Programmed Death 1 Monoclonal Antibody Helped to Treat Mixed Chimeric and Reactivation of Epstein-Barr Virus in a Patient with Adult-onset Chronic Active Epstein-Barr Virus Infection After Allogeneic Hematopoietic Stem Cell Transplantation: A Case...

Rationale: Systemic forms of chronic active Epstein-Barr virus infection (CAEBV) can predispose a patient to a protracted course of fulminant hemophagocytic lymphohistiocytosis, which has a poor prognosis. Epstein-Barr virus (EBV) infection may persist even after theoretically curative hematopoietic stem cell transplantation.

Patient Concerns: A female patient with CAEBV underwent chemotherapy followed by allogeneic hematopoietic stem cell transplantation from her human leukocyte antigen-matched sister. Neutrophil and platelet engraftment was observed on day +12 and +10. Full donor chimerism (DC) was achieved on Day +21.

Diagnoses: From day +38, EBV-DNA in the blood was persistently positive, and DC declined. We attempted empirical interventions such as withdrawal of immune suppression, multiple donor lymphocyte infusion, stem cell boost, and interferon-α treatment. However, EBV-DNA copies continued to increase aggressively, whereas DC decreased rapidly and then reached a nadir of 63.27%.

Interventions: Salvage programmed death 1 (PD-1) antibody treatment was administered as salvage therapy at +69 and +84.

Outcomes: EBV-DNA was negative on day +97 and was ultimately undetectable. Equivalently, a full and stable DC was obtained at +97.

Lessons: We summarize a case of PD-1 antibody used as salvage treatment in a post-transplant patient with CAEBV, which was eradicated and full DC was obtained. This case suggests that the PD-1 antibody appears to be a promising option for fighting EBV and mixed DCs.