Mefloquine improved progressive multifocal leukoencephalopathy in a patient with immunoglobulin A nephropathy

We describe a patient with immunoglobulin A nephropathy who was diagnosed with progressive multifocal leukoencephalopathy (PML) and successfully treated with mefloquine, an antimalarial medication. A 67-year-old man with immunoglobulin A nephropathy presented to the hospital emergency room with fever and generalized tonic-clonic seizure. Cerebrospinal fluid (CSF) nested polymerase chain reaction (PCR) was positive for John Cunningham virus and brain MRI displayed high signal intensity in the white matter in the right parietal lobe without gadolinium enhancement. Tapering of prednisone did not arrest the disease progression and a new lesion was detected on the cerebellum. Administration of mefloquine stopped lesion progression and resulted in dramatic clinical improvement. The CSF nested PCR for the John Cunningham virus also became negative. In reviewing the literature, mefloquine has had a heterogeneous effect in PML patients, and P-glycoprotein polymorphism and proper dosage could contribute to the various effects seen. Mefloquine may be a favorable treatment option in some patients with PML, and P-glycoprotein polymorphism may play an important role in its efficacy. More large studies in other ethnic groups including polymorphism studies for the gene encoding P-glycoprotein (ABCB1/MDR1) and taking into account various underlying conditions with secondary immunosuppression should be carried out to investigate whether mefloquine is effective for treating PML.