Location: Dairy and Functional Foods ResearchTitle: Enhancing therapeutic efficacy of in vivo platelet-targeted gene therapy in hemophilia A
|XUEFENG, WANG - Seattle Children'S Research Institute|
|FU, RICHARD - Seattle Children'S Research Institute|
|CHEN, CHUN-YU - Seattle Children'S Research Institute|
|KONKLE, BARBARA - Bloodworks Northwest|
|ZHANG, JUNPING - Indiana University|
|LI, LEI - Georgia State University|
|XIAO, WEIDONG - Indiana University|
|PONCZ, MORTIMER - Children'S Hospital - Philadelphia, Pennsylvania|
|MIAO, CAROL - Seattle Children'S Research Institute|
Submitted to: Blood Advances
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2020
Publication Date: 11/20/2020
Citation: Xuefeng, W., Fu, R., Chen, C., Firrman, J., Konkle, B., Zhang, J., Li, L., Xiao, W., Poncz, M., Miao, C. 2020. Enhancing therapeutic efficacy of in vivo platelet-targeted gene therapy in hemophilia A. Blood Advances. Volume 4, Issue 22, Pages 5722–5734.
Interpretive Summary: Hemophilia A is a disease caused by a defect in the FVIII protein that results in uncontrolled bleeding. This disease can be treated by giving a patient FVIII protein that functions normally but is sometimes complicated by an immune response that targets the FVIII protein and renders it useless. Here, we found that it was possible to treat hemophilia A in mice by injecting a virus (Lentivirus) into the bone marrow, which was then able to enter specific blood cells (platelets) and produce an engineered version of FVIII that could function normally and not cause an immune response. The novel results of this study demonstrate a new way to treat Hemophilia A that may be beneficial for patients who already have an active immune response against the FVIII protein.
Technical Abstract: Our previous studies demonstrated that intraosseous (IO) infusion of lentiviral vectors (LVs) carrying a modified B-domain deleted factor VIII (FVIII) transgene driven by a megakaryocyte-specific promoter (GP1Ba promoter; G-F8/N6-LV) successfully transduced hematopoietic stem cells (HSCs) to produce FVIII stored in the platelet a-granules. Platelet-FVIII corrected the bleeding phenotype with limited efficacy in hemophilia A (HemA) mice with and without pre-existing anti-FVIII inhibitors. The present study sought to further enhance the therapeutic efficacy of this treatment protocol by increasing both the efficiency of LV transduction and functional activity of platelet-FVIII. A combined drug regimen of dexamethasone and anti-CD8a monoclonal antibody enhanced the percentage of transduced bone marrow and HSCs over time. In G-F8/N6-LV treated HemA mice, significant improvement in phenotypic correction was observed on day 84. To improve platelet-FVIII functionality, genes encoding FVIII variant, F8X10K12 with increased expression or F8N6K12RH with increased functional activity compared to F8/N6 were incorporated into LVs. Treatment with G-F8X10K12-LV in HemA mice produced a higher level of platelet-FVIII however induced anti-FVIII inhibitors. Following treatment with combined drugs and IO infusion of G-F8/N6K12RHLV, HemA mice showed significant phenotypic correction without anti-FVIII inhibitor formation. These results indicated that new human FVIII variant F8/N6K12RH combined with immune suppression could significantly enhance therapeutic efficacy of in vivo platelet targeted gene therapy of murine HemA via IO delivery. This protocol can provide a safe and effective treatment of hemophilia that may be translatable and particularly beneficial for patients with pre-existing inhibitory antibodies to FVIII.