Within the current literature there is little discussion surrounding the aggregate cost consequences associated with a switch from pdFVIII to rFVIII. Outlined below are estimates of the expected FVIII expenditure per purchasing district, based on a population of 500,000, using a prevalence rate of 1 case per 10,000 population. Estimates are calculated based on an average FVIII consumption level per patient per year, reported by Haemophilia Centre Directors’ (HCD) Annual Returns (1994). Presently, pdFVIII is exempted from VAT, whereas rFVIII is VAT chargeable (at a rate of 17.5%). NHS purchases of rFVIII will be subject to VAT charges which are non-reclaimable from HM Customs & Excise (VAT Leaflet 701/31/92, personal communication from HM Customs & Excise). With this VAT issue in mind, cost estimates below are discussed including VAT to give a ‘typical purchaser’ perspective. Estimates excluding VAT will also be presented to offer a ‘public sector’ perspective.
Hemophilia A (HA) is an inherited X-linked bleeding disorder leading to recurrent joint bleeding and chronic arthropathy, if untreated. Prophylaxis (i.e. regular, long- term anti-hemophilic factor replacement) is recommended as a standard of care by organizations such as the World Federation of Hemophilia, for treating severe hemophilia . Based on reports of the 25-year Swedish experience , 3-times-weekly prophylaxis was established in the 90’s as the standard, to help maintain adequate plasma factorVIII (FVIII) trough levels (>0.01 IU/mL), and prevent spontan- eous joint bleeding in severe HA. However, breakthrough bleeding still occurs in certain subjects with severe HA, despite standard thrice-weekly prophylactic doses, perhaps due to variations in FVIII trough levels. Based on pharma- cokinetic principles, more frequent infusions of FVIII at lower doses may result in comparable or improved trough levels [3, 4]. A 2012 pilot study demonstrated that daily prophylaxis is feasible, with a substantial reduction (30 %) in factor concentrate utilization - albeit with a higher bleed rate in certain patients, and a decreased quality of life . Verma et al. recently demonstrated that a very low dose, twice-weekly prophylaxis regimen in chil- dren was effective at lowering bleed rates compared to on-demand treatment .
LSEC-targeted cis FVIII SB-Tns mediate long-term therapeutic expression in knockout hemophilia A mice. We next determined whether selective delivery of nonviral SB-Tn vectors to LSECs via HA nanocapsules could correct the bleeding disorder in hemophilia A mice. A cis SB- Tn pT2/CAGGS-BΔcFVIII//IFSB10 promoter using the second ver- sion of the transposon (pT2) with the mouse eurkaryotic initiation factor 4A1 promoter (IF) driving SB transposase version 10 (SB10) was constructed to express the BΔcFVIII coding sequence (CDS) from the CAGGS promoter, with the rabbit β-globin 3′ UTR and poly(A) signal (Table 1). The SB vertebrate Tn system utilizes a “cut- and-paste” mechanism to insert the transgene flanked by IR/DRs of the Tn into TA dinucleotide sites in the host genome. The trans- position of the Tn from plasmid vector to host genome requires SB transposase, which was expressed from the eukaryotic initiation factor 4A1 promoter carrier on the same plasmid vector (Table 1 and Figure 5). We chose this model because in hemophilia A, endogenous expression of FVIII occurs primarily in LSECs. In addition, LSECs play a unique role in tolerance induction; thus, expression of the BΔcFVIII transgene in LSECs might decrease or eliminate inhibitor formation, which is a significant barrier to cur- rent gene therapy strategies.
Current treatment of hemophilia A (HemA) patients with repeated infusions of factorVIII (FVIII; abbreviated as F8 in constructs) is costly, inconvenient, and incompletely effective. In addition, approximately 25 % of treated patients develop anti-factorVIII immune responses. Gene therapy that can achieve long-term phenotypic correction without the complication of anti-factorVIII antibody formation is highly desired. Lentiviral vector (LV)-mediated gene transfer into hematopoietic stem cells (HSCs) results in stable integration of FVIII gene into the host genome, leading to persistent therapeutic effect. However, ex vivo HSC gene therapy requires pre-conditioning which is highly undesirable for hemophilia patients. The recently developed novel methodology of direct intraosseous (IO) delivery of LVs can efficiently transduce bone marrow cells, generating high levels of transgene expression in HSCs. IO delivery of E-F8-LV utilizing a ubiquitous EF1 α promoter generated initially therapeutic levels of FVIII, however, robust anti-FVIII antibody responses ensued neutralized functional FVIII activity in the circulation. In contrast, a single IO delivery of G-FVIII-LV utilizing a megakaryocytic-specific GP1b α promoter achieved platelet-specific FVIII expression, leading to persistent, partial correction of HemA in treated animals. Most interestingly, comparable therapeutic benefit with G-F8-LV was obtained in HemA mice with pre-existing anti-FVIII inhibitors. Platelets is an ideal IO delivery vehicle since FVIII stored in α -granules of platelets is protected from high-titer anti-FVIII antibodies; and that even relatively small numbers of activated platelets that locally excrete FVIII may be sufficient to promote efficient clot formation during bleeding. Additionally, combination of pharmacological agents improved transduction of LVs and persistence of transduced cells and transgene expression. Overall, a single IO infusion of G-F8-LV can generate long-term stable expression of hFVIII in platelets and correct hemophilia phenotype for long term. This approach has high potential to permanently treat FVIII deficiency with and without pre-existing anti-FVIII antibodies.
