Immune Reconstitution Therapy or Continuous Immunosuppression for the Management of Active Relapsing-Remitting Multiple Sclerosis Patients? A Narrative Review.

The majority of disease-modifying drugs (DMDs) available for the management of active relapsing-remitting multiple sclerosis (RMS) depend on continuous drug intake for maintained efficacy, with escalation to a more active drug when an unacceptable level of disease activity returns. Among continuously applied regimens, interferons and glatiramer acetate act as immunomodulators, while dimethyl fumarate, fingolimod, ocrelizumab, natalizumab and teriflunomide are associated with continuous immunosuppression. By contrast, immune reconstitution therapy (IRT) provides efficacy that outlasts a short course of treatment. Autologous hemopoietic stem cell transplantation is perhaps the classic example of IRT, but this invasive and intensive therapy has challenging side-effects. A short treatment course of a pharmacologic agent hypothesized to act as an IRT, such as Cladribine Tablets 3.5 mg/kg or alemtuzumab, can provide long-term suppression of MS disease activity, without need for continuous treatment (the anti-CD20 mechanism of ocrelizumab has the potential to act as an IRT, but is administered continuously, at 6-monthly intervals). Cladribine Tablets 3.5 mg/kg shows some selectivity in targeting adaptive immunity with a lesser effect on innate immunity. The introduction of IRT-like disease-modifying drugs (DMDs) challenges the traditional maintenance/escalation mode of treatment and raises new questions about how disease activity is measured. In this review, we consider a modern classification of DMDs for MS and its implications for the care of patients in the IRT era.

Cladribine Tablets and Relapsing-Remitting Multiple Sclerosis: A Pragmatic, Narrative Review of What Physicians Need to Know.

Immune reconstitution therapy (IRT) is an emerging management concept for multiple sclerosis, whereby a short course of treatment provides long-lasting suppression of disease activity. "Cladribine tablets 10 mg" refers to a total cumulative dose of cladribine given over 2 years (henceforth referred to as cladribine tablets 3.5 mg/kg); it is a relatively new treatment option that is hypothesised to act as an IRT acting preferentially on the adaptive immune system. A randomised, 2-year, placebo-controlled trial (CLARITY) showed that treatment with cladribine tablets reduced indices of disease activity (relapses, lesions on magnetic resonance images, disability progression) and that this effect outlasted the pharmacologic effect of the treatment on the immune system (mainly a reduction in circulating B and T cells, with little effect on components of the innate immune system such as monocytes). CLARITY Extension, a 2-year extension to this trial, demonstrated durable efficacy, also in patients who received the standard 2-year course of cladribine tablets 3.5 mg/kg and were re-randomised to placebo for a further 2 years. Relative risk reductions for relapse rate with cladribine tablets 3.5 mg/kg were similar for patients with or without prior high disease activity. Reductions in disability progression with cladribine tablets 3.5 mg/kg were higher in patients with prior high relapse rates with or without prior treatment non-response. In this review, we describe the therapeutic profile of cladribine tablets 3.5 mg/kg and provide practical information on initiating this treatment option in the most appropriate patients.