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NCT Number: NCT07439510

A Study to Investigate the Effects and Safety of SPG601 for the Treatment of Fragile X Syndrome in Male Participants

This Phase 2b/3, randomized, double-blind, placebo-controlled, 2-part study will evaluate the efficacy, safety and tolerability of different dose regimens of SPG601 in adult male participants with Fragile X syndrome.

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Key information

Conditions

Fragile X Syndrome (FXS) Chromosome Disorders Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Fragile X Syndrome Genetic Diseases, Inborn Genetic Diseases, X-Linked Heredodegenerative Disorders, Nervous System Intellectual Disability Nervous System Diseases Neurobehavioral Manifestations Neurologic Manifestations Sex Chromosome Disorders X-Linked Intellectual Disability

Age range

18 year–45 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 2 / Phase 3

About this study

This is a Phase 2b/3, randomized, double-blind, placebo-controlled, study designed to evaluate the efficacy, safety and tolerability of multiple dose regimens of SPG601 in male participants with FXS.

The study consists of two parts, Phase 2b, dose-regimen finding, 4-arm parallel design: Eligible participants will be randomized to receive SPG601 or matched placebo. Participants will receive study intervention over 4 weeks and will be followed up for 4 weeks after last dose of study intervention.

Phase 3, 2-arm parallel design: Eligible participants will be randomized 1:1 to receive SPG601 or matched placebo. The dose of SPG601 administered in the Phase 3 will be defined based on analysis of Phase 2b. Participants will receive study intervention over 12 weeks and will be followed up for 4 weeks after last dose of study intervention.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adult males aged 18 to 45 years, inclusive
  • Diagnosis of Fragile X as confirmed with genetic testing
  • Patient must have caregiver
  • Must be in good health with no significant medical history

Exclusion criteria

  • Any physical or psychological condition that prohibits study completion
  • Uncontrolled seizures or history of epilepsy with a seizure in the past 6 months.
  • Auditory or visual impairments that cannot be corrected
  • History of suicidal behavior or suicidal ideation
  • Screening vital signs that are abnormal per protocol specification
  • ECG that are clinically significant abnormal
  • History of substance abuse or dependence within 6 months
  • Other investigational products within 30 days
  • Unable to swallow capsules

Treatment and study plan

SPG601

Drug

synthetic small molecule

Placebo

Drug

Placebo

Primary outcomes

  1. Phase 2b: Change from baseline in Total Cognition Composite Change Sensitive Score from the NIH-TCB

    Time frame: 8 weeks

    The NIH Toolbox (NIH-TCB) Total Cognition Composite Change-Sensitive Score (CSS) is used to measure cognitive change over time. Higher scores indicate higher level of functioning. The scores typically span across the developmental range, often extending well above and below the 500-point mark depending on the age and cognitive ability of the individual.

  2. Phase 2b: Change from baseline in EEG resting state relative power bands during rest

    Time frame: 8 weeks

    Resting-state EEG relative power changes from baseline are characterized by significant shifts in power bands such as gamma, alpha, theta and beta bands

  3. Phase 3:Change from baseline in Total Cognition Composite score from the NIH-TCB

    Time frame: 12 weeks

    The NIH Toolbox (NIH-TCB) Total Cognition Composite Change-Sensitive Score (CSS) is used to measure cognitive change over time. It is calculated by combining the Crystallized Composite (reading/vocabulary) and Fluid Composite (memory/executive function/speed) scores. Higher scores indicate higher level of functioning.

Secondary outcomes

  1. Phase 2b: Change from baseline in Fluid Reasoning Composite Change Sensitive Scores from the NIH-TCB

    Time frame: 8 weeks

    The Fluid Cognition Composite (FCC) from the NIH Toolbox Cognition Battery (NIHTB-CB) is designed to measure changes to neurological functioning. It combines scores from five tests (Dimensional Change Card Sort, Flanker, List Sorting, Pattern Comparison, and Picture Sequence Memory) to provide a measure of executive function, memory, and processing speed. Higher scores indicate higher level of functioning. Superior ability is 130, average is approx. 100 and less than 70 is impairment.

  2. Phase 2b: Change from baseline in Flanker Scores from the NIH-TCB

    Time frame: 8 weeks

    Flanker Inhibitory control will assess inhibitory control and attention through asking participant to focus on one stimuli will not focusing on any stimuli surrounding it. A higher score indicates better performance

  3. Phase 2b: Incidence, nature, and severity of adverse events (AEs) and serious adverse events (SAEs)

    Time frame: 8 weeks

    Incidence, nature, and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs)

  4. Phase 2b: Change from baseline in Columbia-Suicide Severity Rating Scale (C-SSRS) throughout the study

    Time frame: 8 weeks

    Prospective suicidality assessment is performed using the Columbia-Suicide Severity Rating Scale (C-SSRS), a questionnaire to evaluate suicidal ideation and behavior. Answer "yes" on item 4 or 5 of the Suicidal Ideation section or "yes" on any item of the Suicidal Behavior section is considered positive. Range is 2-25

  5. Phase 2b: The PK parameters of SPG601 concentrations in plasma-Cmax

    Time frame: 4 weeks

    Maximum concentration of SPG601 in plasma following dose

  6. Phase 2b: The PK parameters of SPG601 concentrations in plasma-T 1/2

    Time frame: 4 weeks

    Metabolic half life of SPG601 in plasma following dose

  7. Phase 3: Incidence, nature, and severity of adverse events (AEs) and serious adverse events (SAEs)

    Time frame: 16 weeks

    Incidence, nature, and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs)

  8. Phase 3: Change from baseline in Columbia-Suicide Severity Rating Scale (C-SSRS) throughout the study

    Time frame: 8 weeks

    Prospective suicidality assessment is performed using the Columbia-Suicide Severity Rating Scale (C-SSRS), a questionnaire to evaluate suicidal ideation and behavior. Answer "yes" on item 4 or 5 of the Suicidal Ideation section or "yes" on any item of the Suicidal Behavior section is considered positive. Range is 2-25

  9. Phase 3: Change from baseline in Flanker Scores from the NIH-TCB

    Time frame: 12 weeks

    Flanker Inhibitory control will assess inhibitory control and attention through asking participant to focus on one stimuli will not focusing on any stimuli surrounding it.

