IMPORTANCE Although highly effective disease-modifying therapies for multiple sclerosis (MS) have been associated with an increased risk of infections vs injectable therapies interferon beta and glatiramer acetate (GA), the magnitude of potential risk increase is not well established in real-world populations. Even less is known about infection risk associated with rituximab, which is extensively used off-label to treat MS in Sweden. OBJECTIVE To examine the risk of serious infections associated with disease-modifying treatments for MS. DESIGN, SETTING, AND PARTICIPANTS This nationwide register-based cohort study was conducted in Sweden from January 1, 2011, to December 31, 2017. National registers with prospective data collection from the public health care system were used. All Swedish patients with relapsing-remitting MS whose data were recorded in the Swedish MS register as initiating treatment with rituximab, natalizumab, fingolimod, or interferon beta and GA and an age-matched and sex-matched general population comparator cohort were included. EXPOSURES Treatment with rituximab, natalizumab, fingolimod, and interferon beta and GA. MAIN OUTCOMES AND MEASURES Serious infections were defined as all infections resulting in hospitalization. Additional outcomes included outpatient treatment with antibiotic or herpes antiviral medications. Adjusted hazard ratios (HRs) were estimated in Cox regressions. RESULTS A total of 6421 patients (3260 taking rituximab, 1588 taking natalizumab, 1535 taking fingolimod, and 2217 taking interferon beta/GA) were included, plus a comparator cohort of 42 645 individuals. Among 6421 patients with 8600 treatment episodes, the mean (SD) age at treatment start ranged from 35.0 (10.1) years to 40.4 (10.6) years; 6186 patients were female. The crude rate of infections was higher in patients with MS taking interferon beta and GA than the general population (incidence rate, 8.9 [95% CI, 6.4-12.1] vs 5.2 [95% CI, 4.8-5.5] per 1000 person-years), and higher still in patients taking fingolimod (incidence rate, 14.3 [95% CI, 10.8-18.5] per 1000 person-years), natalizumab (incidence rate, 11.4 [95% CI, 8.3-15.3] per 1000 person-years), and rituximab (incidence rate, 19.7 [95% CI, 16.4-23.5] per 1000 person-years). After confounder adjustment, the rate remained significantly higher for rituximab (HR, 1.70 [95% CI, 1.11-2.61]) but not fingolimod (HR, 1.30 [95% CI, 0.84-2.03]) or natalizumab (HR, 1.12 [95% CI, 0.71-1.77]) compared with interferon beta and GA. In contrast, use of herpes antiviral drugs during rituximab treatment was similar to that of interferon beta and GA and lower than that of natalizumab (HR, 1.82 [1.34-2.46]) and fingolimod (HR, 1.71 [95% CI, 1.27-2.32]). CONCLUSIONS AND RELEVANCE Patients with MS are at a generally increased risk of infections, and this differs by treatment. The rate of infections was lowest with interferon beta and GA; among newer treatments, off-label use of rituximab was associated with the highest rate of serious infections. The different risk profiles sh...

Our findings suggest an improved effectiveness and tolerability of rituximab compared with fingolimod in stable RRMS patients who switch from natalizumab due to JC virus antibody positivity. Although residual confounding factors cannot be ruled out, the shared reason for switching from natalizumab and the preferential use of either rituximab or fingolimod in 2 of the centers mitigates these concerns. Ann Neurol 2016;79:950-958.

Objective:To investigate the safety and efficacy of rituximab in multiple sclerosis (MS).Methods:In this retrospective uncontrolled observational multicenter study, off-label rituximab-treated patients with MS were identified through the Swedish MS register. Outcome data were collected from the MS register and medical charts. Adverse events (AEs) grades 2–5 according to the Common Terminology Criteria for Adverse Events were recorded.Results:A total of 822 rituximab-treated patients with MS were identified: 557 relapsing-remitting MS (RRMS), 198 secondary progressive MS (SPMS), and 67 primary progressive MS (PPMS). At baseline, 26.2% had contrast-enhancing lesions (CELs). Patients were treated with 500 or 1,000 mg rituximab IV every 6–12 months, during a mean 21.8 (SD 14.3) months. During treatment, the annualized relapse rates were 0.044 (RRMS), 0.038 (SPMS), and 0.015 (PPMS), and 4.6% of patients displayed CELs. Median Expanded Disability Status Scale remained unchanged in RRMS (p = 0.42) and increased by 0.5 and 1.0 in SPMS and PPMS, respectively (p = 0.10 and 0.25). Infusion-related AEs occurred during 7.8% of infusions and most were mild. A total of 89 AEs grades ≥2 (of which 76 infections) were recorded in 72 patients. No case of progressive multifocal leukoencephalopathy was detected.Conclusions:This is the largest cohort of patients with MS treated with rituximab reported so far. The safety, clinical, and MRI findings in this heterogeneous real-world cohort treated with different doses of rituximab were similar to those reported in previous randomized controlled trials on B-cell depletion therapy in MS.Classification of evidence:This study provides Class IV evidence that for patients with MS, rituximab is safe and effective.

