Codon optimization of human factor VIII cDNAs leads to high-level expression

Blood ◽  
2011 ◽  
Vol 117 (3) ◽  
pp. 798-807 ◽  
Author(s):  
Natalie J. Ward ◽  
Suzanne M. K. Buckley ◽  
Simon N. Waddington ◽  
Thierry VandenDriessche ◽  
Marinee K. L. Chuah ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Viral Vectors ◽  
Hemophilia A ◽  
Lentiviral Vector ◽  
Wild Type ◽  
Fviii Activity ◽  
Human Factor Viii

Abstract Gene therapy for hemophilia A would be facilitated by development of smaller expression cassettes encoding factor VIII (FVIII), which demonstrate improved biosynthesis and/or enhanced biologic properties. B domain deleted (BDD) FVIII retains full procoagulant function and is expressed at higher levels than wild-type FVIII. However, a partial BDD FVIII, leaving an N-terminal 226 amino acid stretch (N6), increases in vitro secretion of FVIII tenfold compared with BDD-FVIII. In this study, we tested various BDD constructs in the context of either wild-type or codon-optimized cDNA sequences expressed under control of the strong, ubiquitous Spleen Focus Forming Virus promoter within a self-inactivating HIV-based lentiviral vector. Transduced 293T cells in vitro demonstrated detectable FVIII activity. Hemophilic mice treated with lentiviral vectors showed expression of FVIII activity and phenotypic correction sustained over 250 days. Importantly, codon-optimized constructs achieved an unprecedented 29- to 44-fold increase in expression, yielding more than 200% normal human FVIII levels. Addition of B domain sequences to BDD-FVIII did not significantly increase in vivo expression. These significant findings demonstrate that shorter FVIII constructs that can be more easily accommodated in viral vectors can result in increased therapeutic efficacy and may deliver effective gene therapy for hemophilia A.

Phenotypic Correction of Adamts13-Deficient Mice by Early Intra-Amniotic Gene Transfer of Lentiviral Vector Encoding ADAMTS13 Genes.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 197-197
Author(s):  
Masami Niiya ◽  
Masayuki Endo ◽  
Philip W. Zoltick ◽  
Nidal E. Muvarak ◽  
David G. Motto ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Gene Transfer ◽  
Proteolytic Activity ◽  
Lentiviral Vector ◽  
Wild Type ◽  
Occlusion Time ◽  
Carboxyl Terminal ◽  
Human Wild Type

Abstract ADAMTS13, a member of A Disintegrin and Metalloprotease with ThromboSpondin type 1 repeats (ADAMTS) family, is mainly synthesized in the hepatic stellate cells, endothelial cells and megakaryocytes or platelets. It controls the sizes of von Willebrand factor (VWF) multimers by cleaving VWF at the Tyr1605-Met1606 bond. Genetic deficiency of plasma ADAMTS13 activity results in hereditary thrombotic thrombocytopenic purpura (TTP), also named Upshaw-Schülman syndrome. To develop a potential gene therapy approach and to determine the domains of ADAMTS13 required for recognition and cleavage of VWF in vivo, a self-inactivating lentiviral vector encoding human wild-type ADAMTS13 or variant truncated after the spacer domain (construct MDTCS) was administrated by intra-amniotic injection on embryonic day 8. Direct stereomicroscopy and immunofluorescent microscopic analysis revealed that the green fluorescent protein (GFP) reporter, ADAMTS13 and MDTCS were predominantly expressed in the heart, kidneys and skin. The synthesized ADAMTS13 and truncated variant were detectable in mouse plasma by immunoprecipitation and Western blot, as well as by proteolytic cleavage of FRETS-VWF73 substrate. The levels of proteolytic activity in plasma of mice expressing ADAMTS13 and MDTCS were 5 ± 7% and 60 ± 70%, respectively using normal human plasma as a standard, and this proteolytic activity persisted for at least 24 weeks in Adamts13−/−mice and 42 weeks in wild-type mice tested (the duration of observation). The mice expressing both recombinant ADAMTS13 and MDTCS showed a significantly decreased ratio of plasma VWF collagen-binding activity to antigen and a reduction in VWF multimer sizes as compared to those in the controls. Moreover, the mice expressing ADAMTS13 and MDTCS showed a significant prolongation of ferric chloride-induced carotid arterial occlusion time (9.0 ± 0.6 and 25.2 ± 3.2 min, respectively) as compared to the Adamts13−/− mice expressing GFP alone (5.6 ± 0.5 min) (p<0.01). The ferric chloride-induced carotid occlusion time in Adamts13−/− mice expressing ADAMTS13 was almost identical to that in wild type mice with same genetic background (C56BL/6) (8.0 ± 0.2 min) (p>0.05). The data demonstrate the correction of the prothrombotic phenotype in Adamts13−/−mice by gene transfer to the fetus by viral vectors encoding human wild type ADAMTS13 and the carboxyl terminal truncated variant (MDTCS), supporting the feasibility of developing a gene therapy based treatment for hereditary TTP. The discrepancy in the proteolytic activity of MDTCS between in vitro (Zhang P et al. Blood, 2007 in press) and in vivo in the present study suggests the potential cofactors in murine circulation that may rescue the defective proteolytic activity of the carboxyl-terminal truncated ADAMTS13 protease seen in vitro.

