Eugene O. Major

Progressive multifocal leukoencephalopathy after rituximab therapy in HIV-negative patients: a report of 57 cases from the Research on Adverse Drug Events and Reports project

Rituximab improves outcomes for persons with lymphoproliferative disorders and is increasingly used to treat immune-mediated illnesses. Recent reports describe 2 patients with systemic lupus erythematosus and 1 with rheumatoid arthritis who developed progressive multifocal leukoencephalopathy (PML) after rituximab treatment. We reviewed PML case descriptions among patients treated with rituximab from the Food and Drug Administration, the manufacturer, physicians, and a literature review from 1997 to 2008. Overall, 52 patients with lymphoproliferative disorders, 2 patients with systemic lupus erythematosus, 1 patient with rheumatoid arthritis, 1 patient with an idiopathic autoimmune pancytopenia, and 1 patient with immune thrombocytopenia developed PML after treatment with rituximab and other agents. Other treatments included hematopoietic stem cell transplantation (7 patients), purine analogs (26 patients), or alkylating agents (39 patients). One patient with an autoimmune hemolytic anemia developed PML after treatment with corticosteroids and rituximab, and 1 patient with an autoimmune pancytopenia developed PML after treatment with corticosteroids, azathioprine, and rituximab. Median time from last rituximab dose to PML diagnosis was 5.5 months. Median time to death after PML diagnosis was 2.0 months. The case-fatality rate was 90%. Awareness is needed of the potential for PML among rituximab-treated persons.

Pathogenesis and molecular biology of progressive multifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain.

Studies of the pathogenesis and molecular biology of JC virus infection over the last two decades have significantly changed our understanding of progressive multifocal leukoencephalopathy, which can be described as a subacute viral infection of neuroglial cells that probably follows reactivation of latent infection rather than being the consequence of prolonged JC virus replication in the brain. There is now sufficient evidence to suggest that JC virus latency occurs in kidney and B cells. However, JC virus isolates from brain or kidney differ in the regulatory regions of their viral genomes which are controlled by host cell factors for viral gene expression and replication. DNA sequences of noncoding regions of the viral genome display a certain heterogeneity among isolates from brain and kidney. These data suggest that an archetypal strain of JC virus exists whose sequence is altered during replication in different cell types. The JC virus regulatory region likely plays a significant role in establishing viral latency and must be acted upon for reactivation of the virus. A developing hypothesis is that reactivation takes place from latently infected B lymphocytes that are activated as a result of immune suppression. JC virus enters the brain in the activated B cell. Evidence for this mechanism is the detection of JC virus DNA in peripheral blood lymphocytes and infected B cells in the brains of patients with progressive multifocal leukoencephalopathy. Once virus enters the brain, astrocytes as well as oligodendrocytes support JC virus multiplication. Therefore, JC virus infection of neuroglial cells may impair other neuroglial functions besides the production and maintenance of myelin. Consequently our increased understanding of the pathogenesis of progressive multifocal leukoencephalopathy suggests new ways to intervene in JC virus infection with immunomodulation therapies. Perhaps along with trials of nucleoside analogs or interferon administration, this fatal disease, for which no consensus of antiviral therapy exists, may yield to innovative treatment protocols. Images

Human macrophages convert l-tryptophan into the neurotoxin quinolinic acid

Substantial increases in the concentrations of the excitotoxin and N-methyl-D-aspartate-receptor agonist quinolinic acid (QUIN) occur in human patients and non-human primates with inflammatory diseases. Such increases were postulated to be secondary to induction of indoleamine 2,3-dioxygenase in inflammatory cells, particularly macrophages, by interferon-gamma. To test this hypothesis, human peripheral-blood macrophages were incubated with L-[13C6]tryptophan in the absence or presence of interferon-gamma. [13C6]QUIN was quantified by gas chromatography and electron-capture negative-chemical-ionization mass spectrometry. [13C6]QUIN was detected in the incubation medium of both unstimulated and stimulated cultures. Exposure to interferon-gamma substantially increased the accumulation of [13C6]QUIN in a dose- and time-dependent manner. The QUIN concentrations achieved exceeded those reported in both cerebrospinal fluid and blood of patients and of non-human primates with inflammatory diseases. Macrophages stimulated with interferon-gamma may be an important source of accelerated L-tryptophan conversion into QUIN in inflammatory diseases.

