Abstract: P447

Type: Poster

Abstract Category: Pathology and pathogenesis of MS - MS and infections

Background: Although the aetiology of Multiple Sclerosis (MS) remains elusive, it is clear that Epstein Barr Virus (EBV) and possibly other viruses have a role in the pathogenesis of MS. Laboratory evidence suggests that a Human Endogenous Retrovirus (HERV) could also have a role, but no interventional therapy has determined what will happen if HERVs are suppressed. Recent epidemiological evidence indicates patients with HIV infection have a significantly lower risk of developing MS and that HIV antiretroviral therapies may be coincidentally inhibiting a HERV or retroelements that could be implicated in MS.

Objectives: To systematically investigate the effects of an HIV integrase inhibitor, raltegravir, on the number of gadolinium (Gd)-enhanced MRI lesions in people with active relapsing MS.

Methods: This is a Phase 2b clinical trial where twenty participants were enrolled in a 3 month baseline phase followed by 3 months of treatment with raltegravir 400mg twice a day. Patients had monthly Gd-enhanced MRI, saliva collection to test for EBV shedding, blood sampling for safety monitoring, virology (including HERVs), measurement of immunological and inflammatory markers; and physical, neurological and quality-of-life assessments.

Results: All patients completed the six months trial period. The primary outcome indicated raltegravir had no significant effect on MS disease activity as measured by either the number or rate of development of Gd-enhancing lesions during the treatment phase compared with the baseline phase. Additionally, there was no change in either disability or quality-of-life measures that could reasonably be attributed to the intervention.

Conclusions: Raltegravir did not have any impact on MS disease activity. This could be due to the choice of anti-retroviral agent used in this study, the need for a combination of agents, as used in treating HIV infection, the short treatment period or dosing regimen, or the lack of a role of HERV expression in MS once the disease is established.

Disclosure: M. Calado Marta Nothing to disclose

D. MacManus Nothing to disclose

T. Yousry Nothing to disclose

D. Miller Nothing to disclose

D. R. Altmann Nothing to disclose

U. C. Meier Nothing to disclose

T. Christensen Nothing to disclose

D. H. Maruszak Nothing to disclose

D. Holden Nothing to disclose

L. Bianchi Nothing to disclose

R. Adiutori Nothing to disclose

R. K. Schmierer Nothing to disclose

B. Turner Nothing to disclose

G. Giovannoni Nothing to disclose

J. Gold Nothing to disclose

This study was funded by Merck Sharpe and Dohme.