The complement system is a tightly controlled signaling network that plays a role in innate immune surveillance. However, abnormal signaling through this pathway contributes to tissue damage in several inflammatory, autoimmune, and degenerative diseases. Myasthenia gravis (MG) and neuromyelitis optica spectrum disorders (NMOSD) have complement dysfunction at the core of pathogenesis, providing a strong rationale for therapeutic targeting of complement components. The purpose of this paper is to briefly review the role of complement activation in the pathogenesis of MG and NMOSD, to discuss the rationale and evidence for complement inhibition as a method to manage these diseases, and to provide a Canadian perspective on the use of complement inhibition therapy through real-world cases of MG and NMOSD.

Recent therapeutic advances in the management of multiple sclerosis (MS) have raised questions about the selection of appropriate patient candidates for various treatments and, if the plan is to move from one treatment to another, the appropriate sequencing of these therapies. The selected approach should provide optimal disease management without limiting future therapeutic options based on safety concerns, and recognize potential future treatments and the possibility of combination therapies. Additional challenges include incorporation of patient needs and preferences into the overall therapeutic approach, in order to ensure optimal outcomes in the short and long term. The objective of this manuscript is to provide an overview of what is currently known regarding the impact of various therapies for MS on future therapeutic choices (sequencing). In this context, we reviewed the available evidence in support of various treatments and, based on the presence of disease activity, suggested a scheme for switching or escalating therapy with the main focus on sequencing of therapeutic approaches.

The treatment of multiple sclerosis has finally become possible with the advent of the current disease-modifying therapies (DMTs) that have had a significant impact on those living with this disease. Though demonstrating clear efficacy on a number of short-term outcome measures, unfortunately, these agents are not “cures” and many patients with multiple sclerosis continue to experience disease activity in spite of treatment. Clinicians are becoming more comfortable initiating therapy with DMTs, but it is now important to focus attention on monitoring the results of the chosen therapy and deciding whether or not a patient is responding well to treatment. At present, however, clinicians lack criteria for defining optimal versus suboptimal responses to DMTs as well as evidence-based guidelines on how to improve treatment outcomes. Using a recently published model as a framework, The Canadian Multiple Sclerosis Working Group developed practical recommendations on how neurologists can assess the status of patients on DMTs and decide when it may be necessary to modify treatment in order to optimize outcomes. The Canadian Multiple Sclerosis Working Group's recommendations are based on monitoring relapses, neurological progression and MRI activity. Other possible causes of suboptimal treatment responses or treatment failure are also considered.

Background: Anti–John Cunningham (JCV) antibodies have been detected in approximately 50% to 60% of multiple sclerosis (MS) patients. Age, sex, and geographic location have been associated with seroprevalence differences. We describe anti-JCV antibody prevalence in the Canadian cohort of patients enrolled in the JCV Epidemiology in MS study. Methods: This cross-sectional multicenter study evaluated the effects of demographic and disease characteristics on anti-JCV antibody seroprevalence in MS patients irrespective of disease type and treatment. A single blood sample was collected for analysis of anti-JCV antibodies using a two-step enzyme-linked immunosorbent assay (ELISA). Chi-square and logistic regression tests were used to determine significance. Results: A total of 4198 Canadian MS patients participated in the study; the overall anti-JCV antibody prevalence was 56.3% (95% confidence interval: 54.8% to 57.8%). Seroprevalence was significantly associated with age (increasing from 45% in young to 61% in those >60 years), sex, and region (p<0.0001 for age and sex; p=0.005 for region). No significant differences in anti-JCV antibody prevalence were associated with race, MS disease type and duration, or number and duration of treatments. Immunosuppressant use was associated with a higher seroprevalence rate (63.4%) compared with no immunosuppressant use (55.9%; p=0.040). Conclusions: Canadian MS patients had an overall anti-JCV antibody seroprevalence that was consistent with previous studies using the two-step ELISA. Significant associations of anti-JCV antibody positivity were found with age, sex, region, and immunosuppressant therapy, whereas seroprevalence was not associated with race, MS type, MS duration, or number or duration of MS treatments.

The Canadian Multiple Sclerosis Working Group (CMSWG) developed practical recommendations in 2004 to assist clinicians in optimizing the use of disease-modifying therapies (DMT) in patients with relapsing multiple sclerosis. The CMSWG convened to review how disease activity is assessed, propose a more current approach for assessing suboptimal response, and to suggest a scheme for switching or escalating treatment. Practical criteria for relapses, Expanded Disability Status Scale (EDSS) progression and MRI were developed to classify the clinical level of concern as Low, Medium and High. The group concluded that a change in treatment may be considered in any RRMS patient if there is a high level of concern in any one domain (relapses, progression or MRI), a medium level of concern in any two domains, or a low level of concern in all three domains. These recommendations for assessing treatment response should assist clinicians in making more rational choices in their management of relapsing MS patients.