What happened?

Shares of Ovid Therapeutics (OVID 1.59%) -- a clinical-stage biotech company -- are down by 55% as of 11:04 a.m. EST on Wednesday, after falling by as much as 56.4% earlier in the day. Investors are selling off shares of the drugmaker following negative results from a pivotal phase 3 clinical trial for one of its leading pipeline candidates, OV101.

So what

Ovid Therapeutics focuses on developing treatments for neurological diseases, and the company was investigating OV101 as a potential medicine for Angelman syndrome. This rare genetic disorder is typically diagnosed in children and causes delayed development, sleep disorders, speech impairment, and seizures, among other things. In a phase 3 clinical trial, Ovid Therapeutics enrolled 104 patients between the ages of 2 and 12 and treated them with either OV101 or a placebo for 12 weeks.

Road sign that says "risk ahead."

Image source: Getty Images.

The goal was to assess the effects of OV101 on patients diagnosed with Angelman syndrome. The primary endpoint of the trial was "change in overall score on the Clinical Global Impression-Improvement-Angelman syndrome (CGI-I-AS) scale." Unfortunately, OV101 failed to meet its primary endpoint during the trial. Patients treated with the drug achieved a 0.7 point improvement on the CGI-I-AS scale, while those treated with placebo achieved a 0.8 point improvement on the scale.

Now what

There is no standard of care and no drug approved by the U.S. Food and Drug Administration (FDA) for Angelman syndrome. And while there remains a dire need for a drug for this condition, it doesn't look as though OV101 will go on to earn regulatory approval, given the results of this clinical trial. That doesn't bode well for Ovid Therapeutics, and it explains why shares of the biotech company -- which has no drugs on the market at the moment -- are getting clobbered on the stock market today.