NT-I7, a Long-Acting Recombinant IL-7 Molecule, as an Immune Reconstitution Strategy for Lymphopenia in Patients With Progressive Multifocal Leukoencephalopathy

Background: Progressive multifocal leukoencephalopathy (PML) is a brain infection. It is caused by a virus. PML can happen in people with a weakened immune system. PML is associated with cognitive and visual impairment as well as motor and speech disturbances. There is no treatment for PML. Researchers want to see if a new drug can help. Objective: To see if the drug NT-I7 can help increase lymphocyte numbers, which may help control PML infection. Eligibility: Adults ages 18 and older with PML who are enrolled in Protocol #13-N-0017. Design: Participants will be screened under Protocol #13-N-0017. Participants will have a 7-day inpatient stay, outpatient visits, and follow-up phone calls. Participants will have a medical history and physical exam. They will give urine samples. Blood will be drawn from an arm vein or through an intravenous (IV) catheter. Participants will get up to 3 doses of NT-I7. It will be given by injection into the muscle. Participants will have lumbar punctures ( spinal taps ). A thin needle will be inserted into the spinal canal in the lower back. Cerebrospinal fluid will be removed. X-ray may be used to guide the procedure. Participants will have magnetic resonance imaging (MRI) of the brain. The MRI scanner is a metal cylinder surrounded by a magnetic field. During MRIs, participants will lie on a table that slides in and out of the scanner. Soft padding or a coil will be placed around their head. They will get gadolinium, a contrast agent, through an IV catheter. Participation will last for 12 to 19 months. ...