A Phase 2 interventional study of Low dose of MRM-3379 and Middle Dose of MRM-3379 in Fragile X Syndrome, sponsored by Mirum Pharmaceuticals, Inc.. Recruiting at 18 sites in 2 countries. Open to male participants aged 13 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-09-29.
Sponsored by Mirum Pharmaceuticals, Inc. · Phase 2, Interventional, and Treatment
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
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
Participants 16-45 years of age randomized to this arm will receive the low dose of MRM-3379
Drug: Low 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
Participants 16-45 years of age randomized to this arm will receive the high dose of MRM-3379
Drug: High dose of MRM-3379
Participants 16-45 years of age randomized to this arm will receive Placebo
Drug: Placebo
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
Oral capsule
Oral capsule
Capsules matched to study drug without the active pharmaceutical ingredient
Oral capsule
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
Plan to share: No
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Mirum Pharmaceuticals, Inc.