ES002, a potentially best-in-class anti-CD39 antibody, binds to CD39 with sub-nanomolar binding affinity and effectively blocks CD39 ATPase activity.
CD39-CD73-adenosine pathway plays an important immuno-suppressive role within the tumor microenvironment (TME). To overcome the immunosuppression by adenosine in TME, we choose to target CD39 for two main reasons:
1. CD39 plays a pivotal role in converting extracellular ATP into adenosine. Blocking CD39 enzymatic activity will not only lead to the inhibition of adenosine generation, but also maintain extracellular ATP which enhances T cell priming by dendritic cells (DCs).
2. CD39 is expressed highly in Tregs and exhausted T cells, inhibition of CD39 activity will likely suppress Treg inhibition and reinvigorate exhausted T cells.
ES002 exhibits a strong efficacy in tumor growth inhibition in vivo. It has the ability to suppress Treg inhibiton on effector T cells as well as engage APC and NK cells for its anti-tumor efficacy in vivo.
We are currently advancing the development of ES004 into a clinical candidate.