scholarly journals Emizicumab Promotes Factor Xa Generation on Activated Endothelium in a Blood Cell-Independent Manner

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3182-3182
Author(s):  
Patrick Ellsworth ◽  
Dougald Monroe ◽  
Maureane Hoffman ◽  
Nigel S Key
Keyword(s):  
Clinical Trial ◽  
Endothelial Cells ◽  
Growth Medium ◽  
Research Funding ◽  
Hemophilia A ◽  
Coagulation Factor ◽  
Standard Of Care ◽  
Factor Ix ◽  
Adhesive Film ◽  
Trial Investigator

Abstract Introduction Hemophilia A (HA) is an inherited bleeding disorder caused by the deficiency of coagulation factor VIII (FVIII) resulting in severe hemorrhage if untreated. Recombinant and plasma derived FVIII products have long been the standard of care in hemophilia. However, approximately 25-30% of patients with severe HA develop inhibitors, neutralizing alloantibodies to FVIII, a significant complication in the treatment of patients with HA that leads to bleeding despite factor therapy. First approved for bleed prophylaxis in HA with inhibitors in the US by the FDA in 2018, emicizumab (Genentech, USA) has initiated a new era of HA treatment. This drug is a bispecific, monoclonal antibody that binds to activated Factor IX (FIXa) and Factor X (FX), mimicking activated FVIII (FVIIIa) by bringing FIXa and FX into proximity to enable FX activation, even in the presence of inhibitors. Emicizumab prophylaxis drastically reduces bleed episodes. However, thromboses and thrombotic microangiopathy (TMA) were observed in trials, all associated with concomitant use of activated prothrombin complex concentrates (aPCC) (Callaghan et al., 2021). The mechanism of this devastating condition is uncertain, as emicizumab is not known to bind to phospholipid or vascular surfaces. We report that FX is more readily activated by FIXa and emicizumab on endothelium that has been activated by tumor necrosis factor alpha (TNF). This finding may partially explain the development of TMA in these patients. Methods We utilized novel, microfluidic devices that are inexpensive to manufacture and were modified from a technique previously described (Alapan et al. 2016). These devices are fabricated using a laser cut double-sided adhesive film sandwiched between a clear, gas-permeable polymer (Ibidi, Germany) and an acrylic top that is laser cut (Universal Laser Systems Inc., USA) (Figure 1). Human umbilical endothelial cells (HUVEC, Lonza, Switzerland) were harvested at passage 3 to 4 and seeded into the devices. These were then cultured under flow conditions using a non-peristaltic, air-driven pump (Ibidi GmbH, Germany) to achieve a confluent and quiescent endothelial surface. HUVEC are then activated by incubating with 5 nM TNF in serum-free growth medium for 4 hours. This treatment induced markers of endothelial activation without gross apoptosis. Non-activated HUVEC were incubated with endothelial cell growth medium (2% serum) until time of experiments. Factors IXa, X (Haemtech, USA), and/or emicizumab (discarded clinical material) were mixed in HEPES-buffered saline with 5 mM calcium chloride for all experimental conditions. Concentrations used of FIXa (30 nM), FX (170 nM), and emicizumab (55 ug/mL) were constant for all conditions. Combinations of factors and emicizumab were then incubated in the endothelialized device for 30 minutes at 37° C. The entire volume of the mixture was then aspirated (20 uL) and stored at -80° C. FXa activity was assayed on the effluent for 60 minutes using a chromogenic FXa substrate (Pefachrome, Pentapharm, Switzerland). Results No significant generation of Xa was noted in the presence of healthy or activated endothelium with emicuzumab alone, emicizumab and FIXa, emicizumab and FX, or factors IXa and X. Median Xa generation observed with the combination of emicizumab, FIXa, and FX on healthy endothelium was 2 nM. Median Xa generation with the same combination on activated endothelium was 8.1 nM, a four-fold increase (P = 0.028, Mann-Whitney test) (Figure 2). Discussion Emicizumab represents an evolving standard of care for hemophilia A. Considering data showing diminishing FVIII expression in the months to years after AAV gene therapy, (Pasi et al., 2020) it may well be the dominant treatment paradigm in HA for some time. However, much remains to be answered in the use of emicizumab, and the mechanism of thrombosis and TMA with concomitant aPCC use has resulted in the avoidance of aPCC use for breakthrough bleeding in patients on emicizumab therapy, even up to 6 months after cessation. Our data demonstrate that activated endothelial cells promote FX activation more readily than quiescent endothelial cells in the presence of FIXa and emicizumab. These findings demonstrate the potential of thrombotic angiopathy in an in vitro system. Further investigation of the interaction of endothelium with FIXa, FX, and FVIIIa-mimetic antibodies is warranted. Figure 1 Figure 1. Disclosures Ellsworth: Takeda: Other: Salary supported as part of NHF-Takeda Clinical Fellowship Award. Monroe: Medexus Pharmaceuticals: Consultancy; Takeda: Consultancy; Otello Medical: Current equity holder in publicly-traded company. Hoffman: Takeda: Research Funding; CSL Behring: Consultancy; Sanofi: Consultancy; BPL (Bio Products Laboratory): Consultancy. Key: BioMarin: Honoraria, Other: Participation as a clinical trial investigator; Takeda: Research Funding; Grifols: Research Funding; Uniqure: Consultancy, Other: Participation as a clinical trial investigator; Sanofi: Consultancy.

