scholarly journals Mim8 - a Next-Generation FVIII Mimetic Bi-Specific Antibody - Potently Restores the Hemostatic Capacity in Hemophilia a Settings in Vitro and In Vivo

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 96-96 ◽  
Author(s):  
Stine L Kjellev ◽  
Henrik Østergaard ◽  
Per Jr Greisen ◽  
Mette B Hermit ◽  
Karina Thorn ◽  
...  
Keyword(s):  
Thrombin Generation ◽  
Bispecific Antibody ◽  
Hemophilia A ◽  
Next Generation ◽  
Employment Equity ◽  
Thrombin Generation Assay ◽  
Equity Ownership ◽  
Target Binding

The treatment of hemophilia A (HA) is primarily based on replacement of factor VIII (FVIII), and in people with HA with inhibitors (HAwI) on the use of by-passing agents. Recently, a FVIII mimetic bispecific antibody emicizumab (Hemlibra®) was approved for treatment of HA and HAwI, offering a subcutaneous, prophylactic treatment opportunity with potential for significantly reducing the treatment burden. We describe the development and pre-clinical characterization of Mim8, a novel, next-generation FVIII mimetic human bispecific antibody. Mim8 is a highly potent molecule bridging factor IXa (FIXa) and factor X (FX) in development for subcutaneous treatment of people with HA and HAwI. Development of Mim8 utilized the Duobody® platform to initially screen for compatible anti-FIXa and anti-FX antibodies followed by several iterations of systematic mutational optimization. In total, more than 30,000 bispecific antibodies were analyzed. The optimization process aimed for efficient Mim8-mediated activation of FX by FIXa in the presence of procoagulant membrane, low target binding in solution, low immunogenicity risk, and for desirable biophysical parameters such as low viscosity. In vitro characterization demonstrated that Mim8 efficiently localizes FIXa and FX to the phospholipid surface and enhances FXa activation. The monovalent anti-FIXa arm alone stimulates the proteolytic activity of FIXa in the range of 15,000-fold and is an important contributor to the activity of the bispecific antibody. The dissociation constants (Kd) of Mim8 for FIXa and FX is in the micromolar range, minimizing target binding in the blood. Using thrombin generation assay in congenital HA plasma and thrombelastography (TEG) in whole blood from healthy volunteers spiked with anti-FVIII antibodies, Mim8 was capable of normalizing thrombin generation and blood clot formation, respectively, with approximately 15 times greater potency than emicizumab (Figure 1). A similar potency improvement was demonstrated in a tail vein transection bleeding model in FVIII-deficient mice co-dosed with human FIX and FX to circumvent lack of Mim8 cross reactivity to murine FIX and FX. The terminal half-life of Mim8 was estimated to 14 days (range 10-17 days) in cynomolgus monkeys and the subcutaneous bioavailability to 97%. In conclusion, Mim8 is a novel, next-generation FVIII mimetic bispecific antibody with anti-FIXa and anti-FX arms that potently stimulates FX activation resulting in efficacious haemostasis in vitro and in vivo. Mim8 has a high potency allowing for administration of small volumes in a pen device, good PK parameters, minimal target binding in the blood, and good biophysical properties. Collectively, these properties support clinical development of Mim8 as a potentially improved next-generation FVIII-mimetic prophylactic treatment option for persons with hemophilia A regardless of inhibitor status. Figure 1: Left: FXI-triggered thrombin generation assay in congenital HA plasma (mean and SD of n = 5). Right: thromboelastography in whole blood from healthy donors spiked with polyclonal anti-FVIII antibody (mean and SD of n = 3). Coagulation was triggered with low concentration (∼30 fM) of tissue factor (Innovin® 1:200,000). Shaded areas: standard deviation of controls. Blue circles: Mim8. Grey squares: a sequence identical analogue (SIA) to emicizumab (comparable data were obtained with a commercially available batch of Hemlibra®). Disclosures Kjellev: Novo Nordisk A/S: Employment, Equity Ownership. Østergaard:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Greisen:Novo Nordisk A/S: Equity Ownership, Patents & Royalties: Patents. Hermit:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Thorn:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Hansen:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Zhou:Novo Nordisk A/S: Equity Ownership, Other: Previous employment, Patents & Royalties: Patents. Bjelke:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Kjalke:Novo Nordisk A/S: Employment, Honoraria. Lund:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Holm:Novo Nordisk A/S: Equity Ownership, Other: Previous employment. Ley:Novo Nordisk A/S: Employment, Equity Ownership. Elenius:Novo Nordisk A/S: Equity Ownership, Other: Previous employment; Leo Pharma A/S: Employment, Equity Ownership. Thygesen:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Loftager:Novo Nordisk A/S: Employment, Equity Ownership. Rasch:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Lorenzen:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Gandhi:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Lamberth:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Egebjerg:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Lund:Novo Nordisk A/S: Employment, Equity Ownership. Henriksen:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Rahbek-Nielsen:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Yang:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Hilden:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties.

scholarly journals Thrombin Generation Assay in Plasma from Hemophilia a Patients with or without Inhibitors on Concizumab Prophylaxis: Spiking with rFVIIa or aPCC

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3639-3639
Author(s):  
Marianne Kjalke ◽  
Mads Kjelgaard-Hansen ◽  
Søren Andersen ◽  
Ida Hilden
Keyword(s):  
Thrombin Generation ◽  
Significant Contribution ◽  
Hemophilia A ◽  
Employment Equity ◽  
Breakthrough Bleeding ◽  
Thrombin Generation Assay ◽  
Bleeding Episodes ◽  
Equity Ownership ◽  
Bypassing Agents

