Progressive multifocal leukoencephalitis (PML) in three patients treated with standard-dose fludarabine (FAMP)

Since 1990 we have treated 60 patients with standard-dose fludarabine for chronic lymphocytic leukemia (B-CLL), on a compassionate basis. Three patients developed grade IV neurologic complications after treatment, with demyelination of white matter on magnetic resonance imaging (MRI) in patient # 1, diffuse demyelination, abnormal oligodendroglia and enlarged astrocytes at brain biopsy in patient no 2, and progressive multifocal leukoencephalitis (PML) with JC virus on brain biopsy in patient # 3. The neurotoxicity of fludarabine was often observed after administration of high doses (90-120 mg/m2). At standard doses (18-25 mg/m2) neurologic complications were observed in very few cases (0.2%). PML was observed in only 0.52% of patients with chronic lymphocytic leukemia (CLL), particularly those with advanced CLL. Our findings are consistent with the results of published studies and show an increase in neurologic complications in patients with advanced CLL treated with fludarabine. This increased vulnerability is probably multifactorial, but may be secondary to the immunodeficiency.