Positive Phase III results for Synergy's plecanatide

US biopharma company Synergy Pharmaceuticals (Nasdaq: SGYP) has announced positive top-line results from the second of two pivotal Phase III clinical trials evaluating the efficacy and safety of two different plecanatide treatment doses (3.0mg and 6.0mg), taken as a tablet once-a-day, in 1,337 adult patients with chronic idiopathic constipation (CIC).

The company’s shares rose about 10% to $9.04 in morning trading on Thursday, a somewhat tempered reaction compared with the 47% leap to $6.80 on release of the first of the studies.

Preliminary analysis of the data indicates that both plecanatide doses met the study’s primary endpoint and demonstrated statistical-significance in the proportion of patients in the intention-to-treat population who were durable overall responders compared to placebo during the 12-week treatment period (20.1% in 3.0mg and 20.0% in 6.0mg dose groups compared to 12.8% in placebo; p=0.004 for both doses). The durable overall responder endpoint is the current FDA endpoint required for US approval in CIC. Importantly, plecanatide was safe and well tolerated at both doses; the most common adverse event was diarrhea, which occurred in 3.2% of patients in 3.0mg and 4.5% of patients in 6.0mg dose groups compared to 1.3% of placebo-treated patients.