Introduction: Concizumab is a humanized monoclonal antibody that inhibits tissue factor pathway inhibitor (TFPI). Concizumab is currently in clinical development as a subcutaneous prophylactic therapy for hemophilia A and B patients with and without inhibitors. Breakthrough bleeding episodes experienced by inhibitor patients while on concizumab prophylaxis may be treated with the bypassing agents recombinant activated factor VII (rFVIIa; NovoSeven®) or activated prothrombin complex concentrate (aPCC; FEIBA®). Aim: To investigate the in vitro effect of rFVIIa and aPCC on hemophilia A plasma containing concizumab using a thrombin generation assay and pooled plasma spiked with concizumab or samples from patients treated prophylactically with concizumab. Methods: Pooled hemophilia A plasma was spiked with concizumab at 1, 3 and 10 nM and patient plasma samples from explorer4 (n=16; hemophilia with inhibitors; NCT03196284) and explorer5 (n=30; hemophilia A; NCT03196297) before and during concizumab prophylaxis at steady state exposure levels were assessed. Samples were spiked with rFVIIa (25 or 75 nM) or aPCC (0.25, 0.5 or 1 U/mL), and analyzed using a thrombin generation assay initiated with tissue factor (PPP-Low, Thrombinoscope). The effects of rFVIIa or aPCC in the absence or presence of concizumab were compared using ANOVA methodology. Results: Addition of rFVIIa or aPCC to hemophilia A plasma with or without inhibitors increased peak thrombin generation both in the absence and presence of concizumab. A significant additional effect of rFVIIa and aPCC was observed for all concizumab concentrations spiked to the plasma pool. Overall, the effects of the combination of concizumab and rFVIIa or aPCC were mainly additive; however, a small but statistically significant drug-drug interaction was observed for rFVIIa (25 nM or 75 nM) and aPCC (0.5 U/ml or 1 U/mL) in the presence of 10 nM concizumab. At this concizumab concentration, the additive effect of aPCC corresponded to 68% of the total observed effect and the additive effect of rFVIIa to 85% of the total observed effect. At lower concizumab concentrations (1 and 3 nM), statistically significant drug-drug effects were only observed in combination with aPCC. No excessive thrombin generation above the level obtained with 1 IU/mL recombinant factor VIII (rFVIII) was observed at 1 nM concizumab combined with either rFVIIa (25 and 75 nM) or aPCC 0.5 U/mL. However, addition of 1 U/mL aPCC to 1 nM concizumab resulted in a thrombin peak modestly above the upper 95% confidence interval of the rFVIII range. In the experiments using plasma from patients treated with concizumab, the increase in thrombin peak upon addition of rFVIIa was within or below the range observed by spiking with 1 IU/mL rFVIII. The increase in thrombin peak upon addition of aPCC was within or above the rFVIII range. The effects of concizumab and rFVIIa or aPCC were mainly additive; however, a small, statistically significant contribution caused by drug-drug interaction was observed for concizumab and rFVIIa (75 nM) in both plasma from patients with and without inhibitors, and for 1 U/mL aPCC in plasma from patients with inhibitors. The additive effects of concizumab and rFVIIa corresponded to between 60% (25 nM rFVIIa, plasma without inhibitors) and 75% (75 nM rFVIIa, inhibitor plasma), and the additive effects of concizumab and 1 U/mL aPCC corresponded to 77% of the total observed effects. Conclusions: Addition of rFVIIa or aPCC to hemophilia A plasma with or without inhibitors increased peak thrombin generation as expected both in the absence and presence of concizumab. Thus, the bypassing agents function as expected in plasma containing concizumab. The effects of concizumab and rFVIIa or aPCC were mainly additive. A small but statistically significant contribution was synergistic in accordance with the concizumab mechanism of action (Hilden I et al, Blood, 2012). These in vitro results support the concomitant use of bypassing agents to treat breakthrough bleeding episodes in hemophilia with inhibitor patients on concizumab prophylactic treatment. Disclosures Kjalke: Novo Nordisk A/S: Employment, Honoraria. Kjelgaard-Hansen:Novo Nordisk A/S: Employment, Equity Ownership. Andersen:Novo Nordisk A/S: Employment, Equity Ownership, Honoraria. Hilden:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties.

scholarly journals The Combination of Marzeptacog Alfa (Activated) or Eptacog Alfa (Activated) with Emicizumab Appears Comparable As Assessed By the Thrombin Generation Test in Hemophilia a Plasma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1112-1112
Author(s):  
Tom Knudsen ◽  
Brajesh Kumar ◽  
Frank Del Greco ◽  
Linda Neuman ◽  
Howard Levy ◽  
...  
Keyword(s):  
Thrombin Generation ◽  
Hemophilia A ◽  
Statistical Significance ◽  
Plasma Concentrations ◽  
Unmet Need ◽  
Surrogate Marker ◽  
Employment Equity ◽  
Thrombin Generation Assay ◽  
Equity Ownership

Background: Hemophilia patients treated prophylactically with emicizumab (Hemlibra®) may experience break-through bleeds or require additional hemostatic coverage for procedures or surgery. Currently available therapies including rFVIIa (Eptacog Alfa (Activated); NovoSeven®) and aPCC (FEIBA®) have been used with Hemlibra to treat bleeding or when additional coverage is required. While NovoSeven appears safe in combination with Hemlibra (HAVEN 1 to 4 clinical trials), thrombotic events have been observed with concurrent use of FEIBA and Hemlibra. While safe and efficacious when used as directed, NovoSeven must be infused intravenously. Ideally, for patients on subcutaneous (SC) prophylaxis with Hemlibra adjunct rFVIIa could be dosed SC too. Marzeptacog alfa (activated) (MarzAA) is a novel rFVIIa differentiated by increased potency and the ability to be administered SC to achieve pharmacologically relevant plasma concentrations. Thus, MarzAA provides a potential solution to address this unmet need in hemophilia therapy. Objective: Demonstrate the procoagulant potential of MarzAA, NovoSeven or FEIBA alone or in combination with Hemlibra using the thrombin generation assay in platelet poor hemophilia A (HA) plasma. The thrombin generation potential will therefore provide a surrogate marker to assess the potential safety and efficacy of SC MarzAA in combination with Hemlibra. Methods: A thrombin generation assay was performed using the PPP-Low Tissue Factor and phospholipid containing thrombin generation assay reagent (#TS31.00, Thrombinoscope, Stago). Citrated hemophilia A plasma was spiked with increasing concentrations (0, 25, 50, and 100 µg/mL) of Hemlibra together with various concentrations of each bypassing agent: MarzAA at 0, 0.1, 0.5, 1, 2.5, 5, and 10 µg/mL, NovoSeven at 1, 2.5, 5, 10, and 50 µg/mL or FEIBA at 0.25, and 0.50 IU/ml. Statistical significance was set at α = 0.05. Results: We assessed the relative potencies of MarzAA and NovoSeven in HA plasma. As expected, MarzAA demonstrated an approximate ten-fold increased potency vs NovoSeven. Both rFVIIa compounds increased peak thrombin generation in the HA plasma to the level of normal plasma and beyond. The effect of adding normalizing levels of MarzAA (1 µg/mL), NovoSeven (10 µg/mL) or FEIBA (0.5 IU/mL) to HA plasma containing clinically relevant concentrations of Hemlibra was evaluated (Fig 1). When correcting for the effect of Hemlibra alone, the increase in peak thrombin generation induced by FEIBA was significantly greater than that observed for both MarzAA and NovoSeven (P<0.002). In contrast, the observed increases in thrombin generation for MarzAA and NovoSeven in combination with Hemlibra were statistically indistinguishable. FEIBA was not tested at the highest clinically relevant concentration (2.0 IU/mL) as assay limitations were already approached at 0.5 IU/ml, corresponding to ~25% of the plasma concentration expected for a clinical FEIBA dose of 100 IU/kg. Furthermore, concentrations of MarzAA (5 µg/mL) or NovoSeven (50 µg/mL) 50-fold higher than expected after standard doses were required before peak thrombin generation became statistically indistinguishable from FEIBA at 0.5 IU/mL when all three compounds were evaluated in the presence of Hemlibra. Conclusion: As assessed by in vitro thrombin generation, equipotent concentrations of MarzAA and NovoSeven exhibit comparable characteristics when spiked into HA plasma containing Hemlibra at clinically relevant concentrations. Based on these data, MarzAA and NovoSeven are expected to behave similarly in combination with Hemlibra when dosed to achieve equipotent plasma concentrations. Figure 1 Disclosures Knudsen: Catalyst Biosciences: Employment, Equity Ownership. Kumar:Catalyst Biosciences: Employment, Equity Ownership. Del Greco:Catalyst Biosciences: Consultancy, Equity Ownership. Neuman:Catalyst Biosciences: Employment, Equity Ownership. Levy:Catalyst Biosciences: Employment, Equity Ownership. Blouse:Catalyst Biosciences: Employment, Equity Ownership.

