Aldeyra Therapeutics, Inc. announced the completion of enrollment in the Phase 2 clinical trial of ADX-2191 (methotrexate injection, USP), an investigational drug candidate, for the treatment of retinitis pigmentosa, a group of rare genetic eye diseases characterized by retinal cell death and loss of vision, for which there is no U.S. Food and Drug Administration (FDA)-approved treatment. The open-label, single-center Phase 2 clinical trial enrolled a total of eight retinitis pigmentosa patients with rhodopsin gene mutations, including the P23H gene mutation. Patients receive either monthly or twice-monthly intravitreal doses of ADX-2191 for three months.

The primary endpoint of the trial is safety. Secondary endpoints include change from baseline in visual acuity; retinal function, as assessed by foveal microperimetry, electroretinography, and dark adaptation; and retinal morphology, as assessed by optical coherence tomography. ADX-2191 is a novel intravitreal formulation of methotrexate, which in preclinical models of retinitis pigmentosa facilitates the clearance of misfolded rhodopsin, a critical visual cycle protein susceptible to genetic mutation.1 The prevalence of retinitis pigmentosa is more than one million people worldwide, and genetic mutations leading to rhodopsin misfolding account for approximately one-third of cases.

ADX-2191 has been granted orphan drug designation by the U.S. Food and Drug Administration for the treatment of retinitis pigmentosa.