Merck stops testing combo drug for lung cancer

(Reuters) -Merck said on Thursday it had discontinued a trial testing a combination immunotherapy treatment in patients with a type of lung cancer after an interim analysis showed the drug was unlikely to succeed.

The patients tested with a combination of its experimental drug, vibostolimab, with Keytruda experienced a higher rate of immune-related side effects, Merck said, adding that patients should stop ongoing treatment with the therapy.

The discontinuation marked yet another setback for vibostolimab and the promising new class of immunotherapies called anti-TIGIT to which it belongs.

Gilead Sciences, Roche and GSK are among half a dozen drugmakers looking to grab a share of the lucrative anti-TIGIT cancer drug market, but the field has experienced multiple setbacks.

Vibostolimab works by selectively binding itself to TIGIT, a receptor on immune cells, to activate the immune system against cancer cells and prevent a misguided immune attack against healthy cells.

Merck was testing vibostolimab along with Keytruda as a first-line treatment for patients with extensive-stage small cell lung cancer in the late-stage study.

Last year, the combination therapy had failed to significantly slow disease progression in lung cancer patients who did not respond to previous treatments.

The drugmaker discontinued another late-stage study in May testing the combination therapy in patients with a severe form of skin cancer after side effects led to high discontinuation.

(Reporting by Leroy Leo in Bengaluru; Editing by Devika Syamnath)