Enthorin Therapeutics Announces Initiation of Phase II Clinical Trial of MRM-3379 (Formerly ENT-3379) for Fragile X Syndrome by Licensing Partner Mirum Pharmaceuticals

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ESCONDIDO, Calif.--(BUSINESS WIRE)--Jan 9, 2026--

Enthorin Therapeutics, LLC, a biotechnology company focused on circuit-modulating treatments for neurological and neurodevelopmental disorders, announced that its licensing partner for MRM-3379 (formerly ENT-3379) , Mirum Pharmaceuticals, Inc. (NASDAQ: MIRM), in December, reported the initiation of the BLOOM Phase 2 clinical study evaluating MRM-3379 in Fragile X syndrome (FXS).

MRM-3379 is an orally available, highly brain-penetrant, selective phosphodiesterase-4D (PDE4D) inhibitor designed to enhance cAMP signaling. The compound was discovered by scientists at Dart Neuroscience (DNS), including current members of Enthorin Therapeutics, and advanced through Phase 1 clinical development at DNS. Preclinical data, including results from an FMR1 knockout mouse model of Fragile X syndrome, suggest that MRM-3379 improves cognition and alleviates behavioral deficits across multiple domains.

The entry of MRM-3379 into Fragile X patient trials by Mirum Pharmaceuticals is the culmination of over a decade of diligent scientific research and development by the clinicians and scientists at Enthorin and DNS. Enthorin wants to acknowledge all of the dedicated clinical and scientific staff who participated in the discovery and development of MRM-3379.

About Enthorin Therapeutics

Enthorin Therapeutics is a clinical stage pharmaceutical company founded with the goal of developing innovative therapeutics that target brain circuit dysfunction to improve quality of life for patients, families, and communities. The company develops therapies designed to restore neural plasticity and network function in neurological and neurodevelopmental diseases. The company’s pipeline includes MRM-3379 which is licensed to Mirum Pharmaceuticals; ENT-7340, an IND enabled PDE2A inhibitor for the potential treatment of intellectual and developmental disabilities; ENT-2675 for treatment of Parkinson’s disease MCI and dyskinesia; and a portfolio of GABA alpha 5 negative allosteric modulators for the potential treatment of Dup15q syndrome. Enthorin leverages translational neurobiology, pharmacology and advanced imaging to bridge pre-clinical and clinical development. Learn more at www.enthorin.com

About Fragile X Syndrome

Fragile X syndrome is a neurodevelopmental disorder caused by mutations in the FMR1 gene. It affects approximately 1 in 4,000 males and 1 in 8,000 females. At present there are no approved treatments that target the underlying biology of Fragile X available. The syndrome manifests in developmental delays, learning difficulties, anxiety, hyperactivity and autistic-like behaviors. PDE inhibitors aim to elevate cyclic AMP (cAMP) levels, rebuild neural signaling networks and restore synaptic plasticity—a pathway particularly relevant in Fragile X and other intellectual and developmental disabilities (IDD). More information about PDE inhibitors and Fragile X is available at:

https://www.fraxa.org/fragile-x-and-pde-inhibitors-a-promising-path-forward-for-brain-disorders/

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KEYWORD: UNITED STATES NORTH AMERICA CALIFORNIA

INDUSTRY KEYWORD: BIOTECHNOLOGY PHARMACEUTICAL HEALTH CLINICAL TRIALS

SOURCE: Enthorin Therapeutics, LLC

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PUB: 01/09/2026 11:55 AM/DISC: 01/09/2026 11:55 AM

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