Natalizumab treatment for multiple sclerosis: updated recommendations for patient selection and monitoring.

Natalizumab, a highly specific α4-integrin antagonist, is approved for treatment of patients with active relapsing-remitting multiple sclerosis (RRMS). It is generally recommended for individuals who have not responded to a currently available first-line disease-modifying therapy or who have very active disease. The expected benefits of natalizumab treatment have to be weighed against risks, especially the rare but serious adverse event of progressive multifocal leukoencephalopathy. In this Review, we revisit and update previous recommendations on natalizumab for treatment of patients with RRMS, based on additional long-term follow-up of clinical studies and post-marketing observations, including appropriate patient selection and management recommendations.

HIV‐1 infection of subcortical astrocytes in the pediatric central nervous system

Early reports of pediatric HIV-1-associated neuropathology described the presence of viral particles in some astrocytes, implicating direct infection of the immature nervous system as a contributing factor to the observed neuropathology. Several recent reports suggest that in those astrocytes infected with HIV-1, the level of antigenic expression of the proviral genome is below the sensitivity limits of conventional histochemical techniques. Identification of these astrocytes would instead require the use of a highly sensitive radiolabeled DNA or RNA probe for in situ hybridization to detect the persistent viral nucleic acids. To test this hypothesis, we examined autopsy tissue from 12 infants and children with AIDS-associated encephalopathy for the presence of HIV-1-infected astrocytes using combined isotopic in situ hybridization for the detection of viral-specific nucleic acids and immunohistochemistry for the identification of astrocytes. We detected HIV-1 nucleic acids in astrocytes in subcortical white matter from four pediatric patients with moderate to extensive leukoencephalitis. While gp41 was detectable only on macrophages and multinucleated giant cells, HIV-1 Nef protein was present in cells morphologically identified as astrocytes in two of these patients, further suggesting that HIV-1 establishes a persistent rather than a productive infection in astrocytes. Subcortical astrocytes may therefore be an unrecognized reservoir for HIV-1 in the developing nervous system of some children with AIDS-associated leukoencephalitis.

Monoclonal antibody-associated progressive multifocal leucoencephalopathy in patients treated with rituximab, natalizumab, and efalizumab: a Review from the Research on Adverse Drug Events and Reports (RADAR) Project

Progressive multifocal leucoencephalopathy (PML) is a serious and usually fatal CNS infection caused by JC polyoma virus. CD4+ and CD8+ T lymphopenia, resulting from HIV infection, chemotherapy, or immunosuppressive therapy, are the primary risk factors. The immune modulatory monoclonal antibodies rituximab, natalizumab, and efalizumab have received regulatory approval in the USA and Europe for treatment of non-Hodgkin lymphoma, rheumatoid arthritis, and chronic lymphocytic leukaemia (Europe only); multiple sclerosis and Crohns disease; and psoriasis, respectively. Efalizumab and natalizumab administration is associated with CD4+ T lymphopenia and altered trafficking of T lymphocytes into the CNS, and rituximab leads to prolonged B-lymphocyte depletion. Unexpected cases of PML developing in people who receive these drugs have been reported, with many of the affected individuals dying from this disease. Herein, we review clinical findings, pathology, epidemiology, basic science, and risk-management issues associated with PML infection developing after treatment with these monoclonal antibodies.

