Lentiviral gene therapy for X-linked chronic granulomatous disease recapitulates endogenousCYBBregulation and expression

Abstract 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. To design a lentiviral vector (LV) capable of recapitulating the endogenous regulation and expression of CYBB, a bioinformatics-guided approach was used to elucidate the cognate enhancer elements regulating the native CYBB gene. Using this approach, we analyzed a 600-kilobase topologically associated domain of the CYBB gene and identified endogenous enhancer elements to supplement the CYBB promoter to develop MyeloVec, a physiologically regulated LV for the treatment of X-CGD. When compared with an 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 Burkholderia cepacia infection, and restored healthy donor levels of antimicrobial oxidase activity in neutrophils derived from HSPCs from patients with X-CGD. Our findings validate the bioinformatics-guided design approach and have yielded a novel LV with clinical promise for the treatment of X-CGD.