After failing a PhII/III, Raptor steers Huntington's drug into a pivotal trial

Just three months after pulling the plug on its drug for NASH, Raptor Pharmaceutical says that it's pushing ahead with a pivotal study for a new drug to treat Huntington's, even though it failed the primary endpoint in a Phase II/III trial.

The Novato, CA-based biotech ($RPTP) recruited 96 patients for the study, tracking a slower rate of motor and functional decline in Huntington's disease patients when comparing a group that started on RP-103 and another group that started on a placebo and switched to the drug after 18 months. There was a 25% treatment effect in the all-drug arm's total motor score rating compared with the placebo/drug arm over 36 months.

That's not statistically significant (meaning it failed the endpoint), says the biotech, but they're counting it as clinically meaningful enough to warrant a pivotal study.

"The 36-month efficacy results from the CYST-HD study are clinically meaningful and suggest that RP103 may play an important role in the treatment of Huntington's disease," said Dr. Dominique Bonneau, professor of medical genetics at the CHU d'Angers and principal investigator for CYST-HD. "These data warrant further assessment as there remains a clear need for new, safe and tolerable therapies to treat this disease."

Pursuing new trials in the face of a clinical failure is a controversial issue in biotech. The drug's shares slipped 6% in early trading Thursday. Those shares were hammered much harder after Raptor reported that its NASH drug had flopped in a trial.

Investigators also tracked three suicides in the trial, which they say is in keeping with a high suicide rate for the patient population as a whole.

- here's the release