T-cell gene therapy for perforin deficiency corrects cytotoxicity defects and prevents hemophagocytic lymphohistiocytosis manifestations

Background: Mutations in the perforM 1 (PRF1) gene account for up to 58% of familial hemophagocytic lymphohistiocytosis syndromes. The resulting defects in effector cell cytotoxicity lead to hypercytokinemia and hyperactivation with inflammation in various organs. Objective: We sought to determine whether autologous gene corrected T cells can restore cytotoxic function, reduce disease activity, and prevent hemophagocytic lymphohistiocytosis (HLH) symptoms in in vivo models. Methods: We developed a gammaretroviral vector to transduce murine CD8 T cells in the Prfl(-/-) mouse model. To verify functional correction of Prfl(-/-) CD8 T cells in vivo, we used a lymphocytic choriomeningitis virus (LCMV) epitopetransfected murine lung carcinoma cell tumor model. Furthermore, we challenged gene-corrected and uncorrected mice with LCMV. One patient sample was transduced with a PRF1-encoding lentiviral vector to study restoration of cytotoxicity in human cells. Results: We demonstrated efficient engraftment and functional reconstitution of cytotoxicity after intravenous administration of gene-corrected Prfl(-/-) CD8 T cells into Prfl(-/-) mice. In the tumor model infusion of Prfl(-/-) gene-corrected CD8 T cells eliminated the tumor as efficiently as transplantation of wild type CD8 T cells. Similarly, mice reconstituted with gene corrected Prfl(-/-) CD8 T cells displayed complete protection from the HLH phenotype after infection with LCMV. Patients' cells showed correction of cytotoxicity in human CD8 T cells after transduction. Conclusion: These data demonstrate the potential application of T -cell gene therapy in reconstituting cytotoxic function and protection against HLH in the setting of perforM deficiency.