Preclinical Optimization and Safety Studies of a New Lentiviral Gene Therapy for p47phox-Deficient Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is an inherited blood disorder that renders patients susceptible to infections and inflammation. A recent clinical trial of lentiviral gene therapy for the most frequent form of CGD, X-linked, has demonstrated stable correction over time, with no adverse events related to the gene therapy procedure. We have recently developed a parallel lentiviral vector for p47-deficient CGD (p47phoxCGD), the second most common form of this disease. Using this vector, we have observed biochemical correction of CGD in a mouse model of the disease. In preparation for clinical trial approval, we have performed standardised pre-clinical studies following Good Laboratory Practice (GLP) principles, to assess the safety of the gene therapy procedure. We report no evidence of adverse events, including mutagenesis and tumourigenesis, in human haematopoietic stem cells transduced with the lentiviral vector. Biodistribution studies of transduced human CD34+ cells indicate that the homing properties or engraftment ability of the stem cells is not negatively affected. CD34+ cells derived from a p47phoxCGD patient were subjected to an optimised transduction protocol and transplanted into immunocompromised mice. After the procedure, patient-derived neutrophils resumed NADPH oxidase production in vivo, suggesting that gene correction was successful. These studies pave the way to a first-in-man clinical trial of lentiviral gene therapy for the treatment of p47phoxCGD

The AAA+ATPase RUVBL2 is essential for the oncogenic function of c-MYB in acute myeloid leukemia

Subtype-specific leukemia oncogenes drive aberrant gene expression profiles that converge on common essential mediators to ensure leukemia self-renewal and inhibition of differentiation. The transcription factor c-MYB functions as one such mediator in a diverse range of leukemias. Here we show for the first time that transcriptional repression of myeloid differentiation associated c-MYB target genes in AML is enforced by the AAA+ ATPase RUVBL2. Silencing RUVBL2 expression resulted in increased binding of c-MYB to these loci and their transcriptional activation. RUVBL2 inhibition resulted in AML cell apoptosis and severely impaired disease progression of established AML in engrafted mice. In contrast, such inhibition had little impact on normal hematopoietic progenitor differentiation. These data demonstrate that RUVBL2 is essential for the oncogenic function of c-MYB in AML by governing inhibition of myeloid differentiation. They also indicate that targeting the control of c-MYB function by RUVBL2 is a promising approach to developing future anti-AML therapies