Platelet-Targeted rFVIIa-Xten Improves Thrombin Generation and Fibrin Formation Compared to Recombinant FVIIa

Abstract The development of inhibitors to replacement plasma factors in hemophilia is an ongoing clinical complication. Bypass therapies, such as recombinant factor VIIa (rFVIIa), have emerged as important alternative on-demand strategies for hemophilic patients with inhibitors to treat spontaneous bleeds and prevent bleeding during surgery. However, general prophylaxis strategies for hemophilia inhibitor patients are lacking. An attractive approach for effective prophylaxis and on-demand treatment includes engineering potent rFVIIa variants with prolonged pharmacokinetics. Because the primary mechanism of action of rFVIIa is thought to occur on the platelet surface, we combined rFVIIa with platelet-targeting and XTEN half-life extension technologies to improve its pharmacokinetic profile and procoagulant activity. Platelet-targeting was achieved by recombinant fusion of an antibody fragment which binds the human alpha IIb integrin. Half-life extension was achieved by fusion of an XTEN polypeptide which increases the hydrodynamic radius, and therefore half-life, of rFVIIa. We have shown that these rFVIIa modifications improve the pharmacokinetics and efficacy of rFVIIa in vivo in humanized alpha IIb transgenic hemophilia A mice. The goal of the current study was to evaluate and compare thrombin generation and fibrin formation kinetics in hemophilic platelet-rich plasma in the presence of platelet-targeted rFVIIa-XTEN or rFVIIa. To achieve this, platelet-rich plasma from normal human donors was treated with an inhibitory factor VIII antibody to model hemophilia A and spiked with doses of platelet-targeted rFVIIa-XTEN or rFVIIa. Reactions were triggered with low tissue factor and recalcification. Thrombin generation (n=9) was monitored by calibrated automated thrombography and fibrin formation (n=7) was monitored optically on a plate reader. Non-linear regression analysis of dose responses was used to determine EC50 values for each parameter for each donor. Platelet-targeted rFVIIa-XTEN increases the rate and peak of thrombin generation with 2- to 6-fold lower EC50 values (peak and rate, respectively) than rFVIIa. These data were confirmed by thrombin generation in platelet-rich plasma from 1 hemophilia A donor and 1 hemophilia B donor which demonstrated similar responses to platelet-targeted rFVIIa-XTEN with 2.5- to 5-fold lower EC50 values (peak and rate, respectively) than rFVIIa. Notably, platelet count-dependent changes in thrombin generation activity were similar between platelet-targeted rFVIIa-XTEN and rFVIIa. Fibrin formation analysis indicated platelet-targeted rFVIIa-XTEN increases the rate and time to plateau of fibrin formation with 5- to 13-fold lower EC50 values (rate and time to plateau, respectively) than rFVIIa. Analysis of fibrin network structure by confocal microscopy indicated platelet-targeted rFVIIa-XTEN increases fibrin network density in platelet-rich plasma clots. Together, these data show platelet-targeted rFVIIa-XTEN has more procoagulant activity than rFVIIa by supporting more thrombin generation and faster fibrin formation and suggest our approach has the potential to be an effective alternative for the treatment and prevention of bleeds in hemophilia patients with inhibitors. Disclosures Aleman: Biogen: Employment, Equity Ownership. Kistanova:Biogen: Employment, Equity Ownership. Moore:Biogen: Employment, Equity Ownership. Schellenberger:Amunix Operating Inc: Employment. Peters:Biogen: Employment. Salas:Biogen: Employment, Equity Ownership.

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

Blood ◽

10.1182/blood-2019-122301 ◽

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.

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Perioperative Efficacy of an Extended Half-Life, Pegylated, Full-Length, Recombinant Factor VIII (BAX 855) in Individual Procedures

Blood ◽

10.1182/blood.v126.23.2299.2299 ◽

2015 ◽

Vol 126 (23) ◽

pp. 2299-2299

Author(s):

Brigitte Brand ◽

Ralph A. Gruppo ◽

Tung T. Wynn ◽

Laimonas Griskevicius ◽

Maria Fernanda Lopez Fernandez ◽

...

