Disease-modifying therapies and symptom management are current standard of care for multiple sclerosis (MS) patients. Repulsive guidance molecule A (RGMa) is an inhibitor of neurite outgrowth and is hypothesized to play a role in MS. Elezanumab (formerly ABT-555) is an investigational monoclonal antibody that neutralizes RGMa and may promote neuroprotection and neuroregeneration.

Two randomized, double-blind, placebo-controlled, multiple-dose phase 2 studies are currently enrolling patients with RMS (RADIUS-R; NCT03737851) or PMS (RADIUS-P; NCT03737812). An estimated 165 patients will be enrolled in RADIUS-R and 90 patients will be enrolled in RADIUS-P. Patients in RADIUS-R must have a diagnosis of relapsing-remitting MS (RRMS) or secondary-progressive MS (SPMS) with relapses within the past 24 months, demonstrated lesions consistent with MS, and evidence of physical disability according to the Expanded Disability Status Scale (EDSS), Timed 25-Foot Walk (T25FW), or 9-hole Peg Test (9HPT). Patients in RADIUS-P must have a diagnosis of primary-progressive MS (PPMS) or SPMS and no relapses for at least 24 months and evidence of physical disability according to EDSS, T25FW, or 9HPT. In both studies, patients are randomized to receive 1 of 2 doses of elezanumab or placebo by intravenous infusion every 4 weeks (W) through W48.

The first patients were enrolled for RADIUS-R and RADIUS-P, on December 11, 2018 and February 5, 2019 respectively. Primary outcome for both studies is Overall Response Score (composite score of the EDSS, T25FW, and 9HPT in the dominant and nondominant hands) at W52.

The RADIUS phase 2 studies are ongoing and designed to evaluate the safety and neurorestorative properties of elezanumab in patients with relapsing or progressive forms of MS.