-primary endpoint, and the new studies give the firm the largest clinical programme for an anti-PD-1 therapy in prostate cancer, it claimed.

Merck Research Laboratories senior vice president Roy Baynes said of the development: “At the core of our research programme is a commitment to investigate the potential of Keytruda, both as combination and monotherapy, to serve as a foundational treatment, especially for cancers where additional therapies are needed.

“Promising data presented at ASCO GU coupled with the significant unmet medical need in patients with metastatic castration-resistant prostate cancer, propelled us to initiate three new Phase III trials to further evaluate these Keytruda combination regimens.”

Another one of the new Phase III trials, KEYLYNK-010, will assess the safety and efficacy of Keytruda and Lynparza combination in 780 mCRPC patients, whilst the randomised, double-blind KEYNOTE-921 trial will study Keytruda in combination with Taxotere (docetaxel) and prednisone in a total of 1,000 participants.