Immune checkpoint inhibitors for progressive multifocal leukoencephalopathy: a new gold standard?

Pembrolizumab for the treatment of progressive multifocal leukoencephalopathy in China

The aim of this study is to analyze the clinical characteristics and outcomes of Chinese patients with progressive multifocal leukoencephalopathy (PML) who were treated with programmed cell death protein 1 (PD1) blockade therapies. We retrospectively analyzed patients who were admitted to our hospital between October 1, 2020, and October 1, 2022, diagnosed with PML and treated with PD1 blockade therapies. Four patients with PML who were treated with PD1 blockade therapies were identified. All patients were male, and their ages ranged from 19 to 54 years old. One patient (Case 2) exhibited mild pleocytosis, while three patients (Cases 2-4) had markedly reduced T lymphocyte cell counts prior to treatment. The time interval between symptom onset and treatment initiation ranged from six to 54 weeks. All patients received pembrolizumab treatment, with a total of two to four doses administered. Three patients who responded to pembrolizumab treatment showed clinical improvement starting around 8 weeks after the initiation of therapy. Although one patient did not show clinical improvement, they ultimately survived until the last follow-up. None of the patients in this study exhibited immune-related adverse events or immune reconstitution inflammatory syndrome. PD1 blockade appears to be a promising novel therapeutic option for PML; additional prospective studies are necessary to confirm its efficacy.

Progressive multifocal leukoencephalopathy, advanced ductal breast carcinoma, systemic sclerosis, and checkpoint inhibitors: a therapeutic dilemma

Progressive multifocal leukoencephalopathy (PML) is a demyelinating central nervous system disease infection by JC virus (JCV) in patients with a significant decline in cellular immunity. No specific treatment has demonstrated efficacy, and the disease progresses to death in most patients. Recent findings have shown stabilization or improvement of PML lesions after treatment with checkpoint inhibitors (CPI) based on immune reconstitution. Nevertheless, immunotherapy may specifically cause autoimmune diseases or may deteriorate pre-existing ones. We report a case of a patient under treatment for advanced ductal breast carcinoma and systemic sclerosis, who developed PML. The therapeutic approach included withdrawal of drugs with possible immunosuppressive effect and treatment with pembrolizumab. In the absence of reliable markers to predict CPIs response and a concern for an autoimmune worsening, immunotherapy was administered late in the course of the disease. Finally, she did not experience an autoimmune disease flare-up; however, pembrolizumab could not prevent disease progression. We believe that potential autoimmune complications should not delay treatment initiation with CPIs in PML.

Impact of Anti PD-1 Immunotherapy on HIV Reservoir and Anti-Viral Immune Responses in People Living with HIV and Cancer

The role of immune checkpoints (ICPs) in both anti-HIV T cell exhaustion and HIV reservoir persistence, has suggested that an HIV cure therapeutic strategy could involve ICP blockade. We studied the impact of anti-PD-1 therapy on HIV reservoirs and anti-viral immune responses in people living with HIV and treated for cancer. At several timepoints, we monitored CD4 cell counts, plasma HIV-RNA, cell associated (CA) HIV-DNA, EBV, CMV, HBV, HCV, and HHV-8 viral loads, activation markers, ICP expression and virus-specific T cells. Thirty-two patients were included, with median follow-up of 5 months. The CA HIV-DNA tended to decrease before cycle 2 (p = 0.049). Six patients exhibited a ≥0.5 log₁₀ HIV-DNA decrease at least once. Among those, HIV-DNA became undetectable for 10 months in one patient. Overall, no significant increase in HIV-specific immunity was observed. In contrast, we detected an early increase in CTLA-4 + CD4+ T cells in all patients (p = 0.004) and a greater increase in CTLA-4+ and TIM-3 + CD8+ T cells in patients without HIV-DNA reduction compared to the others (p ≤ 0.03). Our results suggest that ICP replacement compensatory mechanisms might limit the impact of anti-PD-1 monotherapy on HIV reservoirs, and pave the way for combination ICP blockade in HIV cure strategies.

Innovative therapeutic concepts of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral disease of the brain-caused by human polyomavirus 2. It affects patients whose immune system is compromised by a corresponding underlying disease or by drugs. Patients with an underlying lymphoproliferative disease have the worst prognosis with a mortality rate of up to 90%. Several therapeutic strategies have been proposed but failed to show any benefit so far. Therefore, the primary therapeutic strategy aims to reconstitute the impaired immune system to generate an effective endogenous antiviral response. Recently, anti-PD-1 antibodies and application of allogeneic virus-specific T cells demonstrated promising effects on the outcome in individual PML patients. This article aims to provide a detailed overview of the literature with a focus on these two treatment approaches.