Progressive Multifocal Leukoencephalopathy in Patients on Immunomodulatory Therapies

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the white matter of the human brain caused by lytic infection of oligodendrocytes with the human polyomavirus JCV. Although the majority of PML cases occur in severely immune-suppressed individuals, with HIV-1 infection as the predominant factor, PML has been increasingly diagnosed in patients treated with biological therapies such as monoclonal antibodies that modulate immune system functions. Monoclonal antibodies that target the cell adhesion molecules VLA-4 (natalizumab; Tysabri for multiple sclerosis and Crohns disease) or LFA-1 (efalizumab; Raptiva for severe forms of plaque psoriasis) to prevent extravasation of inflammatory T cells into tissues, or target the cell surface marker CD20 (rituximab; Rituxan for hematologic malignancies and rheumatoid arthritis) to deplete peripheral circulating B cells, have all been associated with PML. The link between the effects of these therapies on the immune system and the occurrence of PML has prompted investigations on JCV sites of latency in the bone marrow, the migration of bone marrow derived cells into the circulation, and intracellular virus entry into the brain.

Involvement of JC Virus–Infected Mononuclear Cells from the Bone Marrow and Spleen in the Pathogenesis of Progressive Multifocal Leukoencephalopathy

PROGRESSIVE multifocal leukoencephalopathy (PML), a subacute demyelinating disease resulting from infection of oligodendrocytes by JC virus, occurs almost exclusively in immunocompromised patients....

Failure of Cytarabine in Progressive Multifocal Leukoencephalopathy Associated with Human Immunodeficiency Virus Infection

BACKGROUND Progressive multifocal leukoencephalopathy affects about 4 percent of patients with the acquired immunodeficiency syndrome (AIDS), and survival after the diagnosis of leukoencephalopathy averages only about three months. There have been anecdotal reports of improvement but no controlled trials of therapy with antiretroviral treatment plus intravenous or intrathecal cytarabine. METHODS In this multicenter trial, 57 patients with human immunodeficiency virus (HIV) infection and biopsy-confirmed progressive multifocal leukoencephalopathy were randomly assigned to receive one of three treatments: antiretroviral therapy alone, antiretroviral therapy plus intravenous cytarabine, or antiretroviral therapy plus intrathecal cytarabine. After a lead-in period of 1 to 2 weeks, active treatment was given for 24 weeks. For most patients, antiretroviral therapy consisted of zidovudine plus either didanosine or stavudine. RESULTS At the time of the last analysis, 14 patients in each treatment group had died, and there were no significant differences in survival among the three groups (P=0.85 by the log-rank test). The median survival times (11, 8, and 15 weeks, respectively) were similar to those in previous studies. Only seven patients completed the 24 weeks of treatment. Anemia and thrombocytopenia were more frequent in patients who received antiretroviral therapy in combination with intravenous cytarabine than in the other groups. CONCLUSIONS Cytarabine administered either intravenously or intrathecally does not improve the prognosis of HIV-infected patients with progressive multifocal leukoencephalopathy who are treated with the antiretroviral agents we used, nor does high-dose antiretroviral therapy alone appear to improve survival over that reported in untreated patients.

PML diagnostic criteria: Consensus statement from the AAN Neuroinfectious Disease Section

Objective: To establish criteria for the diagnosis of progressive multifocal leukoencephalopathy (PML). Methods: We reviewed available literature to identify various diagnostic criteria employed. Several search strategies employing the terms “progressive multifocal leukoencephalopathy” with or without “JC virus” were performed with PubMed, SCOPUS, and EMBASE search engines. The articles were reviewed by a committee of individuals with expertise in the disorder in order to determine the most useful applicable criteria. Results: A consensus statement was developed employing clinical, imaging, pathologic, and virologic evidence in support of the diagnosis of PML. Two separate pathways, histopathologic and clinical, for PML diagnosis are proposed. Diagnostic classification includes certain, probable, possible, and not PML. Conclusion: Definitive diagnosis of PML requires neuropathologic demonstration of the typical histopathologic triad (demyelination, bizarre astrocytes, and enlarged oligodendroglial nuclei) coupled with the techniques to show the presence of JC virus. The presence of clinical and imaging manifestations consistent with the diagnosis and not better explained by other disorders coupled with the demonstration of JC virus by PCR in CSF is also considered diagnostic. Algorithms for establishing the diagnosis have been recommended.