Adenosine and transforming growth factor-β (TGF-β) are two key immune suppressors in the tumor microenvironment (TME) that cause broad immune suppression resulting in resistance to current checkpoint inhibitor immunotherapies. The bifunctional antibody-fusion protein ES014 was created by fusing the TGF-β receptor II ectodomain to an antibody targeting human ectonucleoside triphosphate diphosphohydrolase-1 (ENTPD1, CD39, UniprotKB: P49961). ES014 simultaneously neutralizes autocrine/paracrine TGF-β and inhibits the enzymatic activity of CD39, which results in the stabilization of pro-inflammatory extracellular adenosine triphosphate (eATP) and the restoration of anti-tumor immunity by impairing the accumulation of immune suppressive adenosine and TGF-β within the TME.
The purpose of this first-in-human, open-label, multicenter, non-randomized study designed to determine the maximum tolerated dose (MTD)/maximum administered dose (MAD), optimal biological dose (OBD), and recommended phase 2 dose (RP2D) of ES014 by evaluating the safety, tolerability, PK, pharmacodynamics, and preliminary clinical activity of ES014 administered intravenously to subjects with advanced solid tumors.