Ultrasound-Responsive Cerasome Nanoparticle Improves STING-Driven Immunotherapy in Triple-Negative Breast Cancer

Immunotherapy shows promise for triple-negative breast cancer (TNBC), yet its effectiveness is restricted by low response rates, poor immune cell infiltration, and systemic side effects. Here, an ultrasound-responsive cerasomal nanoplatform integrating a STING agonist (SR-717@PC-iRGD) is developed for synergistic sonodynamic-immunotherapy. The nanocarrier is self-assembled from cerasome-forming lipids (CFL), porphyrin-conjugated lipids (PL), unsaturated phospholipids (DOPC), DSPC, and DSPE-PEG₂₀₀₀-iRGD, with SR-717 loaded in the lipid bilayer. The resulting assembly yields nanoparticles (NPs) with high SR-717 loading and exceptional stability. The siloxane shell (cerasome) confers high stability and prevents premature drug leakage, while iRGD promotes nanoparticle binding to tumor specific integrin to facilitate accumulation and retention in the tumor. Upon ultrasound irradiation, porphyrin generates reactive oxygen species (ROS) that oxidize the lipid bilayer and disrupt the cerasome, enabling on-demand SR-717 release at tumor site. The released SR-717 activates the STING pathway, driving type-I interferon production, dendritic cell maturation, and CD8⁺ T-cell infiltration. This strategy integrates sonodynamic therapy (SDT) with localized immune activation, addressing challenges of instability and inefficient delivery. The platform thus offers a precise and effective approach to stimulate antitumor immunity and enhance therapeutic outcomes for TNBC where no tumor targeted therapy is currently available.