Efficacy and safety of rituximab in patients with multiple sclerosis: An observational study at a tertiary center in Makkah,Saudi Arabia

Objectives:To assess the efficacy and safety of rituximab for multiple sclerosis (MS) treatment in terms of reduction in clinical relapses, magnetic resonance imaging (MRI) activity, Expanded Disability Status Scale (EDSS) score and adverse events.Methods:This is a retrospective cross-sectional study conducted at King Abdullah Medical City, from January 2017 to August 2021, involving patients with MS given rituximab, with 1-year follow-up. Clinical parameters were noted pre- and post-treatment to determine efficacy; adverse events were noted to analyze safety. A paired samples t-test was used to compare responses pre- and post-treatment. A p-value<0.05 was considered significant.Results:Among 31 patients, 6 (19.4%) had progressive MS, and 25 (80.6%) had relapsing-remitting MS (mean disease duration=8.12±5.65 years). The annual relapse rate reduced from 1.67±0.97 to 0.06±0.25 (p<0.001), the EDSS score from 3.16±2.14 to 2.80±2.28 (p=0.141) and the MRI activity score from 1.84±1.03 to 1.03±0.18 (p<0.001). Only one patient had enhancing lesion activity post-treatment. The commonest side effect was urinary tract infection (25.8%). Only 2 patients discontinued the drug.Conclusion:Rituximab is an efficient drug in reducing the annual relapse rate and MRI activity of patients with MS, with few tolerable side effects not leading to drug discontinuation or any lethal outcome.

Multiple sclerosis (MS) is a condition of the central nervous system carrying a chronic course and having autoimmune etiology. The disease has a prevalence of 40.4 per 100,000 people in Saudi Arabia. ¹ MS can have a relapsing-remitting course which begins with an acute attack and is then followed by full or partial recovery (also known as relapsing-remitting MS [RRMS]). Alternative clinical presentation of MS is characterized by progressive neurological worsening without any acute attack (also known as primary progressive MS). Secondary Progressive MS is another advanced stage in the course of disease where disability worsens gradually without a new relapse. ^2,3 The disease process was earlier thought to be mediated by T cells, but research has brought forth the suggestion that B cells, too, do play a role in the pathological process. ⁴ It is now well understood that antigen presentation by B cells is a necessary step in the pathogenesis of the immune-mediated process against the glycoprotein myelin found in central nervous system. ⁵ Therapies targeting T cells (for example, interferon-beta and natalizumab) have been traditionally used for MS, but not all patients improve despite treatment compliance. Moreover, interferon causes a myriad of highly stressful side effects, and natalizumab, in addition to causing minor adverse effects, has a risk of causing a serious condition like progressive multifocal leukoencephalopathy (PML). ⁶ New therapies that target B cells are increasingly being investigated. Rituximab (RTX) is one such drug that targets CD 20 expressing B cells and also reduces T cells. The drug has shown promising results in the treatment process. ^7,8 The safety of RTX usage is established by Class IV evidence. ⁹ Phase 2 trials have shown that RTX reduces magnetic resonance imaging (MRI) inflammatory lesions by up to 88% in the patients of MS. ^10,11 Off-label RTX usage in MS is further supported by several trials. ^11,12,13 One such study showed MRI activity reduce from 88% to 8.3% in only a year and annual relapse rate reduce from 0.75 to 0.36 with the use of RTX. ¹³ The common side effects of RTX usage in patients with MS include infections (36%), with urinary tract infection being the most common, and infusion reactions (8%). This CD 20 targeting drug also increases the risk for fungal infections. ^14,15 Studies comparing the efficacy of RTX to conventional therapies have concluded that RTX has better performance in MS, especially in newly diagnosed cases of RRMS. ¹⁶ Our aim was to study the reduction in MRI inflammatory lesions, disability changes and relapses in patients with MS presenting at King Abdullah Medical City as a result of RTX therapy.