Keyword(s):

Blood Loss ◽

Factor Viii ◽

Half Life ◽

Research Funding ◽

Hemophilia A ◽

Full Length ◽

Recombinant Factor Viii ◽

Employment Equity ◽

Major Procedure ◽

Equity Ownership

Abstract BAX 855 is a pegylated full-length recombinant factor VIII (PEG rFVIII) built on rFVIII (ADVATE) with an extended half-life and is intended for prophylaxis and the treatment of bleeding in patients with hemophilia A.1 This phase 3 surgery study is evaluating the efficacy and safety of BAX 855 for the perioperative control of hemostasis. Patients' informed consent and appropriate ethics committee approvals were obtained. Elective procedures were prospectively classified (major or minor) by the investigator/surgeon and major emergency surgeries were excluded. The target trough FVIII levels for major and minor surgeries were to be ≥80% and 30-60%, respectively. Each patient's pharmacokinetic (PK) profile was used to guide the BAX 855 dose and infusion frequency. BAX 855 PK were consistent with previous PK assessments with terminal half-life ranging from 8.81 to 18.06 hours for the 15 patients in this study. In this interim analysis, 15 male previously treated patients (PTPs) ranging from 19 to 52 years of age have undergone 15 procedures in 7 countries. Individual procedure profiles are compiled to evaluate the control of hemostasis for BAX 855. There were 11 major procedures: 6 orthopedic (3 knee replacements, 2 arthroscopic synovectomies, 1 elbow cyst extirpation) and 5 non-orthopedic procedures (3 dental [root canals for 2 teeth, 2 extractions of ≥4 teeth, 1 radicular cyst removal], 1 cardiovascular [mediport placement], 1 abdominal [gastric band insertion]). The 4 minor surgeries comprised 1 synoviorthesis, 1 dental, 1 dermatological and 1 endoscopy (radiosynovectomy) procedure. Efficacy was evaluated by the surgeon or investigator's rating of hemostatic control using 4-point scale which was based on blood loss and by comparing actual blood loss with predicted blood loss which was specified by the surgeon for non-hemophilia patients prior to the procedure. For all procedures, the hemostatic control of BAX 855 was rated "excellent" for the intraoperative (during the procedure), postoperative (24 hours after completion of the procedure), and perioperative (from start of the procedure until discharge or day 14) periods, except for 1 minor dental procedure in which postoperative efficacy was rated "good" and 1 minor procedure in which a postoperative rating was not provided (for both of these procedures intra- and perioperative ratings were "excellent"). Actual blood loss (ABL) for the intraoperative and postoperative periods were compared with predicted average and maximum values. Intraoperative ABL for all minor and major procedures was less than or equal to predicted averages and maximums, except for 1 minor procedure in which the ABL was greater than the predicted average and maximum and 1 major procedure which did not have ABL recorded. Postoperative ABL was less than or equal to predicted averages and maximums for 4/4 minor procedures and 5 major procedures. For 4 major procedures, postoperative ABL was greater than or equal to predicted average, but less than predicted maximums. For the remaining major procedure (synovectomy with general anesthesia) with reported ABL, postoperative ABL was greater than the predicted the average and maximum - the efficacy assessments at all periods for this procedure were considered "excellent". These results demonstrate the efficacy of BAX 855 for the perioperative control of hemostasis in patients with severe hemophilia A. 1 Konkle BA, Stasyshyn O, Chowdary P et al. Pegylated, full-length, recombinant factor VIII for prophylactic and on-demand treatment of severe hemophilia A. Blood. 2015; Link to Publisher's site: http://www.bloodjournal.org/content/bloodjournal/early/2015/07/08/blood-2015-03-630897.full.pdf Disclosures Brand: CSL Behring: Consultancy; Pfizer: Consultancy; Bayer: Consultancy; Baxalta: Consultancy, Research Funding; Novo Nordisk: Consultancy; Biotest: Consultancy. Gruppo:Baxalta: Consultancy, Research Funding; Novo Nordisk: Consultancy; Pfizer: Consultancy; Alexion: Speakers Bureau. Wynn:Baxalta: Research Funding. Griskevicius:Novartis: Consultancy, Research Funding; Baxalta: Research Funding. Fernanda Lopez Fernandez:Baxalta: Research Funding. Dvorak:Baxalta: Employment, Equity Ownership. Patrone:Baxalta: Employment, Equity Ownership. Abbuehl:Baxalta: Employment, Equity Ownership.

