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

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 22, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 2, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 2, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 7, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 20, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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.

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