scholarly journals Next-Generation FVIII Mimetic Shows Superior Effect in a FIX- and Fx-Humanized Mouse Model In Vivo

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3631-3631
Author(s):  
Carsten Dan Ley ◽  
Thomas Lindebo Holm ◽  
Daniel Elenius ◽  
Heidi Lindgreen Holmberg ◽  
Jais Rose Bjelke ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Thrombin Generation ◽  
Ex Vivo ◽  
Employment Equity ◽  
Tail Vein ◽  
Thrombin Generation Assay ◽  
Equity Ownership ◽  
Tail Clip

People with haemophilia A (HA) lack functional factor VIII (FVIII) and typically receive FVIII replacement therapy to prevent or treat bleeds. However, this requires frequent i.v. access, and efficacy is impaired in inhibitor patients. Mim8 is in development as a subcutaneous prophylactic treatment option for people with HA and HA with inhibitors. Like the recently approved emicizumab (Hemlibra®), Mim8 is a FVIII-mimicking human bispecific antibody bridging FIXa and FX. Mim8 is highly specific towards human FIXa (hFIXa) and human FX (hFX), preventing pre-clinical testing in standard rodent haemophilia models. Pharmacologic characterisation can be conducted in vitro and ex vivo utilizing human components. In vivo studies are feasible in primates due to high sequence homology between human and monkey FIX and FX, however, haemophilic mice are used for the most well-established and widely recognized bleeding models. Our aim was to establish a method to evaluate acute effects of Mim8 using in vivo bleeding models in HA mice, and to compare the potency and efficacy of Mim8 to a sequence-identical-analogue (SIA) of emicizumab. A protocol for dosing HA mice with hFIX and hFX was optimized based on in vitro Thrombin Generation Assay (TGA) in HA mouse plasma spiked with a range of hFIX and hFX concentrations. The thrombin levels required to stop bleeding in the in vivo Tail Vein Transection (TVT) model were known from previous studies. In mouse plasma with a clinically efficacious concentration of 300-350 nM of emicizumab SIA (Mahlangu J et al, N Engl J Med. 2018 Aug 30;379(9)), we found that roughly twice the normal human levels of hFIX and hFX were needed to achieve sufficient thrombin generation for the TVT model. To maintain concentrations at or above this level throughout the bleeding experiments, in vivo doses were set at 1.5mg/kg and 0.9mg/kg, respectively. Based on the in vitro optimization, the haemostatic effect of Mim8 was evaluated by three different methods: 1. Tail Vein Transection (TVT), a venous in vivo bleeding model sensitive to clinical doses of FVIII, and 2. Tail Clip (TC), an arteriovenous in vivo bleeding model with lower sensitivity to FVIII, presumably due to the more severe nature of the bleed, and 3. Ex vivo TGA on plasma from Mim8-dosed mice Briefly, mice were anaesthetized with isoflurane and dosed with hFIX, hFX and test compound. Thereafter, they were subjected to either the TVT bleeding model, the TC bleeding model, or cardiac puncture for plasma collection and ex vivo TGA. All mice were euthanized without awakening from anaesthesia. Both compounds were efficacious in vitro in TGA (Figure A). Potency of Mim8 was significantly greater compared to emicizumab SIA; the efficacy of approximately 40 nM Mim8 corresponded to 300 nM emicizumab SIA. At the highest concentrations (&gt;1000 nM), Mim8 efficacy tapered off, but remained superior to 300 nM emicizumab SIA. In TVT in HA mice, bleeding was reduced in a dose-dependent manner with an ED50 of 0.05 mg/kg for Mim8 or 0.7 mg/kg for emicizumab SIA. Statistically significant reduction of blood loss was observed at doses of or above 0.1 mg/kg Mim8 and 10mg/kg emicizumab SIA, corresponding to measured plasma concentrations above 10 nM for Mim8 and 300nM for emicizumab SIA. In the more severe TC model, blood loss was significantly reduced after treatment with 10 mg/kg of Mim8, whereas the tested doses of emicizumab SIA were not efficacious (Figure B). Mice treated with 4.6 and 10 mg/kg of Mim8, corresponding to a plasma concentration of up to approx. 1000nM, bled significantly less than mice treated with emicizumab SIA. In agreement with the in vitro TGA results, the 22 mg/kg dose (plasma concentration &gt;2200 nM) appeared less efficacious; association of FIXa and FX to different Mim8 molecules is the likely cause. The increased potency of Mim8 was confirmed in TGA ex vivo. In conclusion, we developed a method for evaluating the FVIII-mimetic compounds Mim8 and emicizumab SIA, which require human FIX and FX, in a murine system. This method may be applicable for testing of other FIXa-FX bridging compounds lacking rodent cross-reactivity. In Thrombin Generation Assay and the Tail Vein Transection model, Mim8 showed significantly increased potency compared to emicizumab-SIA, and the observed potency gain corresponded to in vitro findings in the human system. Furthermore, Mim8 could stop a severe bleed in the tail clip model, which was not possible with the tested doses of emicizumab SIA. Figure Disclosures Ley: Novo Nordisk A/S: Employment, Equity Ownership. Holm:Leo Pharma A/S: Employment, Equity Ownership; Novo Nordisk A/S: Employment, Equity Ownership. Elenius:Leo Pharma A/S: Employment, Equity Ownership; Novo Nordisk A/S: Equity Ownership, Other: Previous employment. Holmberg:Novo Nordisk A/S: Employment, Equity Ownership. Bjelke:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Loftager:Novo Nordisk A/S: Employment, Equity Ownership. Hermit:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties: Patents. Hilden:Novo Nordisk A/S: Employment, Equity Ownership, Patents & Royalties. Kjellev:Novo Nordisk A/S: Employment, Equity Ownership.

