Hemophilia clinical gene therapy: brief review

2017 Clinical trials update: Innovations in hemophilia therapy

A surge in therapeutic clinical trials over recent years is paving the way for transformative treatment options for patients with hemophilia. The introduction of recombinant factor concentrates in the early 1990s facilitated the use of prophylactic replacement as standard care for hemophilia rather than on-demand treatment. This has revolutionized health outcomes for hemophilia patients, enabling participation in physical activities and reducing debilitating, chronic joint damage. Challenges of prophylactic factor infusion include the frequency of infusions needed to maintain factor levels greater than 1%, patient adherence, reliable intravenous access, and development of neutralizing alloantibodies ("inhibitors"). Novel therapeutics seek to improve upon current factor concentrates by several different mechanisms: (1) extending the half-life of circulating exogenous factor protein, (2) replacing the gene necessary for production of endogenous factor protein, (3) employing bispecific antibody technology to mimic the coagulation function of factor VIII, (4) disrupting anticoagulant proteins, such as tissue factor pathway inhibitor (TFPI) or antithrombin (AT3) with antibodies, aptamers, or RNA interference technology. Emerging treatment options may reduce the frequency of (extended half-life products) or eliminate (gene therapy) the need for scheduled factor concentrate infusions, or provide a subcutaneous administration option (bispecific antibody, AT3, and TFPI targeting therapies). In addition, the nonfactor replacement strategies provide a promising treatment option for patients with inhibitors, presently the greatest unmet medical need in hemophilia. This review highlights current and recently completed clinical trials that are driving a paradigm shift in our approach to hemophilia care for patients with and without inhibitors. Am. J. Hematol. 91:1252-1260, 2016. © 2016 Wiley Periodicals, Inc.

Comorbidities and inhibitors in adult patients with haemophilia: issues, costs and management strategies

Along with greater life expectancy in patients with haemophilia has been an increase in associated haemophilia-related (arthropathy, osteoporosis, viral infections) and age-related (cardiovascular disease, renal disease, cancer and others) comorbidities, many of which are only just emerging as the population ages. At present, experience in managing these comorbidities is limited. As the demographic shift continues, haemophilia care centres can expect to encounter more patients with greater levels of complexity. In the absence of evidence-based information to guide the management of adult patients with haemophilia, it is important that the scientific position be reviewed on a regular basis. To this end, several topics relevant to the clinical management of adult patients with haemophilia were examined in a symposium entitled Comorbidities and inhibitors in adult patients with haemophilia: issues, costs and management strategies held on 11 February 2015 in Helsinki, Finland, in conjunction with the 8th Annual Congress of the European Association for Haemophilia and Allied Disorders. This article is a summary of that event.

Current and future prospects for hemophilia gene therapy

Here we review the recent literature on Hemophilia gene transfer/therapy. Gene therapy is one of several new technologies being developed as a treatment for bleeding disorders. We will discuss current and pending clinical efforts and attempt to relate how the field is trending. In doing so, we will focus on the use of recombinant Adeno-associated viral (rAAV) vector-mediated gene transfer since all currently active trials are using this vector. Recent exciting results embody nearly 20 years of preclinical and translational research. After several early clinical attempts, therapeutic factor levels that can now be achieved reflect several modifications of the original vectors. Patterns of results are slowly starting to emerge as different AAV vectors are being tested. As with any new technology, there are drawbacks, and the potential for immune/inflammatory and oncogenic risks have emerged and will be discussed.

Preliminary study on non-viral transfection of F9 (factor IX) gene by nucleofection in human adipose-derived mesenchymal stem cells

Background. Hemophilia is a rare recessive X-linked disease characterized by a deficiency of coagulation factor VIII or factor IX. Its current treatment is merely palliative. Advanced therapies are likely to become the treatment of choice for the disease as they could provide a curative treatment.

Methods. The present study looks into the use of a safe non-viral transfection method based on nucleofection to express and secrete human clotting factor IX (hFIX) where human adipose tissue derived mesenchymal stem cells were used as target cells in vitro studies and NOD. Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice were used to analyze factor IX expression in vivo studies. Previously, acute liver injury was induced by an injected intraperitoneal dose of 500 mg/kg body weight of acetaminophen.

Results. Nucleofection showed a percentage of positive cells ranging between 30.7% and 41.9% and a cell viability rate of 29.8%, and cells were shown to secrete amounts of hFIX between 36.8 and 71.9 ng/mL. hFIX levels in the blood of NSG mice injected with ASCs transfected with this vector, were 2.7 ng/mL 48 h after injection. Expression and secretion of hFIX were achieved both in vitro cell culture media and in vivo in the plasma of mice treated with the transfected ASCs. Such cells are capable of eventually migrating to a previously damaged target tissue (the liver) where they secrete hFIX, releasing it to the bloodstream over a period of at least five days from administration.

Conclusions. The results obtained in the present study may form a preliminary basis for the establishment of a future ex vivo non-viral gene/cellular safe therapy protocol that may eventually contribute to advancing the treatment of hemophilia.

Massive exploration of perturbed conditions of the blood coagulation cascade through GPU parallelization

The introduction of general-purpose Graphics Processing Units (GPUs) is boosting scientific applications in Bioinformatics, Systems Biology, and Computational Biology. In these fields, the use of high-performance computing solutions is motivated by the need of performing large numbers of in silico analysis to study the behavior of biological systems in different conditions, which necessitate a computing power that usually overtakes the capability of standard desktop computers. In this work we present coagSODA, a CUDA-powered computational tool that was purposely developed for the analysis of a large mechanistic model of the blood coagulation cascade (BCC), defined according to both mass-action kinetics and Hill functions. coagSODA allows the execution of parallel simulations of the dynamics of the BCC by automatically deriving the system of ordinary differential equations and then exploiting the numerical integration algorithm LSODA. We present the biological results achieved with a massive exploration of perturbed conditions of the BCC, carried out with one-dimensional and bi-dimensional parameter sweep analysis, and show that GPU-accelerated parallel simulations of this model can increase the computational performances up to a 181× speedup compared to the corresponding sequential simulations.

Gene therapy for hemophilia: advancing beyond the first clinical success

PURPOSE OF REVIEW

Consistently measurable and persistent expression of circulating clotting factor activity, associated with decreased clinical bleeding, has been achieved for the first time in a hemophilia gene therapy trial. This review examines the successes and limitations of this clinical trial for hemophilia B and approaches to advance beyond this milestone.

RECENT FINDINGS

Although a self-complementary serotype 8 adeno-associated virus (scAAV8) vector approach directed factor IX expression of up to 6% in a human trial, the apparent need to suppress vector dose-dependent immune-mediated liver inflammation in some patients at the highest dose highlighted the next steps to optimize the risk-benefit of hemophilia gene therapy. The approaches being pursued include manufacturing modifications to eliminate contaminating empty vector capsids, the utilization of factor IX and factor VIII modified transgenes to improve secretion or function of the transgene product, and adjunctive pharmacologic and molecular approaches to overcome limitations imposed by naturally occurring antibodies against vectors and by the large size of the factor VIII gene.

SUMMARY

Preclinical data suggest strategies in development may build upon the first gene therapy success and achieve factor IX correction sufficient to prevent bleeding without toxicity and translate success to hemophilia A gene therapy.

Integration-deficient lentiviral vectors expressing codon-optimized R338L human FIX restore normal hemostasis in Hemophilia B mice

Integration-deficient lentiviral vectors (IDLVs) have been shown to transduce a wide spectrum of target cells and organs in vitro and in vivo and to maintain long-term transgene expression in nondividing cells. However, epigenetic silencing of episomal vector genomes reduces IDLV transgene expression levels and renders these safe vectors less efficient. In this article, we describe for the first time a complete correction of factor IX (FIX) deficiency in hemophilia B mice by IDLVs carrying a novel, highly potent human FIX cDNA. A 50-fold increase in human FIX cDNA potency was achieved by combining two mechanistically independent yet synergistic strategies: (i) optimization of the human FIX cDNA codon usage to increase human FIX protein production per vector genome and (ii) generation of a highly catalytic mutant human FIX protein in which the arginine residue at position 338 was substituted with leucine. The enhanced human FIX activity was not associated with liver damage or with the formation of human FIX-directed inhibitory antibodies and rendered IDLV-treated FIX-knockout mice resistant to a challenging tail-clipping assay. A novel S1 nuclease-based B1-quantitative polymerase chain reaction assay showed low levels of IDLV integration in mouse liver. Overall, this study demonstrates that IDLVs carrying an improved human FIX cDNA safely and efficiently cure hemophilia B in a mouse model.