Hematopoietic Tumors in a Mouse Model of X-linked Chronic Granulomatous Disease after Lentiviral Vector-Mediated Gene Therapy

Abstract

Chronic granulomatous disease (CGD) is a rare inherited disorder due to loss-of-function mutations in genes encoding the NADPH oxidase subunits. Hematopoietic stem and progenitor cell (HSPC) gene therapy (GT) using regulated lentiviral vectors (LVs) has emerged as a promising therapeutic option for CGD patients. We performed non-clinical Good Laboratory Practice (GLP) and laboratory-grade studies to assess the safety and genotoxicity of LV targeting myeloidspecific Gp91 phox expression in X-linked chronic granulomatous disease (XCGD) mice. We found persistence of gene-corrected cells for up to 1 year, restoration of Gp91 phox expression and NADPH oxidase activity in XCGD phagocytes, and reduced tissue inflammation after LV-mediated HSPC GT. Although most of the mice showed no hematological or biochemical toxicity, a small subset of XCGD GT mice developed T cell lymphoblastic lymphoma (2.94%) and myeloid leukemia (5.88%). No hematological malignancies were identified in C57BL/6 mice transplanted with transduced XCGD HSPCs. Integration pattern analysis revealed an oligoclonal composition with rare dominant clones harboring vector insertions near oncogenes in mice with tumors. Collectively, our data support the long-term efficacy of LV-mediated HSPC GT in XCGD mice and provide a safety warning because the chronic inflammatory XCGD background may contribute to oncogenesis.

Hematopoietic stem cell gene therapy ameliorates CNS involvement in murine model of GM1-gangliosidosis

“… 39 Recently, reports of the long-term efficacy of LV-mediated GT in XCGD mouse models have demonstrated that the clinical background of the original disease may play an important role in carcinogenicity rather than random integration. 40 In addition, recent reports of leukemia after gene therapy for sickle cell disease have proposed that it was not due to the conditioning regimen busulfan or the insertional mutagenesis, but was caused by preexisting premalignant clones that were expanded by the stress of gene therapy. This genotoxicity is a very important issue, and we will conduct further evaluation and analysis of the integration sites and any preexisting premalignant characteristics in our future studies.…”

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

“…It is worth highlighting that CGD mice suffer from underlying pre-existing inflammation, a condition which, according to a recent report, can increase tumor incidence in gene therapy settings. 21 Notably, our in vivo study was performed on the p47 phox CGD mouse model.…”

Gene Editing for Inherited Red Blood Cell Diseases

“…Unfortunately, uncontrolled cell proliferation resulting in pre-leukemic or leukemic events has been recently reported in patients transplanted with lentivirally corrected T cells ( Fraietta et al, 2018 ) and HSPCs ( Jofra Hernández et al, 2021 ). This point should be carefully studied in the case of patients affected with hemoglobinopathies, especially SCD, and treated with lentiviral gene therapy ( Goyal et al, 2021 ).…”