Pembrolizumab in Progressive Multifocal Leukoencephalopathy (PML) in Immunocompromised Patients Without HIV Infection
This study aims to assess the efficacy and safety of pembrolizumab in immunocompromised patients with progressive multifocal leukoencephalopathy (PML). This phase II, multicenter, single-arm study includes patients with an underlying cause of immunosuppression hardly reversible, i.e. not the patients with HIV nor those receiving biologics for chronic inflammatory diseases. Patients will receive intravenous pembrolizumab (2 mg/kg, maximum 200 mg) at month 0, 1 and 2 (total of three doses). The primary endpoint will be achieving at least one negative result of JCV viral load in cerebrospinal fluid (CSF) within the M0 to M3 period.
- EligibilityCriteria: Inclusion Criteria:  Age ≥ 18 years old Diagnosis of definite PML since less than 2 months according to American Academy of Neurology Presence of JCV in the CSF in the last CSF sampling. Signed informed consent (from the patient, or if unable to consent, from a surrogate) For women of childbearing potential: negative serum or urine b-HCG test and agree to use a highly effective contraception methods during 8 months (i.e. until 6 months after end of experimental treatment)  Exclusion Criteria:  Patients in whom immune reconstitution is achievable (HIV infection - Multiple sclerosis - Auto-immune and inflammatory diseases) Patients who have received solid organ transplantation Hypersensitivity to the active substance or to any of the excipients Life expectancy less than 1 month Pregnancy or lactating women or planning birth during the study period Having previously been treated by anti-PD1mAb Patient receiving IL-2 or IL-7 for the treatment of PML at inclusion Patient whose weight is > 100kg  Participation in other interventional study [a patient already included in another interventional study for which the treatment can lead to an immunodepression can be included if:  the investigational treatment has been completed and there is no risk of drug interaction with the administration of Pembrolizumab as defined in PENALTY study if this does not alter the study's ability to evaluate the effect of Pembrolizumab in terms of safety and efficacy (from the investigator's point of view)] Patient without national health insurance, and patient on AME (state medical aid) Patient under guardianship or curatorship Patient deprived of their liberty by a judicial or administrative decision - HealthyVolunteers: No - Gender: All - MinimumAge: 18 Years - StdAgeList: Adult, Older Adult