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Fitusiran, an Investigational RNAi Therapeutic Targeting Antithrombin for the Treatment of Hemophilia: Updated Results from a Phase 1 and Phase 1/2 Extension Study in Patients with Inhibitors

Blood ◽

10.1182/blood.v128.22.1397.1397 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1397-1397 ◽

Cited By ~ 9

Author(s):

K John Pasi ◽

Pencho Georgiev ◽

Tim Mant ◽

Toshko Lissitchkov ◽

Michael Desmond Creagh ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Thrombin Generation ◽

Hemophilia A ◽

Phase 1 ◽

Extension Study ◽

Severe Hemophilia ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Abstract Background: Development of inhibitory antibodies, also known as "inhibitors," to replacement factor is considered the most serious unmet need in hemophilia and occurs in up to 30% of persons with severe hemophilia A, and 3-5% of persons with severe hemophilia B. Once inhibitors are present in high titer, treatment or prevention of bleeding can become more difficult due to the decreased responsiveness to factor concentrates, requiring bypassing agents (BPA) for bleed management. Current BPAs have a short half-life and are sub-optimally effective. Fitusiran is a subcutaneously (SC) administered investigational RNA interference (RNAi) therapeutic targeting the endogenous anticoagulant antithrombin (AT) as a means to improve thrombin generation and promote hemostasis in patients with hemophilia. Preliminary data from an ongoing Phase 1, multi-center, study showed that fitusiran was generally well tolerated in patients with hemophilia A or B with and without inhibitors and that administration of once-monthly SC doses of fitusiran led to dose-dependent AT lowering, thrombin generation increase, and decrease in bleeding frequency (Pasi KJ, et al. Haemophilia 2016, 22[Suppl 4]). Here we report the updated safety, pharmacodynamic (PD) effect, and clinical activity of fitusiran in patients with hemophilia with inhibitors as well as long term data from the Phase 1/2 extension study. Methods: We are conducting a multi-center Phase 1, four part (Part A: healthy volunteers; Parts B and C: patients with moderate to severe hemophilia A or B; Part D: patients with hemophilia A or B with inhibitors) study (NCT02035605) followed by a multi-center Phase 1/2 extension study (NCT02554773). Primary endpoints include safety and tolerability; secondary endpoints include AT activity, thrombin generation and exploratory evaluation of bleed pattern. In Part D, patients with inhibitors received once-monthly SC fixed doses of 50 or 80mg fitusiran. After receiving 3 monthly doses in the Phase 1 study, all patients were eligible to continue monthly dosing in the Phase 1/2 extension study. Utilization of BPA for breakthrough bleed management was permissible in these patients. Results: Part D of the Phase 1 study included 12 hemophilia A or B patients with inhibitors in 2 dosing cohorts (50mg SC, qM dosing cohort, n=6; 80mg SC, qM dosing cohort, n=6). Within the 50mg dosing cohort there were five patients with severe hemophilia A with inhibitors and one patient with severe hemophilia B with inhibitors; mean age: 33 ± 7 years; mean weight: 73 ± 17kg. Previously reported safety data from the 50mg dosing cohort demonstrated fitusiran was generally well tolerated in hemophilia A or B patients with inhibitors and that there were no serious adverse events related to study drug and no thromboembolic events. Monthly administration of fitusiran at the 50mg dose led to a mean maximal AT lowering of 81 ± 2% and mean maximal thrombin generation increase of 368 ± 113%. A preliminary, post-hoc analysis suggested a 49-100% reduction in bleeding frequency at the lower dose of 50mg during initial follow-up in the Phase 1 study. As of July 2016, the 80mg dose cohort has been fully enrolled and includes 6 patients with hemophilia A with inhibitors; mean age: 39 ± 15 years; mean weight: 75 ± 19kg, and 5 of the 6 patients in the initial 50mg cohort have transitioned to the Phase 1/2 extension study. Follow-up in the Phase 1, 80mg cohort and Phase 1/2 extension study is ongoing. Updated safety, tolerability and clinical activity from the Phase 1 and Phase 1/2 extension studies among all 12 patients with inhibitors will be presented. Conclusions: Emerging clinical data suggest that targeting AT is generally safe and could be a promising approach for promoting hemostasis in patients with hemophilia with inhibitors. Furthermore, the potential for low volume SC administration, monthly dosing, and applicability to patients with hemophilia A and B with and without inhibitors make fitusiran a potentially encouraging investigational therapy. Disclosures Pasi: Biogen: Consultancy, Honoraria; Octapharma: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; SOBI: Honoraria, Membership on an entity's Board of Directors or advisory committees. Georgiev:Alnylam Pharmaceuticals: Consultancy. Chowdary:Bayer: Honoraria; Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sobi: Honoraria; Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Ragni:Novo Nordisk: Research Funding; Biomarin: Consultancy; Biogen: Consultancy, Research Funding; Alnylam Pharmaceuticals: Consultancy, Research Funding; Genentech: Research Funding; SPARK: Research Funding; Baxalta: Research Funding; CSL Behring: Research Funding; Shire: Consultancy; Vascular Medicine Institute: Research Funding; Tacere Benitec: Consultancy; OPKO: Research Funding. Soh:Alnylam Pharmaceuticals: Employment, Equity Ownership. Akinc:Alnylam Pharmaceuticals: Employment, Equity Ownership. Partisano:Alnylam: Employment, Equity Ownership. Sorenson:Alnylam Pharmaceuticals: Employment, Equity Ownership.

