Epstein-Barr Virus positive post-transplant lymphoproliferative disorders: identifying viral and host variables to predict risk and develop novel management strategies - PROJECT SUMMARY/ABSTRACT Post-transplant lymphoproliferative disorder (PTLD) is the second most common cancer and a leading cause of death in solid-organ transplant recipients. Most PTLD cases are associated with Epstein-Barr virus (EBV), a highly prevalent oncogenic virus. Our limited understanding of PTLD risk, inadequate monitoring strategies, and lack of therapeutic options undermine our ability to address PTLD-associated morbidity and mortality. While we have identified a limited number of PTLD risk factors, these factors are insufficient to predict which patients are at greatest risk. Understanding the specific factors driving PTLD risk and development remains an unmet need required to monitor high risk patients and prevent PTLD development. We hypothesize that disruptions in the balance between host T follicular helper, T regulatory (Treg), cytotoxic T lymphocytes and T follicular cytotoxic lymphocyte subsets, and their associated cytokines, IFN-γ and TGF-β, create a permissive environment for EBV lytic reactivation and B-cell transformation and that these disruptions can be leveraged as predictive biomarkers and therapeutic targets for patients with PTLD. To test this, human samples and a chimeric human-mouse model of EBV driven lymphoproliferative disorder (hu-PBL-SCID) will be utilized. Blood samples from patients who developed PTLD and samples from patients who failed to develop PTLD will be analyzed with a custom spectral flow cytometry panel allowing for the investigation of the indicated immune cell subsets and their relationship to PTLD development. Additionally, a novel and rapid EBV DNA methylation assay will be used to characterize the EBV epigenetic profile in cell-free DNA in the plasma of patients with PTLD and those without PTLD. This assay can distinguish lytic (infectious) from various latent viral states and offers valuable diagnostic information to identify PTLD early. Methylation profiles from plasma and, when available, PTLD tumor biopsies, will be compared to clinical state and contribute toward biomarker development. All epigenetic and immunophenotypic data will be correlated with clinical outcomes to identify biomarkers that predict PTLD risk. Finally, based on preliminary data showing the importance of Tregs in preclinical and clinical studies of EBV driven lymphoproliferative disease, the hu-PBL-SCID model will be treated with a novel monoclonal antibody able to reduce Treg quantity and levels of the Treg associated cytokine, TGF-β. Spectral flow cytometry and methylation studies will be performed on murine samples and survival will be analyzed to explore if treatment is able to diminish PTLD driving subsets and prevent disease. This project holds potential to shed light on PTLD pathogenesis and identify risk factors and therapeutic targets.