scholarly journals Rituximab Monotherapy Is Effective for Inhibitor Eradication with Concomitant Porcine Factor VIII Followed By Emicizumab for Bleed Control in Acquired Hemophilia a

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 348-348
Author(s):  
Patrick Ellsworth ◽  
Sheh-Li Chen ◽  
Christopher Wang ◽  
Nigel S Key ◽  
Alice Ma
Keyword(s):  
Clinical Trial ◽  
Factor Viii ◽  
Research Funding ◽  
Hemophilia A ◽  
Effective Strategy ◽  
Acquired Hemophilia A ◽  
Acquired Hemophilia ◽  
Trial Investigator ◽  
Fviii Activity ◽  
Inhibitor Titer

Abstract Introduction Acquired hemophilia A (AHA) is a rare bleeding disorder in which acquired auto-antibodies to endogenous Factor VIII (FVIII) resulting in decreased FVIII activity. AHA can lead to life-threatening bleeding, with effective treatment requiring both immunosuppressive therapy (IST) and bypassing agents such as recombinant activated Factor VII (rFVIIa) or activated prothrombin complex concentrates (APCC) (Tiede et al. Haematologica 2020). Some, including our group, have begun using emicizumab as well (Knoebl et al. Blood 2020). IST is required for inhibitor eradication, but regimens are heterogenous and have not been systematically compared in the literature. While there is no standard of care IST in these patients, most patients in the literature receive multiple agents, including corticosteroids, mycophenolate mofetil, cyclosporine, and/or rituximab in combination. We report in a prospective cohort that for IST, rituximab monotherapy is an effective strategy. An updated treatment algorithm is offered that has been effective for treatment of these patients at our institution, which adds emicizumab therapy after initial bleed control. Methods We analyzed clinical, pharmacy, and laboratory data from 24 patients treated with rpFVIII at the University of North Carolina for AHA from July 2015 to June 2021. All patients were initially treated according to our previously established dosing algorithm with recombinant porcine FVIII, and the last five patients have received emicizumab after initial factor dosing (see Figure 1). 17 of the patients who received rituximab and were followed at our center subsequently attained inhibitor eradication, six of those received only rituximab therapy. Investigational review board approval was obtained for our data collection and analysis. Patients who did not receive rituximab, failed to reach an inhibitor level <0.5 BU, or who were lost to follow up were excluded from the analysis. For patients that fit the inclusion criteria, the time between date of the first rituximab infusion and the date of inhibitor eradication was calculated. Results All patients in our cohort who we followed until inhibitor eradication (17 of 24 patients) had eradication of inhibitors after a median of 143 days from initiation of immunosuppression. For patients treated with rituximab monotherapy for inhibitor eradication (6 of 17), this goal was reached in a median of 134.5 days (range 76-191 days). For those who received agents in addition to rituximab and have reached inhibitor eradication to date (9 of 17 patients), median days from initiation of immunosuppression to inhibitor eradication was 137.5 days (range 11-485) (P = 0.43 on Mann-Whitney test). Patients were treated as previously reported by our group per an algorithm that starts recombinant porcine FVIII without waiting for a porcine inhibitor and at lower than FDA recommended dosing. Subsequent doses for bleed control are titrated according to one-stage, clot based FVIII activity. This report also includes 5 new patients who, after initial bleed control