An investigational oral drug called ONO-4641 reduced the number of lesions in people with multiple sclerosis (MS), according to the results of a phase II clinical trial supported by Ono Pharmaceutical.

In the phase II trial, 407 patients ages 18-55 with relapsing-remitting MS were randomly given placebo, 0.05mg, 0.10mg or 0.15mg of ONO-4641 once per day for 26 weeks. Study results showed that had 82%, 92% and 77% fewer Gd-enhancing brain lesions, respectively, compared to placebo.

Patients included in the study had two or more relapses in the two years prior to the study, one or more relapses within the year prior to the study or one or more new MS-related brain lesions, also known as Gd-enhancing lesions, which were detected on MRI within three months prior to the study. Brain scans were performed every four weeks from 10 to 26 weeks.

Adverse events appeared to be dose related and included cardiovascular events, such as a slower heartbeat, blood pressure changes and an AV block—the impairment of the conduction between the atria and ventricles of the heart. Other adverse events included liver enzyme elevations. In addition, grade four lymphopenia, which is an abnormally low level of lymphocytes in the blood, occurred in 4% of people receiving the 0.15mg dose of ONO-4641 and in 1% of those receiving the 0.10mg dose.

"In light of recent issues in the oral MS drug market, this is welcome news," said study author Timothy Vollmer, MD, of the University of Colorado in Denver and a fellow with the American Academy of Neurology.