SYN-010 has previously been evaluated in consecutive Phase 2a clinical trials. Sixty-three (63) IBS-C patients with high breath methane (\>10 ppm) at screening were enrolled in a multicenter, randomized, controlled, double-blinded clinical trial (RCT) in which they received SYN-010 21 mg, SYN-010 42 mg or Placebo once daily for 4 weeks. Fifty-four (54) subjects who completed the RCT continued into an open-label extension (EXT) in which all subjects received SYN-010 42 mg once daily for an additional 8 weeks.
The SYN-010 Phase 2a studies were intentionally designed as mechanistic proof-of-concept studies, wherein reductions in breath methane were employed as a rapid and cost-effective means by which to determine if SYN-010 could be effective in treating an underlying cause of symptoms in IBS-C. Breath methane was reduced relative to baseline in SYN-010 treatment groups, and lower breath methane levels correlated with an increased number of complete spontaneous bowel movements (CSBMs) at week 12, consistent with the proposed methane-inhibiting action of lovastatin lactone.
Since lovastatin has not previously been used to treat IBS-C patients, the SYN-010 Phase 2a studies were also focused on the safety of the SYN-010 dosage form. Daily doses of SYN-010 were well-tolerated by IBS-C patients over the 12-week treatment period (at least 8 weeks of SYN-010 42 mg). SYN-010 did not cause clinically meaningful or persistent changes in serum liver and muscle markers in IBS-C patients at daily doses of 21 mg and 42 mg. Modest decreases from baseline in lipid parameters observed after 7 days of SYN-010 21 mg or 42 mg had largely faded by 28 days and were not evident after 12 weeks of dosing. Very few adverse events were reported over 12 weeks of SYN-010 treatment and all were of mild or moderate intensity. No serious adverse events were reported and there were no incidences of drug-related diarrhea, which is an important potential benefit of SYN-010 as an IBS-C therapy.
Although the Phase 2a studies were not prospectively powered for formal statistical evaluation of clinical endpoints, compelling improvements in CSBMs, abdominal pain, and bloating were observed in SYN-010 treatment groups. These clinical findings have been presented in multiple public forums and a panel of clinical advisors affirmed that the Phase 2a data validate the need to evaluate optimal dosing of SYN-010 in a larger patient population over a longer dosing period.
Based on the potential clinical benefit observed in Phase 2a, this Phase 2b clinical study will evaluate in more detail the clinical effects of two dose strengths of SYN-010 administered over a longer treatment period (12 weeks per FDA guidelines) to a larger number of IBS-C patients. The study will seek more definitive evidence regarding potential symptom improvements and safety in IBS-C patients. The study also seeks to provide new information of relevance to both efficacy and safety by measuring changes to the microbiome in patient stool samples; serum level of cytokine markers of inflammation; and expanded breath gas measurements.
SYN-010 is a hydroxypropyl methylcellulose (HPMC) capsule filled with enteric-coated tablets from which lovastatin is released at different intestinal pH values. The tablets are designed to pass through the stomach unchanged then release a small amount of lovastatin into the duodenum and the majority of the lovastatin dose into the ileocecal junction and colon. The amount of lovastatin to be released into the small and large intestine is anticipated to be consistent with the relative levels of methane-producing archaea in each location of the intestine.
Methane production (methanogenesis) is a ubiquitous process in the human intestine, disposing of hydrogen and other by-products formed during bacterial fermentation. Methane production in humans is almost entirely due to the archeon M. smithii. Elevated intestinal methane production reduces intestinal motility and is a cause of constipation, pain and bloating in IBS-C.
Interest in lovastatin as a potential inhibitor of methanogenesis originated with recognition that the rate-limiting step in the synthesis of archaeal lipid membranes is catalyzed by HMG-CoA reductase (HMGR) which is the target enzyme for cholesterol-lowering statins. Subsequent in vitro studies (described above) and computational studies have since determined that HMGR is not the target for lovastatin anti-methanogenic activity; rather, lovastatin lactone appears to exert a direct effect on methanogenesis enzymes. The mechanism by which lovastatin lactone inhibits methane production by M. smithii has not been conclusively determined; however, detailed computational studies showed that lovastatin lactone may competitively inhibit F420-dependent methylenetetrahydromethanopterin dehydrogenase (mtd), an enzyme that is integral to the M. smithii methanogenesis pathway.
Methanogenic archaea reside predominantly in the human colon, with lower methanogen levels measured in the small intestine of some patients. Methane production at both sites contributes to reduced gastrointestinal motility and rat studies suggest that the ileocecal region may be of particular significance. SYN-010 utilizes a dual-pulse release profile to deliver a portion of the lovastatin dose to the small intestine and the majority of the dose to the ileocecal junction and colon where the most methane-producing organisms are found; the relative amounts of lovastatin released into the small and large intestine are consistent with the anticipated relative levels of methanogens in each location.
Lovastatin lactone exerts its methane-reducing effect in the intestinal lumen and systemic absorption of lovastatin is not required for its therapeutic effect in IBS-C.
