Logic-Gated Bioorthogonal In Situ Synthesis of Proteolysis-Targeting Chimeras for Precise Protein Degradation and Synergistic Immunotherapy

catalyst. Only the concurrent action of both inputs enables the bioorthogonal ligation of the fragments in situ to form the active GPX4-degrading PROTAC. This precise synthesis orchestrates a cascade of functions. The in situ-generated PROTAC initiates ferroptosis by degrading GPX4; this effect is powerfully amplified by coreleased copper ions (driving cuproptosis) and by chlorin e6 (Ce6)-mediated photodynamic therapy (PDT), which together generate a massive reactive oxygen species burst. This cooperative induction of ferroptosis and cuproptosis, augmented by PDT, triggers robust immunogenic cell death. Consequently, GVCC treatment reprograms the immunosuppressive triple-negative breast cancer microenvironment and demonstrates potent synergy with anti-PD-L1 checkpoint blockade. This study establishes bioorthogonal in situ PROTAC synthesis as an effective precision strategy for cancer therapy.