Antithrombin Reduction Corrected Thrombin Generation in Samples from Hemophilia A and B Patients with Inhibitors

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 552-552 ◽  
Author(s):  
Gili Kenet ◽  
Tami Livnat ◽  
Emma Fosbury ◽  
Pratima Chowdary ◽  
Alfica Sehgal ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Severe Hemophilia ◽  
Employment Equity ◽  
Advisory Committees ◽  
Advisory Boards ◽  
Equity Ownership

Abstract Background: Severe hemophilia A and B patients with inhibitors experience serious musculoskeletal hemorrhage as well as high risk of limb and life threatening bleeds. However, lack of effect of FVIII or FIX substitution therapy and short functional half-life of by-passing agents, leave these patients with very limited bleed preventive treatment options. ALN-AT3 (Alnylam Pharmaceuticals, Cambridge, MA, USA), a subcutaneously administered investigational RNAi therapeutic targeting reduction of antithrombin for potential treatment of hemophilia is currently in phase 1 clinical development in hemophilia A and B patients without inhibitors. Initial data from that ongoing study in 12 patients suggest an AT KD dependent correction of thrombin generation. This study aims to assess changes in peak thrombin generation in samples from patients with severe hemophilia A and B with inhibitors following in vitro reduction of antithrombin. Materials and methods: Citrated plasma samples were obtained from patients with severe hemophilia A and B with high responding inhibitors. Samples were spiked in vitro with isotype specific control IgG or a monoclonal antibody (Haemtech Inc, Essex Junction, VT, USA) targeting antithrombin knockdown of 50% and 90%. Dynamic formation of thrombin was measured by calibrated automated thrombin generation using 1pM tissue factor PPP reagent and 4μM phospholipid (Thrombinoscope, Maastricht, The Nederlands). The primary effect measure was peak thrombin (nM). Data were tested by a 1-way ANOVA and p<0.05 was considered statistically significant. Results: A total of 12 inhibitor hemophilia samples were investigated; 9 hemophilia A and 3 hemophilia B. All the control samples demonstrated a profound defect in thrombin generation with a median peak thrombin of 19.9 nM (range 6.7 - 42.4). Patients with severe hemophilia A and inhibitors had a median peak thrombin generation of 19.7 nM (range 6.7 - 42.4), whereas patients with severe hemophilia B and inhibitors had a median peak thrombin generation of 19.2nM (range 19.4 - 38.1). An AT reduction dependent improvement in peak thrombin generation was observed in all 12 tested plasma samples (Figure 1). In the first 12 subjects, peak thrombin generation was increased up to 363% from a mean of 22nM (control) to 39 nM (50% AT reduction) and 80nM (90% AT reduction) (p<0.05); levels comparable to thrombin generation observed in healthy male volunteers and in hemophilia patients treated with ALN-AT3. Conclusions: These in vitro data suggest that reduction of AT is a promising approach for restoring hemostatic balance and correcting thrombin generation in hemophilia patients with inhibitors. Furthermore, the present laboratory data compare well with clinical data generated with ALN-AT3 administered to patients with hemophilia A or B. Thus, both laboratory and emerging clinical data suggest that targeting antithrombin could be a promising approach for restoring hemostatic balance in hemophilia. The potential for low volume subcutaneous administration, infrequent dosing, and applicability to persons with hemophilia who have inhibitors, make ALN-AT3 a particularly encouraging investigational therapy. Figure 1. Figure 1. Disclosures Kenet: Bayer, Novo Nordisk: Other: Advisory Boards, Speakers Bureau; Opko Biologics: Consultancy, Other: Advisory Boards; BPL; Baxelta: Research Funding; Pfizer: Honoraria. Off Label Use: ALN-AT3 is an investigational RNAi therapeutic targeting the endogenous anticoagulant antithrombin.. Chowdary:Sobi: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Baxalta: Membership on an entity's Board of Directors or advisory committees; Biogen: Membership on an entity's Board of Directors or advisory committees. Sehgal:Alnylam Pharmaceuticals: Employment, Equity Ownership. Akinc:Alnylam Pharmaceuticals: Employment, Equity Ownership. Sorensen:Alnylam Pharmaceuticals: Employment, Equity Ownership.

scholarly journals Pharmacology and Pharmacokinetics of NXT007; Emicizumab-Based Engineered Fixa/Fx Bispecific Antibody with Improved Properties

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 19-19
Author(s):  
Kazuki Yamaguchi ◽  
Tetsuhiro Soeda ◽  
Motohiko Sato ◽  
Norihito Shibahara ◽  
Hikaru Koga ◽  
...  
Keyword(s):  
Ternary Complex ◽  
Thrombin Generation ◽  
Turnover Rate ◽  
Bispecific Antibody ◽  
Hemophilia A ◽  
Minimal Impact ◽  
Kd Values ◽  
Cofactor Activity