On the other side of the medal, biomarkers related to coagulation disorders have shown prognostic relevance in lung, colorectal, ovarian cancer and glioblastoma, independently on the occurrence of VTE [8–11]. When focusing on breast malignancies, rapidly growing evi- dence comes from both the advanced and early setting. In 84 patients with metastatic disease, pre-treatment plasma levels of D Dimer (DD) were positively associated with prognostically relevant clinicopathologic features and circulating levels of cytokines related to angiogenesis . More recently, circulating tumour cells (CTC) have been linked to plasma DD levels in patients with meta- static breast cancer. This latter study also confirmed the previously described association between CTC and VTE [12, 13]. Evidence from the early setting is also intriguing. In a case–control study of genotypic and phenotypic var- iables related to the tissue factor (TF) pathway, DD levels beyond the 90th percentile were associated with cancer status, with results being not specific to the different sub- sets of patients as defined by hormone receptor (HR) and HER2 status . In 360 HR negative early breast cancer patients, positive staining at the immunohistochemical assessment of D2-40 and factorVIII (FVIII) was associ- ated with less favorable survival outcomes both in the overall cohort and in patient subgroups . In addition, in a case series including 100 women having undergone breast surgery due to newly diagnosed invasive breast cancer, circulating levels of FVIII were significantly asso- ciated with axillary lymph node involvement, number of metastatic nodes, and HER2 status .
Case report: An 80-year-old Japanese male was diagnosed with acquired hemophilia A. He had compartment-like symptoms due to soft tissue hemorrhage in his left forearm and right lower extremity. A blood examination showed neutrophilia with a white blood cell count of 31,900/µL (91.9% neutrophils), an activated partial thromboplastin time of 69.0 seconds, coagulation factorVIII (FVIII) , 1.0%, and anti-FVIII inhibitor, 190 BU/mL. The bleeding episodes were controlled with intravenous activated prothrombin complex concentrate (FEIBA ® )
Proteolytic cleavage of von Willebrand factor (VWF) by ADAMTS13 is enhanced by clotting factorVIII (FVIII). In this study, we test the hypothesis that naturally occurring type 2N VWF variants that are defective in FVIII binding may be compromised in proteolytic cleavage by ADAMTS13 in the presence of FVIII. Recombinant type 2N VWF variants (H817Q, R854Q, R782W, R782W/H817Q, and HPP-VWF) were expressed in human embryonic kidney cells. Binding of FVIII and proteolytic cleavage of the 2N VWF variants were determined. We showed that most 2N VWF variants exhibited reduced proteolytic cleavage by ADAMTS13 in the presence of FVIII under fluid shear stress. The impairment of FVIII in accelerating the cleavage of the 2N VWF variants was proportional to the defects in their FVIII binding. In contrast, these variants, except for HPP-VWF, appeared to be cleaved normally in the presence of ristocetin and platelets, which modulate VWF proteolysis via the A1 domain. These results further support the critical role of the VWF D’D3 domain and the VWF propeptide in regulating VWF proteolysis by ADAMTS13 under physiologically relevant shear stress. Our findings suggest that the compromised cofactor-dependent proteolysis of the 2N VWF variants may be advantageous for mitigating bleeding phenotype in cases of von Willebrand disease.
Hemophilia A is a hereditary disorder resulting in deficient levels of plasma coagulation factorVIII (FVIII) and lifelong bleeding manifestations, particularly repeated hemarthroses leading to permanent joint damage. Major progress has been demonstrated in preventing bleeding and disability when intensive factor replacement therapy is administered prophylactically from an early age . The objective assess- ment of the outcome of different treatment strategies in hemophilia is multidimensional and includes the measure- ment of bleeding rates, joint and musculoskeletal status, pain, physical functioning and social functioning based on holistic models of health as recommended by the WHO . Health-related quality of life (HRQoL) tools are self-administered questionnaires developed in order to measure the perceived impact of a medical condition and its treatment on a person’s physical, emotional and social well-being.
