Spatiotemporally Controlled Sequential Chemo-Immunotherapy Activates Pyroptosis for Robust Anti-Tumor Immunotherapy.

Cancer immunotherapy can be augmented by combination of immune checkpoint inhibitors (ICIs) and chemotherapy. However, the administration pharmacokinetics, timing and sequencing for chemotherapy and immunotherapy affect the synergistic outcomes of a combined therapy. Currently, the stable co-delivery and long -termretention of chemotherapy and immunotherapy drugs into the tumor while well control their respective release at an appropriate time intervals is still challenging. Here, we report a nanotherapeutic strategy to augment tumor immunotherapy using highly stable cerasome nanoparticles that are co-loaded with the ICIs agent, BMS1166, and the chemotherapeutic drug, gemcitabine. Gemcitabine is released under high level of glutathione (GSH) conditions, leading to effective immunogenic cell death, pyroptosis and high PD-L1 expression on the tumor. Then the local ultrasound irradiation at an optimal time triggers the release of BMS1166 to blockade the PD-L1, eliciting a potent and durable anti-tumor immune response. This dual response strategy enables sequentially controlled drug release in the tumor to ensure the same spatiotemporal distribution of different drugs, while playing their respective roles at different times, greatly enhancing the immunotherapy efficiency. In tumor-bearing-mice, treatment with the nanoparticles effectively suppresses primary tumors and distant tumors, while preventing tumor metastasis and causing immune memory effect.