Press Release Details

Gosselies, Belgium – November 6, 2018 – iTeos Therapeutics SA, a biotechnology company developing novel cancer immunotherapies, today announced the presentation of two posters on its novel A_2Areceptor antagonist and TIGIT antibody programs, at the upcoming Society for Immunotherapy of Cancer (SITC) 33rdAnnual Meeting, taking place from November 7-11, 2018 in Washington, D.C.

“The expanding breadth of knowledge and understanding of the suppressive tumor microenvironment has been  fundamental to the design and development of iTeos’ best-in-class oncology drug candidates,” said Michel Detheux, Ph.D., Chief Executive Officer of iTeos. “The preclinical data presented at SITC demonstrate how our adenosine A_2Areceptor antagonist can maintain potency in a high adenosine environment, uniquely evading the limitations faced by repurposed A_2Areceptor antagonists. Enabled by the same approach, our TIGIT antagonist monoclonal antibody induces strong anti-tumor efficacy in both monotherapy and in combination with anti-PD1 for more potent activity. We are excited by these findings and look forward to advancing both of these programs into the clinic in the first half of 2019.” 

The details of the two presentations are as follows:

Title: EOS100850, an insurmountable and non-brain penetrant A_2Areceptor antagonist, inhibits adenosine-mediated T cell suppression, demonstrates anti-tumor activity and shows best-in class characteristics.

Date & Time:Friday, November 9, 2018; 12:20 – 1:50 p.m. and 7:00 – 8:30 p.m.

Authors: Houthuys, et al.

Poster Number: 667

Key Takeaways:

• Adenosine levels are elevated in many tumor microenvironments, promoting tumor immune evasion
• EOS100850 reverses inhibition of immune cell function by potently inhibiting A_2A receptor signalling 
• In both in vitroand in vivotumor models, EOS100850 induces long standing and specific immune protection

Title: Antitumor efficacy of anti-TIGIT antagonist antibody EOS884448 is mediated by a dual mechanism of action involving restoration of T cell effector functions and preferential depletion of Tregs.

Date & Time: Saturday, November 10, 2018; 12:45 – 2:15 p.m. and 6:30 – 8:00 p.m.

Authors: Hoofd, et al.

Poster Number: 666

Key Takeaways:

• EOS884448 is a fully human, potent and specific disruptor of the immunosuppressive binding of CD155 to TIGIT in the tumor microenvironment
• Due to its Fc receptor engagement, EOS884448 not only inhibits CD155 binding but also targets for destruction cells that over-express TIGIT (e.g. Tregs) in the tumor microenvironment
• EOS884448 exhibits efficacy in in vivotumor models and is more effective when combined with other checkpoint inhibitors

About iTeos’ Adenosine A_2AReceptor Inhibitor (EOS100850)

The adenosine A_2Areceptor is the main adenosine receptor expressed on immune cells, which promotes immune suppression, leading to tumor evasion. iTeos’ best-in-class A_2Areceptor antagonist, EOS100850, restores T-cell activation inhibited by adenosine. EOS100850 promotes anti-tumor efficacy in mouse tumor models in combination with several immune-checkpoint inhibitors, retains high potency in the presence of elevated intra-tumoral adenosine concentrations, and is non-brain penetrant. EOS100850 is currently being evaluated for safety and efficacy in preclinical models.

About iTeos’ Human Anti-TIGIT Antibody (EOS884448)

TIGIT is an immunosuppressive receptor expressed on lymphoid cell populations. TIGIT expression increases in cancer patients and marks exhausted T cells. EOS884448 is an antagonist antibody against human TIGIT. Preclinical studies show its potency to restore T cell function and to preferentially deplete Treg cells in cancer patient material. ADCC/ADCP-enabling isotypes of a-TIGIT surrogate Ab show potent monotherapy efficacy in murine tumor models that correlates to increased T cell activation and reduced Treg infiltration of tumors. EOS884448 demonstrates classical human IgG pharmacokinetics profile and a good developability profile. EOS884448 is currently being evaluated for safety and efficacy in preclinical models.

About iTeos Therapeutics 

iTeos Therapeutics is a privately-held, clinical-stage biopharmaceutical company dedicated to extending and improving the lives of cancer patients by designing and developing next generation immunotherapies. The Company is advancing EOS100850, an insurmountable and non-brain penetrant adenosine A_2A receptor antagonist, into a Phase I trial in the second half of 2018. A second program for its human ADCC-enabling anti-TIGIT antibody (EOS884448) is expected to enter the clinic in 2019. Based in Gosselies, Belgium and Cambridge, MA, iTeos Therapeutics was founded out of the Ludwig Institute for Cancer Research (LICR) and the de Duve Institute (Université Catholique de Louvain) in 2011. In June 2018, the Company completed a $75 million (€64 million) Series B financing led by MPM Capital, alongside new investors HBM Partners, 6 Dimensions Capital and Curative Ventures. All previous investors including Fund +, VIVES II and SRIW, as well as SFPI, also participated in this funding round.For more information, please visit www.iteostherapeutics.com.

For further information, please contact:

Michel Detheux, CEO

iTeos Therapeutics

info@iteostherapeutics.com

Amber Fennell, Mathew Neal, Sukaina Virji, Hendrik Thys

Consilium Strategic Communications

+44 203 709 5700

iteos@consilium-comms.com

Sarah McCabe and Carl Mauch

Stern Investor Relations, Inc.

+ 1 212 362 1200

iTeos@sternir.com