Discovery of intratumoral oncolytic bacteria toward targeted anticancer theranostics

Abstract Unveiling the different biomedical functions of tumor-resident microbiota has remained challenging for the development of advanced anticancer medicines. Here we show that isolated intratumoral bacteria with its association with natural purple photosynthetic bacteria have a high innate biocompatibility and drastic immunogenic anticancer efficacies. They preferentially grow and proliferate within targeted tumor milieu, which effectively causes immune cells to infiltrate the tumor and provoke strong anticancer responses in various syngeneic mouse models including those of colorectal cancer, sarcoma, metastatic lung cancer, and extensive drug-resistant breast cancer. Furthermore, these functional bacteria-treated mice, that exhibit excellent anticancerous responses of tumors, have significantly prolonged survival rates with effective immunological memory. Notably, light-harvesting nanocomplexes of microbial consortium of intratumoral bacteria and purple photosynthetic bacteria is capable of tumor diagnosis using bio-optical-window near-infrared light, making them useful theranostic agents for highly targeted immunological elimination of the tumor and for precisely marking tumor location.