per our algorithm, were initiated on emicizumab while awaiting inhibitor eradication. There was no correlation between time to rituximab initiation and time to inhibitor eradication in both those who received rituximab monotherapy and those who had multiple IST agents. There was also no significant difference in initial inhibitor titer between groups with median initial inhibitor titer of 104 BU in the rituximab monotherapy group, and 70 BU in the multiple IST agents group (see Figure 3). Conclusions Rituximab monotherapy appears to be an effective strategy for inhibitor eradication in acquired hemophilia A. In the context of bleed treatment with porcine factor, followed by emicizumab, a standardized, algorithmic approach can be effectively employed for these patients. Though any patients have inhibitor recurrence, as is described in the literature, with emicizumab available, bleeding can be avoided with regular monitoring. Emicizumab given while re-eradicating an inhibitor can prevent morbidity of this disease. Figure 1 Figure 1. Disclosures Ellsworth: Takeda: Other: Salary supported as part of NHF-Takeda Clinical Fellowship Award. Key: Uniqure: Consultancy, Other: Participation as a clinical trial investigator; Grifols: Research Funding; Takeda: Research Funding; BioMarin: Honoraria, Other: Participation as a clinical trial investigator; Sanofi: Consultancy. Ma: Accordant: Consultancy; Takeda: Honoraria, Research Funding. OffLabel Disclosure: Emicizumab is not approved for use in Acquired Hemophilia A and this represents an OFF LABEL use of the drug.

Emicizumab for the treatment of acquired hemophilia A

Blood ◽  
2020 ◽  
Author(s):  
Paul Knoebl ◽  
Johannes Thaler ◽  
Petra Jilma ◽  
Peter Quehenberger ◽  
Karoline Veronika Gleixner ◽  
...  
Keyword(s):  
Hemophilia A ◽  
Coagulation Factor ◽  
Standard Of Care ◽  
Early Discharge ◽  
Severe Bleeding ◽  
Acquired Hemophilia A ◽  
Acquired Hemophilia ◽  
Breakthrough Bleeding ◽  
Hemostatic Efficacy ◽  
Bypassing Agents

Acquired hemophilia A (AHA) is a severe bleeding disorder caused by inhibiting autoantibodies to coagulation factor VIII (FVIII). For hemostatic treatment, bypassing agents, human or porcine FVIII are currently standard of care. Emicizumab is a bispecific, FVIII-mimetic therapeutic antibody, that reduced the annualized bleeding rates in congenital hemophiliacs. Here we report on 12 patients with AHA, 6 male, 6 female, age 74 yrs (64/80) (all data medians and IQR), treated with emicizumab. Initial FVIII was <1%, inhibitor 22.3BU/mL (range 3-2000). Eight patients had severe bleeding. Emicizumab was started with 3mg/kg sc. weekly for 2-3 doses, followed by 1.5mg/kg every 3 weeks to keep the lowest effective FVIII levels. For FVIII monitoring, chromogenic assays with human and bovine reagents were used. All patients received immunosuppression with steroids and/or rituximab. After the first dose of emicizumab, APTT normalized in 1-3 days, FVIII (human reagents) exceeded 10% after 11 (7.5/12) days. Hemostatic efficacy was obtained and bypassing therapy stopped after 1.5 (1/4) days. FVIII (bovine reagents) exceeded 50%, indicating complete remission, after 115 (67/185), and emicizumab was stopped after 31 days (15/79), in median 5 injections (range 3-9) were given. No patient died from bleeding or thromboembolism, and no breakthrough bleeding was observed after the first dose of emicizumab. In conclusion, emicizumab seems to be an effective hemostatic therapy for AHA, with the advantages of sc. therapy (every 1-3 weeks), good hemostatic efficacy, early discharge, reduction of immunosuppression and adverse events.