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

Blood ◽

10.1182/blood.v126.23.552.552 ◽

2015 ◽

Vol 126 (23) ◽

pp. 552-552 ◽

Cited By ~ 3

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.

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

Blood ◽

10.1182/blood-2019-122817 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 96-96 ◽

Cited By ~ 2

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.

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Phospholipid-Independent Activity of Fviiia Mimetic Bispecific Antibodies in Plasma

Blood ◽

10.1182/blood-2018-99-119226 ◽

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.

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Recombinant FVIIIFc-VWF-XTEN Demonstrates Significant Bioavailability Following Subcutaneous Administration in Hemophilia A Mice

Blood ◽

10.1182/blood.v126.23.3492.3492 ◽

2015 ◽

Vol 126 (23) ◽

pp. 3492-3492 ◽

Cited By ~ 5

Author(s):

Douglas Drager ◽

Sue Patarroyo-White ◽

Hoson Chao ◽

Ayman Ismail ◽

Jiayun Liu ◽

...

Keyword(s):

Half Life ◽

Hemophilia A ◽

Subcutaneous Administration ◽

Hek293 Cells ◽

Potential Candidate ◽

Single Chain ◽

Employment Equity ◽

Dosing Interval ◽

Tail Vein ◽

Equity Ownership

Abstract All currently marketed Factor VIII (FVIII) molecules are administered intravenously (IV) for the treatment of hemophilia A (HemA). Conventional FVIII prophylaxis requires a dosing interval of three times per week to every other day. This frequent dosing regimen necessitates repeated venous access and is associated with complications such as secondary infection in children with a venous port/catheter. More recently, extended half-life variants of FVIII have been shown in clinical trials to decrease the dosing interval to twice weekly or less frequent IV dosing, which reduces, but does not eliminate, the burden of treatment. A FVIII molecule with further prolonged half-life and subcutaneous (SQ) delivery potential could significantly relieve the treatment burden for HemA patients and improve the adherence rate to FVIII prophylaxis. Recombinant FVIIIFc-VWF-XTEN has been shown to not bind endogenous VWF, and is able to achieve a 4-fold extension of half-life in hemophilia A mice compared to conventional FVIII, well beyond the approximately 2-fold half-life extension limit demonstrated by other long-acting FVIII variants that bind endogenous VWF. It comprises of two polypeptide chains: 1) a single chain B-domain deleted FVIIIFc-XTEN chain with a XTEN polypeptide inserted at the B-domain region of native FVIII sequence, and 2) a VWF D'D3-XTEN-Fc chain xtend one that n TEN fragemnt o FVIII prophylaxis.ntial rity of the patients depending on the half-life of the FVIII molecule. with a second XTEN polypeptide inserted between D'D3 domain and Fc. The rFVIIIFc-VWF-XTEN protein was produced in HEK293 cells and affinity purified