Development And Application Of A Minimal-Adenoviral Vector System For Gene Therapy Of Hemophilia A

1999 ◽  
Vol 82 (08) ◽  
pp. 562-571 ◽  
Author(s):  
Steven Josephs ◽  
Jiemin Zhou ◽  
Xiangming Fang ◽  
Ramón Alemany ◽  
Cristina Balagué ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Human Factor ◽  
Hemophilia A ◽  
Vector System ◽  
High Level Expression ◽  
Viral Particles ◽  
Human Factor Viii ◽  
High Level

IntroductionHemophilia A and B are the most common bleeding disorders caused by deficiencies of clotting factors VIII and IX, respectively, both of which are X-linked with a recessive heredity.1 Replacement of the deficient factors with frequent intravenous injections of plasma concentrates or recombinant proteins is the standard treatment for these diseases.2 Great efforts have been made for nearly a decade toward developing experimental gene therapy for these diseases and aiming at the development of a medical intervention that is more effective and convenient than the currently available replacement therapies.3 Hemophilia is a suitable clinical model for the development of gene therapy products and has a number of advantages: 1) there is a simple and well defined cause-and-effect relationship between the protein deficiencies and bleeding symptoms; 2) tissue-specific expression and precise regulation of the transgenes are not necessary; 3) well characterized animal models are available for preclinical studies; 4) an unequivocal endpoint for product efficacy can be assessed in clinical trials; and 5) even 1% to 5% of the normal physiological levels of the proteins is therapeutic.For gene therapy of hemophilia, the most challenging hurdle, with respect to the long-term expression of the deficient proteins at adequate levels, is the development of a suitable gene delivery system. Technologies have been evolving from ex vivo to in vivo approaches, from initial use of retroviral vector to recent application of adenviral (Ad) or adeno-associated virus (AAV) vector, demonstrating progress from early results of transient low-level expression to more sustained high-level expression.3 For hemophilia A treatment, Ad vectors are particularly useful, since the liver naturally produces factor VIII, and following intravenous (i.v.) injection, Ad vectors concentrate in the liver. This makes the gene transduction efficiency to liver very high. Adenovirus vectors have been developed for gene therapy due to their high titer, broad infectivity, potential for large payload, and in vivo gene delivery capacity.4 Although the immunogenicity and cytotoxicity associated with the early-generation Ad vectors have been a concern with respect to their clinical application, newly developed vectors, in which the viral coding sequences have been deleted, have significantly reduced the side effects associated with the vectors. The “gutless” Ad vector, or so called helper-dependent, large-capacity, or mini- Ad vectors are the representative examples of these new-generation Ad vectors.5-15 The mini-Ad vector system described in this report was developed based on two major research findings. First, an Ad- SV40 hybrid virus discovered during attempts to grow human Ad in non-permissive monkey COS-7 cells.16 The hybrid virus had a genome structure in which only both ends of the Ad sequences were retained and almost all coding sequences of the Ad genome were replaced by symmetric, tandemly repeated SV40 genomes. The hybrid viruses replicated and were packaged in the presence of a wild-type Ad as a helper. This finding implied that total replacement of the Ad genome was possible to form a mini-Ad vector as long as proper helper function and selective pressure was provided. Secondly, it was discovered that Ad packaging can be attenuated by deleting portions of the packaging signal.17 This finding provided a