The London-based biotech said "data showed no statistically significant difference in either study between Miraxion and placebo with regard to the primary and secondary endpoints."
The studies sought to determine that Miraxion improved motor function according to the Total Motor Score 4 component of the Unified Huntington's Disease Rating Scale. Secondary endpoints included cognition and total functional capacity outcomes.
"We are extremely surprised and disappointed by these top-line results, and we are analyzing the data in order to better understand the full and complete data set and outcomes," the company said. "We are particularly disappointed that, at this time, we are not in a position to bring any positive news to those patients who are suffering from this devastating disease and to the broader HD community."
Shares fell $3.04 to 74 cents.