using VIIISelect resin. The pharmacokinetic (PK) profiles of intravenously (IV) and subcutaneously (SQ) administered rFVIIIFc-VWF-XTEN were compared to those of rFVIII in HemA mice. The duration of the in vivo efficacy of rFVIIIFc-VWF-XTEN post-SQ delivery was assessed in a HemA mouse tail vein transection (TVT) bleeding model. After intravenous dosing in HemA mice, we observed a linear PK profile for rFVIIIFc-VWF-XTEN within the therapeutic dose range (25, 50, 100 IU/kg). The half-life of IV-administered rFVIIIFc-VWF-XTEN was about 37 h, which is more than 4-fold longer than that of rFVIII. In addition, animals that received 25 IU/kg of rFVIIIFc-VWF-XTEN treatment retained 5% of normal FVIII activity at 120 h post-dosing, which suggests the potential for full protection from spontaneous bleeding in this animal model. When delivered subcutaneously, the bioavailability of rFVIIIFc-VWF-XTEN was 20%, a significant increase compared to the bioavailability of rFVIII (less than 1%). Starting at 24 h post-dosing, subcutaneous administration of rFVIIIFc-VWF-XTEN achieved plasma FVIII levels that were equal to or greater than those attained with rFVIII delivered intravenously at the same dose. In addition, greater than 5% of normal circulating FVIII level was observed at 96 h post SQ administration of rFVIIIFc-VWF-XTEN with a 100 IU/kg dose, which provided 80% protection on survival in mice subjected to tail vein transection injury. These results suggest that rFVIIIFc-VWF-XTEN could enable less frequent FVIII replacement treatment compared to rFVIII even when administered subcutaneously. The VWF independence of rFVIIIFc-VWF-XTEN enables a 4-fold increase in circulating half-life compared to that of rFVIII. Also, the addition of D'D3 domains and the two XTEN insertions dramatically increases subcutaneous bioavailability to 20%, compared to less than 1% with conventional FVIII. These unique properties of rFVIIIFc-VWF-XTEN make it a potential candidate for both IV and SQ treatments for hemophilia A. Disclosures Drager: Biogen: Employment, Equity Ownership. Patarroyo-White:Biogen: Employment, Equity Ownership. Chao:Biogen: Employment, Equity Ownership. Ismail:Biogen: Employment. Liu:Biogen: Employment, Equity Ownership. Holthaus:Biogen: Employment. Chhabra:Biogen: Employment, Equity Ownership. Kulman:Biogen: Employment. Schellenberger:Amunix Operating Inc: Employment. Liu:Biogen: Employment, Equity Ownership. Peters:Biogen: Employment.

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Pharmacokinetics Of Recombinant Factor VIII Fc Fusion Protein (rFVIIIFc) in Pediatric Subjects With Hemophilia A: An Interim Analysis Of The Kids A-LONG Study

Blood ◽

10.1182/blood.v122.21.3609.3609 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3609-3609

Author(s):

Guy Young ◽

Johnny Mahlangu ◽

Beatrice Nolan ◽

Simon Brown ◽

Leonard A. Valentino ◽

...

Keyword(s):

