Risk of new disease activity in patients with multiple sclerosis who continue or discontinue disease-modifying therapies (DISCOMS): a multicentre, randomised, single-blind, phase 4, non-inferiority trial.

Background: Multiple sclerosis typically has onset in young adults and new disease activity diminishes with age. Most clinical trials of disease-modifying therapies for multiple sclerosis have not enrolled individuals older than 55 years. Observational studies suggest that risk of return of disease activity after discontinuation of a disease-modifying therapies is greatest in younger patients with recent relapses or MRI activity. We aimed to determine whether risk of disease recurrence in older patients with no recent disease activity who discontinue disease-modifying therapy is increased compared to those who remain on disease-modifying therapy.

Methods: DISCOMS was a multicentre, randomised, controlled, rater-blinded, phase 4, non-inferiority trial. Individuals with multiple sclerosis of any subtype, 55 years or older, with no relapse within the past 5 years or new MRI lesion in the past 3 years while continuously taking an approved disease-modifying therapy were enrolled at 19 multiple sclerosis centres in the USA. Participants were randomly assigned (1:1 by site) with an interactive response technology system to either continue or discontinue disease-modifying therapy. Relapse assessors and MRI readers were masked to patient assignment; patients and treating investigators were not masked. The primary outcome was percentage of individuals with a new disease event, defined as a multiple sclerosis relapse or a new or expanding T2 brain MRI lesion, over 2 years. We assessed whether discontinuation of disease-modifying therapy was non-inferior to continuation using a non-inferiority, intention-to-treat analysis of all randomly assigned patients, with a predefined non-inferiority margin of 8%. This trial is registered at ClinicalTrials.gov, NCT03073603, and is completed.

Findings: 259 participants were enrolled between May 22, 2017, and Feb 3, 2020; 128 (49%) were assigned to the continue group and 131 (51%) to the discontinue group. Five participants were lost to follow-up (continue n=1, discontinue n=4). Six (4·7%) of 128 participants in the continue group and 16 (12·2%) of 131 in the discontinue group had a relapse or a new or expanding brain MRI lesion within 2 years. The difference in event rates was 7·5 percentage points (95% CI 0·6-15·0). Similar numbers of participants had adverse events (109 [85%] of 128 vs 104 [79%] of 131) and serious adverse events (20 [16%] vs 18 [14%]), but more adverse events (422 vs 347) and serious adverse events (40 vs 30) occurred in the discontinue group. The most common adverse events were upper respiratory infections (20 events in 19 [15%] participants in the continue group and 37 events in 30 [23%] participants in the discontinue group). Three participants in the continue group and four in the discontinue group had treatment-related adverse events, of which one in each group was a serious adverse event (multiple sclerosis relapse requiring admission to hospital). One participant in the continue group and two in the discontinue group died; no deaths were deemed to be related to treatment.

Interpretation: We were unable to reject the null hypothesis and could not conclude whether disease-modifying therapy discontinuation is non-inferior to continuation in patients older than 55 years with multiple sclerosis and no recent relapse or new MRI activity. Discontinuation of disease-modifying therapy might be a reasonable option in patients older than 55 years who have stable multiple sclerosis, but might be associated with a small increased risk of new MRI activity.

Funding: Patient-Centered Outcomes Research Institute and the National Multiple Sclerosis Society.