Hemophilia A is a bleeding disorder resulting from coagulation factor VIII (FVIII) deficiency. Exogenously provided FVIII effectively reduces bleeding complications in patients with severe hemophilia A. In approximately 30% of such patients, however, the 'foreignness' of the FVIII molecule causes them to develop inhibitory antibodies against FVIII (inhibitors), precluding FVIII treatment in this set of patients. Moreover, the poor pharmacokinetics of FVIII, attributed to low subcutaneous bioavailability and a short half-life of 0.5 d, necessitates frequent intravenous injections. To overcome these drawbacks, we generated a humanized bispecific antibody to factor IXa (FIXa) and factor X (FX), termed hBS23, that places these two factors into spatially appropriate positions and mimics the cofactor function of FVIII. hBS23 exerted coagulation activity in FVIII-deficient plasma, even in the presence of inhibitors, and showed in vivo hemostatic activity in a nonhuman primate model of acquired hemophilia A. Notably, hBS23 had high subcutaneous bioavailability and a 2-week half-life and would not be expected to elicit the development of FVIII-specific inhibitory antibodies, as its molecular structure, and hence antigenicity, differs from that of FVIII. A long-acting, subcutaneously injectable agent that is unaffected by the presence of inhibitors could markedly reduce the burden of care for the treatment of hemophilia A.
In hemophilia A, routine prophylaxis with exogenous factor VIII (FVIII) requires frequent intravenous injections and can lead to the development of anti-FVIII alloantibodies (FVIII inhibitors). To overcome these drawbacks, we screened asymmetric bispecific IgG antibodies to factor IXa (FIXa) and factor X (FX), mimicking the FVIII cofactor function. Since the therapeutic potential of the lead bispecific antibody was marginal, FVIII-mimetic activity was improved by modifying its binding properties to FIXa and FX, and the pharmacokinetics was improved by engineering the charge properties of the variable region. Difficulties in manufacturing the bispecific antibody were overcome by identifying a common light chain for the anti-FIXa and anti-FX heavy chains through framework/complementarity determining region shuffling, and by pI engineering of the two heavy chains to facilitate ion exchange chromatographic purification of the bispecific antibody from the mixture of byproducts. Engineering to overcome low solubility and deamidation was also performed. The multidimensionally optimized bispecific antibody hBS910 exhibited potent FVIII-mimetic activity in human FVIII-deficient plasma, and had a half-life of 3 weeks and high subcutaneous bioavailability in cynomolgus monkeys. Importantly, the activity of hBS910 was not affected by FVIII inhibitors, while anti-hBS910 antibodies did not inhibit FVIII activity, allowing the use of hBS910 without considering the development or presence of FVIII inhibitors. Furthermore, hBS910 could be purified on a large manufacturing scale and formulated into a subcutaneously injectable liquid formulation for clinical use. These features of hBS910 enable routine prophylaxis by subcutaneous delivery at a long dosing interval without considering the development or presence of FVIII inhibitors. We expect that hBS910 (investigational drug name: ACE910) will provide significant benefit for severe hemophilia A patients.
In our previous study, we found that the antibacterial peptide KLKLLLLLKLK-NH 2 (L5) and its denantiomer (DL5) activate neutrophils to produce superoxide anions (O 2 ؊ ) and prevent death due to infection by methicillin-resistant Staphylococcus aureus, suggesting that these peptides may elicit in vivo antimicrobial activities through host inflammatory responses mediated by neutrophils. In this study, we investigated the mechanisms behind in vivo antimicrobial prophylaxis by the use of L5 for the treatment of bacterial infection introduced via intra-abdominal implantation. We found that the intraperitoneal treatment with L5 before bacterial infection markedly reduced rates of death due to infection. Treatments with L5 were highly effective in preventing death due to intraperitoneal inoculation of not only S. aureus Smith but also Enterococcus faecalis SR1004 and Escherichia coli EC14. The intra-abdominal administration of L5 induced accumulation of neutrophils, increased levels of reactive oxygen species, and augmented antibacterial activity in the abdominal cavity. In addition, administration of L5 upregulated the expression of the Mig/CXCL9 chemokine gene in thioglycolate-elicited peritoneal macrophages. Our results suggested that the prevention of death by treatment of infected mice with L5 might occur primarily through the activation of a host immune response.