Board Of Directors ◽

Half Life ◽

Interim Analysis ◽

Research Funding ◽

Hemophilia A ◽

Additional Time ◽

Employment Equity ◽

Advisory Committees ◽

Age Cohorts ◽

Equity Ownership

Abstract Introduction Prophylactic factor VIII (FVIII) administration is the standard of care for patients with severe hemophilia A; however, frequent injections are required to maintain protective factor levels. To reduce injection frequency, we developed a long-lasting recombinant FVIII Fc fusion protein (rFVIIIFc) consisting of one rFVIII molecule covalently linked to the Fc domain of immunoglobulin G1 (IgG1). rFVIIIFc had a 1.53-fold higher half-life and a 36% reduction in clearance (CL) versus FVIII (Advate®) in a phase 3 study of adults and adolescents (J Thromb Haemost. 2013;11[2]:169). The Kids A-LONG study (NCT01458106) was designed to investigate the pharmacokinetics (PK), safety, and efficacy of rFVIIIFc in pediatric subjects with hemophilia A who were previously treated with FVIII products. The objective of this planned interim analysis was to determine the PK parameters of rFVIIIFc in pediatric subjects and compare these parameters to those of the subjects' prescribed FVIII products. Methods This multi-center, open-label, phase 3 study is currently enrolling previously-treated subjects aged<12 years with severe hemophilia A (≤1 IU/dL endogenous FVIII), at least 50 exposure days (EDs) to FVIII products, and no history of or current inhibitors to FVIII. Subjects are stratified into two age cohorts (<6 years and 6 to<12 years). All subjects are started on a twice-weekly rFVIIIFc prophylactic regimen 25 IU/kg on day 1 and 50 IU/kg on day 4 with subsequent dosing adjustment based on PK data and bleeding frequency. The primary endpoint is the incidence of inhibitor development. A sequential PK analysis is performed to compare the PK parameters of rFVIIIFc with that of the prescribed FVIII product. Subjects undergo a washout period of at least 72 hours before receiving the first dose of either FVIII or rFVIIIFc. For FVIII PK analysis, subjects receive 50 IU/kg of their currently prescribed FVIII product with sampling at baseline and at 4 additional time points after for up to 48 hours. For rFVIIIFc PK assessment, subjects receive 50 IU/kg rFVIIIFc, with sampling prior to rFVIIIFc administration and at 5 additional time points after for up to 72 hours. PK parameters were derived from FVIII activity-over-time profiles estimated by the non-compartmental analysis using the PK data analysis software Phoenix™ WinNonlin 6.2.1.51. FVIII activity was measured by the one-stage clotting assay calibrated against a commercially available FVIII plasma standard. A data cut-off date of 8 February 2013 was used to report PK data in this interim analysis. Results At the time of this analysis, 52 subjects were enrolled and received at least one dose of FVIII and/or rFVIIIFc. Of 37 subjects with evaluable PK profiles, 30 received both FVIII and rFVIIIFc. For PK assessment of FVIII, 7 different FVIII products were used, of which Advate ®, Haemosolvate®, and Kogenate FS® were the most common. A comparison of PK parameters for rFVIIIFc versus FVIII for both age cohorts demonstrated that rFVIIIFc had a longer half-life (∼1.5 fold increase) and a lower CL (30% to 50% reduction) than FVIII (Table 1). Conclusion In comparison to currently available FVIII products, rFVIIIFc had an extended half-life and reduced CL in children. These results are in agreement with those previously observed in adults and adolescents. The final analysis of the Kids A-LONG study will provide additional PK information and evaluate the safety and efficacy of rFVIIIFc in children. Disclosures: Young: Novo Nordisk: Consultancy, Honoraria; Biogen Idec, Baxter, Kedrion: Consultancy. Mahlangu:Bayer, Novo Nordisk: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity’s Board of Directors or advisory committees; Biogen Idec: Research Funding. Brown:Novo Nordisk, Biogen Idec, Baxter: Membership on an entity’s Board of Directors or advisory committees. Valentino:Baxter, Bayer, Biogen Idec, GTC Biotherapeutics, Inspiration Biopharmaceuticals, Novo Nordisk: Consultancy, Membership on an entity’s Board of Directors or advisory committees. Liesner:Bayer, Baxter, Novo Nordisk, Pfizer: Consultancy, Sponsorship Other; Octapharma: Consultancy, Research Funding, Sponsorship, Sponsorship Other; Inspiration Biopharmaceuticals: Research Funding. Dong:Biogen Idec: Employment, Equity Ownership. Diao:Biogen Idec: Employment, Equity Ownership. Jiang:Biogen Idec: Employment; Biogen Idec: Equity Ownership. Nugent:Biogen Idec: Employment, Equity Ownership. Pierce:Biogen Idec: Employment, Equity Ownership. Allen:Biogen Idec: Employment, Equity Ownership.

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A Subcutaneously Administered Investigational RNAi Therapeutic (ALN-AT3) Targeting Antithrombin for Treatment of Hemophilia: Interim Weekly and Monthly Dosing Results in Patients with Hemophilia A or B

Blood ◽

10.1182/blood.v126.23.551.551 ◽

2015 ◽

Vol 126 (23) ◽

pp. 551-551 ◽

Cited By ~ 9

Author(s):

K John Pasi ◽

Pencho Georgiev ◽

Tim Mant ◽

Michael Desmond Creagh ◽

Toshko Lissitchkov ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Thrombin Generation ◽

