Progressive multifocal leukoencephalopathy during ixazomib-based chemotherapy

Progressive multifocal leukoencephalopathy (pml) is a rare demyelinating disease of the central nervous system that most often affects immunocompromised individuals. It is caused by the reactivation of the John Cunningham virus (jcv), which is found in latent form in the majority of adults. We describe a 59-year-old man with multiple myeloma who developed severe neurological deficits during treatment with ixazomib-based chemotherapy. A diagnosis of pml was established with gadolinium-enhanced magnetic resonance imaging (mri) and by detection of jcv in the cerebrospinal fluid. Despite cessation of chemotherapy and treatment with mirtazapine, he had an inexorable neurological decline and died two months after presenting to hospital. Multiple myeloma and its treatments can predispose patients to opportunistic infections including pml. Although there have been case reports of pml in patients with multiple myeloma treated with bortezomib (a different proteosome inhibitor), this is, to our knowledge, the first documented case of pml in a patient treated with a regimen that includes ixazomib.

T cell deficiencies as a common risk factor for drug associated progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a disease of the central nervous system caused by neuropathogenic prototypes of ubiquitous community-acquired JC virus (JCV). The disease became of particular concern following its association with certain therapies that modulate immune system function without heavy immunosuppression. Due to lack of prophylactic/treatment options and poor outcomes, which often include severe disability or death, PML is a considerable concern for development of new drugs that interfere with immune system functions. In this review of clinical and research findings, we discuss the evidence that deficiencies in CD4⁺ T helper cells, cytotoxic CD8⁺ T cells, and interferon gamma are of crucial importance for development of PML under a variety of circumstances, including those associated with use of various drugs, regardless of differences in their mechanisms of action. These deficiencies apparently enable transformation of the harmless JCV archetype into neuropathogenic prototypes, but the site(s), and the mechanisms, of this transformation are yet to be elucidated. Here we discuss the evidence for brain as one of the sites of this transformation, and propose a model of PML pathogenesis that emphasizes the central role of T cell deficiencies in the two life cycles of the JCV, one non-pathogenic and one neuropathogenic. Finally, we conclude that the development of clinical grade T cell functional tests and more consistent use of already available laboratory tests for T cell subset analysis would greatly aid the effort to more accurately predict and assess the magnitude of PML risk for concerned therapeutic interventions.

Failure of mefloquine therapy in progressive multifocal leukoencephalopathy: report of two Japanese patients without human immunodeficiency virus infection

Although progressive multifocal leukoencephalopathy (PML) cases showing responses to mefloquine therapy have been reported, the efficacy of mefloquine for PML remains unclear. We report on the failure of mefloquine therapy in two Japanese patients with PML unrelated to human immunodeficiency virus. One of the patients was a 47-year-old male who had been treated with chemotherapy for Waldenström macroglobulinemia, and the other was an 81-year-old male with idiopathic CD4(+) lymphocytopenia. Diagnosis of PML was established based on MRI findings and increased JC virus DNA in the cerebrospinal fluid in both patients. Mefloquine was initiated about 5 months and 2 months after the onset of PML, respectively. During mefloquine therapy, clinical and radiological progression was observed, and JC virus DNA in the cerebrospinal fluid was increased in both patients. Both patients died about 4 months and 2 months after initiation of mefloquine, respectively. Further studies are necessary to clarify the differences between mefloquine responders and non-responders in PML.