GSK has stopped development of anti-TIGIT antibody belrestotug. The Big Pharma and its partner iTeos Therapeutics took the action after an assessment of the effect on progression-free survival fell short of expectations.
London-based GSK paid iTeos $625 million upfront for rights to belrestotug four years ago. At the time, interest in TIGIT was riding high as Bristol Myers Squibb, Gilead Sciences, Merck & Co. and Roche worked on assets designed to bring the benefits of immunotherapy to more cancer patients. However, the early signs of efficacy have largely failed to translate into the hoped-for improvements in survival.
GSK and iTeos dealt a further blow to the mechanism on Tuesday after reviewing results from phase 2 trials. One study was testing belrestotug in combination with anti-PD-1 checkpoint inhibitor Jemperli in people with previously untreated, unresectable, locally advanced or metastatic PD-L1-high non-small cell lung cancer (NSCLC).
The combination continued to drive improvements in the primary endpoint of objective response rate, iTeos said. However, the progression-free survival results fell short of the level the developers deemed clinically meaningful.
The setback was compounded by an interim look at data from a phase 2 trial in PD-L1-positive head and neck squamous cell carcinoma. That study was comparing belrestotug combination cohorts to Jemperli monotherapy. The interim analysis showed a trend below the meaningful response rate threshold, iTeos said.
Based on the data, GSK and iTeos decided to terminate the belrestotug program and their collaboration. All cohorts that contain belrestotug are ending.
Further, GSK has stopped enrollment in a phase 3 cohort that was testing belrestotug with Jemperli in first-line locally advanced or metastatic PD-1-selected NSCLC.
The setback drove iTeos to take immediate steps to save cash and start reviewing strategic alternatives. The biotech ended March with $624.3 million, an amount it forecast would fund operations through 2027 under its previous spending plan.
Beyond belrestotug, iTeos is developing an ENT1 inhibitor and an anti-TREM2 antibody, both of which are in phase 1 cancer studies.
GSK’s exit from the TIGIT race extends a string of dropouts in the face of disappointing data. Gilead and Arcus Biosciences are continuing to advance domvanalimab through late-phase trials, including in NSCLC, and AstraZeneca is still pushing its TIGITxPD-1 bispecific rilvegostomig through a slate of phase 3 studies.