Recurrent Varicella following Steroids and Fingolimod in a Multiple Sclerosis Patient

Modulation of Tregs and iNKT by Fingolimod in Multiple Sclerosis Patients

The altered numbers and functions of cells belonging to immunoregulatory cell networks such as T regulatory (Tregs) and invariant Natural Killer T (iNKT) cells have been reported in Multiple Sclerosis (MS), an immune-mediated disease. We aimed to assess the frequencies of Tregs and iNKT cells in MS patients throughout a one-year treatment with fingolimod (FTY) and to correlate immunological data with efficacy and safety data. The percentage of Tregs (defined as Live Dead-CD3 + CD4 + FoxP3 + CD25++/CD127- cells) increased steadily throughout the year, while there was no significant difference in the absolute number or percentage of iNKT cells (defined as CD3 + CD14-CD19- Vα24-Jα18 TCR+ cells). However, out of all the iNKT cells, the CD8+ iNKT and CD4-CD8- double-negative (DN) cell percentages steadily increased, while the CD4+ iNKT cell percentages decreased significantly. The mean percentage of CD8+ T cells at all time-points was lower in patients with infections throughout the study. The numbers and percentages of DN iNKT cells were more elevated, considering all time-points, in patients who presented a clinical relapse. FTY may, therefore, exert its beneficial effect in MS patients through various mechanisms, including the increase in Tregs and in iNKT subsets with immunomodulatory potential such as CD8+ iNKT cells. The occurrence of infections was associated with lower mean CD8+ cell counts during treatment with FTY.

Adaptive Immune Responses in a Multiple Sclerosis Patient with Acute Varicella-Zoster Virus Reactivation during Treatment with Fingolimod

Fingolimod, an oral sphingosine 1-phosphate (S1P) receptor modulator, is approved for the treatment of relapsing forms of multiple sclerosis (MS). The interference with S1P signaling leads to retention particularly of chemokine receptor-7 (CCR7) expressing T cells in lymph nodes. The immunological basis of varicella zoster virus (VZV) infections during fingolimod treatment is unclear. Here, we studied the dynamics of systemic and intrathecal immune responses associated with symptomatic VZV reactivation including cessation of fingolimod and initiation of antiviral therapy. Key features in peripheral blood were an about two-fold increase of VZV-specific IgG at diagnosis of VZV reactivation as compared to the previous months, a relative enrichment of effector CD4+ T cells (36% versus mean 12% in controls), and an accelerated reconstitution of absolute lymphocytes counts including a normalized CD4+/CD8+ ratio and reappearance of CCR7+ T cells. In cerebrospinal fluid (CSF) the lymphocytic pleocytosis and CD4+/CD8+ ratios at diagnosis of reactivation and after nine days of fingolimod discontinuation remained unchanged. During this time CCR7+ T cells were not observed in CSF. Further research into fingolimod-associated VZV reactivation and immune reconstitution is mandatory to prevent morbidity and mortality associated with this potentially life-threatening condition.

Infection risk in patients on multiple sclerosis therapeutics

The interface of multiple sclerosis (MS) and infection occurs on several levels. First, infectious disease has been postulated as a potential trigger, if not cause, of MS. Second, exacerbation of MS has been well-documented as a consequence of infection, and, lastly, infectious diseases have been recognized as a complication of the therapies currently employed in the treatment of MS. MS is a disease in which immune dysregulation is a key component. Examination of central nervous system (CNS) tissue of people affected by MS demonstrates immune cell infiltration, activation and inflammation. Therapies that alter the immune response have demonstrated efficacy in reducing relapse rates and evidence of brain inflammation on magnetic resonance imaging (MRI). Despite the altered immune response in MS, there is a lack of evidence that these patients are at increased risk of infectious disease in the absence of treatment or debility. Links between infections and disease-modifying therapies (DMTs) used in MS will be discussed in this review, as well as estimates of occurrence and ways to potentially minimize these risks. We address infection in MS in a comprehensive fashion, including (1) the impact of infections on relapse rates in patients with MS; (2) a review of available infection data from pivotal trials and postmarketing studies for the approved and experimental DMTs, including frequency, types and severity of infections; and (3) relevant risk minimization strategies, particularly as they pertain to progressive multifocal leukoencephalopathy (PML).

Overview and safety of fingolimod hydrochloride use in patients with multiple sclerosis

INTRODUCTION

Fingolimod (Gilenya®, FTY720) is an oral sphingosine-1-phosphate analogue that was approved by the FDA in 2010 for the treatment of relapsing forms of multiple sclerosis (MS). Fingolimod's mechanism of action is primarily related to lymphocyte sequestration in primary and secondary lymphoid tissues. Phase III trials demonstrated a reduction in annualized relapse rate and MRI progression in fingolimod-treated subjects compared with both placebo and IFN-β-treated subjects. Frequent adverse effects include fatigue, gastrointestinal disturbance, headache and upper respiratory tract infection. More serious, but rare, adverse events associated with fingolimod include atrioventricular block, symptomatic bradycardia, herpetic viral infections and macular edema.

AREAS COVERED

We discuss the mechanism of action, pharmacokinetics, clinical efficacy and safety profile of fingolimod in patients with relapsing MS.

EXPERT OPINION

Fingolimod is an effective treatment for relapsing MS and its oral route of administration may be preferred by some. Fingolimod is generally well tolerated but requires diligence in patient selection and monitoring. Additional information is needed regarding risk of infection, malignancy and rebound disease with long-term use of fingolimod.