Development of SYN-004, an oral beta-lactamase treatment to protect the gut microbiome from antibiotic-mediated damage and prevent Clostridium difficile infection.

The gut microbiome, composed of the microflora that inhabit the gastrointestinal tract and their genomes, make up a complex ecosystem that can be disrupted by antibiotic use. The ensuing dysbiosis is conducive to the emergence of opportunistic pathogens such as Clostridium difficile. A novel approach to protect the microbiome from antibiotic-mediated dysbiosis is the use of beta-lactamase enzymes to degrade residual antibiotics in the gastrointestinal tract before the microflora are harmed. Here we present the preclinical development and early clinical studies of the beta-lactamase enzymes, P3A, currently referred to as SYN-004, and its precursor, P1A. Both P1A and SYN-004 were designed as orally-delivered, non-systemically available therapeutics for use with intravenous beta-lactam antibiotics. SYN-004 was engineered from P1A, a beta-lactamase isolated from Bacillus licheniformis, to broaden its antibiotic degradation profile. SYN-004 efficiently hydrolyses penicillins and cephalosporins, the most widely used IV beta-lactam antibiotics. In animal studies, SYN-004 degraded ceftriaxone in the GI tract of dogs and protected the microbiome of pigs from ceftriaxone-induced changes. Phase I clinical studies demonstrated SYN-004 safety and tolerability. Phase 2 studies are in progress to assess the utility of SYN-004 for the prevention of antibiotic-associated diarrhea and Clostridium difficile disease.

Development of a Modified-Release Formulation of Lovastatin Targeted to Intestinal Methanogens Implicated in Irritable Bowel Syndrome With Constipation.

There is growing evidence that methane production, predominantly by Methanobrevibacter smithii, in the intestines is a cause of constipation, pain, and bloating in irritable bowel syndrome with constipation (IBS-C). M smithii resides primarily in the large intestine but can also colonize the small intestine. In vitro studies found that the prodrug lactone form of lovastatin, found in cholesterol-lowering drugs, inhibited methane production in stool samples from patients with IBS-C. However, the cholesterol-lowering lovastatin ß-hydroxyacid was ineffective at inhibiting methane production in this system. A considerable amount of lovastatin is converted to hydroxyacid in the stomach and is absorbed. It was hypothesized that galenic innovations could protect lovastatin from the stomach and allow release in 2 strategic locations, the duodenum and the ileocecal region, to reach M smithii. The desired release profile was achieved by developing an oral dosage form containing lovastatin and coated with 2 different enteric polymers that enabled a pH-dependent "dual pulse" drug release. Combinations of the 2 coated tablets were encapsulated together to deliver the desired amount of lovastatin to the targeted intestinal locations. The capsules have been tested in vitro and in vivo and show promise in treating IBS-C.

Formulation development of SYN-004 (ribaxamase) oral solid dosage form, a ß-lactamase to prevent intravenous antibiotic-associated dysbiosis of the colon.

SYN-004 (ribaxamase) delayed release drug product is a multi-particulate, hard capsule for oral delivery of a recombinant ß-lactamase enzyme designed to degrade ß-lactam antibiotics administered intravenously, and thus prevent colon dysbiosis. Here we describe the development of the SYN-004 enteric coated pellet formulation, which has been tested in multiple clinical trials. Since the SYN-004 drug substance is a buffered liquid, several binder excipients in different ratios were tested to facilitate binding of SYN-004 to sugar spheres. The binding systems were evaluated by droplet pre-evaluation and film casting tests. The most promising formulations were produced in small scale fluidized bed application runs and analyzed by dissolution tests and complementary analytical assays. Hydroxypropyl cellulose was selected as the preferred SYN-004 binding excipient. The formulation included a second, outer coat containing the enteric EUDRAGIT® L 30 D-55 polymer-based formulation to achieve gastric protection, and rapid SYN-004 release in the intestinal tract, when the pH rises above 5.5. Additional formulation improvements resulted in an increase in the SYN-004 load compared to a predecessor oral enzyme formulation (Ipsat P1A). Thus, a novel formulation and process for an orally administered enzyme was developed and used to manufacture drug product for clinical trials.

Tolerability and Pharmacokinetics of SYN-004, an Orally Administered ß-Lactamase for the Prevention of Clostridium difficile-Associated Disease and Antibiotic-Associated Diarrhea, in Two Phase 1 Studies.

BACKGROUND: SYN-004 is an orally administered ß-lactamase enzyme, designed to be given concurrently with certain intravenous ß-lactam antibiotics like cephalosporins. SYN-004 is intended to degrade residual antibiotics excreted into the intestine as a result of hepatobiliary excretion and to prevent the disruption of the gut microbiome by these excess antibiotics. Preserving the gut microbiome is expected to prevent secondary infections by pathogens like Clostridium difficile and protect against other antibiotic-associated diarrheas. METHODS: Two, randomized, double blind, placebo-controlled Phase 1 clinical studies were conducted in normal healthy adult volunteers to assess the tolerability and systemic absorption of single and multiple doses of SYN-004. A single-ascending dose study investigated single oral doses of 75-750 mg SYN-004 and was conducted in 40 subjects (five cohorts of six active and two placebo subjects). A multiple-ascending dose study investigated doses of 75-300 mg SYN-004, administered every 6 h for 7 days and was conducted in 24 subjects (three cohorts of six active and two placebo subjects). The safety and tolerability of SYN-004 was assessed and serial plasma and serum samples were collected to assess the pharmacokinetics and potential immunogenicity of SYN-004. RESULTS: Minimal and mild adverse events were reported in ~30 % of the subjects who received active drug and placebo and no antidrug antibodies were detected in any subject. Analysis of serial plasma samples demonstrated negligible systemic bioavailability of SYN-004 with most plasma concentrations being below the lower limit of quantitation (0.8 ng/mL) for the assay. SYN-004 was well tolerated in the 48 subjects who received active drug, and adverse events in those subjects were comparable to the 16 subjects who received placebo, up to the maximum doses administered in each study. CONCLUSION: SYN-004 was well tolerated up to a single oral dose of 750 mg and multiple doses of 300 mg every 6 h for 7 days. The pharmacokinetic results support that SYN-004 remained localized in the intestine.