Background Emicizumab (HEMLIBRA®) is a factor (F) VIII function-mimetic therapeutic bispecific antibody (BsAb) to FIXa and FX able to prevent bleeding in persons with hemophilia A (PwHA) when injected subcutaneously once every 1, 2 or 4 weeks. To develop a next generation version, we sought an agent able to keep hemostatic potential in non-hemophilic range with more convenient dosing regimen (dosing frequency/volume). We successfully created the emicizumab-based engineered four-chain BsAbs, NXT series. Among these, we selected NXT007 as a clinical candidate. Objectives The aim of this study is to clarify the in vitro and in vivo properties of NXT007 and predict its therapeutic potency non-clinically. Methods We evaluated the pharmacological activities of NXT007 in vitro using a thrombin generation assay (TGA) with FVIII-deficient patient plasma, and in vivo by inducing bleeding in FVIII-neutralizing antibody-treated acquired hemophilia A cynomolgus monkey (cyno) model. To clarify the FVIII-cofactor activity of NXT007, we performed an enzymatic kinetics analysis of FIXa-catalyzed FX activation with and without NXT007, as well as surface plasmon resonance analysis to determine the dissociation constant (KD) of NXT007 to FIX, FIXa, FX and FXa. We obtained its pharmacokinetic (PK) profile in non-human primates in a single dose SC/IV study. Results In vitro addition of NXT007 at 30 μg/mL increased the peak height of TGA in FVIII-deficient plasma to the same levels achieved by recombinant human FVIII at 40-100 IU/dL (FXIa-triggering) or 100-150 IU/dL (tissue factor-triggering). A single bolus intravenous injection of NXT007 (0.075 mg/kg) ameliorated bleeding symptoms in the cyno model to similar as a twice daily intravenous injection of recombinant porcine FVIII (20 U/kg). The in vitro and in vivo results were roughly concordant. NXT007 increased the turnover rate (kcat) of FIXa-catalyzed FX activation by approximately 4,000-folds compared to the condition without cofactor. The impact of NXT007 on the kcat was similar to that of emicizumab. As for binding affinities, the KD values of NXT007 to FIX, FIXa, FX and FXa were 1.08, 0.728, 0.0538 and 0.0231 μM, respectively in buffer solution. Compared to emicizumab, NXT007 bound more strongly to FX/FXa and with similar affinity to FIX/FIXa. This means that NXT007 would have an ability to form more FIX-BsAb-FX ternary complex than emicizumab. Calculated using the above KD values, at 30 μg/mL of BsAb the estimated concentration of FIX-NXT007-FX ternary complex in plasma is approximately 10-fold higher than that of the FIX-emicizumab-FX ternary complex which is roughly concordant with the difference in their FVIII equivalent thrombin generation activity. Prothrombin time (PT) was not clearly prolonged suggesting minimal impact on FX function by in vitro addition of NXT007 at up to 30 μg/mL, which was enough to induce sufficient thrombin burst in FVIII-deficient plasma as described above. A half-life of NXT007 was 19.6 to 24.4 days (0.02-2 mg/kg, SC) and SC bioavailability was 84.4% (2 mg/kg) in the in vivo cyno PK study, in which no obvious change in plasma FIX or FX levels was observed after 0.02-2 mg/kg single SC administration. Conclusions Based on the nonclinical results, NXT007, delivered in every-4-week SC injections, will keep a non-hemophilic range of equivalent FVIII thrombin generation in PwHA, Compared with emicizumab, NXT007's improved cofactor activity may be attributed to its more efficient ternary complex formation while keeping turnover rate with minimal impact on FX function suggested by PT value and antigen accumulation. A phase 1/2 clinical study of NXT007 is now on-going (NXTAGE; JapicCTI-194919). Disclosures Yamaguchi: Chugai Pharmaceutical Co., Ltd: Current Employment. Soeda:Chugai Pharmaceutical Co., Ltd.: Current Employment. Sato:Chugai Pharmaceutical Co., Ltd.: Current Employment. Shibahara:Chugai Pharmaceutical Co., Ltd.: Current Employment. Koga:Chugai Pharmaceutical Co., Ltd.: Current Employment. Ichiki:Chugai Pharmaceutical Co., Ltd.: Current Employment. Joyashiki:Chugai Pharmaceutical Co., Ltd.: Current Employment. Teranishi:Chugai Pharmaceutical Co., Ltd.: Current Employment. Nishimura:Chugai Pharmaceutical Co., Ltd.: Current Employment. Shiraiwa:Chugai Pharmaceutical Co., Ltd.: Current Employment. Kitamura:Chugai Pharmaceutical Co., Ltd.: Current Employment. Igawa:Chugai Pharmaceutical Co., Ltd.: Current Employment. Konishi:Chugai Pharmaceutical Co., Ltd.: Current Employment. Kitazawa:Chugai Pharmaceutical Co., Ltd.: Current Employment.

scholarly journals Phospholipid-Independent Activity of Fviiia Mimetic Bispecific Antibodies in Plasma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2461-2461
Author(s):  
Maria M Aleman ◽  
Siddharth Jindal ◽  
Nina Leksa ◽  
Robert Peters ◽  
Joe Salas
Keyword(s):  
Thrombin Generation ◽  
Hemophilia A ◽  
Bispecific Antibodies ◽  
Molar Ratio ◽  
Phospholipid Vesicles ◽  
Employment Equity ◽  
One Stage ◽  
Equity Ownership ◽  
Substrate Cleavage