  10. Phase 3: Change from baseline in Fluid Reasoning Composite Change Sensitive Scores from the NIH-TCB

    Time frame: 12 weeks

    The Fluid Cognition Composite (FCC) from the NIH Toolbox Cognition Battery (NIHTB-CB) is designed to measure changes to neurological functioning. It combines scores from five tests (Dimensional Change Card Sort, Flanker, List Sorting, Pattern Comparison, and Picture Sequence Memory) to provide a measure of executive function, memory, and processing speed. Higher scores indicate higher level of functioning. Superior ability is 130, average is approx. 100 and less than 70 is impairment.

  11. Phase 3: Change from baseline to week 4 and week 8 in Total Cognition Composite score from the NIH-TCB

    Time frame: 8 weeks

    The NIH Toolbox (NIH-TCB) Total Cognition Composite Change-Sensitive Score (CSS) is used to measure cognitive change over time. It is calculated by combining the Crystallized Composite (reading/vocabulary) and Fluid Composite (memory/executive function/speed) scores. Higher scores indicate higher level of functioning. The scores typically span across the developmental range, often extending well above and below the 500-point mark depending on the age and cognitive ability of the individual.

  12. Phase 3: Change From Baseline in Behavioral Symptoms of Fragile X Syndrome Using the Aberrant Behavior Checklist (ABC) Total Score in Stratum

    Time frame: 12 weeks

    The Aberrant Behavior Checklist-Community edition (ABC-C) is a 58-item, caregiver-rated symptom checklist for assessing problem behaviors of children and adults with mental retardation at home, in residential facilities, and work training centers. The assessment was done by attributing to each item a score from 0 ("not at all a problem") to 3 ("problem is severe in degree") The ABC will be scored using the FXS-specific factoring system (ABC-FX) for which the total score ranks from 0 to 165.

  13. Phase 3: Change from baseline to Week 12 in Vineland Adaptive Behavior Scale 3rd Edition

    Time frame: 12 weeks

    Vineland-3 Adaptive Behavior Scale (Vineland-3), using the composite score and domain scores from communication, daily living skills, and socialization.

    The adaptive behavior composite standard score is computed from the sum of standard scores from the domains and converted into the adaptive behavior composite standard score. Higher scores indicate a higher adaptive level of functioning.

  14. Phase 3: Change from baseline in the Anxiety, Depression and Mood Scale (ADAMS)

    Time frame: 12 weeks

    Anxiety, Depression, and Mood Scale (ADAMS) scores is used assess inappropriate speech, irritability, hyperactivity, lethargy/withdrawal, stereotypy, and social avoidance versus baseline as reported by caregiver. The scale is composed of 5 factors, which address Manic/Hyperactive Behavior, Depressed Mood, Social Avoidance, General Anxiety, and Obsessive/Compulsive Behavior.

  15. Phase 3: Change from baseline in behaviors and other symptoms on Numerical Rating System (NRS) by caregiver

    Time frame: 12 weeks

    Numerical rating scale (NRS) scores based on patient-specific behaviors within the domains of Daily Function, Language, and Academic Skill. Caregiver will rate individual from 0 to 10, where 0 indicates 'worst problem' and 10 indicates' no problem at all.'

  16. Phase 3: Change from baseline in CGI-I as assessed by investigator

    Time frame: 12 weeks

    The Clinical Global Impression-Improvement (CGI-I) scale is a clinician rated scale used to assess treatment response. The score ranges from 1 to 7 (with 1 being "very much improved", 4 being "no change" to 7 being "very much worse")

  17. Phase 3: Change from baseline in Caregiver Global Impression of Improvement (CaGI-I) assessments

    Time frame: 12 weeks

    The Caregiver Global Impression of Improvement (CaGI-I) is a global measure to provide a caregiver's perspective of a subject's overall condition. The caregiver will use a 7-point scale to assess how the condition has changed from baseline. A higher number indicates worsening condition.

  18. Phase 3: The PK parameters of SPG601 concentrations in plasma-Cmax

    Time frame: 12 weeks

    Maximum concentration in plasma following administration of SPG601

  19. Phase 3: The PK parameters of SPG601 concentrations in plasma-T 1/2

    Time frame: 12 weeks

    Metabolic half life of SPG601 in plasma following dose

  20. Phase 3 substudy: Change from baseline in the gamma range in response to the chirp stimulus and to the steady state stimuli

    Time frame: 12 weeks

    Auditory test will be evaluated for difference in responses to stimuli.

  21. Phase 3 substudy: Change from baseline in EEG resting state relative power in the alpha, theta, and gamma bands during rest

    Time frame: 12 weeks

    Resting-state EEG relative power changes from baseline are characterized by significant shifts in power bands such as gamma, alpha, theta and beta bands

Study contacts

Contact information is provided by the study sponsor or research team.

Contact

CONTACT

[email protected]

(503) 673-3842

Sponsors and collaborators

Lead sponsor

Spinogenix

Industry

Registry information

Official study title

A Phase 2b/3, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of SPG601 in Male Participants With Fragile X Syndrome

Important dates

Study start
2026
Primary completion
2030
Study completion
2030
First posted
Feb 27, 2026
Registry last updated
Feb 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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