means to put selective pressure on the helper Ad (referred to as ancillary Ad) by specifically limiting its packaging process and allowing a preferential packaging of the mini-Ad. The system, therefore, is designed to have three main components: the mini-Ad vector, the E1-deleted ancillary Ad, and a production cell line that provides AdE1 complementation.Based on the mini-Ad vector system, MiniAdFVIII was developed. The MiniAdFVIII vector carries a 27 kb expression cassette, in which the full-length human factor VIII cDNA is flanked by a human albumin promoter and cognate genomic sequences. Infection of MiniAdFVIII in vitro showed that the vector mediated expression of functional human factor VIII at levels of 100-200 ng/106 cells per 24 hours in HepG2 and 293 cells. With single-dose intravenous injection of 1011 viral particles in hemophilic mice, MiniAdFVIII produced a sustained high-level expression of human factor VIII (at 100-800 ng/ml for up to 369 days) that corrected the factor VIII-deficient phenotype. Safety studies of MiniAdFVIII showed that there were no significant toxicities in mice and dogs after a single intravenous dose of up to 3×1011 and 6×1012 viral particles, respectively. In this report, other studies for developing the MiniAdFVIII vector with a site-specific integration capability and the development of a human factor VIII-tolerized mouse model for preclinical studies of MiniAdFVIII are described.

Expression of therapeutic levels of factor VIII in hemophilia A mice using a novel adeno/adeno-associated hybrid virus

2004 ◽  
Vol 92 (08) ◽  
pp. 317-327 ◽  
Author(s):  
Dmitri Gnatenko ◽  
Yong Wu ◽  
Jolyon Jesty ◽  
Andrea Damon ◽  
Patrick Hearing ◽  
...  
Keyword(s):  
Factor Viii ◽  
Quantitative Pcr ◽  
Hemophilia A ◽  
High Titer ◽  
Small Nuclear Rna ◽  
Genomic Integration ◽  
Novel Approach ◽  
Fviii Activity

SummaryWe have generated an E1a/E1b/E3-deleted adeno/adeno-associated (Ad/AAV) hybrid virus driven by a small nuclear RNA (pHU1-1) promoter for expression of a B domain-deleted (Thr761-Asn1639) factor VIII transgene (FVIIIΔ761-1639). Productive replication of Ad/AAV/FVIIIΔ761-1639 in AAV repexpressing cells resulted in generation of monomeric and dimeric mini-adenoviral (mAd) replicative forms that retained the AAV integration elements (mAd/FVIIIΔ761-1639). In vitro studies using Ad/AAV/FVIIIΔ761-1639 generated ∼2-logs greater FVIII activity than mAd/FVIIIΔ761-1639. To determine its capacity for in vivo excision and/or genomic integration, Ad/AAV/FVIIIΔ761-1639 was injected by tail vein into three groups of hemophilia A mice (2 X 1011 vp [n = 3]; 4 X 1011 vp [n = 3]; 8 X 1011 vp [n = 3]), with clear concentration-dependent increase in FVIII activity (range 160-510 mU/ml; plasma activity 16% – 51% of normal). Peak activity was seen by Day (D) 5, with slow return to baseline by D28 (0.1 – 0.9% activity); in only 3/9 mice was loss of FVIII activity associated with development of anti-FVIII antibodies. Quantitative-PCR using genomic DNA isolated from D28 liver, spleen, heart, lungs, and kidney demonstrated the highest concentration in liver (∼10 genomes/ cell), with little to no organ toxicity at early (D5 or 6) or late (D28) post-infusion time points. There was no evidence for spontaneous transgene excision or genomic integration in vivo as evaluated by quantitative PCR and genomic blotting. These data establish (i) the feasibility and applicability of developing high-titer Ad/AAV hybrid viruses for FVIII delivery using a small cellular promoter, (ii) the potential utility of this virus for generation of “gutted” monomeric and dimeric mAD/FVIII retaining AAV integration elements, and (iii) that the development of strategies for regulated Rep68/78 co-expression may provide a novel approach for excision, integration, and long-term FVIII transgene expression.

