TIGIT Setback: iTeos and GSK Halt Development of Cancer Immunotherapy

In a significant blow to the field of cancer immunotherapy, iTeos Therapeutics and GlaxoSmithKline (GSK) have announced the termination of their collaboration on belrestotug, a promising TIGIT-blocking drug. This decision comes after disappointing results in a Phase 2 clinical trial, marking another setback for the TIGIT class of cancer treatments that have struggled to meet expectations.

Phase 2 Trial Results Fall Short

The Phase 2 trial, which combined belrestotug with GSK's Jemperli (dostarlimab), failed to significantly delay tumor progression in patients with non-small cell lung cancer. While the drug combination showed a trend towards improved outcomes, it fell below the predetermined threshold for meaningful clinical benefit. Additionally, results in head and neck cancer patients were similarly underwhelming.

iTeos CEO Michel Detheux stated, "Based on these results, we are taking immediate steps to preserve capital and have initiated a strategic review to evaluate alternatives that will maximize shareholder value."

Implications for TIGIT Research

The failure of belrestotug is the latest in a series of disappointments for TIGIT-targeting therapies. Once hailed as a potential breakthrough in cancer treatment, TIGIT inhibitors have faced numerous clinical setbacks in recent years:

• Several major pharmaceutical companies, including Roche, Merck & Co., Bristol Myers Squibb, and Gilead Sciences, have invested heavily in TIGIT research.
• Multiple clinical trials have failed to demonstrate significant improvements in patient outcomes.
• Some companies have already terminated their TIGIT programs in response to negative results.

Despite these setbacks, not all hope is lost for the TIGIT class. Gilead and Arcus Biosciences continue to pursue a Phase 3 trial of their TIGIT inhibitor in gastrointestinal tract cancer, with results expected next year.

Financial Ramifications

The termination of the iTeos-GSK collaboration carries significant financial implications:

• GSK initially paid iTeos $625 million upfront in 2021 for the rights to belrestotug.
• The deal included potential milestone payments of up to $1.45 billion.
• iTeos will no longer receive these future payouts, prompting a strategic review of the company's operations.

As the pharmaceutical industry continues to grapple with the challenges of developing effective cancer immunotherapies, the belrestotug setback serves as a reminder of the complexities and risks inherent in drug development. The coming months will likely see increased scrutiny of ongoing TIGIT research and a potential reassessment of investment strategies in this area of oncology.