Remission of AIDS-associated progressive multifocal leukoencephalopathy after cidofovir therapy

Revisiting JC virus and progressive multifocal leukoencephalopathy

Since its definition 65 years ago, progressive multifocal leukoencephalopathy (PML) has continued to devastate a growing population of immunosuppressed patients despite major advances in our understanding of the causative JC virus (JCV). Unless contained by the immune system, JCV lyses host oligodendrocytes collateral to its life cycle, leading to demyelination, neurodegeneration, and death. Novel treatments have stagnated in the absence of an animal model while current antiviral agents fail to address the now ubiquitous polyomavirus. In this review, we highlight the established pathogenesis by which JCV infection progresses to PML, highlighting major challenges that must be overcome to eliminate the underlying virus and, therefore, the debilitating disease.

Progressive multifocal leukoencephalopathy in patients receiving rituximab and cyclophosphamide after haplo-identical T-cell replete transplantation and review of the literature

John Cunningham virus (JCV) reactivation, occurring mainly in immunocompromised patients, leads to progressive multifocal leukoencephalopathy, an uncommon but lethal disease. JCV reactivation after T-cell replete haploidentical stem cell transplantation, in the pre-cyclophosphamide era, is poorly represented in the literature. We therefore describe two cases of acute myeloid leukemia who developed JCV reactivation after receiving cyclophosphamide and rituximab post haploidentical stem cell transplantation, and review the literature, aiming to a better understanding of the disease course and its risk factors.

Potential of acyclic nucleoside phosphonates in the treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates [HPMPC: cidofovir, Vistide; PMEA: adefovir dipivoxil, Hepsera; and PMPA: tenofovir, Viread] have proven to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections, for example, cidofovir against herpesvirus [herpes simplex virus type 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpesvirus type 6, 7 and 8), polyoma-, papilloma-, adeno- and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus and orf) infections; adefovir against herpesvirus, hepadnavirus [human hepatitis B virus] and retrovirus [HIV type-1 and 2, simian immunodeficiency virus and feline immunodeficiency virus] infections; and tenofovir against both hepadna- and retrovirus infections. Cidofovir has been officially approved for the treatment of cytomegalovirus retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) for the treatment of HIV infections (i.e., AIDS) and adefovir dipivoxil for the treatment of chronic hepatitis B.

Progressive multifocal leukoencephalopathy: what's new?

Progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease that is caused by human JC polyomavirus, was first described as a complication of immune suppression 50 years ago and emerged as a major complication of HIV infection in the 1980s. The prognosis has remained dismal since then, with discouraging results from clinical trials of various therapeutic approaches, including immunomodulation and/or inhibition of viral replication. PML is caused by reactivation of latent JC virus, and serotonergic 5-HT(2a) receptors have been identified as being critical for viral infection of glial cells. In recent years, immunosuppressive therapeutic antibodies have been associated with an increased incidence rate of PML. Here, the authors review findings on the pathogenesis of PML and the encouraging case reports of novel treatments.

Treatment options for AIDS patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating viral disease produced by the John Cunningham (JC) virus, which is ubiquitously distributed. Up to 80% of adults seroconvert to JC virus. Classically, PML is a life-threatening AIDS-defining disease of the CNS, usually occurring in severely immunocompromised individuals. Until now, and despite several therapeutic attempts, there is no specific treatment for PML. Soon after the widespread use of combination antiretroviral therapy (CART), several studies showed prolonged survival for patients with AIDS-associated PML who were treated with CART. The outcome of PML in patients receiving CART is unpredictable at disease onset. Prognostic markers are needed. The JC virus DNA detection in cerebrospinal fluid by nucleic acid amplification techniques and the CD4+ cell count are the most promising parameters. Higher levels of CD4+ cell counts were independently associated with an improved survival in different clinical observations. A summary of the main current knowledge about AIDS-related PML is presented. The most effective strategy is to optimize CART to completely suppress HIV-1 viral load and allow the best CD4+ T-cell immune recovery. Nowadays, AIDS-related PML is no longer an ultimately fatal disease. A substantial number of HIV-1-infected patients with this condition can improve with CART.