Evaluation of an Adenoviral Vector Encoding Full-Length Human Factor VIII in Hemophiliac Mice

1999 ◽  
Vol 81 (02) ◽  
pp. 234-239 ◽  
Author(s):  
Sheila Connelly ◽  
Julie Andrews ◽  
Angela Gallo-Penn ◽  
Luigina Tagliavacca ◽  
Randal Kaufman ◽  
...  
Keyword(s):  
Factor Viii ◽  
Adenoviral Vector ◽  
Human Factor ◽  
Hemophilia A ◽  
Adenoviral Vectors ◽  
Full Length ◽  
Human Factor Viii ◽  
Immunohistochemical Analyses

SummaryAdenoviral vectors provide a promising gene therapy system for the treatment of hemophilia A. Potent vectors encoding a human factor VIII (FVIII) cDNA were developed that mediated sustained FVIII expression in normal and hemophiliac mice and complete phenotypic correction of the bleeding disorder in hemophiliac mice and dogs (Connelly and Kaleko, Haemophilia 1998; 4: 380-8). However, these studies utilized vectors encoding a truncated version of the human FVIII cDNA lacking the B-domain (BDD FVIII). In this work, an adenoviral vector encoding the human full-length (FL) FVIII cDNA was generated and characterized. While functional FL FVIII was secreted in vitro, expression of the FL protein was not detected in the plasma of vector-treated hemophiliac mice. Unexpectedly, the FL FVIII vector-treated animals demonstrated phenotypic correction of the bleeding defect as measured by a tail-clip survival study. FL FVIII protein was visualized in the mouse livers using human FVIII-specific immunohistochemical analyses. These data demonstrate that adenoviral vector-mediated in vivo expression of BDD FVIII is more efficient than that of the FL protein and that phenotypic correction can occur in the absence of detectable levels of FVIII.

Bioengineering of coagulation factor VIII for improved secretion

Blood ◽  
2004 ◽  
Vol 103 (9) ◽  
pp. 3412-3419 ◽  
Author(s):  
Hongzhi Z. Miao ◽  
Nongnuch Sirachainan ◽  
Lisa Palmer ◽  
Phillip Kucab ◽  
Michael A. Cunningham ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Hemophilia A ◽  
Coagulation Factor ◽  
Mrna Levels ◽  
Golgi Transport ◽  
Recombinant Fviii ◽  
Therapy Strategies