Towards the Care of Hemophilia a Patients Using Induced Pluripotent Stem Cell (iPSC)-Derived Megakaryocytes (iMks) Expressing Coagulation Factor (F) VIII

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2266-2266
Author(s):  
Randolph B Lyde ◽  
Li Zhai ◽  
Karen Vo ◽  
Danuta Jadwiga Jarocha ◽  
Spencer Sullivan ◽  
...  
Keyword(s):  
Whole Blood ◽  
Neutralizing Antibodies ◽  
Research Funding ◽  
Hemophilia A ◽  
Specific Activity ◽  
Coagulation Factor ◽  
Clot Formation ◽  
Patient Specific ◽  
Furin Cleavage ◽  
Furin Cleavage Site

Abstract We and others have shown that FVIII expressed ectopically in platelets (pFVIII) is stored in α-granules, released at sites of vascular injury and restores hemostasis in FVIIInull mice, even in the presence of neutralizing antibodies to FVIII. These studies support the concept that unlike therapeutic interventions that correct plasma FVIII, pFVIII may be a useful therapy in hemophilia A with intractable inhibitors and significant bleeds. We have also demonstrated this approach has several limitations that may make pFVIII gene therapy bone marrow transplantation (BMT) strategies problematic: 1) pFVIII is not equivalent to plasma FVIII and its efficacy in joint and intracranial bleeds has yet to be shown, especially in the presence of inhibitors, and 2) pFVIII expressed during megakaryopoiesis can cause injury to the Mks, potentially exacerbating post-BMT thrombocytopenia. We propose an alternative strategy: interval prophylactic infusions of FVIII-containing platelets generated from patient-specific iMks expressing either human B-domain-deleted (BDD) FVIII or variants of this FVIII that have greater stability and longer half-lives; making them especially efficacious as pFVIII as we previously demonstrated. iPSCs are a renewable source of cells that can be pre-screened prior to clinical usage for lines that express optimal levels of pFVIII and also release optimal numbers of platelets after differentiation into iMks. Such iPSCs were transfected with a self-inactivating lentivirus containing cDNA for one of three FVIII variants: wildtype BDD FVIII (WT FVIII), R1645H PACE/furin cleavage site FVIII (FVIIIR1645H), and amino acid 1645 to 1648 deletion FVIII (FVIIIΔ). FVIIIR1645H and FVIIIΔ show greater stability and consequently greater specific activity with no increase in injuring Mks. All FVIII variants were expressed using the MK-specific Cxcl4 promoter and were shown to be effective in several bleeding models in FVIIInull mice. Differentiated and transduced iMKs were analyzed for RNA and protein expression. All of the FVIII variant iMKs expressed at least forty-fold higher levels of mRNA compared to the non-transduced control (n=6) and protein was expressed at >550 pg/106 CD42b+ iMKs (n=6). Transduced MKs released FVIII into the supernatant when activated by thrombin showing the pFVIII was likely stored in α-granules. Annexin staining was the same between FVIII-expressing iMKs and control iMks suggesting that the level of pFVIII did not cause the iMks to become apoptotic. To test the ability of FVIII-expressing iMKs to correct the coagulopathy in hemophilia A, 5x105 iMKs were added to FVIIInull murine whole blood and evaluated for clot formation using rotational thromboelastometry (ROTEM). Each FVIII variant showed a decrease in clotting time, clot formation time, and an increase in maximum clot firmness when compared to the non-transduced control (n=4). These data show that iMKs expressing FVIII variants can improve hemostasis in a whole blood clotting assay. Our next goal is to generate sufficient platelets from these iMKs to test for correction of the bleeding diathesis in immunodeficient FVIIInull mice and to determine their efficacy in improving hemostasis in a number of clinically relevant hemostatic models. Disclosures Arruda: Pfizer: Consultancy, Patents & Royalties, Research Funding; Spark Therapeutics: Patents & Royalties. Camire:Pfizer: Consultancy, Patents & Royalties, Research Funding; NovoNordisk: Research Funding; Spark Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Immunogenicity of BAX 855 in Previously Treated Patients with Congenital Severe Hemophilia Α