Cidofovir in addition to antiretroviral treatment is not effective for AIDS-associated progressive multifocal leukoencephalopathy: a multicohort analysis

OBJECTIVE

To establish the effectiveness of cidofovir for AIDS-related progressive multifocal leukoencephalopathy (PML) in patients concomitantly receiving combination antiretroviral therapy.

DESIGN

Analysis of raw data pooled from one prospective and five cohort studies.

SETTING

Tertiary care centers for the treatment of HIV-associated complications.

PATIENTS

Three hundred seventy HIV-infected PML patients diagnosed from 1996 treated with combination antiretroviral therapy with or without cidofovir. All studies had already published their results but for four of them, additional patients and followup data are included in this report. Follow-up was started from the date of first abnormal neuroimaging; those treated with cidofovir were entered at risk at the date of cidofovir initiation. Main study outcomes were time to PML-related death and odds of 12-month moderately severe to severe disability (Rankin score >or=4).

RESULTS

Sixty-four percent of the PML cases were confirmed by histopathology or JC virus DNA detection in cerebrospinal fluid; 185 (50%) received cidofovir (median five cycles). During 463 person-years of follow-up, 167 PML-related deaths occurred (36.6 per 100 person-years of follow-up). Estimated 1 year survival was 0.56 (95%confidence interval, 0.50-0.61). In multivariate models stratified by cohort and adjusted for type of diagnosis and relevant prognostic confounders, cidofovir treatment was not associated with survival (hazard ratio for death 0.93, 0.66-1.32). Results were similar using time to death from any cause as the outcome. Furthermore, 12-month moderately severe to severe disability was not associated with the use of cidofovir.

CONCLUSION

In combination antiretroviral therapy-treated PML patients, cidofovir use did not influence PML-related mortality or residual disability. New treatments for AIDS-related PML are urgently needed.

Progressive multifocal leukoencephalopathy: report of three cases in HIV-negative hematological patients and review of literature

Progressive multifocal leukoencephalopathy (PML) is a central nervous system (CNS) disease usually observed in immunodeficient patients, especially human immunodeficiency virus (HIV)-positive, caused by John Cunningham virus. This infectious complication has been described in many HIV-negative hematological patients, especially affected by lymphoproliferative diseases. PML has been observed after both chemotherapy and bone marrow transplantation and, recently, in association with rituximab. Diagnosis can be complicated, and often a CNS biopsy is required. Current treatment approaches are not effective in both HIV-positive and HIV-negative patients, and the outcome remain very poor in the majority of cases, even after combination therapies. We report three cases of PML in hematological patients, treated respectively with conventional chemotherapy and autologous and haploidentical transplantation, and review the literature on PML. All of them received rituximab, which has recently been in the focus of a Food and Drug Administration warning.

Evolution of purely infratentorial PML under HAART--negative outcome under rapid immune reconstitution

Progressive multifocal leukoencephalopathy (PML) caused by the polyomavirus JC is a well-recognised complication of AIDS. Purely infratentorial manifestations are rare. Introduction of highly active antiretroviral therapy (HAART) has been associated with a reduction in morbidity and an improvement in overall survival among HIV-infected individuals. Recently, several reports have described adverse events in patients with PML who begin HAART and show evidence for immune reconstitution. We describe the clinical course of two patients with PML with purely infratentorial manifestation, whose clinical course deteriorated despite the successful introduction of HAART. Possible underlying immunological mechanisms are discussed.

Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections: cidofovir against herpesvirus (herpes simplex virus types 1 and 2 varicella-zoster virus, cytomegalovirus [CMV], Epstein-Barr virus, and human herpesviruses 6, 7, and 8), polyomavirus, papillomavirus, adenovirus, and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus, and orf virus) infections; adefovir against herpesvirus, hepadnavirus (human hepatitis B virus), and retrovirus (human immunodeficiency virus types 1 [HIV-1] and 2 [HIV-2], simian immunodeficiency virus, and feline immunodeficiency virus) infections; and tenofovir against both hepadnavirus and retrovirus infections. Cidofovir (Vistide) has been officially approved for the treatment of CMV retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) has been approved for the treatment of HIV infections (i.e., AIDS), and adefovir dipivoxil (Hepsera) has been approved for the treatment of chronic hepatitis B. Nephrotoxicity is the dose-limiting side effect for cidofovir (Vistide) when used intravenously (5 mg/kg); no toxic side effects have been described for adefovir dipivoxil and tenofovir disoproxil fumarate, at the approved doses (Hepsera at 10 mg orally daily and Viread at 300 mg orally daily).

