Programmable Bacterial Architects Crafting Sonosensitizers for Tumor-Specific Sonodynamic Immunotherapy

Sonodynamic therapy (SDT) is a non-invasive cancer treatment that uses ultrasound to activate sonosensitizers for selective tumor ablation. With its superior tissue penetration compared to photodynamic therapy, SDT demonstrates the potential to stimulate antitumor immune responses by modulating the tumor microenvironment. However, its clinical application remains limited by poor tumor specificity and suboptimal sonosensitizer accumulation, which reduces efficacy and causes off-target effects. To address these challenges, an Engineered Probiotic-based Calibrated 5-ALA Supply system (SPEC5) is developed to confer tumor selectivity for SDT. Engineered non-pathogenic E. coli with recombinant plasmids enables efficient 5-ALA biosynthesis through kinetic remodeling. Homologous tumor cell membrane cloaking further enhances tumor targeting and immune evasion. Upon intravenous injection, SPEC5 selectively colonizes in the tumor, supporting the sonosensitizer protoporphyrin IX (PpIX) in situ biosynthesis via 5-aminolevulinic acid (5-ALA) continuous supply. A hypoxia-inducible promoter regulating O-acetylserine sulfhydrylase ensures the tumor specificity of PpIX production. This system achieves robust sensitizer accumulation in tumors, enhancing SDT efficacy and inducing potent antitumor immune activation with minimal systemic toxicity. Post-treatment, the bacteria are rapidly cleared to ensure safety. This study presents a novel strategy for tumor-specific sonosensitizer supply, revolutionizing 5-ALA-based SDT and paving the way for advanced tumor-targeted therapies with enhanced immunotherapeutic outcomes.