Intravenous Brincidofovir as an Antiviral for Treatment of Progressive Multifocal Leukoencephalopathy: A Pilot Study

Background: Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal brain infection caused by the JC virus. The JC virus is common. More than half of adults have been exposed to it. Most people do not get sick from the JC virus, but in people with weakened immune systems, it can cause PML. Brincidofovir (BCV) is an antiviral drug approved to treat smallpox. Researchers want to know if it can help people with PML. Objective: To test BCV in people with PML. Eligibility: People aged 18 years or older with PML. Design: Participants will be screened. They will have a physical exam with blood tests. They will have an imaging scan of the brain with contrast dye. They will have a lumbar puncture (spinal tap): A thin needle will be inserted into their lower back to draw out a sample of the fluid around their spinal cord. BCV will be given through a tube attached to a needle inserted into a vein. Participants will receive the drug 2 times a week for 4 weeks (this is 1 cycle). If the drug is helping them, they may have up to 3 drug cycles (12 weeks). Imaging scans, spinal taps, and other tests will be repeated after every 4 weeks of treatment. Participants will have 6 follow-up visits in 1 year after treatment ends. The imaging scan, spinal tap, and other tests will be repeated at each visit.

NCT Number	NCT07511049
Lead Sponsor	National Institute of Neurological Disorders and Stroke (NINDS)
Conditions	Progressive Multifocal Leukoencephalopathy
Enrollment	24 participants
Start Date	2026-06-05
Primary Completion	2029-12-31 (estimated)
Study Completion	2029-12-31 (estimated)
Updated on ClinicalTrials.gov	2026-07-22