Participants will receive a single injection of the imaging agent, followed by a series of imaging sessions that combine PET and CT scans to look at the transplanted kidney, nearby lymph nodes, spleen, liver and bone marrow. A small blood sample will also be taken to measure immune cells using a laboratory technique called flow cytometry. The study lasts for a short period of time after the injection, during which the imaging and blood tests are performed to assess the distribution of the agent and the activity of immune cells.

The study aims to determine if RLS-0071 is safe and effective for treating this condition. Patients will receive different doses of RLS-0071 over a period of up to 14 days. Some patients will also receive another medication called ruxolitinib as part of their treatment. The treatment will be given to patients while they are in the hospital.

During the study, doctors will monitor how well patients respond to the treatment by checking their symptoms, particularly those affecting the skin, liver, and digestive system. They will also track changes in the patients’ condition for up to 180 days after starting treatment. The study will measure various aspects of patient recovery, including pain levels, ability to eat, and overall well-being.

The study is planned in two parts. In the first part, maribavir is taken for about 6 months. If the virus level drops but does not fall enough, treatment may continue for about 3 more months. During the study, the health of the participants and the amount of virus in the body are followed over time, along with whether the virus comes back after treatment is stopped.

Epstein-Barr virus is a common virus that can stay active in the body after infection. In people who have had a kidney transplant, the immune system is weakened to protect the new organ, and this can make it harder to control the virus. Maribavir is an antiviral medicine, which means it is designed to stop a virus from making more copies of itself.