Raptor's NASH gamble blows up in Phase II pediatric trial

Raptor Pharmaceuticals ($RPTP) is pulling the plug on a treatment for a pervasive liver disease after its top prospect failed in a Phase IIb study, torpedoing the company's market value.

In a trial on 169 children with nonalcoholic steatohepatitis (NASH), Raptor's oral RP103 missed its primary endpoint of improving symptoms without worsening tissue scarring. Raptor studied three doses of the drug over 52 weeks, hoping to track at least a two-point improvement on a NASH-related scale compared with placebo. In the end, RP103 fell well short of statistical significance on its main goal, the company said.

The failure sent Raptor's share price down as much as 35% on Monday morning, plunging the biotech's market cap below $1 billion.

The company is releasing only top-line results for now, but Raptor has no plans to push RP103 forward in NASH, CEO Julie Anne Smith said, focusing instead on its two approved treatments.

"This clarifies our near-term priorities, which are to maximize the reach of Procysbi in nephropathic cystinosis, further the development of RP103 in Huntington's and mitochondrial diseases, prepare for Quinsair's launch and initiate at least one trial in nontuberculous mycobacteria or bronchiectasis," Smith said in a statement.

The market potential of NASH, estimated to affect as many as 5% of Americans, has attracted a surge of interest from drug developers large and small. Leading the way is Intercept Pharmaceuticals ($ICPT) and its breakthrough-designated obeticholic acid, a drug slated to enter Phase III in NASH this quarter. Behind it, French biotech Genfit is pressing into Phase III with a once-failed NASH treatment, while Gilead Sciences ($GILD), Shire ($SHPG), Enanta Pharmaceuticals ($ENTA) and many others advance treatments of their own.

- read the statement