Regulating stool for microbiota transplantation.

In 2017 Gut Microbes published "A proposed definition of microbiota transplantation for regulatory purposes," in which the authors suggest that regulators should draw a line between microbiota transplants and biologic drugs composed of microbial communities (or other products derived from the human microbiome). They develop a definition of microbiota transplantation (MT) to help regulators draw such a line, and suggest that MT need not be, and cannot be, regulated as a biologic drug (a live biotherapeutic product). However, an agency's regulatory scrutiny of a medical product should be commensurate with that product's degree of risk to patients. Products for MT, such as stool, are likely to be as or more dangerous than more highly manipulated microbial products that scientists and regulators agree should be regulated as biologic drugs. Therefore, we argue that MT, as defined by the authors, should receive the same regulatory oversight as any other biologic product intended to cure, mitigate, treat, or prevent disease. We also suggest that regulators might not be able to operationalize the proposed definition of MT.