42 Background: Hemophilia A is treated by intravenous replacement therapy with factor VIII (FVIII), either on demand to resolve bleeding or as a prophylactic to prevent bleeding. Recently, routine prophylactic treatment is recommended to effectively prevent bleeding and to reduce bleeding-related chronic joint damage. However, the need for frequent intravenous injections of FVIII negatively affects patients' quality of life and their adherence to the routine prophylactic regimen. More importantly, approximately 30% of severe hemophilia A patients develop inhibitory antibodies toward the injected FVIII, rendering the replacement therapy ineffective. To overcome these drawbacks, we generated a bispecific antibody (termed ACE910) against activated factor IX (FIXa) and factor X (FX), which mimics the cofactor function of FVIII. Objectives: The aims of the present study were to examine the FVIII-mimetic cofactor activity of ACE910 in vitro and its hemostatic activity in vivo. Methods: The FVIII-mimetic cofactor activity of ACE910 was evaluated by a thrombin generation assay in human FVIII-deficient plasma as well as by an enzymatic assay using purified coagulation factors. For in vivo studies, an acquired hemophilia A model was established in cynomolgus monkeys by a single intravenous injection of mouse monoclonal anti-FVIII neutralizing antibody, which was cross-reactive to cynomolgus monkey FVIII but not to porcine FVIII. After artificial bleeding had been induced, ACE910 or porcine FVIII was intravenously administered in a single dose or in twice-daily repeated doses, respectively. Bleeding symptoms, including anemia and skin bruising, were monitored for three days. A pharmacokinetic study of ACE910 was also performed with a single intravenous or subcutaneous administration to cynomolgus monkeys. Results: ACE910 concentration-dependently showed FVIII-mimetic cofactor activity in the enzymatic assay and improved thrombin generation parameters in human FVIII-deficient plasma. Intravenous administration of ACE910 (a single dose of 3 mg/kg) significantly reduced the bleeding symptoms in the acquired hemophilia A model of a non-human primate. This hemostatic effect was comparable to twice-daily intravenous administration of porcine FVIII (repeated doses of 10 U/kg). The half-life of ACE910 was approximately three weeks for both single intravenous and subcutaneous administrations. The subcutaneous bioavailability of ACE910 was nearly 100%. Conclusion: The bispecific antibody against FIXa and FX, ACE910, exerted FVIII-mimetic cofactor activity in vitro. Furthermore, a single dose of ACE910 demonstrated hemostatic activity comparable to twice-daily repeated doses of 10 U/kg porcine FVIII in vivo. Moreover, ACE910 exhibited high subcutaneous bioavailability and approximately three-week half-life in a non-human primate. Our bispecific antibody against FIXa and FX is a subcutaneously injectable, long-acting agent that removes the need to consider the induction or presence of FVIII inhibitors and may establish a novel principle for the prophylactic treatment of hemophilia A patients. Disclosures: Muto: Chugai Pharmaceutical Co., Ltd.: Employment. Kitazawa:Chugai Pharmaceutical Co., Ltd.: Employment. Yoshihasi:Chugai Pharmaceutical Co., Ltd.: Employment. Takeda:Chugai Pharmaceutical Co., Ltd.: Employment. Soeda:Chugai Pharmaceutical Co., Ltd.: Employment. Igawa:Chugai Pharmaceutical Co., Ltd.: Employment. Sampei:Chugai Pharmaceutical Co., Ltd.: Employment. Sakamoto:Chugai Pharmaceutical Co., Ltd.: Employment. Okuyama-Nishida:Chugai Pharmaceutical Co., Ltd.: Employment. Saito:Chugai Pharmaceutical Co., Ltd.: Employment. Kawabe:Chugai Pharmaceutical Co., Ltd.: Employment. Shima:Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Research Funding. Hattori:Chugai Pharmaceutical Co., Ltd.: Employment.
