Targeted tumor therapy with L-cyst(e)ine-addicted bacteria-nanodrug biohybrids

Bacteria-based metabolic therapy has been acknowledged as a promising strategy for tumor treatment. However, the insufficient efficiency of wild-type bacteria severely restricts their therapeutic efficacy. Here, we elaborately develop an ʟ-cyst(e)ine-addicted bacteria-nanodrug biohybrid for metabolic therapy through a dual-selection directed evolution strategy. Our evolved strain exhibits a 36-fold increase in ʟ-cystine uptake and a 23-fold improvement in total activity of cysteine desulfhydrases compared with the wild-type strain. By conjugating with DMXAA-loaded liposomes, the engineered bacteria-nanodrug biohybrid not only prevents the influx of nutrients into the tumor by blocking neovasculature but also achieves efficient and durable CySS catabolism locally. The unavailable of Cys species disrupts redox homeostasis and strikingly increases intracellular ROS level, achieving favorable therapeutic outcomes in multiple tumor models. Our study not only highlights the promise of directed evolution strategy in enhancing the stability and efficiency of bacteria-based living biocatalyst but also provides new opportunities for antitumor metabolic therapy.