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NCT Number: NCT07209462

Study of MRM-3379 in Male Participants With Fragile X Syndrome (BLOOM)

This study is a multicenter, double-blind, randomized, placebo-controlled study to assess the safety and tolerability of 3 doses of MRM-3379 in male participants with Fragile X Syndrome ages 16 to 45 (inclusive). In addition, a parallel cohort of participants ages 13 to <16 will receive open-label MRM-3379. All participants will participate for 12 weeks of treatment. The study is also intended as a proof-of-concept investigation to evaluate whether MRM-3379 can improve FXS symptoms

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Key information

Conditions

Fragile X Syndrome Chromosome Disorders Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities 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

13 year–45 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 2

Primary location

Southwest Autism Research & Resource Center, Phoenix, Arizona, United States

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Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Willing and able to provide signed informed consent/assent. Where local regulations permit inclusion of participants deemed unable to provide informed consent, a legally authorized representative must provide informed consent on the participant's behalf, and the participant must provide assent if applicable.
  • Male, 13-45 years of age (inclusive)
  • Weight ≥30 kg and BMI between 18 and 36 kg/m2 (inclusive) at the screening visit
  • Diagnosis of FXS with a molecular genetic ≥200 CGG repetitions .
  • Able to perform the PVT and ORRT of the NIH-TCB
  • Have a consistent caregiver(s) who is willing and able to be present regularly and reliably with the participant
  • Able to swallow tablets or capsules

Exclusion criteria

History of or current medical condition other than FXS and related issues that would place the participant at higher risk from study participation

Treatment and study plan

Low dose of MRM-3379

Drug

Oral capsule

Middle Dose of MRM-3379

Drug

Oral capsule

High dose of MRM-3379

Drug

Oral capsule

Placebo

Drug

Capsules matched to study drug without the active pharmaceutical ingredient

Low dose of MRM-3379 Open-Label

Drug

Oral capsule

Primary outcomes

  1. Incidence and severity of treatment-emergent adverse events and Withdrawal due to adverse events and withdrawal due to adverse events

    Time frame: Baseline to Week 12

Sponsors and collaborators

Lead sponsor

Mirum Pharmaceuticals, Inc.

Industry

Registry information

Official study title

Randomized, Double-Blind, Placebo-Controlled, Phase 2 Study of MRM-3379 in Male Participants With Fragile X Syndrome

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Oct 7, 2025
Registry last updated
Jul 28, 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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