Nuclear-Targeting Lipid Pt^IV Prodrug Amphiphile Cooperates with siRNA for Enhanced Cancer Immunochemotherapy by Amplifying Pt-DNA Adducts and Reducing Phosphatidylserine Exposure

Patients treated with Pt-based anticancer drugs (Pt-II) often experience severe side effects and are susceptible to cancer recurrence due to the limited bioavailability of Pt-II and tumor-induced immunosuppression. The exposure of phosphatidylserine on the cell's outer surface induced by Pt-II results in profound immunosuppression through the binding of phosphatidylserine to its receptors on immune cells. Here, we report a novel approach for enhanced cancer chemoimmunotherapy, where a novel nuclear-targeting lipid Pt-IV prodrug amphiphile was used to deliver a small interfering RNA (siXkr8) to simultaneously amplify Pt-DNA adducts and reduce the level of exposure of phosphatidylserine. This drug delivery vehicle is engineered by integrating the Pt-IV prodrug with self-assembly performance and siXkr8 into a lipid nanoparticle, which shows tumor accumulation, cancer cell nucleus targeting, and activatable in a reduced microenvironment. It is demonstrated that nuclear-targeting lipid Pt-IV prodrug increases the DNA cross-linking, resulting in increased Pt-DNA adduct formation. The synergistic effects of the Pt-IV prodrug and siXkr8 contribute to the improvement of the tumor immune microenvironment. Consequently, the increased Pt-DNA adducts and immunogenicity effectively inhibit primary tumor growth and prevent tumor recurrence. These results underscore the potential of utilizing the nuclear-targeting lipid Pt-IV prodrug amphiphile to enhance Pt-DNA adduct formation and employing siXkr8 to alleviate immunosuppression during chemotherapy.