Multifocal motor neuropathy (MMN) is an immune-mediated disorder characterized by slowly progressive asymmetrical limb weakness.
Immunoglobulins (IVIg) remains the primary, FDA-approved, means to treat the condition.
Anecdotal evidence suggests that immunosuppressive drugs as adjunctive therapy may be beneficial.
Safety and efficacy of mycophenolate mofetil (CellCept) as adjunctive therapy for MMN patients receiving IVIg maintenance treatment were evaluated in a randomized controlled trial.
MMN patients responding to IVIg treatment were eligible for randomization.
Muscle strength and functional status were assessed at monthly intervals for 1 year.
Three months after the start of CellCept or placebo treatment, IVIg doses were reduced step-wise, until a deterioration of functioning or decline in muscle strength could be observed.
An IVIg dose reduction of 50% during adjunctive treatment was defined as a primary endpoint.
Secondary outcome measures were improvement in muscle strength and functional status after 3 months and reduction of anti GM1-IgM titres after 12 months of CellCept treatment.
Twenty-eight patients were randomized, while one patient allocated to CellCept reached the primary endpoint of 50% IVIg dose reduction.
After 12 months IVIg reduction did not differ significantly between the two treatment groups.
Patients did not experience drug toxicity and none of the patients showed significant disease progression after 12 months.
Muscle strength and functional scores after 3 months and anti GM1-IgM titres after 12 months did not change.
Adjunctive treatment of MMN patients with CellCept at a dose of 1 g twice daily is safe but does not alter disease course or allow significant reduction of IVIg doses.
After the study was published the FDA came out with an alert of a possible relationship between CellCept and a rare, but serious, neurological disease called multifocal leukoencephalopathy (PML). Other diseases associated with CellCept arePolyomavirus associated nephropathy (PVAN), cytomegalovirus (CMV) infections, reactivation of hepatitis B (HBV) or hepatitis C (HCV).