Zynerba Pharmaceuticals Inc (NASDAQ: ZYNE) shares retreated to their lowest level since early April following a clinical readout from the company.

What Happened: The Devon, Pennsylvania-based pharma that focuses on developing cannabinoid therapies for rare and near-rare neuropsychiatric disorders said its Zygel did not meet the primary and secondary endpoints of a pivotal study dubbed CONNECT-FX that evaluated the safety and efficacy of the pipeline asset in Fragile X syndrome patients.

Fragile X syndrome is a rare genetic developmental disability that is the leading known cause of both inherited intellectual disability and autism spectrum disorder.

Zygel did not achieve statistical significance versus placebo in the primary endpoint of improvement in the Social Avoidance subscale of the Aberrant Behavior Checklist, the company said.

It also did not show statistical significance versus placebo in the three key secondary endpoints, which were the change from baseline to the end of the treatment period in the Irritability subscale score, the Socially Unresponsive/Lethargic subscale score and Improvement in Clinical Global Impression.

However, the company noted a pre-planned ad hoc analysis of the most severely impacted patients in the trial, as defined by patients having at least 90% methylation of the impacted FMR1 gene, demonstrated that patients receiving Zygel achieved statistical significance in the primary endpoint. This group, according to the company, comprised 80% of the patients enrolled in the study.

What Next: Based on the positive result from the subset analysis, Zynerba said it intends to meet with the FDA regarding a regulatory path forward for Zygel.

The stock plummeted 48% to $3.37 per share.