Abstract Factor VIII (FVIII) functions as a cofactor within the intrinsic pathway of blood coagulation. Quantitative or qualitative deficiencies of FVIII result in the inherited bleeding disorder hemophilia A. Expression of FVIII (domain structure A1-A2-B-A3-C1-C2) in heterologous mammalian systems is 2 to 3 orders of magnitude less efficient compared with other proteins of similar size compromising recombinant FVIII production and gene therapy strategies. FVIII expression is limited by unstable mRNA, interaction with endoplasmic reticulum (ER) chaperones, and a requirement for facilitated ER to Golgi transport through interaction with the mannose-binding lectin LMAN1. Bioengineering strategies can overcome each of these limitations. B-domain-deleted (BDD)-FVIII yields higher mRNA levels, and targeted point mutations within the A1 domain reduce interaction with the ER chaperone immunoglobulin-binding protein. In order to increase ER to Golgi transport we engineered several asparagine-linked oligosaccharides within a short B-domain spacer within BDD-FVIII. A bioengineered FVIII incorporating all of these elements was secreted 15- to 25-fold more efficiently than full-length FVIII both in vitro and in vivo. FVIII bioengineered for improved secretion will significantly increase potential for success in gene therapy strategies for hemophilia A as well as improve recombinant FVIII production in cell culture manufacturing or transgenic animals. (Blood. 2004;103: 3412-3419)

scholarly journals The Factor VIII Variant X5 Enhances Hemophilia a Gene Therapy Efficiency By Its Improved Secretion

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3356-3356
Author(s):  
Franziska Horling ◽  
Johannes Lengler ◽  
Wenjing Cao ◽  
Biao Dong ◽  
Bagirath Gangadharan ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Liver Cell ◽  
Human Liver ◽  
Hemophilia A ◽  
Employment Equity ◽  
Fviii Activity ◽  
Human Liver Cell ◽  
Equity Ownership

Introduction. Adeno-associated virus (AAV)-based factor VIII (FVIII) gene therapy holds great promise to provide clinical benefit in patients with hemophilia A. However, very high doses are currently needed to achieve therapeutic factor levels and the durability appears to be limited to a couple of years. Vector efficiency could be improved by employing more potent liver-specific promoters, but this might come at the price of overstraining the cellular protein folding capacity, causing FVIII to misfold in the lumen of the Endoplasmic Reticulum (ER). This event would in turn activate the unfolded protein response, cause oxidative stress, and if not resolved may even induce cell death. Aims. The objective of the presented study was to test whether the B-domain deleted (BDD)-FVIII-X5 variant can overcome the secretion challenge of high level FVIII expression in the context of hepatic gene therapy. Methods. The human FVIII variant BDD-FVIII-X5 harboring 5 amino acid exchanges in the A1 domain was previously isolated in a screen aimed at identifying those residues in porcine FVIII that are critical for efficient secretion. BDD-FVIII and BDD-FVIII-X5 were produced in Chinese Hamster Ovary (CHO) cells and purified to apparent homogeneity using standard procedures. The preparations were assayed for total protein by UV absorbance at 280 nm and FVIII activity by a chromogenic assay. Both FVIII variants were vectorized using AAV8 and tested in the human liver cell line HepG2 and FVIII knockout mice (E17) at various doses. Resulting samples were assayed for FVIII chromogenic activity. The potential immunogenic risk was evaluated in three hemophilic mouse strains (E17, human FVIII transgenic, humanized HLA-DRB1*1501). Results. A characterization of purified recombinant Refacto-like BDD-FVIII and the corresponding X5 variant revealed similarity of the two proteins and their specific activities in particular, indicating that introduction of the 5 amino acids from porcine FVIII did not alter functionality of human BDD-FVIII. In vitro expression of BDD-FVIII-X5 in a human liver cell line resulted in substantially increased FVIII activity levels in the supernatant compared with the non-modified BDD-FVIII, commensurate with enhanced secretion of the X5 variant. Intravenous delivery of liver-targeted AAV8 vectors carrying the BDD-FVIII-X5 transgene achieved substantial increases in plasma coagulation activity over BDD-FVIII in FVIII-deficient mice, even when highly efficient codon-optimized F8 nucleotide sequences were employed. Evaluation of the immunogenicity of the BDD-FVIII-X5 variant by an immunological risk assessment did not reveal any increased immunogenic risk compared to BDD-FVIII. Conclusions: The fully active BDD-FVIII-X5 variant demonstrated improved secretion in vitro and in vivo, resulting in substantially higher FVIII levels in a hemophilia A mouse model. No signs of enhanced immunogenicity were noted in a comparative immunogenicity study. The results obtained warrant further exploration of the BDD-FVIII-X5 variant for a next generation hemophilia A gene therapy. Disclosures Horling: Baxalta Innovations GmbH, a Takeda company: Employment. Lengler:Baxalta Innovations GmbH, a Takeda company: Employment. Gangadharan:Baxalta Innovations GmbH, a Takeda company: Employment. De La Rosa:Baxalta Innovations GmbH, a Takeda company: Employment, Equity Ownership. Hoellriegl:Baxalta Innovations GmbH, a Takeda company: Employment, Equity Ownership. Reipert:Baxalta Innovations GmbH, a Takeda company: Employment, Equity Ownership. Scheiflinger:Baxalta Innovations GmbH, a Takeda company: Employment, Equity Ownership. Xiao:Ivygen: Other: Patent application on FVIII-X5 has been submitted. Rottensteiner:Baxalta Innovations GmbH, a Takeda company: Employment, Equity Ownership.

