Rituximab for people with multiple sclerosis.

Background: Multiple sclerosis (MS) is the most common neurological cause of disability in young adults. Off-label rituximab for MS is used in most countries surveyed by the International Federation of MS, including high-income countries where on-label disease-modifying treatments (DMTs) are available. This updates the 2021 version of the review.

Objectives: To assess the benefits and harms of rituximab as 'first choice' and 'switching' treatment for adults with any form of MS.

Search methods: We searched CENTRAL, MEDLINE, Embase, CINAHL, and three trials registers on 31 December 2023, together with reference checking and contacting study authors to identify unpublished studies.

Selection criteria: We included randomised controlled trials (RCTs) and controlled non-randomised studies of interventions (NRSIs) comparing rituximab with placebo or another DMT for adults with any form of MS.

Data collection and analysis: We followed standard Cochrane methods. We used RoB 1 to assess risk of bias in RCTs and ROBINS-I in NRSIs. We assessed the certainty of evidence for critical and important prioritised outcomes using GRADE: disability worsening, relapse, serious adverse events (SAEs), health-related quality of life (HRQoL), common infections, cancer, and mortality. We conducted separate analyses for rituximab as 'first choice' or as 'switching' treatment, relapsing or progressive MS, comparison with placebo or another DMT, and RCTs or NRSIs.

Main results: In this update, the number of study participants increased from 16,429 (15 studies) to 37,443 (28 studies; 13 new studies: 1 RCT and 12 NRSIs). The studies were conducted worldwide; most originated from high-income countries (25 studies). Public institutions funded 22 (79%) of the studies. Most studies investigated the effects of rituximab on people with relapsing MS (19 studies; 27,500 (73%) participants). We identified 12 ongoing studies. Rituximab as 'first choice' for active relapsing MS None of the included studies compared rituximab to placebo. One RCT compared rituximab to dimethyl fumarate, with 24 months' follow-up. Rituximab may reduce the recurrence of relapse (odds ratio (OR) 0.16, 95% confidence interval (CI) 0.04 to 0.57; 195 participants; low-certainty evidence). The evidence is very uncertain on disability worsening and SAEs. Rituximab may result in little to no difference in upper respiratory tract infections (rate ratio (RR) 1.03, 95% CI 0.79 to 1.34; low-certainty evidence). The evidence is very uncertain for urinary tract, skin, and viral infections. HRQoL, cancer, and mortality were not reported. One NRSI compared rituximab to other DMTs, with 24 months' follow-up. Disability worsening was not reported. Compared with interferon beta or glatiramer acetate, rituximab likely delays relapse (hazard ratio (HR) 0.14, 95% CI 0.05 to 0.39; 1 study, 335 participants; moderate-certainty evidence). Compared with dimethyl fumarate and natalizumab, rituximab may delay relapse (dimethyl fumarate: HR 0.29, 95% CI 0.08 to 1.00; 1 study, 206 participants; low-certainty evidence; natalizumab: HR 0.24, 95% CI 0.06 to 1.00; 1 study, 170 participants; low-certainty evidence). The evidence for relapse is very uncertain when comparing rituximab to fingolimod. The effect on SAEs is uncertain due to very few events in all the comparison groups. No deaths were reported. HRQoL, common infections, and cancer were not reported. Rituximab as 'first choice' for primary progressive MS One RCT compared rituximab to placebo, with 24 months' follow-up. Rituximab likely results in little or no difference in disability worsening (OR 0.71, 95% CI 0.45 to 1.11; 439 participants; moderate-certainty evidence). The evidence is very uncertain on relapse, SAEs, common infections, cancer, and mortality. HRQoL was not reported. None of the included studies compared rituximab as 'first choice' treatment to other DMTs for primary or secondary progressive MS. Rituximab as 'switching' treatment for relapsing MS One small RCT compared rituximab to placebo, with 12 months' follow-up. Disability worsening was not reported. Rituximab may reduce recurrence of relapses (OR 0.38, 95% CI 0.16 to 0.93; 1 study, 104 participants; low-certainty evidence). The evidence is very uncertain regarding SAEs, common infections, cancer, and mortality. HRQoL was not reported. Twelve NRSIs compared rituximab to other DMTs, with 24 months' follow-up. The evidence on disability worsening is very uncertain in comparison with interferons or glatiramer acetate, natalizumab, alemtuzumab, and ocrelizumab. Rituximab likely delays time to relapse in comparison with interferons or glatiramer acetate (HR 0.18, 95% CI 0.07 to 0.49; 1 study, 1383 participants; moderate-certainty evidence), fingolimod (HR 0.08, 95% CI 0.02 to 0.32; 1 study, 256 participants; moderate-certainty evidence), and may result in little or no difference compared with natalizumab (HR 0.96, 95% CI 0.83 to 1.10; 3 studies, 1922 participants; low-certainty evidence). The evidence is very uncertain on relapse in comparison with alemtuzumab. There is uncertainty regarding SAEs when comparing rituximab to natalizumab and fingolimod. Rituximab likely increases serious common infections when compared with interferon beta or glatiramer acetate (OR 1.71, 95% CI 1.11 to 2.62; 1 study, 5477 participants; moderate-certainty evidence) and natalizumab (OR 1.58, 95% CI 1.08 to 2.32; 2 studies, 5001 participants; moderate-certainty evidence). The evidence for common infections is very uncertain when comparing rituximab to fingolimod and ocrelizumab. Rituximab may slightly reduce the risk of cancer compared with natalizumab (HR 0.79, 95% CI 0.62 to 0.99; 2 studies, 6202 participants; low-certainty evidence), whereas the evidence is very uncertain in comparison with fingolimod. The effect of rituximab on mortality is very uncertain due to very few events in all the comparison groups. HRQoL was not reported.

Authors' conclusions: For preventing relapses in relapsing MS, rituximab as 'first choice' and 'switching' treatment compares favourably with a wide range of approved DMTs. The protective effect of rituximab against disability worsening is uncertain. There is limited information to determine the effect of rituximab on primary progressive MS. There is limited evidence for long-term adverse events of rituximab in people with MS. Evidence for serious adverse events, cancer, and mortality was of very low certainty due to few events. There is an increased risk of serious (hospital-treated) infections with rituximab compared with other DMTs, although the absolute risk is low. High-quality (prospectively registered) NRSIs should be conducted to draw more reliable conclusions about the potential benefits and harms of rituximab in people with MS.