Liver-directed lentiviral gene therapy corrects hemophilia A mice and achieves normal-range factor VIII activity in non-human primates

Abstract

Liver gene therapy with adeno-associated viral (AAV) vectors delivering clotting factor transgenes into hepatocytes has shown multiyear therapeutic benefit in adults with hemophilia. However, the mostly episomal nature of AAV vectors challenges their application to young pediatric patients. We developed lentiviral vectors, which integrate in the host cell genome, that achieve efficient liver gene transfer in mice, dogs and non-human primates, by intravenous delivery. Here we first compare engineered coagulation factor VIII transgenes and show that codon-usage optimization improved expression 10-20-fold in hemophilia A mice and that inclusion of an unstructured XTEN peptide, known to increase the half-life of the payload protein, provided an additional >10-fold increase in overall factor VIII output in mice and non-human primates. Stable nearly life-long normal and above-normal factor VIII activity was achieved in hemophilia A mouse models. Overall, we show long-term factor VIII activity and restoration of hemostasis, by lentiviral gene therapy to hemophilia A mice and normal-range factor VIII activity in non-human primate, paving the way for potential clinical application.

Gene therapy for urea cycle defects: An update from historical perspectives to future prospects

“…Lentiviral vectors are single‐stranded RNA vectors which release their cargo in the cytoplasm, where reverse transcription and synthesis of a second DNA strand enables nuclear migration and insertion into the genome (Figure 2). Integration carries a theoretical risk of insertional mutagenesis but has not been observed with lentiviral vectors in various preclinical models, for example, mouse, dog, and non‐human primate, following in vivo delivery 80,81 …”

Gene transfer and genome editing for familial hypercholesterolemia

“…Insertional mutagenesis remains a concern for integrating vectors. It should be noted, however, that LVmediated liver gene transfer did not result in liver carcinogenesis, even in mice treated as newborns and genetically tumor-prone or tumor-promoted, followed for long time (over 1 year) (Cantore et al, 2015;Milani et al, 2022). Moreover, analysis of LV integrations in the liver of mice, dogs, and NHPs did not show clonal expansions or enrichment of integrations near cancer genes (Cantore et al, 2015;Milani et al, 2019;Cesana et al, 2021), thus offering reassurance for a possible clinical translation.…”

Spatio-temporal dynamics of the liver shapes hepatocytes heterogeneity and impacts in vivo gene transfer and editing

“…We and others have shown that i.v. administration of lentiviral vectors (LV), which integrate into target cells' chromatin, results in stable liver gene transfer, in both small and large animal models, allowing long-term correction of hemophilia and metabolic diseases in mouse models, treated either as adults or newborns [17][18][19][20][21] . LV-mediated liver gene therapy is currently under development towards clinical testing 22 .…”