Lentiviral Gene Therapy for X-Linked Chronic Granulomatous Disease Recapitulates Endogenous CYBB Regulation and Expression.

X-Linked Chronic Granulomatous Disease (X-CGD) is a primary immunodeficiency caused by mutations in the CYBB gene resulting in the inability of phagocytic cells to eliminate infections. In order to design a lentiviral vector capable of recapitulating the endogenous regulation and expression of CYBB, a bioinformatics-guided approach was utilized to elucidate the cognate enhancer elements regulating the native CYBB gene. Using this approach, we analyzed a 600 kb topologically associated domain of the CYBB gene and identified endogenous enhancer elements to supplement the CYBB promoter to develop MyeloVec, a physiologically regulated lentiviral vector (LV) for the treatment of X-CGD. When compared to a LV currently in clinical trials for X-CGD, MyeloVec showed improved expression, superior gene transfer to hematopoietic stem and progenitor cells (HSPCs), corrected an X-CGD mouse model leading to complete protection against B. cepacia infection, and restored healthy donor levels of anti-microbial oxidase activity in neutrophils derived from X-CGD patient HSPCs. Our findings validate the bioinformatics-guided design approach and have yielded a novel lentiviral vector with clinical promise for the treatment of X-CGD.