Octopus-inspired engineered bacteria with a plug-and-play surface display system achieves enhanced tumor-specific...

Bacteria-mediated cancer therapy leverages bacteria to modulate the tumor immune microenvironment and deliver therapeutics. However, its clinical application is limited by toxicity, off-target effects, and uncontrolled drug release. Improving tumor targeting and precise payload delivery through rational bacterial engineering is essential for increasing efficacy and safety.

An attenuated Salmonella ΔhtrA::luxI-VNP20009 strain expressing OmpA-SpyTag (AISI-ST) was constructed for the modular surface conjugation of SpyCatcherΔ (SC)-fused quadruple arginine-glycine-aspartic acid (RGD) peptides (named AISI-ST/SC-RGD×4) and for building biointerfaces for enhanced tumor adhesion via RGD-mediated integrin αvβ3 interactions. The tumor-bearing mice received intravenous injections of AISI-ST/SC-RGD×4, and their biodistribution was analyzed using bioluminescence imaging and colony-forming unit (CFU) counts. Quorum-sensing (QS)-regulated high-temperature requirement A (HtrA) and anti-programmed cell death protein 1 (anti-PD1) nanobody expression based on the LuxI promoter in strains was validated by Western blotting. Immune responses were assessed using flow cytometry.

The incubation of the fused proteins with the AISI-ST strain for 1 h was sufficient to form a stable biological interface. The quadruple RGD-modified bacteria (AISI-ST/SC-RGD×4) exhibited greater enrichment in various solid tumors and lung metastases with reduced off-target accumulation. QS induced the expression of the HtrA protein within tumors, resulting in enhanced extracellular polysaccharide-mediated immunogenicity to activate immune cells. Further expression of anti-PD1 nanobodies synergistically enhanced antitumor immunity, increasing the percentage of M1 macrophages (MACS) and CD8⁺ T cell proliferation while suppressing M2 MACS and regulatory T cells (Tregs). This approach achieves potent tumor suppression via targeted immune remodeling.

This study presents octopus-inspired engineered bacteria with a "plug-and-display" system and tumor-specific drug delivery that achieves enhanced tumor targeting and potent antitumor effects. This study describes a promising strategy for the precise and safe clinical translation of bacteria-mediated cancer immunotherapy.