Abstract 507: Identification of CD73 and A2AR/CD73 small molecule inhibitors for cancer immunotherapy as single agents or in combination with Immune-checkpoint therapies

Adenosine generated by CD73 is a key driver of immunosuppression in the hypoxic tumour microenvironment (TME) and particularly involved in angiogenic process and immunity. In immune-inflamed tumours, with CD8+ T-cell infiltrates, adenosine signalling is a cause of resistance to immune checkpoint therapies (ICTs) through the inhibition of T-cells, NK cells and more largely of the overall antitumor immunity. Evotec and Exscientia are collaborating to develop an innovative drug discovery platform for accelerating small molecule development in Immuno-Oncology targeting the adenosine pathway. The platform has integrated a unique biophysical screening approach for the adenosine receptors and CD73 to drive automated medicinal chemistry design with a translational-focused screening cascade. We have initiated research of CD73 specific inhibitory molecules based on SPR fragment screening and have identified lead compounds which fully bind in the active site of the CD73 protein in both the open and closed states. In vitro functional potency has been demonstrated for the CD73 inhibitors for inhibiting adenosine production by Rapid Fire technology performed using CD73 recombinant protein. Moreover, we demonstrated that CD73 inhibitors induce recovery of AMP-induced inhibition of T-cells activation as measured through IL-2 production. The series are under lead optimization to improve ADME/DMPK parameters in order to enable evaluation in PK/PD assays and in vivo efficacy studies specifically developed for the project. Finally, from the perspective of developing a dual pharmacological profile for A2AR and CD73 inhibition, we have assessed, using primary human CD3+ T-lymphocytes isolated from healthy donors, the synergy between the inhibition of the two targets in order to enhance the recovery of T-cell activation. We have demonstrated that EVOEXS21546, our pre-development A2AR inhibitor candidate, and our lead compound for CD73 inhibition act in synergy in functional human T-cell assays. Our SPR screening approach has also identified hit compounds with dual bispecific pharmacological activity against both A2AR and CD73. Citation Format: Pierre Fons, Andrew Bell, Michael Esquerre, Stephanie Versluys, Florie Bertrand, Adrian Schreyer, Iva Hopkins-Navratilova, Leonardo-Silvestre Hernani, Celia Bergeaud, Celine Poussereau-Pomie, Ghislaine Marchand, Sean Robinson, Simone Culurgioni, Richard Cox, Jeremy Besnard, Andrew Payne, Peter Ray, Emilie Pelissier, Michael Paillasse, Joanna Lisztwan, Craig Johnstone, Mark Whittaker, Andrew Hopkins. Identification of CD73 and A2AR/CD73 small molecule inhibitors for cancer immunotherapy as single agents or in combination with Immune-checkpoint therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 507.