A combination of PD-L1-targeted IL-15 mRNA nanotherapy and ultrasound-targeted microbubble destruction for tumor immunotherapy

PD-1/PD-L1-based immune checkpoint blockade therapy has shown limited benefits in tumor patients, partially attributed to the inadequate infiltration of immune effector cells within tumors. Here, we established a nanoplatform named DPPA/IL-15 NPs to target PD-L1 for the tumor delivery of IL-15 messenger RNA (mRNA). DPPA/IL-15 NPs were endowed with ultrasound responsiveness and contrast-enhanced ultrasound (CEUS) imaging performance. They effectively protected IL-15 mRNA from degradation and specifically transfected it into tumor cells through the utilization of ultrasound-targeted microbubble destruction (UTMD). This resulted in the activation of IL-15-related immune effector cells while blocking the PD-1/PD-L1 pathway. In addition, UTMD could generate reactive oxygen species (ROS) that induce endoplasmic reticulum (ER) stress-driven immunogenic cell death (ICD), initiating anti-tumor immunity. In vitro and in vivo studies revealed that this combination therapy could induce a robust systemic immune response and enhance anti-tumor efficacy. Thus, this combination therapy has the potential for clinical translation through enhanced immunotherapy and provides real-time ultrasound imaging guidance.