Hemophilia A ◽

Advisory Board ◽

Employment Equity ◽

Advisory Committees ◽

Educational Support ◽

Monthly Dosing ◽

Equity Ownership

Abstract Background: Hemophilia A and B are bleeding disorders characterized by a profound defect in thrombin generation (TG). Furthermore, in the presence of normal levels of endogenous anticoagulants a deficiency in factor VIII and IX results in major hemostatic imbalance and a bleeding phenotype. ALN-AT3 is a subcutaneously administered investigational RNAi therapeutic targeting the endogenous anticoagulant antithrombin (AT) that aims to restore the hemostatic balance by increasing TG. Methods: We are conducting a phase 1 multi-center study (NCT02035605) in healthy volunteers and patients with moderate to severe hemophilia A or B. Part A of this study has been completed and assessed a single ascending dose study in healthy volunteers. Parts B and C are multiple ascending dose studies in patients with hemophilia who are receiving weekly or monthly dosing, respectively. Primary endpoints are safety and tolerability. Secondary endpoints include PK, AT knockdown; change in thrombin generation and whole blood clot formation as measured by Calibrated Automated Thrombin generation and ROTEM thromboelastometry. Exploratory endpoints include evaluations of bleed pattern and control. Results: Part A enrolled 4 healthy volunteers, randomized (3:1) to 30 mcg/kg ALN-AT3 or placebo; no serious adverse events (SAE) or injection site reactions were observed. A total of 12 patients with severe hemophilia (10 hemohilia A; 2 hemophilia B) were enrolled in Part B and received 3 weekly subcutaneous doses of ALN-AT3 at 15 (n=3), 45 (n=6), and 75 (n=3) mcg/kg. Similar to part A, weekly administration of ALT-AT3 was generally safe and well tolerated in patients with hemophilia; no SAEs, discontinuations, clinical thromboembolic events or clinically significant D-dimer increases were reported. In the 75 mcg/kg dosing cohort, the mean maximum AT knockdown was 59% (p<0.05, relative to baseline), with nadir levels achieved between days 28 and 42. Maximum plasma AT knockdown of 86% was achieved, resulting in thrombin generation increases that correlated with AT knockdown and a bleed-free period of 114 days in the patient achieving the highest level of AT knockdown. The association between AT KD and TG was assessed in a post hoc exploratory analysis in which AT KD was categorized into tertiles. Part C aims to enroll several cohorts (n=3 per cohort) and will assess a monthly dosing schedule (x3 doses) of ALN-AT3. Patients in cohort 1 and 2 were dosed at 225 and 450 mcg/kg, respectively. Up to 4 additional cohorts may be enrolled within Part C. Updated safety, PK, AT knockdown, TG results as well as bleed patterns from Parts B and C will be presented. Conclusions: Emerging clinical data suggest that targeting AT could be a promising approach for restoring hemostatic balance in hemophilia. The potential for low volume subcutaneous administration, monthly dosing, and applicability to patients with hemophilia A and B with and without inhibitors make ALN-AT3 a potentially encouraging investigational therapy. Disclosures Pasi: Octapharma: Research Funding; Biogen, Octapharma, Genzyme, and Pfizer: Consultancy, Honoraria. Off Label Use: ALN-AT3 is an investigational RNAi therapeutic targeting the endogenous anticoagulant antithrombin.. Mant:Quintiles: Employment, Equity Ownership. Creagh:Bayer Healthcare UK: Honoraria. Austin:SOBI: Other: member of advisory board and received educational support; Pfizer: Other: member of advisory board and received educational support; Novo Nordisk: Other: member of advisory board and received educational support; CSL Behring: Other: member of advisory board and received educational support; Bio Products Laboratory: Other: member of advisory board and received educational support; Bayer: Other: member of advisory board and received educational support; Baxter: Other: member of advisory board and received educational support. Brand:Alnylam: Honoraria. Chowdary:Bayer: Consultancy; Biogen Idec: Consultancy; Baxter: Consultancy; CSL Behring: Consultancy, Research Funding; Novo Nordisk: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; SOBI: Consultancy. Ragni:Tacere Benitec: Membership on an entity's Board of Directors or advisory committees; Alnylam: Research Funding; Bristol Myers Squibb: Research Funding; Biogen: Research Funding; Shire: Membership on an entity's Board of Directors or advisory committees, Research Funding; Dimension: Research Funding; Bayer: Research Funding; SPARK: Research Funding; Genentech Roche: Research Funding; Pfizer: Research Funding; Vascular Medicine Institute: Research Funding; Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biomarin: Research Funding; CSL Behring: Research Funding. Chen:Alnylam Pharmaceuticals: Employment, Equity Ownership. Akinc:Alnylam Pharmaceuticals: Employment, Equity Ownership. Sorensen:Alnylam Pharmaceuticals: Employment, Equity Ownership. Rangarajan:Octapharma: Other: Investigator.