Clinical course and prognostic factors of progressive multifocal leukoencephalopathy in patients treated with highly active antiretroviral therapy

We analyzed survival rates, neurologic function, and prognostic factors for 118 consecutive patients with acquired immunodeficiency syndrome-associated progressive multifocal leukoencephalopathy (PML) treated with highly active antiretroviral therapy (HAART) in 11 hospitals throughout Spain. Seventy-five patients (63.6%) remained alive for a median of 114 weeks (2.2 years) after diagnosis of PML. Neurologic function of the survivors was categorized as cure or improvement in 33, stabilization or worsening in 40, and unknown in 2. The baseline CD4+ cell count was the only variable found with prognostic significance. The odds ratio of death was 2.71 (95% confidence interval, 1.19-6.15) for patients with CD4+ cell counts of <100 cells/microL, compared with patients who had CD4+ cell counts of > or =100 cells/microL. One-third of patients with PML died despite receipt of HAART; neurologic function improved in approximately one-half of the survivors. A CD4+ cell count of <100 cells/microL was associated with higher mortality.

Progressive multifocal leukoencephalopathy after stem cell transplantation, unsuccessfully treated with cidofovir

We report a patient with progressive multifocal leukoencephalopathy (PML) after autologous stem cell transplantation (SCT) for non-Hodgkin's lymphoma (NHL). This is an unusual association, and to date only seven cases have been reported. This is the first case of PML after SCT treated with cidofovir, and the fifth case treated with this drug in a patient without human immunodeficiency virus (HIV) infection. In the previous four patients treated with cidofovir the outcome was discouraging, as was the case in this patient.

Relationships between cognition and structural neuroimaging findings in adults with human immunodeficiency virus type-1

Infection of the central nervous system with human immunodeficiency virus type-1 (HIV) is associated with cognitive impairments that range from mild cognitive and motor difficulties to dementia. Structural neuroimaging abnormalities are also common in HIV-infected patients both with and without cognitive disturbances. The most common abnormalities include high signal intensities in the white matter and atrophy. Research over the past 12 years has helped define the relationship between these neuroimaging abnormalities and the manifestation of cognitive disturbance in HIV. In the present paper, we provide a synopsis of these studies and report the current state of the literature. Our review revealed that atrophy of the caudate nucleus is most consistently associated with cognitive impairment in HIV. The current literature does not support a strong relationship between cortical atrophy or white matter abnormalities and cognitive dysfunction in this population, though methodological issues may have influenced the results. Suggestions for study design and new research directions are provided.

Focal neurological disease in patients with acquired immunodeficiency syndrome

Focal neurological disease in patients with acquired immunodeficiency syndrome may be caused by various opportunistic pathogens and malignancies, including Toxoplasma gondii, progressive multifocal leukoencephalopathy (PML), cytomegalovirus (CMV), and Epstein-Barr virus-related primary central nervous system (CNS) lymphoma. Diagnosis may be difficult, because the findings of lumbar puncture, computed tomography (CT), and magnetic resonance imaging are relatively nonspecific. Newer techniques have led to improved diagnostic accuracy of these conditions. Polymerase chain reaction (PCR) of cerebrospinal fluid specimens is useful for diagnosis of PML, CNS lymphoma, and CMV encephalitis. Recent studies have indicated the diagnostic utility of new neuroimaging techniques, such as single-photon emission CT and positron emission tomography. The combination of PCR and neuroimaging techniques may obviate the need for brain biopsy in selected cases. However, stereotactic brain biopsy, which is associated with relatively low morbidity rates, remains the reference standard for diagnosis. Highly active antiretroviral therapy has improved the prognosis of several focal CNS processes, most notably toxoplasmosis, PML, and CMV encephalitis.

Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy is a subacute demyelinating disease that occurs in patients with defects in cell-mediated immunity, including those with AIDS and lymphoproliferative disorders. It is caused by reactivation of JC virus (JCV), which infects 70% to 90% of the population by adulthood, but remains latent in normal hosts. Once reactivated, JCV infects oligodendrocytes and astrocytes, with resultant cell lysis, leading to focal areas of demyelination and necrosis in cerebral white matter causing focal neurologic deficits and characteristic findings on MRI. Polymerase chain reaction for the detection of JCV is a sensitive and specific test, replacing brain biopsy as the initial diagnostic test in the appropriate clinical setting. Historically, the prognosis of progressive multifocal leukoencephalopathy is poor, with most patients dying within 6 months of diagnosis. Antiviral medications targeted against JCV have shown little success. However, with the use of highly active antiretroviral therapy, survival of AIDS patients with progressive multifocal leukoencephalopathy has improved.

Cidofovir in AIDS-associated progressive multifocal leukoencephalopathy: a monocenter observational study with clinical and JC virus load monitoring

A monocenter observational study was conducted to determine the clinical and virological effects of cidofovir added to highly active anti-retroviral therapy (HAART) in AIDS-associated progressive multifocal leukoencephalopathy (PML). Exposure to other anti-viral drugs or late initiation of cidofovir were exclusion criteria. Of the 53 consecutive patients with virologically proven PML admitted at the NeuroAIDS Unit of Bicêtre Hospital between May 1996 and July 2000 and having received HAART with or without cidofovir, 46 met the inclusion criteria. Cidofovir was initiated in most cases on compassionate grounds. The 22 patients treated with HAART only (HAART group) were compared to the 24 patients treated with HAART and cidofovir (CDV group). Survival, neurological outcome assessed by the expanded disability status scale (EDSS), and monitoring of the JC virus (JCV) load in CSF were investigated prospectively. At baseline (date of initiation or intensification of HAART), both groups were similar regarding CD4 cell count, plasma HIV load, CSF JCV load, EDSS, and demographic features. Both groups had similar response to HAART in terms of plasma HIV load and CD4 cell count. At month 6, CSF-JCV load was below the detection level in 8 out of 24 (33%) patients from the CDV group and 7 out of 18 (39%) patients from the HAART group (P = 0.71). One-year cumulative probability of being alive was 62% in the CDV group and 53% in the HAART group (P = 0.72). However, an additional benefit with respect to survival was observed in patients who were given cidofovir after adjustment to the following baseline variables (CSF-JCV load, CD4 cell count, and EDSS). Despite the addition of cidofovir to HAART, no significant benefit had been observed in neurological outcome, particularly in patients with an early worsening.

Use of cidofovir in progressive multifocal leukoencephalopathy

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating illness caused by the JC virus, a polyomavirus that occurs in 4-5% of HIV-positive patients. Mortality is high, and no useful therapy has been identified. Highly active antiretroviral therapy (HAART) has been reported to be effective in halting progression of the disease in some, but not all, patients. Cidofovir has been shown to be active against polyomaviruses.

OBJECTIVE

To review data on the use of cidofovir to treat PML.

DATA SOURCES

English-language case reports and clinical studies were located through a literature search (MEDLINE and AIDSLINE, 1995-July 2000).

STUDY SELECTION AND DATA EXTRACTION

Relevant case reports and studies describing the use of cidofovir for PML were reviewed.

DATA SYNTHESIS

Most case reports describing the use of cidofovir have shown that the drug is effective in the treatment of PML. Some patients were also receiving HAART concurrently; therefore, it is not clear which treatment modality had a greater impact on PML. However, cidofovir may be effective in patients whose disease has progressed despite HAART or who are-unable to tolerate these regimens. A pilot study of cidofovir for treating PML has completed enrollment, but preliminary results showed no benefit.

CONCLUSIONS

Cidofovir may be the most reasonable treatment option for PML in HIV-infected individuals who fail to improve with HAART or who are unable to tolerate these regimens. Patients who receive cidofovir should be monitored for renal and ocular toxicity.

