Dr Izanne Roos

The more potent disease-modifying drugs in multiple sclerosis are superior to low-efficacy therapy in reducing relapses in patients with active but not inactive secondary progressive multiple sclerosis (SPMS), Australian research shows.

A study led by neurologists Dr Izanne Roos and Professor Tomas Kalincik,  of the Clinical Outcomes Research (CORe) Unit, Melbourne University, investigated relapse rates and disability progression in two large observational cohorts of 1000 patients treated with high-efficacy (natalizumab, alemtuzumab, mitoxantrone, ocrelizumab, rituximab, cladribine, fingolimod) or low-efficacy (interferon β, glatiramer acetate, teriflunomide) therapies after SPMS onset.

After accouting for therapeutic lag, patients with active or recently active (those experiencing relapses within the past two years) SPMS treated with high-efficacy therapy experienced less frequent relapses over 10 years of follow up than those on low-efficacy therapy (hazard ratio [HR] 0.7, p=0.006).

People in the high-efficacy group experienced an average of 0.17 relapses per year compared 0.27 relapses per year in the low-efficacy group.

However there was no significant difference in relapse frequency between high and low-efficacy therapies in patients with inactive SPMS, (HR=0.8,p=0.39).

There was also no evidence for a difference in the risk of disability progression, according to the results published in Neurology.

Commenting on the results,  Prof Kalincik said high-efficacy medications were prescribed in early multiple sclerosis to more aggressively treat the disease and have been found to more effectively prevent flare-ups and modify progression, but less is known about how effective these therapies may be later when relapsing-remitting MS transitions to secondary progressive MS.

“Our study finding that high-efficacy therapies are superior to low-efficacy therapies only in reducing relapses in people with active secondary progressive MS provides valuable guidance for neurologists when choosing the most effective therapies for people with this form of MS,” he said.

“When the goal is to alleviate ongoing relapse activity, more potent therapy is justified. But when the goal is to limit disability progression in secondary progressive MS, both types of drugs show comparable effectiveness.”

A limitation of the study was that participants were grouped by those taking high-efficacy or low-efficacy therapies. Patients in each group were matched for factors such as disability level and how long they had secondary progressive MS. However, therapies were not studied individually, and Prof Kalincik said it was possible that individual therapies may have different effects on symptoms and disability.