GSK Terminates $625M TIGIT Program as Clinical Data Falls Short of Expectations

GSK and iTeos Therapeutics End Collaboration on Belrestotug

GSK has announced the discontinuation of its anti-TIGIT antibody program, belrestotug, following disappointing clinical trial results. The decision, made in conjunction with development partner iTeos Therapeutics, comes after an assessment of progression-free survival data failed to meet expectations in multiple studies.

The termination of the program marks a significant setback for both companies, with GSK having invested $625 million upfront for the rights to belrestotug just four years ago. This move also represents another blow to the TIGIT inhibitor class, which has seen diminishing enthusiasm in recent years as early promising results have failed to translate into meaningful survival benefits.

Clinical Trial Results Fall Short

Two key phase 2 trials contributed to the decision to halt the belrestotug program:

1. A study testing belrestotug in combination with GSK's anti-PD-1 checkpoint inhibitor Jemperli in previously untreated, unresectable, locally advanced or metastatic PD-L1-high non-small cell lung cancer (NSCLC) patients. While the combination continued to show improvements in the primary endpoint of objective response rate, the progression-free survival results did not reach the threshold deemed clinically meaningful by the developers.

2. An interim analysis of a phase 2 trial in PD-L1-positive head and neck squamous cell carcinoma, comparing belrestotug combination cohorts to Jemperli monotherapy. This study showed a trend below the meaningful response rate threshold.

Based on these results, GSK and iTeos have decided to terminate all cohorts containing belrestotug. Additionally, GSK has halted enrollment in a phase 3 cohort testing belrestotug with Jemperli in first-line locally advanced or metastatic PD-1-selected NSCLC.

Impact on iTeos Therapeutics and Future Plans

The termination of the belrestotug program has prompted iTeos Therapeutics to take immediate steps to conserve cash and explore strategic alternatives. The biotech company reported $624.3 million in cash reserves at the end of March, which was previously expected to fund operations through 2027 under their original spending plan.

Despite this setback, iTeos continues to develop other candidates in its pipeline, including an ENT1 inhibitor and an anti-TREM2 antibody, both currently in phase 1 cancer studies.