Synergy Pharmaceuticals Inc. shares (NASDAQ:SGYP) leapt 67.7 percent to close at $7.78 Wednesday on news that the company's wholly owned chronic idiopathic constipation (CIC) drug, plecanatide, met the primary endpoint in the first of two pivotal phase III studies, laying the groundwork for it to file a new drug application (NDA) with the FDA in the fourth quarter, with the expectation of an early 2017 launch.

The data suggested Synergy may field a strong competitor in the functional gastrointestinal (GI) space and, some analysts said, may make Synergy a potential acquisition target.

The trial evaluated two doses of the drug, a guanylate cyclase C (GC-C) receptor agonist and a synthetic analog of uroguanylin, a natural hormone that regulates ion and fluid transport in the intestine. Synergy execs said the molecule is capable of restoring the normal balance of fluid in the organ to help patients suffering from GI disorders, such as CIC and constipation-predominant irritable bowel syndrome (IBS-C), another indication for which it's developing plecanatide.

In a preliminary analysis, the New York-based company found that about one-fifth of the 1,346 adult CIC patients treated with the drug experienced durable overall responses, the FDA-required endpoint for new CIC drugs, as compared to about one-tenth of those patients given a placebo.

Of the two different doses of plecanatide tested, each met the primary endpoint, with 21 percent of patients taking a 3-mg dose having durable responses and 19.5 percent of patients taking a 6-mg dose meeting the criteria vs. just 10.2 percent of those who got a placebo (p<0.001 for both doses).

Patients are considered to be durable overall responders if they have both more than three complete spontaneous bowel movements (CSBM) per week plus an increase of more than one CSBM from their normal baseline in the same week, for nine out of the 12 treatment weeks. In addition, the same patient must be an overall responder for at least three of the last four treatment weeks in order to be considered a durable overall responder.

If Synergy's NDA is successful, plecanatide would be the first drug approved for CIC under the requirement for durability in response.

Stool consistency was the sole secondary endpoint reported with top-line analyses, with both the 3-mg and 6-mg doses showing statistically significant improvement from baseline in Bristol Stool Form Scale scores compared to placebo.

Plecanatide was safe and well tolerated at both doses, with the most common adverse event being diarrhea, which occurred in 5.9 percent of patients in the 3-mg group and 5.5 percent of patients in the 6-mg dose group. About 1.3 percent of placebo-treated patients experienced the side effect. The company has yet to decide which dose or doses to include in its NDA, but pointed to the rates for both doses as validating plecanatide.

The relatively low diarrhea rates, which Synergy attributes to the drug's self-regulatory nature, could potentially give plecanatide an advantage over other therapies currently approved for treating CIC, such as Linzess (linaclotide, Ironwood Pharmaceuticals Inc. and Allergan plc) and Amitiza (lubiprostone, Sucampo Pharmaceuticals Inc. and Takeda Pharmaceuticals North America Inc.). Each recorded higher rates of diarrhea among subjects in their pivotal studies, with 16 percent of the 430 patients treated with a 145-mcg dose of Linzess experiencing the side effect and 12 percent of 1,113 patients treated with a 24-mcg dose of Amitiza twice daily.

Despite that, Cowen and Co. analyst Boris Peaker pointed out, patients in the Linzess pivotal trials also had slightly higher rates of diarrhea on placebo. "Ultimately, we believe that both linaclotide and plecanatide will be viewed as equal by the medical community, and the drivers of adoption will be brand awareness by patients and docs as well as cost," he wrote in a note assessing Synergy's news for Ironwood shareholders.

"What's really nice is that we control our own future right now," Synergy's president, CEO and chairman, Gary Jacob, told BioWorld Today. He said that "going it alone" for as long as possible has always been part of the company's business model. Asked whether Synergy would seek a partner, as Ironwood and Sucampo did, he said that with a second pivotal study of plecanatide in CIC expected to report in the third quarter and considerable work left to be done on the company's registration filing, "there will be plenty of time as we move along to consider what our options are in terms of our business development activities."

Meanwhile, the company is continuing to pursue IBS-C, with an NDA filing in that indication expected toward the end of 2016, with a launch in the beginning of 2018.

If Ironwood's leadership or its investors are concerned, they're not showing it. During a session at the Goldman Sachs Healthcare Conference, June 10, Ironwood CEO Peter Hecht said, "I think multiple entrants in multiple categories will help grow the functional GI space, and the IBS-C and IBS categories, in general. I think there's room for multiple entrants and lots of players."

Ironwood shares (NASDAQ:IRWD) fell 39 cents, closing at $11.89 on Wednesday. Sucampo (NASDAQ:SCMP) shares fell 2 cents, closing at $16.53.