ASC63

ASC63 is an **oral small molecule programmed cell death-ligand 1 inhibitor** being developed by Ascletis for oncology, particularly advanced solid tumors. Preclinical data indicate that, after oral administration, ASC63 is rapidly converted in vivo to an active metabolite, ASC63-A, which promotes **PD-L1 dimerization and internalization from the cell membrane**, thereby disrupting the PD-1/PD-L1 immune checkpoint interaction and enhancing T-cell activation. In a humanized mouse tumor model, ASC63 showed antitumor activity comparable to atezolizumab at higher doses, but publicly available information as of the latest accessible sources appears limited to preclinical and pipeline disclosures, with no clear evidence of approved use or late-stage clinical development.