Development of B-lineage predominant lentiviral vectors for use in genetic therapies for B cell disorders

Abstract

Sustained, targeted, high-level transgene expression in primary B lymphocytes may be useful for gene therapy in B cell disorders. We developed several candidate B-lineage predominant self-inactivating lentiviral vectors (LV) containing alternative enhancer/promoter elements including: the immunoglobulin Β (IgΒ) (B29) promoter combined with the immunoglobulin ν enhancer (EνB29); and the endogenous BTK promoter with or without Eν (EνBtkp or Btkp). LV-driven enhanced green fluorescent protein (eGFP) reporter expression was evaluated in cell lines and primary cells derived from human or murine hematopoietic stem cells (HSC). In murine primary cells, EνB29 and EνBtkp LV-mediated high-level expression in immature and mature B cells compared with all other lineages. Expression increased with B cell maturation and was maintained in peripheral subsets. Expression in T and myeloid cells was much lower in percentage and intensity. Similarly, both EνB29 and EνBtkp LV exhibited high-level activity in human primary B cells. In contrast to EνB29, Btkp and EνBtkp LV also exhibited modest activity in myeloid cells, consistent with the expression profile of endogenous Bruton's tyrosine kinase (Btk). Notably, EνB29 and EνBtkp activity was superior in all expression models to an alternative, B-lineage targeted vector containing the EνS.CD19 enhancer/promoter. In summary, EνB29 and EνBtkp LV comprise efficient delivery platforms for gene expression in B-lineage cells. © The American Society of Gene & Cell Therapy.