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.