WATERTOWN, MA, USA and GOSSELIES, Belgium I July 08, 2024 I iTeos Therapeutics, Inc. (Nasdaq: ITOS) (“iTeos”), a clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of immuno-oncology therapeutics for patients, today announced the dosing of the first patient in GALAXIES Lung-301, a global, randomized, double-blind Phase 3 registrational clinical trial of belrestotug + dostarlimab versus placebo + pembrolizumab in patients with first-line advanced, unresectable, or metastatic PD-L1 high NSCLC. This event has triggered $35 million in development milestone payments from GSK, its partner for belrestotug.

“Dosing the first patient in the GALAXIES Lung-301 study marks a significant milestone for belrestotug + dostarlimab. iTeos was founded with the goal of advancing therapeutic options for patients by leveraging best-in-class science. The decision to launch our first TIGIT:PD-1 doublet Phase 3 trial underscores our disciplined, data-driven investment approach and was informed by several promising preliminary clinical surrogates such as safety, ORR, and depth of response from the latest interim analysis in May 2024,” said Michel Detheux, Ph.D., president and chief executive officer of iTeos. “We are excited about the ongoing Phase 2 GALAXIES Lung-201 trial and look forward to presenting data from the most recent interim analysis of this study at a medical meeting in 2024.”

iTeos and GSK entered into an exclusive development and commercialization collaboration in June 2021 for belrestotug, an anti-TIGIT monoclonal antibody, enabling novel next-generation immuno-oncology combinations. Per the agreement, iTeos received a $625 million upfront payment from GSK with development and regulatory milestones up to $550 million and commercial milestones up to $900 million. In addition to the milestones, GSK and iTeos will jointly commercialize and equally split profits in the US. Outside the US, GSK will receive an exclusive license for commercialization and iTeos will receive tiered royalty payments. Within the collaboration, GSK and iTeos share responsibility and costs for the global development of belrestotug.

About iTeos Therapeutics, Inc.
iTeos Therapeutics is a clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of immuno-oncology therapeutics for patients. iTeos Therapeutics leverages its deep understanding of tumor immunology and immunosuppressive pathways to design novel product candidates with the potential to restore the immune response against cancer. The Company’s innovative pipeline includes three clinical-stage programs targeting novel, validated immunosuppressive pathways designed with optimized pharmacologic properties for improved clinical outcomes, including the TIGIT/CD226 axis and the adenosine pathway. iTeos Therapeutics is headquartered in Watertown, MA with a research center in Gosselies, Belgium.

About Belrestotug (EOS-448/ GSK4428859A)
Belrestotug is an Fc active human immunoglobulin G1, or IgG1, monoclonal antibody (mAb) targeting T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT), an important inhibitory receptor which contributes to the suppression of innate immune responses against cancer. As an optimized high-affinity, potent anti-TIGIT mAb, belrestotug is designed to enhance the antitumor response through a multifaceted immune modulatory mechanism by engaging with TIGIT and FcγR, a key regulator of immune responses which induces cytokine release and antibody dependent cellular cytotoxicity (ADCC). The therapeutic candidate is progressing in multiple indications in collaboration with GSK.

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