Abstract Introduction: An important coagulation regulatory mechanism is localization of clotting complexes to exposed phosphatidylserine (PS) on cell surfaces. All components of the intrinsic tenase complex (factor (F)VIIIa, FIXa, and FX) bind to PS. FVIIIa mimetic bispecific antibodies are drugs in development for hemophilia A that aim to mimic the cofactor function of FVIIIa by bringing together FIXa and FX to generate FXa. However, these antibodies differ from FVIII in many ways including no requirement of activation and a lack of direct PS binding. Emicizumab is a bispecific antibody currently on the market for hemophilia A patients with inhibitors. It binds to factor FIX, FIXa, FX, and FXa with micromolar affinities in solution. Previously, we have shown that in-house preparations of sequence-identical emicizumab (SI-Emi) showed similar weak affinities to its antigens and similar in vitro activity to published emicizumab results by one-stage clotting, chromogenic FXa generation, and thrombin generation. However, in chromogenic FXa generation using antibody concentrations in the range of the mean steady state plasma concentration of patients on emicizumab prophylaxis [~360 nM, (Oldenburg, et al., NEJM 2017)], SI-Emi maintained 28% of its activity even in the absence of PS-containing phospholipid vesicles. Another FVIIIa mimetic antibody, BS-027125, was discovered by our group and binds with low nanomolar affinity to FIX, FIXa and FX, with no detectable binding to FXa. In one-stage clotting, BS-027125 achieved clot times similar to physiological levels of FVIII, but had poor activity in thrombin generation at these concentrations. Furthermore, it too maintained small amounts of phospholipid-independent activity in chromogenic FXa generation. Given the artificial nature of the chromogenic FXa generation assay, and that activity of prothrombinase is PS-dependent thereby precluding omission of phospholipids from thrombin generation assays, we developed an assay to detect FXa generation in a plasma milieu by FVIIIa mimetic antibodies or FVIII with and without phospholipid vesicles. Methods: FVIIIa mimetic antibodies or recombinant FVIII (rFVIII) were incubated with thrombin for 5 minutes, quenched with hirudin, then spiked into platelet-free congenital hemophilia A plasma treated with additional hirudin. FXIa (to generate FIXa in situ) with and without PC:PE:PS (40:40:20 molar ratio) phospholipid vesicles was added and reactions were triggered with a solution of CaCl2 and fluorogenic FXa substrate (Mes-D-LGR-ANSN(C2H5)2). Substrate cleavage was monitored kinetically on a fluorescent plate reader. Substrate cleavage by FXIa could not be detected, yet another unknown plasma peptidase did cleave substrate at a constant low rate that was background subtracted. Results: In the absence of phospholipid vesicles, SI-Emi maintained 51±3.7% of its FXa generation activity at all concentrations tested (3.8±0.4 versus 8.0±1.1 RFU/min at 333 nM). BS-027125 showed very low activity (0.43±0.12 RFU/min at 50 nM) in the presence of phospholipid vesicles, however, in the absence of phospholipid vesicles, BS-027125 activity was not detectable above baseline. Nearly all rFVIII activity (>99%) was lost in the absence of phospholipid vesicles (0.14±0.04 versus 15.1±1.8 RFU/min at 0.3 IU/mL). Addition of annexin V was sufficient to block all rFVIII activity in the presence or absence of phospholipid vesicles, but could not block SI-Emi activity. Furthermore, addition of rivaroxaban, a direct FXa inhibitor, confirmed that detection of substrate cleavage was due to FXa activity. Conclusions: In the absence of phosphatidylserine-containing phospholipid vesicles, SI-Emi promoted the generation of FXa in plasma triggered with FXIa. The activity of BS-027125 was too low in this assay to clearly determine its phospholipid-independent activity. These results suggest SI-Emi has mis-regulated (PS-independent) procoagulant activity due to a lack of phospholipid localization of the antibody-FIXa-FX complex. Given the weak affinity of SI-Emi for its antigens, the exact mechanism enabling this activity is unclear. Further study of this phenomenon and its relevance to overall thrombin generation and in vivo activity are needed. Disclosures Aleman: Bioverativ, a Sanofi company: Employment. Jindal:Bioverativ, a Sanofi company: Employment. Leksa:Bioverativ a Sanofi company: Employment. Peters:Bioverativ a Sanofi company: Employment, Equity Ownership. Salas:Bioverativ a Sanofi company: Employment, Equity Ownership.

An Immunodeficient Mouse Model With Circulating Human Platelets To Evaluate The Platelet Clearance and Pharmacokinetics Of Platelet-Targeted Coagulation Factor VIIa

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2345-2345
Author(s):  
Siyuan Tan ◽  
Kai Chen ◽  
Joe Salas ◽  
Robert Peters ◽  
David R. Light ◽  
...  
Keyword(s):  
Half Life ◽  
Hemophilia A ◽  
Human Platelet ◽  
Human Platelets ◽  
Employment Equity ◽  
In Vivo Models ◽  
Nsg Mice ◽  
Equity Ownership

Abstract Treatment of bleeding episodes in hemophilia patients with inhibitory antibodies to factor VIII or factor IX by recombinant activated factor VII (rFVIIa, NovoSeven) has been sub-optimal partly due to its low affinity to activated platelets and its short half-life in circulation. To develop a rFVIIa variant with enhanced coagulant activity, we have targeted rFVIIa to platelets by monoclonal antibodies that recognize the human platelet receptor αIIbβ3. However, the assessment of pharmacokinetic parameters in mice is limited by the lack of recognition of mouse αIIbβ3 by antibodies to human αIIbβ3. The present study addresses the need to develop appropriate in vivo models to study this new class of bypass therapeutics. First, we evaluated the survival of human platelets in hemophilia A, NOD/SCID, and NOD/SCID/gamma (NSG) mice. Platelet concentrates were prepared from normal human donors and transfused retro-orbitally into mice. The whole blood from dosed mice was then collected via tail vein laceration at various times and the human platelet counts in blood was determined by flow cytometry after staining with fluorescently labeled antibodies against human CD42b, mouse CD61, human FVII to visualize the human platelets, mouse platelets, and the FVIIa candidate that bound to human platelets, respectively. The half-life of human platelets in NOD/scid/gamma (NSG) mice was approximately 4 hours, which is considerably longer than the 0.8 hour half-life observed in hemophilia A mice. The effect of platelet-targeted FVIIa variants on the clearance of human platelets was then investigated in NSG mice. The FVIIa candidates were pre-selected for their inactivity toward human platelet activation and aggregation, as determined in a battery of in vitro assays. In agreement with the in vitro results, all of these selected candidates did not affect the clearance of the transfused human platelets when dosed in NSG mice at 5 nmol/kg. In contrast, a control antibody fusion protein that is known to activate platelets and cause thrombocytopenia in vivo led to rapid platelet clearance in NSG mice. Similar results were observed for these proteins in cynomolgous monkeys when dosed at 2 nmol/kg. The NSG mice with circulating human platelets were also explored to evaluate the clearance of FVIIa candidates that remain platelet-associated in vivo. To improve the pharmacokinetics, we have fused XTEN, a hydrophilic peptide that increases the dynamic radius of payload proteins, to the platelet-targeted FVIIa candidates. When tested in NSG mice model for the clearance of platelet-associated protein, addition of XTEN markedly reduced the clearance rate, resulting in several fold increase in exposure. Together these data indicate that NSG mice with circulating human platelets can be used to assess the safety and pharmacokinetics of the platelet-targeted FVIIa variants, and the method can be adapted to evaluate other agents designed to utilize platelet-targeting approaches. Disclosures: Tan: Biogen Idec: Employment, Equity Ownership. Chen:Biogen Idec: Employment, Equity Ownership. Salas:Biogen Idec: Employment, Equity Ownership. Peters:Biogen Idec: Employment, Equity Ownership. Light:Biogen Idec: Employment; Biogen Idec: Equity Ownership. Jiang:Biogen Idec: Employment; Biogen Idec: Equity Ownership.

