GSK and iTeos End Belrestotug TIGIT Program After Disappointing Lung Cancer Results

GSK and iTeos Therapeutics have mutually agreed to discontinue development of belrestotug, an anti-TIGIT cancer therapy, after it failed to show meaningful benefit in lung cancer trials345.

The GALAXIES Lung-201 Phase 2 trial, which tested belrestotug in combination with dostarlimab for advanced non-small cell lung cancer (NSCLC), did not meet the criteria for clinically meaningful improvements in progression-free survival, despite some improvement in objective response rate45.

All belrestotug cohorts will be terminated, and new enrollment in ongoing Phase 3 trials will be halted as a result of the program's lack of efficacy4.

Setbacks for TIGIT-targeting drugs are part of a broader trend, with similar agents from Merck, Roche, and BeiGene also failing to deliver improved clinical outcomes in recent studies5.

iTeos is now exploring strategic alternatives and has engaged TD Cowen to advise on preserving shareholder value following the program’s termination4.

Market sentiment toward TIGIT inhibitors remains negative, as the class has recently been met with skepticism and indifference from investors due to repeated clinical failures5.

Sources:

3. https://kfgo.com/2025/05/13/iteos-gsk-discontinue-lung-cancer-therapy-development/

4. https://www.nasdaq.com/articles/iteos-therapeutics-and-gsk-terminate-belrestotug-development-program-following-galaxies

5. https://pharma.economictimes.indiatimes.com/news/pharma-industry/gsk-partner-iteos-scrap-development-of-lung-cancer-therapy/121150205