Belrestotug showed underwhelming efficacy outcomes in mid-stage studies of non-small cell lung cancer and head and neck squamous cell carcinoma.
GSK and Massachusetts-based partner iTeos Therapeutics will no longer advance their investigational TIGIT therapy belrestotug following disappointing mid-stage results, GSK announced on Tuesday. The decision adds another therapy to the spate of failed TIGIT therapies across the industry.
“The collaboration [with iTeos] and all belrestotug-containing study cohorts are ending,” GSK wrote in its news release. The decision to discontinue the development of belrestotug was “mutual,” iTeos CEO Michel Detheux said in a statement alongside the biotech’s own announcement.
In the aftermath of belrestotug’s discontinuation—and of losing a powerhouse partner—iTeos is “taking immediate steps” to shore up its financial position. The biotech on Tuesday kicked off a “targeted” strategic review of its business to identify opportunities to maximize capital and value to shareholders, as per its press announcement.
GSK and iTeos were studying belrestotug in the Phase II GALAXIES Lung-201 study in non-small cell lung cancer (NSCLC). Topline results from this trial, reported Tuesday, showed that while the TIGIT therapy did meet its primary endpoint of objective response rate, it was unable to elicit “clinically meaningful improvements in . . . progression-free survival,” a key secondary outcome of the study, according to iTeos’ release.
The partners were also running the GALAXIES H&N-202 Phase II study in head and neck squamous cell carcinoma. GALAXIES H&N-202 also delivered disappointing results, with belrestotug showing a “trend below the meaningful threshold for” objective response rate.
GALAXIES Lung-201 and GALAXIES H&N-202 paired belrestotug with GSK’s PD-1 blocker Jemperli and compared the combo against Jemperli alone. The companies did not provide specific figures for either study on Tuesday, though Detheux noted that “it is important to share these data with the scientific community at an upcoming medical meeting.”
GSK and iTeos came together for this collaboration in 2021, in a deal that had GSK paying iTeos $625 up front and up to $1.45 billion in downstream milestone payments.
Belrestotug joins the growing group of TIGIT treatments that have been shelved over the past year, highlighting the difficulties of developing therapies in this class.
Last month, for instance, BeiGene announced that it would no longer pour money into its anti-TIGIT antibody ociperlimab, which it had been assessing for NSCLC. An independent data monitoring committee found that the Phase III AdvanTIG-302 trial was “unlikely to meet the primary endpoint of overall survival.”
In July 2024, Roche likewise dumped its TIGIT candidate tiragolumab after disappointing data from the Phase II/III SKYSCRAPER-06 trial in NSCLC. This followed Merck’s May 2024 discontinuation of a late-stage study for the anti-TIGIT treatment vibostolimab, which it was combining with its blockbuster Keytruda as a treatment for melanoma.