A Novel Deletion in the Fviii B-Domain That Reduces Transgene Size While Preserving FVIII Activity.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3182-3182
Author(s):  
Yi-Lin Liu ◽  
Hua Zhu ◽  
Alexander Schlachterman ◽  
Heesoon Chang ◽  
Rodney M. Camire ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Dose Group ◽  
Hemophilia A ◽  
Specific Activity ◽  
Post Injection ◽  
Vector Genome ◽  
Fviii Activity

Abstract Hemophilia A is an inherited X-linked bleeding disorder caused by a deficiency in Factor VIII (FVIII). Clinically significant improvement of hemophilia phenotype can be achieved with low circulating factors, thus makes it a good target disease for gene therapy. Adeno-associated virus (AAV) vectors have proven successful for the delivery of the factor IX gene in humans with hemophilia B. For the treatment of hemophilia A, a problem in the packaging of the rFVIII cDNA or various B-domainless derivatives (i.e. rFVIII-SQ) in AAV vectors is the large size of the insert, which combined with required elements, can exceed the packaging capacity of AAV (~5 kb). This difficulty limits the choice of both promoter and regulatory elements when designing an expression cassette for AAV vectors. Here we developed strategies to overcome these limitations by (1) development of a novel FVIII B-domain deleted molecule (2) construction of a short liver-specific promoter. We further tested these vectors in a series of in vitro and in vivo experiments. Factor VIII-SQ is a well-characterized derivative of FVIII and has been used by several groups in a gene therapy setting; the recombinant protein is used clinically to treat hemophilia A. We have constructed a shorter version of FVIII-SQ, by deleting the entire B-domain. In addition, we have engineered this FVIII to be intracellularly processed using a PACE-furin recognition site such that the protein is secreted from cells as two chains (FVIII-RKR; fully processed heavy and light chains). This FVIII-RKR along with FVIII-SQ was transiently expressed in COS-1 cells and conditioned media was collected at 24, 48 and 72 hrs post transfection. Using a combination of ELISA and functional assays we were able to demonstrate that FVIII-RKR was efficiently secreted from these cells. The data also revealed that FVIII-RKR has a 4–8-fold increase in specific activity compared to FVIII-SQ. We further tested whether FVIII-RKR could function in an in vivo setting. Plasmid DNA (50μg) containing FVIII-RKR or FVIII-SQ with liver-specific mouse transthyretin (mTTR) promoter were introduced into hemophilia A (HA) mice hydrodynamically via tail vein. Two out of four mice in the SQ group and three out of four mice in the RKR group had significant shortening of the clotting time at days 1 and 3 post injection, indicating that this shortened version of FVIII is functional in vivo. To address FVIII long-term expression we synthesized AAV vectors and delivered to immuno-deficient HA mice through hepatic portal vein. AAV vectors containing an expression cassette of mTTR promoter and FVIII-SQ have been administered. Expression of physiological FVIII levels was observed in high dose group (4.0E+12 vector genome per animal, n=4). FVIII activity averages 1.88 U/ml by Coamatic assay or 0.81 U/ml by aPTT assay at 12 weeks post injection. In low dose group (1.0E+12 vector genome per animal, n=5) therapeutic level of FVIII is achieved, 0.59 U/ml by Coamatic assay or 0.23 U/ml by aPTT assay at 12 weeks post injection. Finally, AAV vectors with FVIII-RKR have been produced and shown to have similar packaging efficiency to AAV-FVIII-SQ. Studies are currently underway with AAV-FVIII-RKR to evaluate the ability of this vector to drive long-term expression of functional protein. In summary, we developed a novel FVIII molecule that has high specific activity and is suitable for efficiently packaging in the AAV vectors.

