US drugmaker NPS Pharmaceuticals saw its shares plummet nearly 30% yesterday morning as investors shrank back on news that its promising short bowel syndrome candidate failed to meet its primary goal in a late-stage study.

The clinical study of Gattex (teduglutide, recombinant GLP-2) assessed a low dose and higher dose of the drug, the clinical efficacy endpoint being a reduction in parenteral nutrition (intravenous feeding) of at least 20% comparing baseline to weeks 16 to 24.

While a significant result was achieved in the lower dose group, only 25% of patients receiving the higher dose achieved a reduction in PN compared to those on placebo, failing to reach statistical significance.

But while investor confidence has taken a hit, the company remains confident in the future of the drug as a successful treatment for SBS. “The results of the study underline the importance of Gattex as a potential new standard of care for SBS,” Dr Tony Coles, president and chief executive of NPS, stressed.

“We are particularly encouraged to see a reduction in PN over six months in patients with SBS who received the lower dose of Gattex. Patients who responded to this dose were able to reduce their reliance on parenteral nutrition by over 20%, which represents a clinically meaningful benefit, and we are very excited that two of the 35 patients on the lower dose were able to eliminate their PN entirely by week 20, and a third patient was also able to stop PN altogether at week 24.”

An appetite suppressant

Offering potential explanations for the different response rates between the groups, NPS pointed to one theory that, at higher doses, GLP-2 suppresses appetite so “it is possible that patients on the higher dose consumed fewer calories from food and thus did not decrease their PN regimens. And a second hypothesis suggests that GLP-2 may have different dose-related effects, so that could increase nutrient absorption at low-doses while having a greater effect on mucosal and epithelial regeneration at higher ones.

NPS says it now plans to meet with US regulators to discuss the path to regulatory approval for Gattex.

In September, Nycomed bought worldwide licensing rights to Gattex outside the US, Canada and Mexico.