270SYN-004, a Class A Beta-Lactamase Therapy for the Prevention of Antibiotic-Induced Disruption of Intestinal Microflora

Background. ß-lactam antibiotics that are excreted into the intestine can damage the microflora, which can lead to serious infections such as Clostridium difficile (C. diff ). SYN-004 is a potent ß-lactamase formulated for oral use with intravenous (IV) antibiotics to degrade antibiotics in the intestine. Methods. SYN-004, formerly called P3A, was developed and evaluated by Ipsat Therapies, Helsinki, Finland. SYN-004 was engineered from the Bacillus licheniformis PenP enzyme to expand the hydrolysis of ß-lactams to cephalosporins, including ceftriaxone (cfx), while maintaining its anti-penicillin activity. The use of cfx is a major risk factor for the development of C. diff. Antibiotic hydrolysis was assessed in vitro. In vivo, SYN-004 activity was evaluated in the intestinal tract of jejunal-fistulated dogs (n = 6) following administration of oral SYN-004 (0.44 mg/kg) and IV cfx (30 mg/kg). Results. In vitro antibiotic hydrolysis assays demonstrated that, compared to PenP, SYN-004 displayed improved degradation of cephalosporins: cfx, cefotaxime, cefazolin, cefoperazone, and cefuroxime. Activities against ampicillin and piperacillin were unchanged. Dog studies revealed that cfx was excreted at high levels into the intestine following IV delivery (mean Cmaxof 1500 μg/g of jejunal chyme), and a second cfx peak (mean 167 μg/g) was observed six hours later, after an additional feeding. Following delivery of SYN-004 ten minutes prior to IV cfx, the cfx concentration stayed low (<5 μg/g chyme) for five hours in 4/6 dogs. The other two dogs did not eat prior to dosing and showed higher cfx concentrations at the early timepoints, presumably due to delayed gastric emptying. The second peak in cfx levels was not detected in any SYN-004-treated animal demonstrating that SYN-004 was present, remained functional, and hydrolyzed the cfx in the intestines of all treated dogs. Conclusion. SYN-004 is a potent ß-lactamase specifically engineered to hydrolyze an expanded range of antibiotics including the cephalosporins. Oral delivery of SYN-004 resulted in efficient degradation of intestinal ceftriaxone in dogs. Therefore, SYN-004 is a promising candidate to protect the intestinal microflora to prevent antibiotic-associated adventitious infections such as C. diff. Disclosures. M. Kaleko, Synthetic Biologics, Inc.: Employee, Salary and Stock options A. Bristol, Synthetic Biologics: Employee and Shareholder, Salary S. Connelly, Synthetic Biologics: Employee, Salary P. Koski, Synthetic Biologics, Inc.: Consultant, Consulting fee