Using bugs as drugs: Administration of bacteria-related microbes to fight cancer

Bioengineering of bacteria-related microbes has demonstrated a great potential in targeted cancer therapy. Presently, the major administration routes of bacteria-related microbes for cancer treatment include intravenous injection, intratumoral injection, intraperitoneal injection, and oral delivery. Routes of bacteria administration are critical since different delivery approaches might exert anticancer effects through diverse mechanisms. Herein, we provide an overview of the primary routes of bacteria administration as well as their advantages and limitations. Furthermore, we discuss that microencapsulation can overcome some of the associated challenges with the administration of free bacteria. We also review the latest advancements in combining functional particles with engineered bacteria to fight cancer, which can be coupled with conventional therapies to improve therapeutic effects. Moreover, we highlight the application prospect of emerging 3D bioprinting in cancer bacteriotherapy, which represents a new paradigm for personalized cancer treatment. Eventually, we provide insights into regulatory expectations and concerns regarding this field for the future translation from bench to clinic.