Shares in Axovant Sciences Ltd sank almost 50 percent after investors shrank back on new of the failure of lead drug intepirdine in a mid-stage study in patients with a particular kind of dementia.

The company said the investigational drug did not meet its primary efficacy endpoints in the Phase IIb HEADWAY and pilot Phase II Gait and Balance studies, which assessed its potential in patients with patients with dementia with Lewy bodies (DLB).

In the HEADWAY study, neither 35mg nor 70mg dose of intepirdine resulted in statistically significant improvements after 24 weeks of treatment compared with placebo-treated patients.

“Based on the totality of intepirdine data to date, there is no evidence to support its further development. We are incredibly disappointed and saddened for the millions of people living with these difficult conditions, and are deeply grateful to the patients, caregivers and investigators who participated in our trials,” said David Hung, the UK-headquartered firm’s chief executive.

On the plus side, the company said it would move to a larger confirmatory study of nelotanserin focusing on motor function and paralysis in patients with Parkinson’s disease.

The move comes after the investigational drug met its prespecified primary endpoint of safety in patients with DLB and Parkinson’s disease dementia who were experiencing visual hallucinations.