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2594-2594
Author(s):  
Frank Michael Horling ◽  
Peter Allacher ◽  
Herwig Koppensteiner ◽  
Werner Engl ◽  
Fritz Scheiflinger ◽  
...  
Keyword(s):  
Adverse Events ◽  
Neutralizing Antibodies ◽  
Research Funding ◽  
Hemophilia A ◽  
De Novo ◽  
Coagulation Factor ◽  
Severe Hemophilia ◽  
Increased Risk ◽  
Previously Treated Patients ◽  
Previously Treated

Abstract Background and objectives BAX 855 (Antihemophilic Factor [Recombinant] pegylated, rurioctocog alfa pegol) is an extended half-life (EHL) recombinant human coagulation factor VIII (rFVIII) modified with polyethylene glycol (PEG) (Turecek et al., 2012). It was recently approved in the US and Japan for on-demand treatment of bleeding events and for prophylactic treatment for patients with congenital severe hemophilia A. The efficacy and safety of BAX 855 were extensively studied during clinical development of this compound (Konkle et al., 2015). The assessment of BAX855 immunogenicity was of particular interest because the development of neutralizing antibodies (FVIII inhibitors) is the most serious complication following replacement therapies with FVIII products. FVIII inhibitors develop in about 20-32% of previously untreated patients (Gouw SC et al., 2013) and with a rate of 1.55- 3.8 per 1000 patients per year in previously treated patients (Kempton CL, 2010) with severe hemophilia A. To fully understand the potential of BAX855 to induce antibody responses, both FVIII inhibitors and total FVIII-binding antibodies were assessed. Furthermore, potential antibody development against PEG-FVIII, PEG and CHO proteins was investigated. Methods The clinical protocols (ClinicalTrials.gov identifier: NCT02585960, NCT02210091, NCT01736475, NCT01913405, NCT01945593, NCT01599819, NCT02615691) and the methods used for antibody analytics (Whelan et al 2013; Lubich et al 2016) were previously described. ELISA technologies were used for the analysis of total binding antibodies, the Nijmegen modification of the Bethesda assay was used for the detection of FVIII inhibitors. Correlation analyses were done to assess any potential correlation between the development of antibodies and potential adverse events. Results None of the 243 subjects (6 PUPs and 237 PTPs) included in the analysis developed FVIII inhibitors (≥ 0.6 BU/mL) A total of 44 subjects tested positive for binding antibodies against FVIII, PEG-FVIII or PEG at single time points. 28 of these 44 subjects showed pre-existing antibodies against FVIII, PEG-FVIII, or PEG prior to first exposure to BAX 855, which disappeared during the study. 13 subjects who tested negative at screening developed transient antibodies against FVIII, PEG-FVIII, or PEG at one or two consecutive study visits after exposure to BAX 855. Antibodies were transient and not detectable at subsequent visits or at completion of the study. Five subjects showed positive results for binding antibodies at study completion or at the time of the data cutoff. No conclusion can be drawn whether these antibodies are of transient or persistent nature. There was no confirmed causal relationship between the appearance of binding antibodies against FVIII, PEG or PEG-FVIII and adverse events, nor was there an impact on hemostatic efficacy in any of the 44subjects. No subject had pre-existing antibodies or developed de novo antibodies to CHO proteins during the study at any time point. Conclusion Our data indicate that BAX855 did not show an increased risk for PTPs to develop FVIII inhibitors. We did not see any FVIII inhibitor development in PUPs, but the small number of overall exposures does not allow general conclusions for PUPs. Importantly, the data suggest that BAX855 did not induce immune responses associated with impaired treatment efficacy or with altered PK parameters. Disclosures Horling: Shire: Employment. Allacher:IMC Krems: Research Funding. Koppensteiner:Shire: Employment. Engl:Shire, formerly Baxalta and Baxter: Employment, Equity Ownership. Scheiflinger:Shire: Employment, Research Funding. Abbuehl:Baxalta (now part of Shire): Employment. Reipert:Shire: Employment.

