Updated from 8:12 a.m. with current stock price.
NEW YORK (TheStreet) -- Synergy Pharmaceuticals' (SGYP) experimental drug plecanatide significantly reduced chronic constipation compared to a placebo, achieving the primary goal of a late-stage study, the company announced Wednesday.
Shares of Synergy are up 52% to $7.06 in midday trading on the positive plecanatide results, which also suggest the drug is better tolerated than Linzess, a competing chronic constipation drug already approved and marketed by Ironwood Pharmaceuticals (IRWD).
Synergy is conducting a second phase III study of plecanatide, with results due early in the third quarter. If the second study is also positive, the company intends to seek U.S. approval for plecanatide in the fourth quarter.
In a study of 1,346 adults patients with chronic constipation, 21% and 19.5% of patients treated with one of two doses of plecanatide had a durable response compared to 10.2% of placebo patients. The differences in durable response rate favoring both plecanatide doses were statistically significant, the company said.
Durable response was defined as having three or more bowel movements per week plus an increase of one or more bowel movements from baseline in the same week for nine of the 12 treatment weeks. The same patient had to respond for at least three of the last four weeks of treatment in order to be counted as a durable response.
Plecanatide also showed a statistically significant improvement in stool consistency compared to placebo.
The rate of diarrhea, a key adverse event, was 5% to 6% in the plecanatide patients, compared to 1.3% in placebo patients. Notably, plecanatide's observed diarrhea rate is considerably lower than the 16% listed in the Linzess label approved by the FDA.
Plecanatide is a pill taken once per day. The drug works by mimicking the activity of a hormone which increases the flow of fluids through the gut.
Synergy has been the subject of takeover speculation, which will only intensify given the positive results from the plecanatide study announced Wednesday.