Objective: Our aim was to assess the real‐world effectiveness of immune checkpoint inhibitors for treatment of patients with progressive multifocal leukoencephalopathy (PML).Methods: We conducted a multicenter survey compiling retrospective data from 79 PML patients, including 38 published cases and 41 unpublished cases, who received immune checkpoint inhibitors as add‐on to standard of care. One‐year follow‐up data were analyzed to determine clinical outcomes and safety profile. Logistic regression was used to identify variables associated with 1‐year survival.Results: Predisposing conditions included hematological malignancy (n = 38, 48.1%), primary immunodeficiency (n = 14, 17.7%), human immunodeficiency virus/acquired immunodeficiency syndrome (n = 12, 15.2%), inflammatory disease (n = 8, 10.1%), neoplasm (n = 5, 6.3%), and transplantation (n = 2, 2.5%). Pembrolizumab was most commonly used (n = 53, 67.1%). One‐year survival was 51.9% (41/79). PML–immune reconstitution inflammatory syndrome (IRIS) was reported in 15 of 79 patients (19%). Pretreatment expression of programmed cell death‐1 on circulating T cells did not differ between survivors and nonsurvivors. Development of contrast enhancement on follow‐up magnetic resonance imaging at least once during follow‐up (OR = 3.16, 95% confidence interval = 1.20–8.72, p = 0.02) was associated with 1‐year survival. Cerebrospinal fluid JC polyomavirus DNA load decreased significantly by 1‐month follow‐up in survivors compared to nonsurvivors (p < 0.0001). Thirty‐two adverse events occurred among 24 of 79 patients (30.4%), and led to treatment discontinuation in 7 of 24 patients (29.1%).Interpretation: In this noncontrolled retrospective study of patients with PML who were treated with immune checkpoint inhibitors, mortality remains high. Development of inflammatory features or overt PML‐IRIS was commonly observed. This study highlights that use of immune checkpoint inhibitors should be strictly personalized toward characteristics of the individual PML patient. ANN NEUROL 2023;93:257–270

Despite the growing evidence supporting the existence of CNS involvement in acute and chronic graft-versus-host disease (CNS-GvHD), the characteristics and course of the disease are still largely unknown. In this multicenter retrospective study, we analyzed the clinical, biological, radiological, and histopathological characteristics, as well as the clinical course of 66 patients diagnosed with possible CNS-GvHD (pCNS-GvHD), selected by predetermined diagnostic criteria. Results were then contrasted depending on whether pCNS-GvHD occurred before or after day 100 following allogeneic hematopoietic stem cell transplantation. Median time between hematopoietic stem cell transplantation and pCNS-GvHD onset was 149 days (IQ_25–75 48-321), and pCNS-GvHD onset occurred before day 100 following transplantation in 44% of patients. The most frequent findings at presentation were cognitive impairment (41%), paresis (21%), altered consciousness (20%), sensory impairment (18%), and headache (15%). Clinical presentation did not significantly differ between patients with pCNS-GvHD occurring before or after day 100 following transplantation. Brain MRI found abnormalities compatible with the clinical picture in 57% of patients, while CT detected abnormalities in only 7%. Seven patients had documented spinal cord MRI abnormalities, all of them with pCNS-GvHD occurring after day 100 following transplantation. In the cerebrospinal fluid, white blood cell count was increased in 56% of the population (median 18 cells/μL). Histopathological analyses were performed on 12 specimens and were suggestive of pCNS-GvHD in 10. All compatible specimens showed parenchymal and perivascular infiltration by CD3+ and CD163+ cells. Immunosuppressive therapy was prescribed in 97% of patients, achieving complete clinical response in 27%, partial improvement in 47% and stable disease in 6%. Response to immunosuppressive therapy did not significantly differ between patients with pCNS-GvHD occurring before or after day 100 following transplantation. Clinical relapse was observed in 31% of patients who initially responded to treatment. One-year overall survival following pCNS-GvHD onset was 41%. Onset before day 100 following hematopoietic stem cell transplantation (HR [95%CI]: 2.1 [1.0-4.5]; P=0.041) and altered consciousness at initial presentation (HR [95%CI]: 3.0 [1.3-6.7]; P=0.0077) were associated with a reduced one-year overall survival probability. Among surviving patients, 61% had neurological sequelae. This study supports that immune-mediated CNS manifestations may occur following allo-HSCT. These can be associated with both acute and chronic GvHD and carry a grim prognosis. The clinical presentation as well as the radiological and biological findings appear variable.

Opportunistic viral infections of the central nervous system represent a significant cause of morbidity and mortality among an increasing number of immunocompromised patients. Since antiviral treatments are usually poorly effective, the prognosis generally relies on the ability to achieve timely immune reconstitution. Hence, strategies aimed at reinvigorating antiviral immune activity have recently emerged. Among these, virus-specific T-cells are increasingly perceived as a principled and valuable tool to treat opportunistic viral infections. Here we briefly discuss how to develop and select virus-specific T-cells, then review their main indications in central nervous system infections, including progressive multifocal leukoencephalopathy, CMV infection, and adenovirus infection. We also discuss their potential interest in the treatment of progressive multiple sclerosis, or EBV-associated central nervous system inflammatory disease. We finish with the key future milestones of this promising treatment strategy.