Background: An important question in the treatment of MS is whether to start treatment for relapsing MS with a powerful therapy at the outset (called induction therapy), or to take a more traditional approach of starting with less powerful therapy and ramping up to a more powerful approach if relapses or other signs of disease activity continue (called escalation therapy).
Researchers from the Karolinska Institute (Stockholm, Sweden) set out to compare outcomes of people receiving induction therapy with a drug called rituximab, which is not specifically approved for the treatment of MS, compared to those receiving escalation therapy with one of the approved disease-modifying therapies. The investigators tracked whether the participants remained on therapy or discontinued it, which is an indirect measure of how well the treatment performed.
Rituximab: Rituximab is a monoclonal antibody (a protein made in the laboratory) that targets a specific protein (“CD20”) on the surface of immune B cells. B cells are known to be involved in the inflammation and damage to the brain and spinal cord in MS. Rituximab is FDA-approved for the treatment of several conditions including some cancers and rheumatoid arthritis, and it has been used “off-label” to treat several immune-mediated conditions, including MS. Rituximab is given by intravenous (into a vein) infusions every six months. A similar B-cell therapy approach that is manufactured differently, called ocrelizumab, was approved by the FDA in 2017 for the treatment of relapsing MS and primary progressive MS.
The Study: The researchers used data from the Swedish MS Registry and medical records of 494 people from two counties in Sweden who had been recently diagnosed with relapsing-remitting MS. About 24% had been started on rituximab; other initial therapies included injectable therapies (such as interferons and glatiramer acetate = 43.5%), oral therapies (dimethyl fumarate =17.4% and fingolimod =3.4%), and natalizumab given by IV infusion (24.3%). The key outcome measured was the proportion of people who discontinued specific therapies.
Results: A higher proportion of people given rituximab remained on it, compared to those who received other initial therapies. The reasons for therapy discontinuation differed by type of treatment, but the most common reasons were side effects, disease activity or pregnancy. The authors also reported a trend for increased relapses and brain lesions in participants using treatments other than rituximab.
This study was funded by the Swedish Medical Research Council and others. The report, by Drs. Fredrik Piehl, Mathias Grandqvist and others (Karolinska Institute), was published online January 8, 2018 in JAMA Neurology.
Comment: Understanding which individuals do best on what therapies is important for enabling people with MS to make the best treatment choices. Unlike well-designed clinical trials that have protocols for patient selection and assessment of outcomes, and that randomly assign participants to treatment groups, this observational study was not able to account for factors that determined why any particular therapy was prescribed for any individual, or for all factors that may have triggered an individual or doctor to discontinue a particular therapy. Results of controlled trials – several of which are now underway – are needed to understand the comparative effectiveness of MS therapies.