1st patient enrolled in Phase 2 trial of treatment for fragile X syndrome
Oral therapy being tested in boys, men; top-line results expected in 2027
The first patient has been enrolled in a Phase 2 clinical trial testing MRM-3379, Mirum Pharmaceuticals’ experimental oral treatment, in boys and men with fragile X syndrome. Top-line results are expected in 2027.
The recently launched study, called BLOOM (NCT07209462), is recruiting up to 60 male patients, ages 13 to 45 years, at up to four sites in the U.S.
“In preclinical models, MRM-3379 shows improvement in multiple cognitive and behavioral domains associated with Fragile X syndrome, as well as favorable tolerability in healthy volunteers,” Joanne Quan, MD, chief medical officer at Mirum, said in a company press release. “This study is an important next step in evaluating whether MRM-3379 can meaningfully help improve cognition and daily function for people living with FXS [fragile X syndrome].”
For Michael Tranfaglia, MD, medical director and co-founder of the FRAXA Research Foundation, “it’s incredibly encouraging to see a company like Mirum step into the fragile X space with a potential therapy that holds real promise. This study is actively enrolling, and we encourage eligible families to consider participation in this important research.”
MRM-3379 designed to block key enzyme
Mutations in a gene on the X chromosome cause fragile X syndrome. It can lead to a range of symptoms, from developmental delays and learning difficulties to anxiety and hyperactive behavior. Symptoms are usually milder in female than in male patients.
MRM-3379 is designed to block phosphodiesterase 4D (PDE4D), an enzyme that is highly active in regions of the brain involved in learning, memory, and emotional regulation. PDE4D helps fine-tune levels of cAMP, a signaling molecule involved in communication between nerve cells, by breaking it down.
By suppressing the enzyme’s activity, MRM-3379 is expected to increase levels of cAMP, which are typically low in people with fragile X syndrome. Higher levels of cAMP may ease symptoms by supporting the rebuilding of the communication networks that are disrupted in the disease.
The BLOOM study is testing MRM-3379 in boys and men with fragile X. Participants aged 16-45 years will be randomly assigned to receive one of three doses of MRM-3379 or a placebo for 12 weeks, or about three months.
Boys, ages 13 to 16, will receive the lowest dose of MRM-3379 for 12 weeks. This group will help researchers evaluate the therapy’s effects in younger boys closer to the age of diagnosis.
BLOOM’s primary goal is to assess the safety and tolerability of the therapy, while the key secondary goal is to measure changes in cognitive function, as assessed using the National Institutes of Health Toolbox Cognitive Function Battery. Researchers will also assess changes in mood, behavior, and other relevant symptoms.
“The fragile X community is energized by the launch of this study. Each new clinical program brings hope and potential breakthroughs,” said Hilary Rosselot, executive director of the National Fragile X Foundation. “We applaud Mirum’s commitment to advancing an innovative therapy that could offer a much-needed option for our families.”
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