Barts-MS rose-tinted-odometer ★★★
By definition an immune reconstitution therapy (IRT) for MS is given as a short course, i.e. as a one-off treatment in the case of HSCT or intermittently as in the case of alemtuzumab or cladribine. IRTs are not given continuously and additional courses of the therapy are only given if there is a recurrence of inflammatory activity. IRTs have the ability to induce long-term remission and in some cases potentially a cure.
Immune reconstitution simply refers to the restoring of a competent immune system after a cycle, or cycles, of depletion. Immune competence in the context of an IRT refers to the ability of the immune system to respond to infection, in particular, opportunistic infections, mount an antibody response to vaccines and to perform normal systemic tumour surveillance.
Immune reconstitution has been best shown in the context of hematopoietic stem cell transplantation (HSCT). In the case of an IRT, for example, alemtuzumab or cladribine, which are given as short courses breakthrough disease activity can be used as an indicator to retreat rather than to necessarily switch therapy. Therefore, there a rebaselining MRI should be delayed until after the final initial course of therapy, e.g. 2 years, or close enough to the time when a third, or subsequent course, can be administered
A major concern in relation to the wide adoption of IRTs is the uncertainty about the duration of their effectiveness and the concern that disease activity may reoccur at a level below the clinical and MRI monitoring thresholds used in routine clinical practice. If disease activity does reoccur will it cause irreversible end-organ damage? In addition, some IRTs, in particular, alemtuzumab and HSCT, are associated with a high rate of secondary autoimmunity and rarely with early and severe rebound disease activity.
One strategy we are exploring is to use an IRT as true induction therapy and then maintain the treatment effect with safer maintenance therapies. In the case of alemtuzumab and HSCT, certain maintenance therapies could potentially prevent secondary autoimmunity and early rebound disease activity.
We are in the process of preparing a grant application to explore the safety of an induction-maintenance treatment. Would you be interested in helping by completing the following survey?