Merck calls quits on two immunotherapies for cancer
The company is scrapping two drugs aimed at targets called TIGIT and LAG-3, both of which were in the middle of Phase 3 testing.
Merck & Co. has long been dominant in cancer immunotherapy, with its drug Keytruda earning 40 approvals en route to becoming the world’s best-selling medicine. But the New Jersey-based drugmaker has had difficulty finding a successor, and a Monday announcement is the latest evidence.
In a statement, Merck said it will end development of two experimental cancer drugs that are currently in late-stage testing. One, called vibostolimab, is aimed at a target called TIGIT. The other, favezelimab, homes in a protein named LAG-3. Both were being evaluated in combinations with Keytruda, and have been touted by Merck as a way to extend Keytruda’s market advantage beyond 2028, when its main U.S. patent will expire.
The two drug targets have been central to drugmakers’ efforts to find new cancer medicines that can boost the benefit of immunotherapies like Keytruda. LAG-3, for example, is the target of a drug Bristol Myers Squibb has brought to market for melanoma, as well as experimental therapies from Regeneron and others. Several drugmakers, among them Roche, GSK and Gilead Sciences, have invested heavily in TIGIT therapies, so far with mostly disappointing results.
According to Merck, emerging findings from trials of vibostolimab and favezelimab led it to scrap each. Following an interim check of two Phase 3 lung cancer studies, trial monitors found the Keytruda-vibostolimab combination met a pre-specified “futility criteria,” meaning patients who’d received it were unlikely to live longer than those treated with Keytruda alone. Rates of immune-related side effects were higher with the combination as well.
Merck separately chose to terminate favezelimab development after reviewing data from all of its trials and concluding it should prioritize other medicines instead.
“Following a careful analysis of the data, the decision has been made to discontinue development of these candidates to prioritize other ongoing programs,” Marjorie Green, head of oncology global clinical development at Merck Research Laboratories, said in a statement. “We continue to pursue the most promising science with a focus on agents with the greatest potential to improve outcomes for more patients with cancer.”
In a note to clients, Leerink Partners analyst Daina Graybosch noted how the vibostolimab combination’s failure was likely the result of “toxicity and difficulty in maintaining patients on treatment through toxicity.” She likened Merck’s decision to discard that drug and favezelimab as “ripping off the Band-Aid,” as investor expectations had already cooled and Merck can now shift its attention to launching a form of Keytruda injected under the skin.
They would be smart to JV with Theralase and try are drug in a combo.