An Injectable Thermosensitive Hydrogel Codelivering Permeability-Promoting Nintedanib-loaded Phase-transition Nanoparticles and Doxorubicin to Potentiate Immunogenic Cell Death in Triple-Negative Breast Cancer for Chemoimmunotherapy.

Immunogenic cell death (ICD) represents a promising strategy to stimulate antitumor immunity. Doxorubicin (DOX) is one drug that can trigger ICD. However, DOX has limitations for treating triple-negative breast cancer (TNBC). Its ability to stimulate a strong immune response is weak. The drug also promotes an immunosuppressive tumor microenvironment. This suppression hinders the antitumor immune response. Since reactive oxygen species (ROS) generation is a pivotal ICD trigger, we therefore hypothesized that nintedanib, a triple tyrosine kinase inhibitor known to promote immune cell infiltration and activation within tumors, potentiates DOX-induced ICD by augmenting intratumoral ROS generation. To address this, we engineered a targeted nanoenhancer for TNBC by coencapsulating liquid nintedanib and perfluoropentane (PFP), within a peptide-functionalized (tLyp-1) liposomal shell, creating tLyp-1-Nintedanib-PFP Nanoparticles (tNP-NPs) for use in sonodynamic therapy. This tNP-NP platform is intended for combination therapy with DOX in a chemoimmunotherapeutic strategy. With the assistance of low-intensity focused ultrasound (LIFU), tNP-NPs exhibited potent targeting and penetrating capabilities toward 4T1 TNBC cells, enhanced drug cytotoxicity, ROS production, and ICD markers in vitro. Subsequently, for the in vivo study, to mitigate systemic toxicity, an injectable thermosensitive hydrogel coencapsulating tNP-NPs and DOX was applied for local peritumoral injection. In orthotopic 4T1 TNBC models, this combination elicited potent ICD, promoting dendritic cell (DC) cells maturation and cytotoxic T lymphocyte activation within tumors and draining lymph nodes. This approach achieved exceptional antitumor efficacy and systemic immunity while reversing the immunosuppressive tumor microenvironment, without observable organ toxicity, presenting a robust chemoimmunotherapeutic strategy for TNBC.