Human renal organic anion transporter 1 (hOAT1) and its role in the nephrotoxicity of antiviral nucleotide analogs

hOAT1 is a renal membrane protein able to efficiently transport acyclic nucleoside phosphonates (ANPs). When expressed in CHO cells, hOAT1 mediates the uptake and cytotoxicity of ANPs suggesting that it plays an active role in the nephrotoxicity associated with cidofovir CMV therapy and high-dose adefovir HIV therapy. Although efficiently transported by hOAT1, tenofovir did not show any significant cytotoxicity in isolated human proximal tubular cells, which correlates with the lack of nephrotoxicity observed in HIV-infected patients on prolonged tenofovir therapy.

Cidofovir added to HAART improves virological and clinical outcome in AIDS-associated progressive multifocal leukoencephalopathy

OBJECTIVES

To analyse the virological and clinical efficacy of cidofovir combined with highly active antiretroviral therapy (HAART) in AIDS-related progressive multifocal leukoencephalopathy (PML).

DESIGN

Multicentre observational study of consecutive HIV-positive patients with histologically or virologically-proven PML. Group A, 26 patients treated with HAART; group B, 14 patients treated with HAART plus cidofovir 5 mg/kg intravenously per week for the first 2 weeks and alternate weeks thereafter. JC virus DNA was quantified in cerebrospinal fluid (CSF) by PCR.

RESULTS

Baseline virological, immunological and clinical characteristics were homogeneous between the groups. In one case cidofovir was discontinued because of severe proteinuria. There was no significant difference in HIV RNA responses and changes in the number of CD4 cells between group A and B. After 2 months of therapy, five out of 12 (42%) patients from group A and seven out of eight (87%) from group B reached undetectable JC virus DNA in the CSF (Chi-square P = 0.04); moreover, 24% of group A and 57% of group B patients showed neurological improvement or stability (P = 0.038). One-year cumulative probability of survival was 0.67 with cidofovir and 0.31 without (log-rank test, P = 0.01). Variables independently associated with longer survival were the use of cidofovir, HAART prior to the onset of PML, a baseline JC virus DNA load in CSF < 4.7 log10 copies/ml, and a baseline Karnofsky performance status > or = 60.

CONCLUSIONS

In AIDS-related PML, cidofovir added to HAART is associated with a more effective control of JCV replication, with improved neurological outcome and survival compared with HAART alone.

Progressive Multifocal Leukoencephalopathy

Before embarking on experimental therapies for progressive multifocal leukoencephalopathy (PML), the diagnosis needs to be unequivocally established. Improving the underlying immunodeficiency state is the best initial approach to the management of PML. Immunosuppressive therapies should be discontinued when feasible. In the patient with AIDS, highly active antiretroviral therapy should be administered; this appears to prolong survival. At present, no therapy has been demonstrated to be effective in a well-designed prospective trial. Cytosine arabinoside, which has demonstrated efficacy in vitro against JC virus, has not been effective when administered intravenously or intrathecally to patients with AIDS and PML. The failure of regimens employing cytosine arabinoside in PML may have been the consequence of inadequate penetration of the drug to sites of infection in the brain. Other drugs with established in vitro activity against JC virus, such as topoisomerase and camptothecin, are poorly tolerated. The use of cidofovir in patients with AIDS and PML remains anecdotal, although it is currently under investigation. Interferon alfa may improve survival in patients with AIDS and PML and may have general applicability to PML regardless of the cause of the underlying immunodeficient state. Approximately 7% to 9% of patients with PML demonstrate prolonged survival (>12 months) and associated improvement in clinical and radiographic abnormalities in the absence of specific therapy. In patients with AIDS-related PML, prolonged survival correlates with PML as the presenting manifestation of AIDS, higher CD4 T-lymphocyte counts, and contrast enhancement of PML lesions on radiographic imaging. A brisk inflammatory response may also be associated with improved survival. The increased understanding of the pathophysiology of JC virus provides hope for the development of curative strategies. The growing number of persons affected with PML has allowed the organization of carefully designed therapeutic trials to address this issue.