Merck stops testing combo drug for skin cancer as more patients discontinue

FILE PHOTO: The Merck logo is seen at a gate to the Merck & Co campus in Rahway, New Jersey, New Jersey

(Reuters) -Merck said on Monday it had discontinued an experimental combination treatment testing a new type of immunotherapy in patients with a severe form of skin cancer after side effects led to high discontinuation.

This is the latest setback for the experimental drug, vibostolimab, and the related promising new class of immunotherapies called anti-TIGIT.

Merck was testing vibostolimab along with Keytruda, its top-selling cancer drug, in a late-stage study in patients with resected high-risk melanoma.

An analysis showed the trial will not achieve the main goal of statistically significant improvement in recurrence-free survival as more side effects led to several patients discontinuing the combination treatment versus those on Keytruda alone, Merck said.

The company will recommend patients receiving the combination treatment be offered the Keytruda monotherapy.

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

Merck said it still had an extensive clinical development program evaluating the vibostolimab-Keytruda combination.

The combination treatment had earlier failed to significantly slow disease progression in lung cancer patients in a late-stage study last year.

Data from another trial in March last year had also showed that it was less effective than a generic medicine called docetaxel in some patients with non-small cell lung cancer.

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 seen multiple setbacks.

Gilead and its partner Arcus Biosciences in January stopped a late-stage trial involving their anti-TIGIT candidate domvanalimab in a type of lung cancer. Gilead has announced a $320 million investment in its biotech partner as it refocused its anti-TIGIT push.

(Reporting by Mariam Sunny and Leroy Leo in Bengaluru; Editing by Tasim Zahid and Sriraj Kalluvila)