Synergy Pharmaceuticals (SGYP) reported positive data from the first of two phase 3 trials for its constipation drug plecanatide on Wednesday. The results topped most investor expectations, with plecanatide meaningfully outperforming its closest competition, Ironwood Pharma’s (IRWD) Linzess, on some key secondary endpoints.
The stock is up 60% in pre-market trading to $7.50. Read more about Synergy here.
Synergy tested two plecanatide doses, 3.0 mg and 6.0 mg, once-a-day in 1,346 adult patients with chronic idiopathic constipation (CIC). Both doses met the study’s primary endpoint and – the proportion of patients who were durable overall responders – compared to placebo during the 12-week treatment period, with 21.0% in the 3.0 mg and 19.5% in the 6.0 mg dose groups compared to 10.2% in the placebo arm (p<0.001). The durable overall responder endpoint is the current FDA endpoint required for approval in CIC.
Plecanatide was well tolerated at both doses, with a low diarrhea rate that puts Linzess to shame. Diarrhea occurred in 5.9% of patients on the 3.0 mg dose and 5.5% of patients on the 6.0 mg dose, compared to 1.3% of placebo-treated patients. This is a facet of the data that we’ve written about at length in the past. Linzess produces diarrhea in about 20% of patients. Investors had been looking for a diarrhea rate of 10% or less with the 6mg dose in this trial – 5.5% is a homerun. 
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