Poly (ADP-ribose) polymerase 1-targeted photosensitizer as a dual-activator of pyroptosis and the STING pathway for enhanced cancer photoimmunotherapy

Immunotherapy has shown promise in cancer treatment, yet its efficacy is often hindered by the immunosuppressive tumor microenvironment characterized by poor immunogenicity and limited cytotoxic T cell infiltration. To address these limitations, we developed Ola-PS, a poly (ADP-ribose) polymerase 1 (PARP1)-targeted photosensitizer, to enhance cancer photoimmunotherapy through dual activation of pyroptosis and the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway. Ola-PS combines the PARP1 inhibitor Olaparib with the near-infrared photosensitizer Nile Blue, enabling reactive oxygen species (ROS)-mediated DNA damage and PARP1 inhibition. This dual action induces pyroptosis via the caspase-3/GSDME pathway, releasing tumor-associated antigens and damage-associated molecular patterns (DAMPs) to stimulate adaptive immunity. Concurrently, accumulated cytosolic DNA activates the cGAS-STING pathway, amplifying innate immune responses. In vitro and in vivo studies demonstrated that Ola-PS effectively eradicated tumor cells, promoted CD8⁺ and CD4⁺ T cell infiltration, and suppressed tumor growth. This study highlights the potential of PARP1-targeted photosensitizers to synergize pyroptosis-driven immunogenicity with STING-mediated innate immunity, offering a promising strategy to overcome immunosuppression and advance cancer photoimmunotherapy. STATEMENT OF SIGNIFICANCE: Breast cancer remains a leading cause of cancer-related mortality, with limited treatment options. Immunotherapy is also restricted by the immunosuppressive tumor microenvironment (TME). We developed Ola-PS, a dual-functional PARP1-targeted photosensitizer, to enhance cancer photoimmunotherapy by cooperatively inducing pyroptosis and activating the cGAS-STING pathway. Under light irradiation, Ola-PS generates abundant reactive oxygen species (ROS), causing DNA damage and caspase-3/GSDME-mediated pyroptosis, thereby eliciting immunogenic cell death (ICD). Its PARP1 inhibitory activity further impairs DNA repair, potentiating cGAS-STING activation. In addition, Ola-PS also exhibits superior tumor-targeting, achieving robust tumor regression and systemic immune activation in 4T1-bearing mice. This work establishes PARP1-targeted photosensitizers as a promising targeted strategy for precision photoimmunotherapy, with broad implications for cancer treating.