scholarly journals Elucidating the Excessive Pro-Coagulant Effect of a Sequence Identical Analogue to ACE910 in Combination with Bypassing Agents

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 90-90
Author(s):  
Rudolf Hartmann ◽  
Tjerk Feenstra ◽  
Sabine Knappe ◽  
Michael Dockal ◽  
Friedrich Scheiflinger
Keyword(s):  
Whole Blood ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Thrombus Formation ◽  
Phase Iii ◽  
Hek293 Cells ◽  
Employment Equity ◽  
Equity Ownership ◽  
Bypassing Agents

Abstract Introduction: Emicizumab (ACE910), an antibody to FIX(a) and FX(a), is currently under investigation for treatment of hemophilia with inhibitors. In a phase III trial, two thromboembolic complications and three cases of microangiopathy were reported in patients on ACE910 prophylaxis [Oldenburg et al. NEJM 2017], whose breakthrough bleeding was treated with activated prothrombin complex concentrate aPCC (FEIBA) or aPCC and rFVIIa. We generated a sequence identical analogue (SIA) to ACE910 and analyzed its synergistic interplay with bypassing agents. Aims: To monitor in vitro the pro-coagulant activity of SIA ACE910 in the presence of FEIBA and rFVIIa, and detect the source of excessive coagulation induced by SIA ACE910 combined with FEIBA. Methods: A sequence identical analogue (SIA) to ACE910 was expressed in HEK293 cells, purified as previously described [Sampei et al. PLoS One 2013], and analyzed in several global hemostatic assays at different concentrations and test conditions using plasma and whole blood assays. In thrombin generation (TG) experiments, platelet-poor plasma (PPP) from hemophilia A inhibitor patients and hemophilia A plasma reconstituted with platelets from 3 healthy donors (PRP) was used. A normal TG range was established in healthy donor plasma. Therapeutic concentrations of SIA ACE910 (20-600 nM) were tested alone and with FEIBA (0.05-1 U/mL) or rFVIIa (0.88-5.25 µg/mL). To measure FEIBA components' contribution to the synergistic effect with SIA ACE910, PPP was spiked with select FEIBA components at concentrations corresponding to 0.5 U/mL FEIBA in combination with the antibody. Thrombus formation was analyzed in FVIII-inhibited blood using rotational thromboelastometry (ROTEM) and Total Thrombus-formation Analysis System (T-TAS). Results: Normal peak thrombin was 47-144 nM for PPP and 88-231 nM for PRP. rFVIIa and FEIBA had an additive effect on TG in combination with SIA ACE910 in both plasma types. Combined with rFVIIa (0.88 µg/mL) or FEIBA (0.5 U/mL), SIA ACE910 (600 nM) induced a ~2- and ~16-fold increase over SIA ACE910 alone. SIA ACE910+rFVIIa did not reach the normal range, while SIA ACE910+FEIBA far exceeded it. Adding individual FEIBA components to PPP showed that FIX was, with a half-maximal effect, the main driver for enhanced TG, followed by FIXa. formation in FVIII-inhibited whole blood using ROTEM and T-TAS confirmed the excessive effect of SIA ACE910+FEIBA. In ROTEM, FEIBA and rFVIIa reduced clotting time to shorter than normal, whereas SIA ACE910 had only little effect. Moreover, adding SIA ACE910 to rFVIIa exerted no effect over rFVIIa alone. Conclusion: Combining SIA ACE910 at plasma concentrations observed in patients [Oldenburg et al. NEJM 2017] with FEIBA induced excessive thrombin generation and faster clot formation. In vitro, this effect is mainly mediated by FEIBA component FIX. ACE910 binds to FIX and FIXa to the same extent, and displays its pro-coagulant effect via an unregulated mechanism. Therefore, careful judgement is needed in treating breakthrough bleeds with FEIBA. Disclosures Hartmann: Shire: Employment. Feenstra: Shire: Employment. Knappe: Shire: Employment. Dockal: Baxalta: Patents & Royalties; Shire: Employment, Equity Ownership; Baxter: Equity Ownership, Patents & Royalties. Scheiflinger: Baxter: Equity Ownership; Shire: Employment, Equity Ownership.

scholarly journals Phenotype Does Not Always Equal Function: HDAC Inhibitors and UM171, but Not SR1, Lead to Rapid Upregulation of CD90 on Non-Engrafting CD34+CD90-Negative Human Cells

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 659-659
Author(s):  
Kevin A. Goncalves ◽  
Megan D. Hoban ◽  
Jennifer L. Proctor ◽  
Hillary L. Adams ◽  
Sharon L. Hyzy ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Small Molecule ◽  
Hdac Inhibitors ◽  
Employment Equity ◽  
Nsg Mice ◽  
Cd34 Cells ◽  
Equity Ownership ◽  
Human Hscs