Restoration of Porcine Factor VIII Procoagulant Activity to Hemophilia A Mice with Pre-Existing Immunity to Human Factor VIII.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3284-3284
Author(s):  
Christopher B. Doering ◽  
Bagirath Gangadharan ◽  
Hillary Z. Dukart ◽  
H. Trent Spencer
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Hemophilia A ◽  
Donor Cell ◽  
Activity Levels ◽  
Cell Engraftment ◽  
Fviii Activity ◽  
Human Factor Viii ◽  
Total Body ◽  
High Level

Abstract The development of inhibitory antibodies directed against human factor VIII (hfVIII) remains the most significant clinical complication associated with the treatment of hemophilia A. Recently, we demonstrated that transplantation of genetically-modified hematopoietic stem cells (HSCs) containing a high-expression porcine (HEP) fVIII transgene promoted sustained, high-level fVIII expression in naïve, genetically-immunocompetent hemophilia A mice (Gangadharan et al. 2006. Blood 107, 3859–64). In the current study, HEP-fVIII HSC transplantation (HSCT)-based gene therapy was tested in the setting of hemophilia A complicated by the presence of circulating anti-hfVIII inhibitory antibodies. Following a series of intravenous injections with recombinant hfVIII, hemophilia A mice developed anti-hfVIII antibodies with clinically-significant inhibitory titers. The median ELISA and Bethesda (inhibitory) titers were 2938 and 55 (n = 18), respectively, and a significant correlation between the anti-hfVIII ELISA and Bethesda (inhibitory) titers was observed (P < 0.001). With the exception of two mice, all plasma samples analyzed contained anti-HEP-fVIII cross-reactive antibodies by ELISA, and 5 of 16 displayed detectable anti-HEP-fVIII inhibitory activity. HSCs were transduced ex vivo with recombinant retrovirus carrying a HEP-fVIII transgene and transplanted into lethally-irradiated (11 Gy total body irradiation) hemophilia A mice (n = 11). Twelve wks post-HSCT, all mice displayed high-level donor cell engraftment in peripheral blood mononuclear cells (PBMCs) at 81 ± 22% (mean ± SD) and expressed therapeutic levels of fVIII with a mean activity of 3 ± 1.3 units/ml (Figure 1). A second cohort of mice (n = 7) underwent a similar HSCT gene therapy procedure with the exception that they received a sub-lethal dose of total body irradiation (5.5 Gy). These mice exhibited lower-level donor cell engraftment at 6.5 ± 6% (range 0.7 – 13%) in PBMCs at 12 weeks post-HSCT. At day 9 post-HSCT, the mice in this cohort contained circulating fVIII activity levels at 1 ± 0.6 units/ml (Figure 1). However in 6 of 7 mice, fVIII activity levels returned to baseline (≤0.01 units/ml) by day 28 post-HSCT, and in 4 of 7 mice, fVIII activity remained below the level of detection. The remaining 3 mice displayed 0.22 ± 0.3 (range 0.04 – 0.57) units/ml fVIII activity at 12 weeks post-HSCT and showed a trend towards greater donor PBMC engraftment, 12.8 ± 0.2% versus 1.8 ± 1.3% (P = 0.057). Analysis of the anti-hfVIII ELISA titers post-HSCT in both cohorts of mice revealed that while the titers steadily decreased in the lethally-irradiated mice (initial t1/2 ~ 12 days), the titers remained unchanged in the sub-lethally-irradiated mice possibly explaining the differences observed for donor cell engraftment and fVIII expression between the 2 groups. These data provide proof-of-concept that HSCT-based gene therapy incorporating a HEP-fVIII transgene could be utilized for the treatment of high-risk patients with refractory anti-hfVIII inhibitors. Figure Figure