Objective: Novel, highly effective disease-modifying therapies have revolutionized multiple sclerosis (MS) care. However, evidence from large comparative studies on important safety outcomes, such as cancer, is still lacking. Methods: In this nationwide register-based cohort study, we linked data from the Swedish MS register to the Swedish Cancer Register and other national health care and census registers. We included 4,187 first-ever initiations of rituximab, 1,620 of fingolimod, and 1,670 of natalizumab in 6,136 MS patients matched for age, sex, and location to 37,801 non-MS general population subjects. Primary outcome was time to first invasive cancer. Results: We identified 78 invasive cancers among treated patients: rituximab 33 (incidence rate [IR] per 10,000 personyears = 34.4, 95% confidence interval [CI] = 23.7-48.3), fingolimod 28 (IR = 44.0, 95% CI = 29.2-63.5), and natalizumab 17 (IR = 26.0, 95% CI = 15.1-41.6). The general population IR was 31.0 (95% CI = 27.8-34.4). Adjusting for baseline characteristics, we found no difference in risk of invasive cancer between rituximab, natalizumab, and the general population but a possibly higher risk with fingolimod compared to the general population (hazard ratio [HR] = 1.53, 95% CI = 0.98-2.38) and rituximab (HR = 1.68, 95% CI = 1.00-2.84). Interpretation: In this first large comparative study of 3 highly effective MS disease-modifying therapies, no increased risk of invasive cancer was seen with rituximab and natalizumab, compared to the general population. However, there was a borderline-significant increased risk with fingolimod, compared to both the general population and rituximab. It was not possible to attribute this increased risk to any specific type of cancer, and further studies are warranted to validate these findings.

ObjectiveTo assess safety outcomes for the induction therapies alemtuzumab and autologous hematopoietic stem cell transplantation (AHSCT) compared to noninduction disease-modifying therapies.MethodsWe performed a population-based cohort study linking the Swedish Multiple Sclerosis Register to national health care registers. Alemtuzumab, AHSCT, and a matched reference group of noninduction therapies (natalizumab, dimethyl fumarate, rituximab, fingolimod) were included if started between 2008 and 2017. Main outcomes were death, thyroid disease, nonthyroid autoimmune disease, and infection.ResultsWe identified 132 alemtuzumab-treated and 139 AHSCT-treated (68% high-dose cyclophosphamide and anti-thymocyte globulin [ATG], 32% BCNU, etoposide, cytosine-arabinoside, and melphalan/ATG) patients, together with 2,486 matched patients treated with noninduction therapies. Four patients in the alemtuzumab group died (incidence rate [IR] per 1,000 person-years 8.6, 95% confidence interval [CI] 2.3–22.0) compared to 1 patient in the AHSCT group (IR 1.7, 95% CI 0.0–9.6), and the mortality rate in the reference group was 0.7 (95% CI 0.3–1.3). Thyroid disease was most frequent in the alemtuzumab group (IR 109, 95% CI 75–154) but also occurred more often for AHSCT (IR 34, 95% CI 18–56) compared to the reference (IR 5.3 95% CI 3.9–7.1). The incidence of nonthyroid autoimmune disease was similar in all groups. IR for infection diagnosed ≥6 months from therapy initiation was 53 (95% CI 30–87) for alemtuzumab, 108 (95% CI 75–150) for AHSCT, and 51 (95% CI 46–57) for the reference.ConclusionWe confirmed a high incidence of thyroid disease in alemtuzumab- and, to a smaller extent, AHSCT-treated patients and found a higher incidence of infection for AHSCT compared to both alemtuzumab and noninduction therapies. The incidence of nonthyroid autoimmune disease was low for both therapies.Classification of EvidenceThis study provides Class III evidence of an increased risk of thyroid disease with alemtuzumab and an increased risk of infection with AHSCT treatment.