Extracellular adenosine is a signalling molecule known as an inhibitor of immune functions. High levels of adenosine and adenosine-producing enzymes are found in various tumor indications. The adenosine A₂ₐ receptor is the main adenosine receptor expressed on immune cell subsets including T-cells, NK cells and dendritic cells and binding of adenosine to the A₂ₐ receptor on immune cells blocks the activation and effector functions of anti-tumor immune cells and promotes a regulatory, immune-suppressive phenotype.
A significant amount of scientific data underlines that targeting the adenosine-cancer axis through the A₂ₐ receptor can promote anti-tumor immune responses and lead to tumor regression. Several clinical development programs in oncology are currently ongoing with compounds which were initially designed for Parkinson Disease. However these compounds were designed as competitive antagonists to be active in the brain of patients having low concentration of adenosine whereas high levels adenosine are produced by ectonucleotidases, especially CD73 and CD39 that are overexpressed in the tumor microenvironment.
iTeos has patented selective proprietary A₂ₐ antagonists which inhibit adenosine-mediated suppression of T-cell activation and cytotoxic activity and promoted anti-tumor efficacy in mouse tumor models. iTeos A₂ₐ antagonists are not brain-penetrant and the preclinical candidate from this research is currently being evaluated and is expected to enter the clinic in early 2019.