IMD303

IMD303 is a tumor microenvironment-activated (TMEA) monoclonal antibody targeting Programmed Cell Death Ligand 1 (PD-L1), developed by Affinity (Chengdu) Biopharmaceutical. The drug utilizes a proprietary masking technology where the antibody's antigen-binding site is shielded by a masking peptide, preventing binding to PD-L1 in healthy tissues and reducing systemic exposure. Upon reaching the tumor microenvironment, the mask is selectively cleaved by tumor-associated proteases, such as matrix metalloproteinases (MMPs), which are overexpressed in malignant tissues. This cleavage releases the active antibody, allowing it to block the PD-1/PD-L1 immune checkpoint pathway specifically within the tumor. This localized activation strategy is designed to maintain potent anti-tumor efficacy while significantly minimizing systemic immune-related adverse events (irAEs) typically associated with conventional checkpoint inhibitors. IMD303 is currently being evaluated in Phase 1 clinical trials for the treatment of various advanced solid tumors.

Other names

TMEA anti-PD-L1 antibodytumor microenvironment-activated anti-PD-L1 antibody