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An Evaluation of Safety with an Extended Half-Life, Pegylated, Full-Length Recombinant Factor VIII (BAX 855) in the Treatment of 243 Patients with Hemophilia a

Blood ◽

10.1182/blood.v128.22.3801.3801 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3801-3801

Author(s):

Werner Engl ◽

Lisa Patrone ◽

Dyck-Jones Jacqueline ◽

Srilatha D. Tangada ◽

Brigitt E. Abbuehl

Keyword(s):

Factor Viii ◽

Safety Profile ◽

Half Life ◽

Perioperative Management ◽

Hemophilia A ◽

Recombinant Factor Viii ◽

Employment Equity ◽

Equity Ownership ◽

Inhibitory Antibodies

Abstract BAX 855 is an extended half-life, pegylated full-length recombinant factor VIII (PEG-rFVIII) built on ADVATE and is approved for prophylaxis and the treatment of bleeding in hemophilia A. Safety data from 7 clinical studies were integrated to evaluate single, short-term, and long-term exposure with BAX 855. These clinical trials included the following patients: previously treated adult, adolescent, and pediatric patients (PTPs) and previously untreated patients (PUPs). Immunogenicity, adverse events (AEs), and clinical laboratory parameters were assessed during prophylaxis, treatment of bleeding, perioperative management, and PK evaluations. Of 243 patients, the mean ±SD (range) age was 23.4 ±15.84 (0-61) years, there was 1 female; 74.9% of patients were White, 21.4% were Asian, and 2.5% were Black. Overall, 97 million IUs of BAX 855 were infused, resulting in a median (Q1; Q3) of 111 (73-196) exposure days (EDs) per patient, which ranged from 1 to 322 EDs. No patient developed inhibitory antibodies to FVIII (≥0.6BU) at any time. The 95% confidence intervals for developing inhibitory antibodies based on exposure are as follows: 0-0.19 for 191 PTPs with ≥50 EDs, 0-0.027 for 135 patients with ≥100 EDs, 0-0.37 for 98 patients with ≥150 EDs, and 0-0.68 for 52 patients with ≥200 EDs. At the time of the last blood sample analyzed, no patient had any antibodies to CHO proteins or persistent binding antibodies to FVIII, PEG-FVIII, or PEG. Binding antibodies were either pre-existing (28 patients) or transient (13 patients). No conclusion can be drawn as yet for 5 patients who developed binding antibodies shortly before or at the data cut-off for the analysis. The presence of binding antibodies could not be correlated to an altered PK or impaired efficacy. The only AE considered related to BAX 855 occurring in ≥1% of patients was headache; other related AEs (nausea; diarrhea, flushing, rash, and hypersensitivity) were observed in <1% of patients. No SAEs related to the use of BAX 855 were reported. One PUP discontinued due to a treatment-related AE: a mild, non-serious AE of hypersensitivity (a rash), which resolved. In total, 819 AEs were reported in 182/243 subjects administered ≥1 BAX 855 infusion. The overall rate of AEs/infusion was 2.7% (819 AEs/30,865 infusions), for non-serious AEs 2.5% (773 AEs/30,865), and for serious AEs 0.1% (46/30,865). No trends were observed in laboratory parameters or in vital signs. This safety update for BAX 855 confirms that the safety profile of BAX 855 is consistent with the safety profile of ADVATE. Overall, short- and long-term treatment with BAX 855 was safe and well tolerated in 243 pediatric, adolescent and adult subjects with severe hemophilia A from 3 completed and 4 ongoing studies. As experience with BAX 855 grows, this integrated safety update continues to confirm the safe use of BAX 855 for prophylaxis, the treatment of bleeding episodes, and perioperative management. Disclosures Engl: Shire, formerly Baxalta and Baxter: Employment, Equity Ownership. Patrone:Shire, formerly Baxalta and Baxter: Employment, Equity Ownership. Jacqueline:Baxalta US Inc., now part of Shire: Employment, Equity Ownership. Tangada:Baxalta US Inc., now part of Shire: Employment, Equity Ownership. Abbuehl:Shire, formerly Baxalta and Baxter: Employment, Equity Ownership.

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