Recruiting
Phase 2

MRM-3379

Sponsor:

Mirum Pharmaceuticals, Inc.

Code:

NCT07209462

Conditions

Fragile X Syndrome

Eligibility Criteria

Sex: Male

Age: 13 - 45

Healthy Volunteers: Not accepted

Interventions

Low dose of MRM-3379

Middle Dose of MRM-3379

High dose of MRM-3379

Placebo

Low dose of MRM-3379 Open-Label

Study Details

Brief summary:

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

Conditions

Fragile X Syndrome

Study ID

NCT07209462

Start date

Nov 22, 2025

Status verified date

Aug, 2026

Completion date

Oct, 2027

Anticipated

Primary completion date

Oct, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Male

Age: 13 - 45

Healthy Volunteers: Not accepted

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 Design

Enrollment

60 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

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

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

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

placebo comparator: Arm 4 :Placebo

Participants 16-45 years of age randomized to this arm will receive Placebo

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

Interventions

Low dose of MRM-3379

Oral capsule

Middle Dose of MRM-3379

Oral capsule

High dose of MRM-3379

Oral capsule

Placebo

Capsules matched to study drug without the active pharmaceutical ingredient

Low dose of MRM-3379 Open-Label

Oral capsule

Primary outcome measure

  • 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 ]

Central Contacts and Locations

Locations

Southwest Autism Research & Resource Center

Recruiting

Phoenix, Arizona, United States, 85006

Contacts

Riley Stark

480-351-0567rstark@autismcenter.org

Padmaja Lakamsani

PLakamsani@autismcenter.org

Principal Investigator:

Christopher Smith

Amnova Clinical Research, LLC

Recruiting

Irvine, California, United States, 92604

Contacts

Maggie Wang

949-358-7447maggie@amnovaresearch.com

Jannet Guerrero

949-861-7479jannet.guerrero@amnovaresearch.com

Principal Investigator:

Gary Feldman

Children's Hospital of Orange County - Pediatric Subspecialty

Recruiting

Orange, California, United States, 92868

Contacts

Adrienne Moore

714-288-7456Adrienne.Moore@choc.org

Stanley Friers

(714) 288-7683Stanley.Friers@choc.org

Principal Investigator:

Sailaja Golla

Uc Davis Mind Institute

Recruiting

Sacramento, California, United States, 95817

Contacts

Melissa Heys

916-703-0301meheys@health.ucdavis.edu

Abigail Borbe

916-703-0281amoradelhigareda@health.ucdavis.edu

Principal Investigator:

Randi Hagerman

Children's Hospital Colorado

Recruiting

Aurora, Colorado, United States, 80045

Contacts

Nicole Tartaglia

720-777-6895Nicole.Tartaglia@childrenscolorado.org

Principal Investigator:

Nicole Tartaglia

Neurology

Recruiting

Miami, Florida, United States, 33136

Contacts

Dr. Barbara Coffey

305-243-2759bjc134@miami.edu

Principal Investigator:

Barbara Coffey

Emory University - The Emory Clinic - Clifton Road

Recruiting

Atlanta, Georgia, United States, 30322

Contacts

Robin Vinson

404-778-8533robin.vinson@emory.edu

Nadia Ali

404-778-8613nadia.ali@emory.edu

Principal Investigator:

Amy Talboy

Rush University Medical Center-Clinical Operation

Recruiting

Chicago, Illinois, United States, 60612

Contacts

Lorelai Konen

312-942-2815Lorelai_Konen@rush.edu

Molly Flanagan

312-942-1876Molly_L_Flanagan@rush.edu

Principal Investigator:

Elizabeth Berry-Kravis

Kennedy Krieger Institute, John Hopkins School of Medicine

Recruiting

Baltimore, Maryland, United States, 21205

Contacts

Kennedy Krieger

443-923-3850ResearchTrials@KennedyKrieger.org

Principal Investigator:

Stephanie Morris

Boston Children's Hospital

Recruiting

Boston, Massachusetts, United States, 02115

Contacts

Michelle Coughlin

857-218-3842michelle.Coughlin@childrens.harvard.edu

Katherine Pawlowski

857-218-5472Katherine.pawlowski@childrens.harvard.edu

Principal Investigator:

Lisa Prock

UMass Memorial Health

Recruiting

Worcester, Massachusetts, United States, 01655

Contacts

Taylor Merk

774-455-4119Taylor.merk@umassmed.edu

Lauren Venuti

774-455-4113Lauren.venuti@umassmed.edu

Principal Investigator:

Isha Jalnapurkar

University of Minnesota Department of Medicine

Recruiting

Minneapolis, Minnesota, United States, 55414

Contacts

Rachel Floersch

612-626-8424Floer013@umn.edu

Brittany Faanes

612-625-5929Grego318@umn.edu

Principal Investigator:

Amy Esler

Cincinnati Children's Hospital Medical Center

Recruiting

Cincinnati, Ohio, United States, 42229

Contacts

Hannah Sachs

513-803-1150Hannah.Sachs@cchmc.org

Priya Ramesh

513-636-4433Priya.Ramesh@cchmc.org

Principal Investigator:

Rana Elmaghraby

Suburban Research Associates

Recruiting

Media, Pennsylvania, United States, 19063

Contacts

Naya Square

610-891-9024Nsquare@suburbanresearch.com

Principal Investigator:

Kristen Dopf

More Information

Sponsor

Mirum Pharmaceuticals, Inc.

Last update posted

Aug 24, 2026

Last verified

Aug, 2026

Keywords

  • Fragile X Syndrome
  • FXS
  • FMR
  • Phosphodiesterase 4
  • PDE4

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Mirum Pharmaceuticals, Inc. on 2026-08-24.