Inspired heat shock protein alleviating prodrug enforces immunogenic photodynamic therapy by eliciting pyroptosis

Despite immunotherapy involving immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy, the clinical efficacy is limited due to ICI resistance. Pyroptosis is a gasdermin-mediated programmed cell death that enhances responses to ICIs. However, nontargeted elicitation of pyroptosis may induce systemic side effects and toxicity. Therefore, we reasonably design and construct a tumor-specific prodrug that combines the heat shock protein 90 inhibitor tanespimycin (17-AAG) with the photosensitizer chlorin e6 (Ce6) to induce pyroptosis, by utilizing the high glutathione level in the tumor microenvironment. The released Ce6 and 17-AAG produce reactive oxygen species by laser triggering, which induces gasdermin E-mediated pyroptosis. Furthermore, 17-AAG reduces myeloid-derived suppressor cells and sensitizes tumors to anti-programmed death-1 (PD-1) therapy. Thus, our prodrug strategy achieves tumor-targeted pyroptosis to suppress tumor growth, thereby improving the response to anti-PD-1 therapy and extending the survival of 4T1 breast tumor-bearing mice. Consequently, this pyroptosis-based prodrug represents a novel strategy for enforcing immunogenic photodynamic therapy.