(Reuters) -Merck & Co Inc said on Wednesday it was discontinuing a late-stage trial of its blockbuster immunotherapy Keytruda in some prostate cancer patients after interim data showed it was unlikely to meet the study's main goals.
The interim analysis showed the therapy did not extend survival or help extend the time a patient lives without the disease worsening, the U.S. drugmaker said.
The drug was being tested in combination with androgen deprivation therapy and Xtandi, made by Pfizer Inc and Astellas Pharma Inc, in patients with hormone-sensitive prostate cancer that has spread to other parts of the body.
The interim data comes as a setback for Merck, which has been working to expand the use of Keytruda, a drug that has powered its growth for years but is nearing an end to its exclusivity in 2028.
The trial had enrolled 1,251 patients who received the combination therapy with Keytruda or a placebo.
Prostate cancer is the most common cancer in the United States with nearly 270,000 new cases and 34,500 deaths in the country in 2022, according to government data estimates.
Up to one in three patients with the disease develop metastatic form of the cancer and face a five-year survival rate of 30%, according to the drugmaker.
Separately, Merck said Keytruda in combination with a chemotherapy showed significant improvement in overall survival in patients with an advanced type of bile duct cancer.
The drugmaker's shares fell marginally to $107.86 in premarket trading.
(Reporting by Raghav Mahobe and Manas Mishra in Bengaluru; Editing by Arun Koyyur)