ITOS iTeos Therapeutics Inc

iTeos Therapeutics, Inc. (Nasdaq: ITOS), a clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of immuno-oncology therapeutics for patients, today announced a poster presentation of preclinical data on EOS-984, a potential first-in-class small molecule inhibitor targeting the equilibrative nucleoside transporter 1 (ENT1) in oncology, at the American Association for Cancer Research (AACR) Annual Meeting, being held April 5-10, 2024 in San Diego, California.

Based on the Company’s discovery and characterization of ENT1 in adenosine-mediated immunosuppression, this novel mechanism allows for the intracellular accumulation of adenosine, which then suppresses proliferation and effector function of T cells in the high adenosine tumor microenvironment. In mouse models, deletion of ENT1 led to potent control of tumor proliferation and increased CD8+ T cell frequency, proliferation, and cytokine production within tumors, further supporting ENT1’s role in tumor growth. In preclinical studies, blockade of intracellular adenosine accumulation by EOS-984 enabled proliferation of memory T cells and TILs despite high adenosine concentrations, resulting in the restoration of T cell function and enhanced tumor cell killing. Furthermore, combination of EOS-984 with anti-PD-1 therapy synergistically led to the control of tumor growth in a humanized mouse model of triple negative breast cancer resistant to anti-PD-1 blockade. Due to its mechanism of action, EOS-984 holds potential as a combination partner beyond anti-PD-1 therapy, including other immuno-oncology agents, cell therapies, and bispecific T cell engagers.

EOS-984 is currently in the dose escalation portion of a Phase 1 trial in advanced malignancies. Topline data from the Phase 1 trial is anticipated in the second half of 2024.

Abstracts are available on AACR’s website located at www.aacr.org. Posters will be archived in the Investors section of the Company’s website located at www.iteostherapeutics.com.

Poster Presentation Details

Title: “Inhibition of equilibrative nucleoside transporter 1 relieves intracellular adenosine-mediated immune suppression”Session Title: Experimental and Molecular Therapeutics: Tumor MicroenvironmentAbstract Number: 734Date and Time: Sunday, April 7, 2024, 1:30 p.m. – 5:00 p.m. PTLocation: Poster Section 29

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 EOS-984

EOS-984 is a potential first-in-class small molecule targeting the equilibrative nucleoside transporter 1 (ENT1) designed to inhibit the immunosuppressive activity of adenosine and restore immune cell proliferation. The therapeutic candidate has the potential to fully reverse the profound immunosuppressive action of adenosine on T and B cells and is in Phase 1 development.

Internet Posting of Information

iTeos Therapeutics routinely posts information that may be important to investors in the 'Investors' section of its website at www.iteostherapeutics.com. The company encourages investors and potential investors to consult our website regularly for important information about iTeos Therapeutics.

Forward-Looking Statements

This press release contains forward-looking statements. Any statements that are not solely statements of historical fact are forward-looking statements. Words such as “believe,” “anticipate,” “plan,” “expect,” “will,” “may,” “intend,” “prepare,” “look,” “potential,” “possible” and similar expressions are intended to identify forward-looking statements. These forward-looking statements include statements relating to the potential benefits of EOS-984, the potential of EOS-984 to be first-in-class, and EOS-984’s potential as a combination partner beyond anti-PD-1 therapy, including other immuno-oncology agents, cell therapies, and bispecific T cell engagers.

These forward-looking statements involve risks and uncertainties, many of which are beyond iTeos’ control. Actual results could materially differ from those stated or implied by these forward-looking statements as a result of such risks and uncertainties. Known risk factors include the following: success in preclinical testing and early clinical trials does not ensure that later clinical trials will be successful; the data for our product candidates may not be sufficient for obtaining regulatory approval to move into later stage trials or to commercialize products; iTeos may not be able to execute on its business plans, including meeting its expected or planned regulatory milestones and timelines, research and clinical development plans, and bringing its product candidates to market, for various reasons, some of which may be outside of iTeos’ control, including possible limitations of company financial and other resources, manufacturing limitations that may not be anticipated or resolved for in a timely manner, negative developments in the field of immuno-oncology, such as adverse events or disappointing results, including in connection with competitor therapies, and regulatory, court or agency decisions such as decisions by the United States Patent and Trademark Office with respect to patents that cover our product candidates; and those risks identified under the heading “Risk Factors” in iTeos’ Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission (SEC) as well as other SEC filings made by the Company which you are encouraged to review.

Any of the foregoing risks could materially and adversely affect iTeos’ business, results of operations and the trading price of iTeos’ common stock. We caution investors not to place considerable reliance on the forward-looking statements contained in this press release. iTeos does not undertake any obligation to publicly update its forward-looking statements other than as required by law.

For further information, please contact:

Investor Contact:Carl MauchiTeos Therapeutics, Inc.carl.mauch@iteostherapeutics.com

Media Contact:media@iteostherapeutics.com