Seres Therapeutics, Inc. is a microbiome therapeutics company. The Company is developing a class of biological drugs, which are designed to treat disease by modulating the microbiome to restore health by repairing the function of a disrupted microbiome to a non-disease state. Its lead product candidate, SER-109, is designed to reduce further recurrence of CDI, a debilitating infection of the colon, in patients who have received antibiotic therapy for recurrent CDI by restructuring the gastrointestinal microbiome and modulating the metabolic landscape to address CDI. Building upon SER-109, it is developing microbiome therapeutics, such as SER-155, to specifically target infections and antimicrobial resistance. SER-155, a microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to reduce incidences of gastrointestinal infections, bloodstream infections and GvHD in patients receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT).