The development of inhibitory antibodies directed against human factor Vlll (h-fVIII) remains the most signiflcant clinical complication associated with the treatment of hemophilia A and is a critical barrier to gene therapy approaches. Not dissimilar to what occurs in the majority of monogenic diseases treated using protein replacement therapy, 20 - 30% of hemophilia A patients develop an immune response to the infused fVIII product that renders treatment ineffective. Therefore, the discovery and development of new methods to induce immune tolerance or hypo-responsiveness are needed. Hematopoietic stem cell transplantation (HSCT) protocols are showing promise in clinical trials for the treatment of a variety of human autoimmune disorders. Furthermore, HSCT combined with gene therapy has been shown, at least in animal models, to facilitate the introduction of and tolerance to neo or allo-antigens, such as those proteins deficient in monogenic diseases like hemophilia A. Our laboratories recently reported that transplantation of geneticallymodified HSCs containing a high-expression porcine (p)-fVIII transgene into hemophilia A mice results in the production of high levels of circulating fVlll activity. None of the recipient mice developed anti-fVlll antibodies following HSCT gene therapy, even in the context of non-myeloablative and non-radiation-based conditioning. Subsequently, we studied HSCT gene therapy in hemophilia A mice harboring anfi-hfVlll inhibitory antibody titers. Even though the majority of mice contained circulating antibodies that cross-reacted with and inhibited p-fVIII activity in vitro, transplantation of genetically-modified HSCs expressing p-fVlll into myeloablated hemophilia A mice restored circulating fVIII activity. Curative p-fVlll activity levels persisted and anti-h-fVIII antibody titers steadily declined throughout the course of the study in all mice. In contrast, the use of non-myeloablative total body irradiation (TBI) was only partially successful in promoting the engraftment of genetically-modified cells and resulted in a delayed reduction of anti-fVIII antibody titers. Therefore, pre-existing immunity presents an additional barrier to HSCT gene therapy. These data suggest that, while HSCT-based gene therapy incorporating a p-fVIII can be utilized successfully for the treatment of patients with refractory anti-hfVIII inhibitors, 1) more aggressive transplant conditioning is necessary to achieve disease correction, 2) the use of an orthologous (or other non-idenfical antigen) transgene product is critical, and 3) enduring tolerance/hyporesponsiveness can be achieved. The focus of this proposal is to develop an HSCT gene therapy strategy for the treatment of hemophilia A when complicated by inhibitors.
Gene therapy offers the potential for long-term impact on the health of patients with hemophilia A. However, the immune response to fVIII remains a significant obstacle, and existing immunity represents a formidable challenge to the development of gene therapy treatments for hemophilia. The goal of this proposal is to develop a gene therapy treatment that can be applied to patients with fVlll inhibitors.
|Brown, Harrison C; Zakas, Philip M; George, Stephan N et al. (2018) Target-Cell-Directed Bioengineering Approaches for Gene Therapy of Hemophilia A. Mol Ther Methods Clin Dev 9:57-69|
|Zhang, Yun; Qiu, Yongzhi; Blanchard, Aaron T et al. (2018) Platelet integrins exhibit anisotropic mechanosensing and harness piconewton forces to mediate platelet aggregation. Proc Natl Acad Sci U S A 115:325-330|
|Healey, J F; Parker, E T; Lollar, P (2018) Identification of aggregates in therapeutic formulations of recombinant full-length factor VIII products by sedimentation velocity analytical ultracentrifugation. J Thromb Haemost 16:303-315|
|Batsuli, G; Ito, J; Mercer, R et al. (2018) Anti-C1 domain antibodies that accelerate factor VIII clearance contribute to antibody pathogenicity in a murine hemophilia A model. J Thromb Haemost 16:1779-1788|
|Qiu, Yongzhi; Ahn, Byungwook; Sakurai, Yumiko et al. (2018) Microvasculature-on-a-chip for the long-term study of endothelial barrier dysfunction and microvascular obstruction in disease. Nat Biomed Eng 2:453-463|
|Sakurai, Yumiko; Hardy, Elaissa T; Ahn, Byungwook et al. (2018) A microengineered vascularized bleeding model that integrates the principal components of hemostasis. Nat Commun 9:509|
|Brockman, Joshua M; Blanchard, Aaron T; Pui-Yan Ma, Victor et al. (2018) Mapping the 3D orientation of piconewton integrin traction forces. Nat Methods 15:115-118|
|Hansen, Caroline E; Myers, David R; Baldwin, W Hunter et al. (2017) Platelet-Microcapsule Hybrids Leverage Contractile Force for Targeted Delivery of Hemostatic Agents. ACS Nano 11:5579-5589|
|Zerra, Patricia E; Cox, Courtney; Baldwin, W Hunter et al. (2017) Marginal zone B cells are critical to factor VIII inhibitor formation in mice with hemophilia A. Blood 130:2559-2568|
|Kahle, Joerg; Orlowski, Aleksander; Stichel, Diana et al. (2017) Frequency and epitope specificity of anti-factor VIII C1 domain antibodies in acquired and congenital hemophilia A. Blood 130:808-816|
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