DDAVP-Induced Increase of Factor VIII Activity in Blood Is Likely Due To Release of Factor VIII That Is Synthesized by Endothelial Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 692-692 ◽  
Author(s):  
Lingfei Xu ◽  
Timothy C. Nichols ◽  
Stephanie McCorquodale ◽  
Aaron Dillow ◽  
Elizabeth Merricks ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Endothelial Cells ◽  
Factor Viii ◽  
Hemophilia A ◽  
Fold Increase ◽  
Von Willebrand Disease ◽  
Major Site ◽  
Von Willebrand

Abstract Desmopressin (1-deamino-8-D-arginine vasopressin, DDAVP) is commonly used as a nonreplacement therapy for mild von Willebrand disease (VWD) and hemophilia A. In humans, IV injection of 0.3 μg/kg of DDAVP induces a rapid 2 to 5-fold increase in plasma levels of both von Willebrand factor (VWF) and Factor VIII (FVIII) within 30–60 minutes, which is due to release from Wiebel-Palade bodies (WPBs) in endothelial cells. The stored FVIII may be synthesized by endothelial cells, which express FVIII in vitro. However, hepatoma cells can also express FVIII in vitro, and liver transplantation can correct hemophilia A. Thus, the liver may be the major site of production of FVIII in vivo, thus, an alternative explanation is that endothelial cells take up FVIII from blood and store it in WPBs with VWF, which can be released after DDAVP. DDAVP is effective in humans and dogs, but not in mice. In this study, we tested the effect of DDAVP on hemophilia A dogs after neonatal hepatic gene therapy with a retroviral vector (RV) expressing canine FVIII (cFVIII). With this gene therapy approach, canine hepatocytes express high levels of a reporter gene from an RV, but no expression is observed in endothelial cells. Thus, the major site of FVIII synthesis is the hepatocyte in this model. Our hypothesis is that if DDAVP increases FVIII levels in this dog model, it would indicate that the FVIII increase is due to uptake from blood by endothelial cells. Alternatively, if no increase in FVIII occurs after DDAVP stimulation, it would suggest that the increase in normal dogs is due to synthesis of FVIII by endothelial cells. An RV that contains the liver-specific human α1-antitrypsin promoter and the canine B-domain deleted FVIII cDNA was generated. RV was given IV to two hemophilia A dogs at 8x109 transducing units (TU)/kg at 3 days after birth. The whole blood clotting time (WBCT) and APTT time in both dogs have been normalized, and the plasma cFVIII COATEST activity has been maintained at 100–200% of normal for 11 months to date. DDAVP was injected IV at 0.5 μg/kg into RV-treated hemophilia A dogs at 7 months of age. Two separate doses of DDAVP were given with an interval of one week. The same dose of DDAVP was given to normal dogs as controls (N=4). In normal dogs, both VWF and FVIII levels increased 40% and 50% between 15 to 60 minutes after DDAVP, respectively. However, FVIII levels were not changed in RV-treated dogs, although VWF levels increased 150% or 60%. Thus, our data suggest that the normal FVIII increase after DDAVP administration is due to release of FVIII that is synthesized by endothelial cells. These data also demonstrate that DDAVP will not be effective at increasing FVIII activity in patients that receive liver-directed gene therapy and only achieve partial correction. Such patients would need to be treated with factor replacement if bleeding episodes occur.

Sign in / Sign up

Export Citation Format

Share Document