, according to recent research published in Annals of Neurology.
Fredrik Piehl, MD, PhD, of the department of clinical neuroscience at Karolinska Institutet in Stockholm, and colleagues analyzed results from a cohort study in Sweden of 2449 patients with relapsing-remitting MS who started an initial disease-modifying therapy (DMT), and 2463 patients who switched from their first therapy between 2011 and 2018, with 1148 patients overlapping in both groups. DMTs evaluated in the group that started an initial treatment included rituximab (591 patients), natalizumab (334 patients), dimethyl fumarate (416 patients), interferon (992 patients), and glatiramer acetate (116 patients), while DMTs included in the group switching therapies were rituximab (748 patients), natalizumab (541 patients), dimethyl fumarate (570 patients), fingolimod (443 patients), and teriflunomide (161 patients).
The researchers compared patients receiving low-dose rituximab with other MS therapies, with confirmed disability worsening (CDW) over 12 months and change in disease-related impact on daily life as measured by MS Impact Scale-29 (MSIS-29) subscales as primary outcomes at 3 years after therapy initiation or switching. They also assessed the rate of relapse, discontinuation of therapy, and serious adverse events as secondary outcomes.
At 3 years, among patients who received rituximab, 9.1% of patients who initiated therapy and 5.1% who switched therapy experienced CDW, and there were no significant differences in disease worsening between patients who received rituximab and those who received other MS therapies. “Most instances of CDW on rituximab were in subjects with no relapse within 3 years of treatment start,” the researchers said.
Patient MSIS-29 physical subscores at 3 years improved by 1.3 points in the initial DMT group and by 0.4 points in the DMT-switching group, while MSIS-29 psychological scores improved by 8.4 points in the initial DMT and by 3.6 points in the DMT-switching group. “Adjusted for baseline characteristics, MSIS-29 physical subscale scores decreased more with natalizumab, both as a first DMT and after a DMT switch, compared with rituximab, although absolute differences were small,” Dr. Piehl and colleagues said.
With regard to secondary outcomes, there was a reduction in mean overall Expanded Disability Status Scale (EDSS) score compared with baseline in the initial rituximab group at 3 years (–0.2 points), with 28.7% of patients experiencing improvement and 19.0% experiencing worsening, while there was no overall change in mean EDSS score in the rituximab-switching group. At 5 years, mean EDSS scores decreased compared with baseline in the initial rituximab group (–0.1 point), with 27.1% patients experiencing improvement and 20.8% experiencing worsening, and there was an increase in overall EDSS score (0.1 point) at 5 years for the rituximab-switching group, with improvement in 17.9% of patients and worsening in 26.4% of patients. However, there were no significant differences between rituximab and other DMTs.
Patients in both initial and switching rituximab groups had a lower annualized relapse rate (ARR) compared with other DMTs, with the exception of natalizumab in the initial DMT group (3 vs 2 additional relapses per 100 patients per year). The highest ARR in the initial DMT group belonged to interferon (13 additional relapses per 100 patients per year) and teriflunomide (8 additional relapses per 100 patients per year). “Similar differences were evident also at 5 years, with significantly higher ARRs with all other DMTs compared with rituximab, except for natalizumab, in both the first DMT and DMT switch groups,” Dr. Piehl and colleagues said.
In the group of patients who received rituximab, 75.7% of patients had no evidence of disease activity (NEDA-3) at 3 years in the initial DMT group and 82.1% of patients in the DMT-switching group, which was “greater than for all comparators, except natalizumab as a first DMT,” the researchers said. “Proportions fulfilling NEDA-3 status at 5 years were higher with rituximab than with all comparators in both cohorts,” they noted.
Concerning safety, the researchers said there were minor differences in safety outcomes between rituximab and comparators, but patients in the DMT-switching group who received rituximab had a higher risk of severe infections compared with other groups.