Promise and Challenges of Checkpoint Inhibitor Therapy for Progressive Multifocal Leukoencephalopathy in HIV

PURPOSE OF REVIEW

Progressive multifocal leukoencephalopathy (PML) is a severe opportunistic infection that remains an important cause of morbidity and mortality in people living with HIV (PLWH). Immune checkpoint molecules are negative regulators of the immune response that have been targeted as a strategy to bolster anti-viral immunity in PML, with varied outcomes reported. While initiation and optimization of antiretroviral therapy remains the standard of care in HIV-related PML, the specific opportunities and risks for checkpoint blockade in these cases should be explored.

RECENT FINDINGS

As of April 15, 2022, only 5 of the 53 total published cases of PML treated with checkpoint blockade had underlying HIV infection; four of these had a favorable outcome. The risk of promoting immune reconstitution inflammatory syndrome is a major concern and underscores the importance of patient selection and monitoring. Checkpoint blockade warrants further exploration as a potentially promising option for treatment escalation in HIV-related PML.

Advances in Treatment of Progressive Multifocal Leukoencephalopathy

Progressive multifocal encephalopathy (PML) is a severe demyelinating disease of the central nervous system (CNS) caused by JC virus (JCV), which occurs in immunocompromised individuals. Management of PML relies on restoration of immunity within the CNS. However, when this restoration cannot be readily achieved, PML has a grim prognosis. Innovative strategies have shown promise in promoting anti‐JCV immune responses, and include T‐cell adoptive transfer or immune checkpoint inhibitor therapies. Conversely, management of immune reconstitution inflammatory syndrome, particularly in iatrogenic PML, remains a major challenge. In this paper, we review recent development in the treatment of PML. ANN NEUROL 2021;90:865–873

Immune checkpoint inhibitors for progressive multifocal leukoencephalopathy: Identifying relevant outcome factors

INTRODUCTION

Progressive multifocal leukoencephalopathy (PML) is an infectious brain disease caused by JC virus in immunocompromised individuals. Immune checkpoint inhibitors (ICIs) recently emerged as a therapeutic hope for these patients but identification of those likely to respond to the treatment is still an unmet need.

METHOD

We performed a systematic PubMed search for reports of patients treated for PML using an ICI. Clinical, biological and radiological characteristics were contrasted between patients who responded to the treatment (RP) and those who did not (NRP).

RESULTS

Thirty-five patients were included in the present study. Twenty-one of them reportedly benefited from the treatment. Age, blood CD4+ cells count, pretreatment viral load in the cerebrospinal fluid (CSF), PML lesions localization, treatment delay since first PML symptoms, type of ICI used and immune-related adverse events (irAEs) occurrence did not significantly differ between RP and NRP. By contrast, a history of therapeutic immune suppression and the use of an immunosuppressive therapy at treatment initiation were significantly associated with a poor response. Besides, reaching an undetectable viral load in the CSF and reduction of the lesion load on magnetic resonance imaging after ICI administration was associated with a good clinical response.

CONCLUSION

Current data suggest that patients with PML under immunosuppressive therapy are less likely to respond to ICIs and raises the issue of the optimal management of irAEs during ICI treatment in this setting.

Pembrolizumab for treatment of progressive multifocal leukoencephalopathy in primary immunodeficiency and/or hematologic malignancy: a case series of five patients

Progressive multifocal leukoencephalopathy is a rare opportunistic infection of the brain by John Cunningham polyomavirus in immune-compromised patients. In cases where no overt option for immune reconstitution is available [e.g., in patients with primary immunodeficiency (PID)], the disease is lethal in the majority of patients. Immune checkpoint inhibition has been applied in recent years with mixed outcomes. We present four novel patients and the follow-up of a previously published patient suffering from progressive multifocal leukoencephalopathy (PML) due to PID and/or hematologic malignancy who were treated with the immune checkpoint inhibitor pembrolizumab. In two patients with PID, symptoms improved and stabilized. One patient died because of worsening PML another of intracranial hemorrhage which was unrelated to PML or its treatment with pembrolizumab. The fifth patient suffered from PID and died of a pre-existing immune dysregulation, possibly exacerbated by pembrolizumab. The long-term follow-up of the first patient provides support for therapeutic decisions during this therapy and is the longest published clinical course of a patient with checkpoint inhibition for PML. We conclude that pembrolizumab can control PML symptoms long term in a subgroup of patients with PID, in our cases for 21 and 36 months. However, therapy must be started early because symptoms are only partially reversible. In light of severe adverse events, application of pembrolizumab is only justified if the prognosis for the individual patient is very poor.