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

August 20, 2026 updated by: Mirum Pharmaceuticals, Inc.

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

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

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85006
    • California
      • Irvine, California, United States, 92604
      • Orange, California, United States, 92868
        • Recruiting
        • Children's Hospital of Orange County - Pediatric Subspecialty
        • Principal Investigator:
          • Sailaja Golla
        • Contact:
        • Contact:
      • Sacramento, California, United States, 95817
    • Colorado
      • Aurora, Colorado, United States, 80045
    • Florida
      • Miami, Florida, United States, 33136
        • Recruiting
        • Neurology
        • Principal Investigator:
          • Barbara Coffey
        • Contact:
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Recruiting
        • Emory University - The Emory Clinic - Clifton Road
        • Contact:
        • Principal Investigator:
          • Amy Talboy
        • Contact:
    • Illinois
      • Chicago, Illinois, United States, 60612
        • Recruiting
        • Rush University Medical Center-Clinical Operation
        • Principal Investigator:
          • Elizabeth Berry-Kravis
        • Contact:
        • Contact:
    • Maryland
      • Baltimore, Maryland, United States, 21205
        • Recruiting
        • Kennedy Krieger Institute, John Hopkins School of Medicine
        • Principal Investigator:
          • Stephanie Morris
        • Contact:
    • Massachusetts
    • Minnesota
      • Minneapolis, Minnesota, United States, 55414
        • Recruiting
        • University of Minnesota Department of Medicine
        • Contact:
        • Principal Investigator:
          • Amy Esler
        • Contact:
    • Ohio
      • Cincinnati, Ohio, United States, 42229
        • Recruiting
        • Cincinnati Children's Hospital Medical Center
        • Principal Investigator:
          • Rana Elmaghraby
        • Contact:
        • Contact:
    • Pennsylvania
      • Media, Pennsylvania, United States, 19063
        • Recruiting
        • Suburban Research Associates
        • Principal Investigator:
          • Kristen Dopf
        • Contact:
    • Utah
      • Salt Lake City, Utah, United States, 84108
        • Not yet recruiting
        • Intermountain Healthcare - Park City Specialty Clinic
        • Principal Investigator:
          • Victoria Wilkins
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Arm 1: Low Dose of MRM-3379
Participants 16-45 years of age randomized to this arm will receive the low dose of MRM-3379
Drug: Low dose of MRM-3379
Oral capsule
Experimental: Arm 2: Middle dose of MRM-3379
Participants 16-45 years of age randomized to this arm will receive the middle dose of MRM-3379
Drug: Middle Dose of MRM-3379
Oral capsule
Experimental: Arm 3: High dose of MRM-3379
Participants 16-45 years of age randomized to this arm will receive the high dose of MRM-3379
Drug: High dose of MRM-3379
Oral capsule
Placebo Comparator: Arm 4 :Placebo
Participants 16-45 years of age randomized to this arm will receive Placebo
Drug: Placebo
Capsules matched to study drug without the active pharmaceutical ingredient
Experimental: Arm 5: Low dose of MRM-3379 Open-Label
Participants 13 to < 16 years of age will receive the low dose of MRM-3370 Open-Label
Drug: Low dose of MRM-3379 Open-Label
Oral capsule

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
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
Baseline to Week 12

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Mirum Pharmaceuticals, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 22, 2025

Primary Completion (Estimated)

October 1, 2027

Study Completion (Estimated)

October 1, 2027

Study Registration Dates

First Submitted

October 2, 2025

First Submitted That Met QC Criteria

October 2, 2025

First Posted (Actual)

October 7, 2025

Study Record Updates

Last Update Posted (Actual)

August 24, 2026

Last Update Submitted That Met QC Criteria

August 20, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ENV-202

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe