A Clinical Study for Fragile X Syndrome
If your male loved one has been diagnosed with Fragile X Syndrome, he may be eligible to enroll in the BLOOM clinical study. This study is exploring if MRM-3379, an investigational medication, can safely and effectively help improve certain symptoms in male participants with Fragile X Syndrome.1
This in-person visit is to see if your loved one is eligible to receive the treatment, and to collect information about his health.
Treatment lasts 12 weeks with 3 in-person visits you will attend with your loved one and 2 phone calls with just you, the caregiver.
You will receive 2 phone calls within 4 weeks after treatment ends: an exit interview call and a follow-up call.
is an investigational medication designed to work by increasing levels of a signaling molecule in the brain that is often lower in people with Fragile X Syndrome. When this molecule is low, it can affect how the brain communicates, which may impact learning, memory, and managing emotions. MRM-3379 aims to help increase this molecule in patients with Fragile X Syndrome.2,3
The BLOOM clinical study is enrolling males with Fragile X Syndrome ages 13 to 45 to see if MRM-3379 can safely and effectively help improve certain symptoms of Fragile X Syndrome.1
In this study, based on your loved one’s age, he will receive either MRM-3379 or a placebo (a capsule with no active ingredient), taken orally twice a day.
This study aims to explore if this investigational medicine:
Your loved one will visit a clinical site for safety assessments and other assessments to see how well the treatment is working.
Additional safety assessments will also be done via phone calls.
Participating in the BLOOM clinical study is designed to be as convenient and supportive as possible. The study will last about 16 weeks. During that time, the study team will ask general questions about your loved one’s health, and perform study-related tests to monitor overall health, side effects, and changes in quality of life.
Throughout the study, a dedicated medical team will monitor your loved one’s health. Support will be provided every step of the way.
Review the study information at clinicaltrials.gov
Additional study requirements and exclusions apply. A study representative will discuss these with you during the screening period.
You may call a study representative directly at 1-512-351-7045, Monday – Friday, 8am to 8pm EST.
Reasonable study-related travel is covered by Mirum for you and your loved one with Fragile X Syndrome who participate in the BLOOM clinical study.
These services include:
If you travel, related reasonable expenses including child care may be reimbursed as permitted by study site policies.
Our study representatives will be able to provide more details.
FRAXA Research Foundation and the National Fragile X Foundation websites are provided for informational purposes only. Mirum Pharmaceuticals is not responsible for the content on these third‑party sites.
An investigational medication is a drug that has not been approved by the Food and Drug Administration (FDA) or other health organizations. However, it can still be given to participants in a clinical study as part of research. A clinical study tests how safe and effective an investigational medication is in volunteers. Every investigational medication must go through clinical studies.
Agreeing to join a clinical trial is entirely up to you and your loved one. Even if you and your loved one sign the informed consent form, he’ll be free to leave the trial at any time.
Qualified participants may receive compensation for time and travel-related expenses (including long-distance travel). Study-related medications, procedures, and examinations are provided at no cost to study participants.
If you and your loved one agree to participate, you both will be expected to follow the rules and instructions to the best of your ability. If your loved one is not able to follow these rules and instructions, your loved one may be asked to withdraw from the study.
In order to help provide maximum protection for your loved one’s health, the study will be under the direct supervision of the study doctor and will be conducted by trained personnel. You will need to provide all information about your loved one’s current and past health (medical history) at the Screening Visit and each Follow-Up Visit, including participation in any other research studies. This information is needed to help protect your loved one’s health.
1. Clinicaltrials.gov. NCT07209462. Updated October 24, 2025. Accessed October 30, 2025. https://www.clinicaltrials.gov/study/NCT07209462 2. Data on file. Mirum Pharmaceuticals, Inc. 3. Berry-Kravis EM, Harnett MD, Reines SA, et al. Inhibition of phosphodiesterase-4D in adults with fragile X syndrome: a randomized, placebo-controlled, phase 2 clinical trial. Nat Med. 2021;27(5):862-870. doi:10.1038/s41591-021-01321-w
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We offer the convenient option of allowing you to participate in our studies from the comfort of your own home. A healthcare professional will monitor you through a mix of telemedicine and home visits. The study doctor’s role is limited to the clinical study. While in the study, you will continue your routine medical care and see your regular doctors for check-ups and prescriptions.
