iTeos Therapeutics Announces New Preliminary Data Indicating Clinical Activity with its Anti-TIGIT Antibody, EOS-448, at the AACR Annual Meeting 2021

• Initial data from the Phase 1 dose escalation part of the Phase 1/2a trial in adult patients with advanced solid tumors indicated EOS-448 was generally well tolerated with no dose-limiting toxicities observed
  
  
• EOS-448 showed preliminary signs of clinical activity as a monotherapy, including a partial response in one pembrolizumab-resistant melanoma patient, and stable disease in multiple patients
  
  
• EOS-448 reduced TIGIT⁺ suppressive T regulatory cells and CD8 T cells considered to be exhausted at all tested doses, indicating engagement of FcγR, an essential component in many immune system effector functions
  
  
• Company to advance EOS-448 into combination trials with pembrolizumab and other novel agents in both checkpoint-naïve and resistant patients
  
  
• Company to host conference call on Monday, April 12^th at 8:00 a.m. EDT to discuss results
  

CAMBRIDGE, Mass. and GOSSELIES, Belgium, April 10, 2021 (GLOBE NEWSWIRE) -- iTeos Therapeutics, Inc. (Nasdaq: ITOS), clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of highly differentiated immuno-oncology therapeutics for patients, today announced a presentation featuring preliminary clinical data from 22 adult patients in the ongoing Phase 1/2a trial of its anti-TIGIT antibody, EOS-448, at the American Association of Cancer Research (AACR) Annual Meeting 2021, taking place virtually April 10-15. The presentation highlights initial findings from the completed dose escalation monotherapy portion of the trial, indicating a favorable tolerability profile and early signs of clinical activity in advanced cancers.

“We are pleased to share these data showing promising preliminary signs of clinical activity and a favorable tolerability profile with our anti-TIGIT antibody, EOS-448, in patients with advanced cancers,” said Joanne Jenkins Lager, M.D., chief medical officer of iTeos Therapeutics. “The results support our excitement around TIGIT as a therapeutic target capable of harnessing the immune system to treat patients with advanced, difficult to treat cancers. We believe the depletion of TIGIT⁺ suppressive and exhausted cells shown at even the lowest tested dose provides evidence of engagement of the FcγR, and therefore the potential of EOS-448 to activate multiple immune mechanisms. Based on these encouraging results, we are enrolling a total of 40 patients in this study to evaluate the effects of EOS-448 within the tumor. We are advancing EOS-448 into the next stage of clinical development as both a monotherapy and in combination for the treatment of multiple indications, with the goal of improving outcomes for people with advanced cancers.”