Merck scraps third prostate cancer study as Keytruda therapy disappoints

[March 01, 2023]  By Bhanvi Satija

(Reuters) - Merck & Co on Tuesday scrapped a late-stage trial of a combination therapy with its cancer drug Keytruda as interim data showed it was unlikely to meet the main goals, making it the drugmaker's third trial for the disease to be abandoned.

The setbacks were likely to put Merck further behind in its quest to develop a treatment for advanced forms of the most common cancer type in the United States.

It had in January stopped a late-stage study of the drug in some prostate cancer patients. Keytruda belongs to a class of drugs known as checkpoint inhibitors, which disables the programmed death 1, or PD-1, protein that helps tumors evade the immune system.

The decision did not come as a surprise as prostate cancers have historically not been responsive to this class of drugs, said Mara Goldstein, analyst at Mizuho Securities.

"The incremental cost to (pursue these trials) is probably low relative to what the potential return is," said Goldstein.

An interim analysis showed the combination therapy did not extend survival or help extend the time a patient lives without the disease worsening compared to placebo, Merck said.

Signage is seen at the Merck & Co. headquarters in Kenilworth, New Jersey, U.S., November 13, 2021. REUTERS/Andrew Kelly/

The treatment was also associated with a higher rate of serious adverse events compared to placebo group, the U.S. drugmaker said.

Merck was testing its blockbuster immunotherapy in combination with androgen deprivation therapy and Xtandi, made by Pfizer Inc and Astellas Pharma Inc, in patients with an advanced form of treatment-resistant prostate cancer.

Additionally, Merck said another combination treatment with Keytruda did not meet the main goal in a separate late-stage study for a type of lung cancer that can spread to other parts of the body.

Shares of the New Jersey-based company fell nearly 2% to $107.44 in early trading.

(Reporting by Bhanvi Satija in Bengaluru; Editing by Arun Koyyur)

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