Kaerus Bioscience has been granted Orphan Drug Designation and Rare Pediatric Disease Designation by the US Food and Drug Administration (FDA) for its lead candidate, KER-0193, intended for the treatment of Fragile X syndrome (FXS). The decision follows the successful completion of a Phase 1 clinical trial, which the company reports confirmed safety, tolerability, and favorable pharmacokinetics in healthy volunteers.

Fragile X syndrome is the most common inherited cause of intellectual disability and autism, affecting approximately 1 in 7,000 males and 1 in 11,000 females. There are currently no approved therapies for the condition. It is typically characterized by a broad spectrum of behavioral, cognitive, and sensory impairments, and is associated with dysfunction in neural excitability pathways.

KER-0193 is described as a novel, orally available small molecule that modulates BK channels—calcium-activated potassium channels believed to play a critical role in maintaining excitability across the nervous system. According to the company, a reduction in BK channel function is directly implicated in the pathophysiology of FXS.

The recent Phase 1 trial included a sub-study using electroencephalography (EEG) to monitor central nervous system activity in healthy participants. Kaerus reports that KER-0193 crossed the blood-brain barrier and produced measurable effects in regions commonly implicated in FXS. The company claims these findings are consistent with preclinical animal data and support the proposed mechanism of action.

Orphan Drug and Rare Pediatric Disease designations offer sponsors access to development incentives, including tax credits, fee waivers, and potential eligibility for priority review and a transferable priority review voucher, subject to regulatory milestones.

The company is currently preparing for a Phase 2 proof-of-concept trial in individuals with FXS. No start date or enrolment targets have been disclosed.

Beyond FXS, the therapeutic platform is being explored for other neurological conditions marked by BK channel deficits, including epilepsy and certain rare genetic encephalopathies. While data in these indications remain preclinical, the company has indicated ongoing evaluations are underway.

If successful, the program could represent one of the first targeted therapies for FXS and may help validate BK channel modulation as a broader neurodevelopmental treatment strategy.

“The FDA’s granting of Orphan Drug Designation and Rare Pediatric Drug Designation for KER-0193 is an important step towards our objective of delivering an effective treatment for people with Fragile X syndrome,” said Dr Robert Ring, CEO of Kaerus Bioscience.

“Not only do these two FDA designations affirm the therapeutic potential of KER-0193, they also provide Kaerus with access to significant regulatory and financial incentives as we look to progress the drug through clinical trials.”