Bioorthogonal/Ultrasound Activated Oncolytic Pyroptosis Amplifies In Situ Tumor Vaccination for Boosting Antitumor Immunity.

Personalized in situ tumor vaccination is a promising immunotherapeutic modality. Currently, seeking immunogenic cell death (ICD) to generate in situ tumor vaccines is still mired by insufficient immunogenicity and an entrenched immunosuppressive tumor microenvironment (TME). Herein, a series of tetrazine-functionalized ruthenium(II) sonosensitizers have been designed and screened for establishing a bioorthogonal-activated in situ tumor vaccine via oncolytic pyroptosis induction. Based on nanodelivery-augmented bioorthogonal metabolic glycoengineering, the original tumor is selectively remolded to introduce artificial target bicycle [6.1.0] nonyne (BCN) into cell membrane. Through specific bioorthogonal ligation with intratumoral BCN receptors, sonosensitizers can realize precise membrane-anchoring and synchronous click-activation in desired tumor sites. Upon ultrasound (US) irradiation, the activated sonosensitizers can intensively disrupt the cell membrane with dual type I/II reactive oxygen species (ROS) generation for a high-efficiency sonodynamic therapy (SDT). More importantly, the severe membrane damage can eminently evoke oncolytic pyroptosis to maximize tumor immunogenicity and reverse immunosuppressive TME, ultimately eliciting powerful and durable systemic antitumor immunity. The US-triggered pyroptosis is certified to effectively inhibit the growths of primary and distant tumors, and suppress tumor metastasis and recurrence in "cold" tumor models. This bioorthogonal-driven tumor-specific pyroptosis induction strategy has great potential for the development of robust in situ tumor vaccines.