Spinogenix Announces CLARITY: a Phase 2b/3 trial of SPG601 for the Treatment of Fragile X Syndrome

LOS ANGELES, April 23, 2026 /PRNewswire/ -- Spinogenix, Inc., a clinical-stage biopharmaceutical company pioneering first-in-class therapeutics designed to restore synapses to improve the lives of patients, is initiating CLARITY, a Phase 2b/3 adaptive trial evaluating SPG601 in male patients with Fragile X Syndrome (FXS). SPG601 is a first-in-class, oral tablet designed to modulate the activity of large-conductance, calcium-activated potassium ("BK") channels to correct specific synaptic dysfunctions that underlie many core symptoms of FXS. The trial has received grant support from the FRAXA Research Foundation in recognition of the high potential of novel therapies directed at normalizing BK channel function in FXS.

CLARITY is a two-part, randomized, double-blind, placebo-controlled Phase 2b/3 study evaluating the efficacy, safety, and tolerability of SPG601. An initial Phase 2b study will enroll up to 48 adult males with FXS (confirmed to have fully methylated Fmr1 mutations) to compare the effect of three different dose regimens of SPG601 (400mg q.d., 800mg q.d. and 800mg b.i.d.) vs placebo on electroencephalogram (EEG) signatures and behavioral outcomes over 28 days of treatment. Primary endpoints assess cognitive function using the NIH Toolbox Total Cognition Composite Change-Sensitive Score and change from baseline in EEG resting state relative power in the alpha, theta, and gamma bands. Secondary endpoints include the Fluid Cognition Composite from the NIH Toolbox Cognition Battery, the Flanker inhibitor control and attention test, and changes in everyday functioning as measured by the FXS Functional Rating Scale. A subsequent Phase 3 study will evaluate the efficacy of one dose regimen selected from Phase 2b on these measures and a broader set of cognitive and behavioral outcomes in 200 adult and adolescent male FXS participants treated for 12 weeks. 

"I am delighted that the clinical program for SPG601 is advancing to Phase 2b/3," shared Craig Erickson, M.D., Principal Investigator of the CLARITY trial and Chief Medical Advisor at Spinogenix. "The complementary neurophysiological and executive functioning efficacy signals we observed in Phase 2a are the first I have seen like this in any human trial to date. It provides me hope when addressing the many families I treat."

The CLARITY design was based on findings from the recently published Phase 2a study in Nature Scientific Reports (Pedapati et al, 2026), in which treatment with SPG601 resulted in improvements in a signature neurophysiological biomarker of FXS and in a core behavioral deficit. At a neurophysiological level, SPG601 reduced excessive high-frequency gamma band activity, an abnormality seen in EEG recordings of FXS patients that shows a negative correlation with cognition and occurs at the expense of normal brain activity levels used for learning and memory.

"People living with Fragile X and their families face significant daily challenges," said Dr. Stella Sarraf, CEO and Founder of Spinogenix. "We remain committed to supporting this community through advancing SPG601 to the next stage of clinical development."

About SPG601

SPG601 is an oral investigational medication being developed to treat FXS, and potentially other conditions on the autism spectrum, by mitigating key underlying abnormalities in synaptic function and neural excitability. FXS involves a reduction in the activity of large conductance, calcium-activated potassium (BK) channels, which contributes to synaptic dysfunction, cortical hyperexcitability, and multiple symptoms of FXS. SPG601, a novel small molecule, is the first positive modulator of BK channels to be clinically evaluated in FXS patients in a Phase 2a study and demonstrated the potential to improve cognitive, emotional, and sensory symptoms by boosting BK channel activity. SPG601 has received both Orphan Drug designation and Fast Track designation from the FDA for FXS, as well as orphan disease designation from the EMA. Plans for a registrational-directed Phase 2b/3 trial have been agreed to with the FDA.

About Fragile X Syndrome 

Fragile X Syndrome (FXS) is the leading inherited form of intellectual disability and a known cause of autism that results from the silencing of the Fmr1 gene. FXS is an orphan disease affecting approximately 1 in 4-5000 men and 1 in 6-8000 women globally. In addition to intellectual disability, FXS patients endure a wide range of disabling symptoms, including severe anxiety, social aversion, hyperactivity and attention deficit, sensory hypersensitivity, aggression, developmental seizures, and others. Providing care for individuals with FXS often becomes a full-time commitment for at least one parent and imposes significant financial strain, with direct family healthcare costs totaling $4.1 billion annually in the United States alone. Despite the considerable impact of FXS, there are currently no FDA-approved drugs available for those with the condition.

About Spinogenix

Current treatments for neurodegenerative, neuropsychiatric and neurodevelopmental conditions primarily focus on slowing disease progression or minimizing symptoms, leaving many without hope for improvement. Spinogenix is aiming to transform the treatment of these conditions through its pioneering first-in-class and paradigm-shifting synaptic regenerative and synaptic corrective therapeutics designed to restore depleted synapses and reverse synaptic degeneration and dysfunction.

Spinogenix is developing two novel therapeutics: Tazbentetol (formerly SPG302), which is designed to trigger neurons to produce new glutamatergic synapses and restore cognitive, motor, and other functions in ALS, Alzheimer's disease, schizophrenia and other diseases; and SPG601, which is designed to work at the synaptic level to correct specific dysfunctions in Fragile X Syndrome (FXS) that underlie many core symptoms. The company has received FDA and EMA Orphan Drug Designations for ALS as well as FDA Orphan Drug and Fast Track designations for FXS. More information on Spinogenix can be found at www.spinogenix.com or follow us on LinkedIn.

Media Contact
Daniel Davis
FINN Partners for Spinogenix
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Investor Relations 
Dan Albosta
Spinogenix, Inc.
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SOURCE Spinogenix