We have localized the binding region of a previously described monoclonal anti-factorVIII (FVIII) inhibitory antibody (C5) to amino acid residues Thr351-Ser365 of the thrombin- generated 54-kD fragment of the heavy chain of FVIII. Synthetic FVIII peptides were examined for the ability to competitively inhibit the binding of C5 to FVIII in an ELISA system. The synthetic FVIII peptide Thr351-Ser365 blocked C5 binding to FVIII in a dose- dependent manner in this system. Two other synthetic FVIII peptides, Asn340-Glu354 and Glu342-Asp356, which partially overlapped Thr351-Ser365, also blocked C5 binding to FVIII. Blocking of C5 binding with these peptides, however, required much greater
Vast majority (73%) of inhibitors are identified within the first10-20 exposure days to factor concentrates While it is known that most inhibitors develop within the first 10-20 exposure days . 45 Early exposure to FVIII during the first 6 months of life was associated with a higher incidence of inhibitor formation. 54 Whether early exposure to FVIII is related to inhibitor development has potentially important implications for the initial management of infants with haemophilia, particularly those who require treatment at a very young age. The option of delaying FVIII exposure in young infants was explored recently by Rivard et al in a small pilot study in which the aim was to use rFVIIa in place of FVIII until the age of 2 years. Of the 11 infants in this study, six still required FVIII to control bleeding and four subsequently developed inhibitors, which suggests that this is unlikely to be a feasible approach 54,38 . The highest risk of developing inhibitors is observed within the first 50 exposures to FVIII with the risk reducing substantially after 200 treatment days . 43,55
Haemorrhages and haemarthoses per year were re- duced during the prophylaxis period with rFVIIa. How- ever, it is not justifiable to compare the pre-prophylactic periods with the prophylaxis period because the risk of haemorrhage—particularly haemarthrosis—increases with age, body weight and activity . It is more relevant and interesting to compare our results with those from haemophilia A patients of similar ages without inhibitor who are receiving early prophylaxis with FactorVIII. In the Manco-Johnson series , patients had a mean age of 1.6 years, and had previously suffered a mean of 6.2 haemorrhages, but with a longer follow-up period, a mean of 49 months per patient. In the on-demand group, the incidence of haemorrhage was 17.7 per patient/year and the incidence of haemarthroses was 4.9 per patient/ year, while the number of haemorrhages was 3.3 per pa- tient/year and haemarthroses 0.63 per patient/year among patients receiving prophylaxis with FVIII. In our study, incidences were clearly lower, 0.17 haemorrhages per patient/year and 0.049 haemarthroses per patient/year.
patients suffered from prolonged bruising and bleeding with manifestations ranging from severe and recurrent joint hemorrhages to life-threatening bleeding episodes and had a decreased life expectancy. HA is defined as mild when endogenous FVIII levels are > 5%, moderate when between 1% and 5%, and severe when < 1%. Treatment for HA with replacement factor first started with the use of fresh frozen plasma in the 1950s followed by cryoprecipitate in the 1960s. Finally, in the 1970s, lyophilized FVIII derived from pooled plasma became available and revolutionized treatment for HA, even allowing home infusion therapy. The HA community then suffered from the contamination of factor supplies with the HIV in the 1980s. This tragedy stimulated research and technical advances such as heat inactivation and solvent detergent treat- ment to generate safer plasma-derived FVIII products. The cloning of the gene for FVIII in 1984 resulted in recombinant FVIII preparations becoming available in the 1990s. Currently, the standard of care in developed countries is to offer primary prophylactic
concentration. The optimal pH range for binding is from 7.0 to 7.5. At a concentration of 2 mM, EGTA inhibits 86% of the binding; however, 20 mM of Ca++, Mg++, or EDTA have little effect. Binding sites for FVIII/vWF were found only on platelets, and no significant binding was detected with human erythrocytes or polymorphonuclear leukocytes.
