Rituximab is generally safe and effective in treating multiple sclerosis — with comparable effectiveness to Tysabri (natalizumab) in people with relapsing-remitting forms of the disease, a Swiss study reports.
But patients using this therapy can develop recurrent infections, its researchers noted, and doctors should be vigilant.
The observational study, “Effectiveness and safety of Rituximab in multiple sclerosis: an observational study from Southern Switzerland,” was published in the journal PLOS One.
Rituximab is an antibody that targets CD20, a protein that is expressed on the surface of immune B-cells that are known to be involved in MS development. Studies have shown that the treatment can reduce inflammatory activity, as well as the incidence of relapses and new demyelinating lesions in patients with relapsing-remitting MS (RRMS).
Similarly, there have been some suggestions that patients with progressive MS may also benefit from rituximab treatment, particularly younger patients with evidence of inflammatory activity on MRI (magnetic resonance imaging) scans.
Current data suggests that rituximab is generally well-tolerated and safe, even in the long term.
Despite encouraging results and a favorable cost-effectiveness profile, rituximab is not an approved MS treatment and is used off-label. Sold as Rituxan in the U.S. and MabThera in Europe, the treatment is indicated for diseases that include certain non-Hodgkin’s lymphomas and chronic lymphocytic leukemia.
In the absence of randomized Phase 3 comparative trials, observational studies can be helpful in providing evidence of rituximab’s potential benefits to MS patients. In this study, the scientists “report additional data from the largest collection of MS patients treated with RTX [rituximab] within Switzerland in a clinical practice setting, providing additional evidence that RTX is effective and relatively safe in this highly disabling condition,” the study states.
The research team evaluated 82 patients — 42 with relapsing-remitting MS (RRMS) and 39 with progressive MS (PMS) treated with at least one rituximab infusion between September 2009 and February 2018 — to investigate its effectiveness and safety. Outcomes in rituximab-treated patients were also compared to those in patients using Tysabri, an established disease-modifying therapy (DMT), to judge effectiveness.
Patients reasons for trying rituximab, the researchers reported, included “disease progression” and “side effects of previous DMTs.”
Patients were followed for a median of 1.5 years, with results finding no evidence of disease activity in 80% of all rituximab-treated MS patients (59 people). Three PMS patients experienced “minor” relapses during this time, the study said.
Notably, the researchers also wrote, “no relapses occurred in the 16 MS patients who were switched from NTZ [Tysabri] to RTX [rituximab] because of positive JCV serology,” meaning they had evidence of the JC virus, which put them at risk for a severe brain infection associated with certain MS medications. Tysabri is known to carry “a potential risk of disease rebound following its discontinuation,” the study noted.
Adverse events, mostly recurrent respiratory tract and urinary infections, were reported in 24 patients, and were most often found in PMS patients. Side effects led to six people discontinuing rituximab treatment.
“[T]his study provides additional evidence for the use of RTX in MS, with a comparable effectiveness to that of NTZ within the relapsing-remitting subtype and a potential benefit also in progressive cases,” the researchers wrote.
Rituximab, they concluded “could represent an additional effective, relatively cheap and safe therapy in the panel of existing MS treatments,” although “clinicians must be vigilant for the potential occurrence of infections.”