Spinogenix's SPG601 Receives FDA Fast Track Designation for Fragile X Syndrome

Craig Erickson, MD

(Credit: Cincinnati Children's)

According to a new announcement, the FDA has granted fast track designation to Spinogenix’s investigational therapy SPG601 for the treatment of patients with Fragile X syndrome (FXS), a leading cause of genetic autism. Spinogenix also announced that it recently completed its phase 2 study (NCT06413537) assessing the agent in adult men with FXS, with topline results anticipated by end of the first quarter in 2025.¹

"Fragile X syndrome profoundly impacts patients and families yet remains without FDA-approved treatments. Beyond intellectual disability, individuals with FXS often experience debilitating symptoms that severely affect their quality of life, including severe anxiety, hyperactivity and attention deficit, sensory hypersensitivity, and at times irritability marked by aggression and self-injurious behavior," Craig Erickson, MD, chief medical advisor at Spinogenix and associate professor in the division of child and adolescent psychiatry at Cincinnati Children's, told NeurologyLive^®.

The phase 2 trial is a randomized, double-blind, placebo-controlled crossover study that evaluated a single dose of SPG601 compared with a placebo in patients with FXS. Spinogenix noted that the trial was specifically designed to assess significant brain target engagement in first-in-human FXS studies, utilizing validated neurophysiological markers of brain activity. These markers have been rigorously validated over the past decade by principal investigator Erickson and his team, with support from the National Institutes of Health Centers for Collaborative Research in Fragile X program.

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In May 2024, the FDA granted orphan drug designation to the agent for the treatment of patients living with FXS.² SPG601 targets synaptic dysfunction in FXS by addressing a well-documented molecular impairment, with the goal of alleviating core symptoms and improving the overall quality of life for patients. This small-molecule therapy acts as an activator of large-conductance, calcium-activated potassium (BK) channels. By binding to these channels, it aims to enhance their activation, helping to correct the synaptic deficits that contribute to many of the primary symptoms of FXS.

FXS, a leading genetic cause of autism resulting from the silencing of the Fmr1 gene, is a rare disorder affecting approximately 1 in 4,000–5,000 men and 1 in 6,000–8,000 women worldwide. Patients with FXS experience a spectrum of disabling symptoms, including intellectual disability, severe anxiety, social withdrawal, hyperactivity, attention deficits, sensory hypersensitivity, aggression, and developmental seizures. Deficient activity of BK channels has been implicated in many of these core symptoms.

“People with FXS—the most common single gene cause of autism--and their families face immense challenges; providing care often becomes a full-time often lifelong commitment for at least one parent or guardian and imposes significant financial strain, with direct family healthcare costs totaling $4.1 billion annually in the United States alone,” Erickson said. “We are committed to improving the lives of the underserved FXS community by addressing core symptoms through correction of specific synaptic dysfunctions. The FDA Fast Track designation of SPG601 will allow us to accelerate its development to offer a much-needed potential therapy that already has a solid demonstrated safety track record in humans.”

REFERENCES
1. FDA Grants Fast Track Designation to Spinogenix's SPG601 for Treatment of Fragile X Syndrome, a Common Inherited Form of Autism. News Release. Spinogenix. Published January 13, 2025. Accessed January 14, 2025. https://www.spinogenix.com/fda-grants-fast-track-designation-to-spinogenixs-spg601-for-treatment-of-fragile-x-syndrome-a-common-inherited-form-of-autism/
2. Spinogenix Announces U.S. FDA Orphan Drug Designation Granted to SPG601 for the Treatment of Fragile X syndrome. News Release. Spinogenix. Published May 20, 2024. Accessed January 14, 2025. https://www.spinogenix.com/spinogenix-announces-u-s-fda-orphan-drug-designation-granted-to-spg601-for-the-treatment-of-fragile-x-syndrome/