The study was the largest of MS patients treated with rituximab to date.
Rituximab was deemed safe in a real world cohort of multiple sclerosis (MS) patients, according to recent study results.
Using the Swedish MS register, which launched in 2001, a team of researchers retrospectively identified 822 total MS patients who were being treated with off label rituximab across three university hospitals in order to determine the safety and efficacy of rituximab for this population. There were 557 patients with relapsing remitting MS, 198 patients with secondary progressive MS and the remaining 67 patients had been diagnosed with primary progressive MS. According to the study authors, this study was the largest reported cohort of patients with MS treated with rituximab to date. And, they added, since the publication of two randomized, placebo controlled Phase II trials, OLYMPUS and HERMES, the use of off label rituximab to treat MS has been increasing.
According to baseline data that the investigators obtained from patients’ medical charts and the MS register, 26.2% of MS patients had contrast enhanced lesions. Patients were treated with 500 or 1000 mg rituximab IV every six to 12 months during a mean period of about 22 months. Approximately 300 patients were on the treatment for more than two years. In some cases, the researchers reported, patients were increased to a higher dose treatment course, i.e., 1000-2000 mg rituximab divided into two infusions given within one month. Usually, those patients were more likely to have contrast enhanced lesions on their baseline MRI scans, which made further analysis based on their initial treatment course difficult, the researchers explained.
One fifth of the patients had received rituximab as their first disease modulatory drug (DMD), and the remainder switched from other DMDs (typically natalizumab and interferon beta).
There were a total of 59 relapses with use of the rituximab treatment, corresponding to the following annualized relapse rates (ARRs): 0.044 for relapsing remitting MS, 0.038 for secondary progressive MS, and 0.015 for primary progressive MS.
Each patient in the study had a median of two MRI scans, including the baseline; the researchers learned that after the baseline scan where about a quarter of patients showed lesions, 4.6% of patients had lesions after treatment initiation. The appearance of these lesions was more common during the first six months of treatment compared to the later treatments.
The investigators also determined there were 89 adverse events, categorized on the Common Terminology Criteria for Adverse Events, grades two through five: deaths, malignancies, autoimmune disorders, and infections. The grade one adverse events were not recorded, the researchers said, including uncomplicated lower urinary or upper respiratory infections, since the team expected the sensitivities to be low.
“A large proportion of decisions to initiate rituximab treatment were based on MRI,” the study authors concluded. “Although we included a relatively high proportion of progressive patients, the formation of new lesions on MRI was high at baseline. Despite this, the observed ARR and MRI disease activity were low during rituximab treatment. This observational study provides level IV evidence that rituximab is safe and effective for treating MS for up to two years. A phase III randomized controlled trial is motivated and may be performed as an investigator driven effort. This should be given high priority for public funding agencies given the potential patient and societal (low treatment costs) benefits.”
The paper, titled “Rituximab in multiple sclerosis: A retrospective observational study on safety and efficacy,” was published in the journal Neurology in November.