Programmable Bacterial Architects Crafting Sonosensitizers for Tumor-Specific Sonodynamic Immunotherapy

Area of Science:

• Biomedical Engineering
• Cancer Therapy
• Immunotherapy

Background:

• Sonodynamic therapy (SDT) offers non-invasive tumor ablation with potential for immune stimulation.
• Clinical SDT is limited by poor tumor specificity and low sonosensitizer accumulation, causing off-target effects.

Purpose of the Study:

• To develop a tumor-specific delivery system for sonosensitizers to improve SDT efficacy and safety.
• To enhance antitumor immune responses through targeted sonosensitizer production within the tumor microenvironment.

Main Methods:

• Engineered E. coli (SPEC5) engineered for 5-aminolevulinic acid (5-ALA) biosynthesis and tumor cell membrane cloaking.
• SPEC5 selectively colonizes tumors, supplying 5-ALA for in situ protoporphyrin IX (PpIX) production regulated by a hypoxia-inducible promoter.
• Ultrasound activation of PpIX for sonodynamic therapy and assessment of antitumor immune responses.

Main Results:

• SPEC5 demonstrated selective tumor colonization and continuous 5-ALA supply, leading to high PpIX accumulation in tumors.
• Enhanced SDT efficacy was observed with significant tumor ablation and potent antitumor immune activation.
• The system showed minimal systemic toxicity, with rapid clearance of bacteria post-treatment.

Conclusions:

• The engineered probiotic system (SPEC5) provides a novel strategy for tumor-specific sonosensitizer supply, improving SDT.
• This approach enhances therapeutic efficacy and induces robust antitumor immunity, offering a promising platform for advanced cancer therapies.