Dual Targeting of Nucleotidase-Dependent and -Independent Functions via PROTAC-Mediated CD73 Degradation

CD73 (ecto-5′-nucleotidase) drives immunosuppressive and tumor progression through both enzymatic adenosine production and nonenzymatic mechanisms, limiting the efficacy of current CD73-targeted therapies, including small-molecule enzymatic inhibitors and antibodies. Here, we reported NUCC-0227579 (C79), a first-in-class proteolysis-targeting chimera (PROTAC) that degraded CD73 via the VHL E3 ligase–dependent proteasomal and lysosomal pathways. C79 eliminated CD73 at the cell surface and intracellular compartments across multiple human cancer cell lines, abolishing nucleotidase activity and more effectively reversing adenosine-mediated immunosuppression than enzymatic inhibitors. C79 enhanced NF-κB/NFAT signaling, increased IFN-γ and TNF-α production, and promoted human CD8 + T cell activation and proliferation. In addition, C79 impaired tumor cell metabolic fitness, proliferation, migration, and adhesion through non-nucleotidase-dependent mechanisms. In humanized NSG mouse models of triple-negative breast cancer, C79 significantly suppressed tumor growth while enhancing antitumor immune responses, highlighting CD73 degradation as a mechanistically distinct strategy to overcome the limitations of existing CD73-targeted therapies.