Neurocrine Biosciences, said on Wednesday its drug helped reduce the severity of schizophrenia symptoms in a mid-stage trial, but its shares fell nearly 17 per cent on worries whether the benefit could be replicated in larger trials.
A 20 milligram dose of the drug, the lowest, achieved a 7.5 points reduction in a scale used to measure the severity of symptoms in the study that enrolled 210 patients, the company said, performing better than higher doses.
The results sparked questions over whether or not the drug, called NBI-1117568, could reproduce a similar effect in larger trials.
The outperformance was “not something that is necessarily typical in this class – and something that is likely to call into question the replicability of the results in phase III (trials),” said RBC Capital analyst Brian Abrahams.
Schizophrenia, which causes symptoms such as delusions, hallucinations and emotional withdrawal, affects about 24 million people worldwide, according to the World Health Organization.
It is typically treated with antipsychotic medicines, which cause side effects including sleepiness, weight gain and involuntary movement.
The Neurocrine drug belongs to a new class of treatments that target proteins called muscarinic receptors in the central nervous system, while existing antipsychotic drugs block proteins called dopamine receptors.
Bristol Myers Squibb and AbbVie have recently inked multi-billion dollar deals to gain similar drugs, which are both being tested in clinical trials.
In the study, Neurocrine said the drug was generally safe and well-tolerated. Drowsiness, dizziness and headaches were the most common adverse effects.
Shares of the California-based company were trading at $127.2 before the opening bell. The stock has gained nearly 16 per cent this year, giving the company a market capitalisation of $15.4 billion as of Tuesday’s close.