1126 Exogenous factor VIII (FVIII) is used to reduce bleeding complications in patients with severe hemophilia A. However, there are two drawbacks of current routine prophylaxis by FVIII. One is the requirement of frequent intravenous administration due to its short half-life and low subcutaneous bioavailability of FVIII. Second is the development of anti-FVIII antibodies (inhibitors) in approximately 30% of the severe patients which deprives the patients from routine prophylaxis by FVIII. To overcome these drawbacks, bispecific IgG antibody against activated factor IX (FIXa) and factor X (FX), which mimics the cofactor function of FVIII by placing these two factors into spatially appropriate positions, was screened from approximately 40,000 bispecific antibodies recognizing FIXa by the one arm and FX by the other arm. The therapeutic potential of the bispecific antibody identified from the screening was marginal due to insufficient FVIII-mimetic activity and poor pharmacokinetics, and moreover, large scale purification of recombinant bispecific IgG antibody was challenging. Therefore, the lead bispecific antibody, after humanization, was subjected to multidimensional optimization process in order to improve both the therapeutic potential and the manufacturability of the bispecific antibody. FVIII-mimetic activity was improved by modifying its binding properties to FIXa and FX, and the pharmacokinetics was improved by engineering the charge properties of the variable region. Difficulty of manufacturing bispecific antibody was overcome by identifying common light chain for anti-FIXa and FX heavy chain through framework/complementarity determining region shuffling, and by isoelectric point engineering of the two heavy chain variable regions to facilitate ion exchange chromatography purification of the bispecific antibody. Engineering to overcome low solubility and deamidation was also performed to enable stable high concentration liquid formulation for clinical use. ACE910, multidimensionally optimized bispecific antibody, exhibited potent FVIII-mimetic activity in human FVIII deficient plasma (more than 10% of FVIII activity at 300 nM in thrombin generation assay), and half-life of approximately 3 weeks with high subcutaneous bioavailability in cynomolgus monkey, enabling effective prophylaxis by subcutaneous administration with long dosing interval. In silico immunogenicity prediction analysis suggested that ACE910 was minimally immunogenic in human, in contrast to high immunogenicity of FVIII in human. Importantly, the activity of ACE910 was not affected by the presence of inhibitors, while polyclonal anti-ACE910 antibody did not inhibit FVIII activity, allowing the use of ACE910 without considering the development or presence of inhibitors. Furthermore, ACE910 could be purified in a large scale manufacturing, and formulated into patient-friendly subcutaneously injectable liquid formulation for clinical use. We believe that ACE910, with its multidimensionally optimized profile, would significantly improve the quality of life of hemophilia A patients by reducing not only bleeding but also the burden on the patients themselves, their parents, and all medical staff. Disclosures: Igawa: Chugai Pharmaceutical Co.,Ltd: Employment. Sampei:Chugai Pharmaceutical Co., Ltd.: Employment. Soeda:Chugai Pharmaceutical Co.,Ltd: Employment. Okuyama-Nishida:Chugai Pharmaceutical Co., Ltd.: Employment. Moriyama:Chugai Pharmaceutical Co.,Ltd: Employment. Wakabayashi:Chugai Pharmaceutical Co.,Ltd: Employment. Tanaka:Chugai Pharmaceutical Co.,Ltd: Employment. Muto:Chugai Pharmaceutical Co., Ltd.: Employment. Kojima:Chugai Pharmaceutical Co.,Ltd: Employment. Kitazawa:Chugai Pharmaceutical Co., Ltd.: Employment. Yoshihashi:Chugai Pharmaceutical Co.,Ltd: Employment. Harada:Chugai Pharmaceutical Co.,Ltd: Employment. Funaki:Chugai Pharmaceutical Co.,Ltd: Employment. Haraya:Chugai Pharmaceutical Co.,Ltd: Employment. Tatsuhiko:Chugai Pharmaceutical Co.,Ltd: Employment. Suzuki:Chugai Pharmaceutical Co.,Ltd: Employment. Esaki:Chugai Pharmaceutical Co.,Ltd: Employment. Nabuchi:Chugai Pharmaceutical Co.,Ltd: Employment. Hattori:Chugai Pharmaceutical Co., Ltd.: Employment.
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