Abstract Background. The ability to expand human hematopoietic stem cells (HSCs) has the potential to improve outcomes in HSC transplantation and increase the dose of gene-modified HSCs. While many approaches have been reported to expand HSCs, a direct comparison of the various methods to expand transplantable HSCs has not been published and clinical outcome data for the various methods is incomplete. In the present study, we compared several small molecule approaches reported to expand human HSCs including HDAC inhibitors, the aryl hydrocarbon antagonist, SR1, and UM171, a small molecule with unknown mechanism, for the ability to expand phenotypic HSC during in vitro culture and to expand cells that engraft NSG mice. Although all strategies increased the number of phenotypic HSC (CD34+CD90+CD45RA-) in vitro, SR1 was the most effective method to increase the number of NOD-SCID engrafting cells. Importantly, we found that HDAC inhibitors and UM171 upregulated phenotypic stem cell markers on downstream progenitors, suggesting that these compounds do not expand true HSCs. Methods. Small-molecules, SR1, HDAC inhibitors (BG45, CAY10398, CAY10433, CAY10603, Entinostat, HC Toxin, LMK235, PCI-34051, Pyroxamide, Romidepsin, SAHA, Scriptaid, TMP269, Trichostatin A, or Valproic Acid) and UM171 were titrated and then evaluated at their optimal concentrations in the presence of cytokines (TPO, SCF, FLT3L, and IL6) for the ability to expand human mobilized peripheral blood (mPB)-derived CD34+ cells ex vivo . Immunophenotype and cell numbers were assessed by flow cytometry following a 7-day expansion assay in 10-point dose-response (10 µM to 0.5 nM). HSC function was evaluated by enumeration of colony forming units in methylcellulose and a subset of the compounds were evaluated by transplanting expanded cells into sub-lethally irradiated NSG mice to assess engraftment potential in vivo . All cells expanded with compounds were compared to uncultured or vehicle-cultured cells. Results. Following 7 days of expansion, SR1 (5-fold), UM171 (4-fold), or HDAC inhibitors (&gt;3-35-fold) resulted in an increase in CD34+CD90+CD45RA- number relative to cells cultured with cytokines alone; however, only SR1 (18-fold) and UM171 (8-fold) demonstrated enhanced engraftment in NSG mice. Interestingly, while HDAC inhibitors and UM171 gave the most robust increase in the number and frequency of CD34+CD90+CD45RA- cells during in vitro culture, these methods were inferior to SR1 at increasing NSG engrafting cells. The increase in CD34+CD90+CD45RA- cells observed during in vitro culture suggested that these compounds may be generating a false phenotype by upregulating CD90 and down-regulating CD45RA on progenitors that were originally CD34+CD90-CD45RA+. We tested this hypothesis by sorting CD34+CD90-CD45RA+ cells and culturing these with the various compounds. These experiments confirmed that both HDAC inhibitors (33-100 fold) and UM171 (28-fold) led to upregulation of CD90 on CD34+CD90-CD45RA+ cells after 4 days in culture. Since approximately 90% of the starting CD34+ cells were CD90-, these data suggest that most of the CD34+CD90+CD45RA- cells in cultures with HDAC inhibitors and UM171 arise from upregulation of CD90 rather than expansion of true CD34+CD90+CD45RA- cells and may explain the disconnect between in vitro HSC phenotype and NSG engraftment in vivo . This was further confirmed by evaluation of colony forming unit frequency of CD34+CD90-CD45RA+ cells after culture with compounds. Conclusions. We have showed that AHR antagonism is optimal for expanding functional human HSCs using the NSG engraftment model. We also demonstrated that UM171 and HDAC inhibitors upregulate phenotypic HSC markers on downstream progenitors. This could explain the discrepancy between impressive in vitro phenotypic expansion and insufficient functional activity in the NSG mouse model. Therefore, these data suggest caution when interpreting in vitro expansion phenotypes without confirmatory functional transplantation data, especially as these approaches move into clinical trials in patients. Disclosures Goncalves: Magenta Therapeutics: Employment, Equity Ownership. Hoban: Magenta Therapeutics: Employment, Equity Ownership. Proctor: Magenta Therapeutics: Employment, Equity Ownership. Adams: Magenta Therapeutics: Employment, Equity Ownership. Hyzy: Magenta Therapeutics: Employment, Equity Ownership. Boitano: Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Cooke: Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties.

scholarly journals Highly Differentiated Anti-CD47 Antibody, AO-176, Potently Inhibits Hematologic Malignancies Alone and in Combination

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1844-1844
Author(s):  
John Richards ◽  
Myriam N Bouchlaka ◽  
Robyn J Puro ◽  
Ben J Capoccia ◽  
Ronald R Hiebsch ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Combination Therapy ◽  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Cells ◽  
Tumor Growth Inhibition ◽  
Employment Equity ◽  
Equity Ownership

AO-176 is a highly differentiated, humanized anti-CD47 IgG2 antibody that is unique among agents in this class of checkpoint inhibitors. AO-176 works by blocking the "don't eat me" signal, the standard mechanism of anti-CD47 antibodies, but also by directly killing tumor cells. Importantly, AO-176 binds preferentially to tumor cells, compared to normal cells, and binds even more potently to tumors in their acidic microenvironment (low pH). Hematological neoplasms are the fourth most frequently diagnosed cancers in both men and women and account for approximately 10% of all cancers. Here we describe AO-176, a highly differentiated anti-CD47 antibody that potently targets hematologic cancers in vitro and in vivo. As a single agent, AO-176 not only promotes phagocytosis (15-45%, EC50 = 0.33-4.1 µg/ml) of hematologic tumor cell lines (acute myeloid leukemia, non-Hodgkin's lymphoma, multiple myeloma, and T cell leukemia) but also directly targets and kills tumor cells (18-46% Annexin V positivity, EC50 = 0.63-10 µg/ml) in a non-ADCC manner. In combination with agents targeting CD20 (rituximab) or CD38 (daratumumab), AO-176 mediates enhanced phagocytosis of lymphoma and multiple myeloma cell lines, respectively. In vivo, AO-176 mediates potent monotherapy tumor growth inhibition of hematologic tumors including Raji B cell lymphoma and RPMI-8226 multiple myeloma xenograft models in a dose-dependent manner. Concomitant with tumor growth inhibition, immune cell infiltrates were observed with elevated numbers of macrophage and dendritic cells, along with increased pro-inflammatory cytokine levels in AO-176 treated animals. When combined with bortezomib, AO-176 was able to elicit complete tumor regression (100% CR in 10/10 animals treated with either 10 or 25 mg/kg AO-176 + 1 mg/kg bortezomib) with no detectable tumor out to 100 days at study termination. Overall survival was also greatly improved following combination therapy compared to animals treated with bortezomib or AO-176 alone. These data show that AO-176 exhibits promising monotherapy and combination therapy activity, both in vitro and in vivo, against hematologic cancers. These findings also add to the previously reported anti-tumor efficacy exhibited by AO-176 in solid tumor xenografts representing ovarian, gastric and breast cancer. With AO-176's highly differentiated MOA and binding characteristics, it may have the potential to improve upon the safety and efficacy profiles relative to other agents in this class. AO-176 is currently being evaluated in a Phase 1 clinical trial (NCT03834948) for the treatment of patients with select solid tumors. Disclosures Richards: Arch Oncology Inc.: Employment, Equity Ownership, Other: Salary. Bouchlaka:Arch Oncology Inc.: Consultancy, Equity Ownership. Puro:Arch Oncology Inc.: Employment, Equity Ownership. Capoccia:Arch Oncology Inc.: Employment, Equity Ownership. Hiebsch:Arch Oncology Inc.: Employment, Equity Ownership. Donio:Arch Oncology Inc.: Employment, Equity Ownership. Wilson:Arch Oncology Inc.: Employment, Equity Ownership. Chakraborty:Arch Oncology Inc.: Employment, Equity Ownership. Sung:Arch Oncology Inc.: Employment, Equity Ownership. Pereira:Arch Oncology Inc.: Employment, Equity Ownership.

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