Transforming “cold” tumors into “hot” ones via tumor-microenvironment-responsive siRNA micelleplexes for enhanced immunotherapy

It is highly desirable to turn “cold” tumors into “hot” ones to improve the efficacy of antitumor immunotherapy. Herein, we develop the peptide-based small interfering RNA (siRNA) micelleplexes (PA7R@siPD-L1) for normalizing vascular-immune crosstalk to establish a positive feedback loop in potentiating antitumor immunotherapy. These micelleplexes are equipped with tumor-microenvironment-responsive property for precise drug delivery and release. The prepared PA7R@siPD-L1-mediated photodynamic therapy could eliminate solid tumors and trigger immunogenic cell death to generate systematic immune responses. Meanwhile, the antiangiogenic peptide A7R normalizes the tumor vasculature by converting chaotic vascular systems into matured and organized ones, thus alleviating tumor hypoxia and promoting intratumoral infiltration by immune cells. Antitumor immunogenicity would be further strengthened with the aid of siPD-L1 by muting the resistance of tumor cells against immune effector cells. This study provides a unique therapeutic strategy in turning “cold” tumors into “hot” tumors enabled by siRNA nanomaterial.