Hemostasis is tightly regulated by pro- and anticoagulant pathways. Any irregularity in these regulatory pathways may shift the balance to a hypercoagulable state, which in turn could lead to venous thromboembolism (VTE). Elevated levels of the procoagulant proteins factorVIII (FVIII) and von Willebrand factor (VWF) are associated with a moderate to high risk for VTE . For instance, individuals with FVIII levels >150 IU/dL have a 6-fold increased risk for VTE relative to those with FVIII levels lower than 100 IU/dL . Conversely, reduced plasma levels (85 IU/dL) of the anticoagulant antithrombin (AT) are also associated with
cleavage site. Incubation of FVIII-EH plasma with penicillamine or DTT causes a five- to sixfold increase in FVIII-EH VIII:C, at 80 and 1 mM, respectively. While there is no FVIII-EH light chain cleavage when thrombin is added in the presence of penicillamine or DTT, these reducing agents disrupt the FVIII-vWf complex. For example, the addition of 5 mM DTT to normal or FVIII-EH plasma causes a 50% reduction in FactorVIII binding to vWf. These observations suggested that DTT increases FVIII-EH VIII:C by partial dissociation of FVIII- EH from vWf. This was verified by showing that vWf-free FVIII-EH had VIII:C activity of 21 U/dl, while the starting plasma level was 2.5 U/dl. Removal of other FVIII-EH plasma
mark) is a powerful drug with a short half-life (< 4 h) belonging to the so called "by-passing agents". It is indi- cated for the treatment of haemophilia complicated by the presence of anti-factorVIII (FVIII) inhibiting anti- bodies which impair the use of FVIII concentrates. Addi- tional indications are congenital FVII deficiency and Glanzmann's disease but rFVIIa has been successfully used in a number of off-label bleeding situations includ- ing warfarin overdose or critical bleeding during warfarin treatment within the normal range . It was success- fully used in VKCFD during an emergency minor surgical setting . A total dose of 1.2 mg (~ 20 μgr/Kg of body weight) provided a sudden normalization of the PT-INR with the shortest value at the 4-hour post-infusion assay as expected because of the increased FVII. Interestingly, a double rate increase in FII, FIX and FX activities was detected, remarking the role of rFVIIa as a powerful acti- vator of the whole coagulation system, a finding that only a complex defect with multiple factors deficiency allowed the opportunity to explore. Since rFVIIa and vitamin K show different peaks of action (4 hours and 24 hours respectively), their combined use with a simultaneous infusion at the above mentioned doses can obtain a sus- tained normalization of clotting times to be used in case of major bleeding and more complex surgical procedures. This "combination therapy" is a feasible alternative option for life-threatening bleeding episodes in VKCFD.
Hemophilia A (HA) is an X-linked autosomal recessive bleeding disorder in which factorVIII (FVIII) is inad- equately synthesized. In humans, FVIII is found to be synthesized by liver sinusoidal endothelial cells (LSECs) . Gene knockout studies have recently confirmed that endothelial cells (ECs) are the principal source of plasma FVIII [2, 3]. In treatment of HA, gene replacement ther- apy showed initially encouraging results in life-long correction of HA in animal models [4–6], although the outcome of the phase I clinical trial was not conclusive; there was a gradual loss of its potency because of the formation of inhibitors . As an alternative to gene therapy, transplantation of LSECs has shown encour- aging therapeutic benefits in HA mice . Owing to a profound shortage of transplantable donor LSECs, bone marrow cell (BMC) therapy is considered as an alterna- tive for these patients. Attempts have been made to cor- rect some genetic liver diseases by transplanting BMCs, which are capable of engrafting in the liver and replacing the parenchyma in the regenerating liver micro- environment and thereby produce prophylactic levels of missing proteins [9–12]. All of the above studies were based on transplantation of syngeneic BM-derived cells in mice with perturbed liver in which no humoral re- sponse to the missing proteins was observed.
Decision makers of national heath care system should decide whether to use the available resources for importation of PDM or investing on developing infrastructure for local production of such medicines. Impor- tation of PDM and especially plasma derived coagulating factors which are now available commercially at about 0.15-0.25 USD per IU could provide prompt access to these medicines. However, even with minimum factor use, treating one hemophilia patient will cost at least several thousands USD per year. Much higher costs attributed to treatment of patients in need of IvIG with current price of about 40-60 USD per gram, will
hemophilia retaining less than 1% of normal activity levels of FVIII or FIX. Notably, an increase in sustained activity levels to just above 1% can have a profound impact on the disease phenotype and a patient’s quality of life, with levels over 5% almost entirely ameliorating day-to-day symptoms. Mild and moderate hemophilia are usually caused by missense or late nonsense mutations, while large deletions, rearrangements, early stop codons or frame shifts, partial duplications, or inversions typically result in severe disease. The most common mutation, affecting up to 40% of patients with severe HA, is an inversion breaking intron 22 and reversing the first 22 exons of FVIII 22 . Patients with the intron 22 inversion or some of the other severe mutations have no circulating FVIII or FIX, depending on the affected gene, in their bloodstream (described as negative for cross reactive material; CRM-).