Clinical-Stage, Oral β-Lactamase Enzyme to Prevent Clostridium difficile Infection Triggered by Antibiotic-Mediated Gut Microbiome Disruption

Sheila Connelly1, J. Andrew Bristol1, Steven Hubert1, Christian Furlan-Freguia1, Poorani Subramanian2, Nur Hasan2, Joseph Sliman1, Michael Kaleko1 1Synthetic Biologics, Inc., Rockville, MD, 2CosmosID, Inc., Rockville, MD Background: Antibiotic-mediated disruption of the gut microbiome can lead to serious infections such as Clostridium difficile (CDI). SYN-004 (ribaxamase), previously called SYN-004, in Phase 2b clinical testing, is a b-lactamase enzyme for oral use with certain IV b-lactam antibiotics intended to preserve the gut microbiome by inactivating antibiotics in the GI tract. The b-lactamase strategy for microbiome protection from both IV and orally-delivered antibiotics was explored using pig models of antibiotic-mediated gut dysbiosis. Methods: The b-lactamase was produced in E. coli and the clinical formulation, ribaxamase, was manufactured as enteric-coated pellets for duodenal release. Pig models (20 kg, n=5 per cohort) of ceftriaxone(CRO) and amoxicillin(AMX) +/ribaxamase mediated gut dysbiosis were established. Fecal DNA whole genome shotgun sequence analyses assessed microbiome preservation and systemic antibiotic absorption was quantified by HPLC or LC/MS/MS. New formulations of the b-lactamase, engineered to be released in the GI tract at a point distal to oral antibiotic absorption but proximal enough to protect the microbiome, were tested