scholarly journals Surgical Experience from the Phase III STASEY Trial of Emicizumab Prophylaxis in Persons with Hemophilia A with FVIII Inhibitors: Final Analysis

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 344-344
Author(s):  
Giancarlo Castaman ◽  
Jerzy Windyga ◽  
Hazza Alzahrani ◽  
Susan Robson ◽  
Fabian Sanabria ◽  
...  
Keyword(s):  
Research Funding ◽  
Hemophilia A ◽  
Knee Prosthesis ◽  
Coagulation Factor ◽  
Left Knee ◽  
Phase Iii ◽  
Postoperative Treatment ◽  
Research Centre ◽  
Case Report Form ◽  
Knee Arthrodesis

Abstract Background: Emicizumab, a bispecific monoclonal antibody, bridges activated factor (F) IX and FX, replacing the function of missing activated FVIII in persons with hemophilia A (PwHA). The Phase IIIb, multicenter, single-arm STASEY study (NCT03191799) assessed the safety and efficacy of emicizumab prophylaxis in PwHA with FVIII inhibitors. Surgical experiences in STASEY are reported here. Methods: Following informed consent and ethics committee approval, PwHA aged ≥12 years with FVIII inhibitors received 3 mg/kg/week emicizumab for 4 weeks (loading dose), then 1.5 mg/kg/week for the remaining 2-year treatment period. Minor and major surgeries were managed per the investigators' discretion. The type and number of procedures performed, additional prophylaxis, and frequency and management of postoperative bleeds were analyzed. Surgeries occurring up to 28 days after the last dose of emicizumab were included, due to emicizumab's ~28-day half-life (Emicizumab Prescribing Information, United States Food and Drug Administration, 2017). Surgeries were documented using an electronic case report form by the treating physicians and classified as minor or major based on manual medical review (Santagostino, et al. Haemophilia, 2015). Bleed and prophylactic hemophilia medication data were recorded in the electronic Bleed Medication Questionnaire by participants. Case narratives were provided by trial investigators. Results: Overall, 46 patients reported ≥1 on-study surgery. Thirty-seven patients had 56 minor surgeries (central venous access device [CVAD], n=9; dental, n=20; joint, n=4; other, n=23) (Figure), one of which (skin laceration and suture insertion on Day 9) was performed during the loading phase. Twenty-four surgeries (42.9%) were managed with additional prophylactic medications (Table). Of these, 11/24 (45.8%) resulted in postoperative bleeds, of which 6/11 were treated (54.5%). Of surgeries managed without additional prophylactic medications, 15/32 (46.9%) resulted in postoperative bleeds, of which 5/15 (33.3%) were treated. A total of 13 patients had 22 major on-study surgeries (arthroplasty, n=13; other, n=9). 'Other' included hemorrhoid operations, coronarography, sigmoidectomy, colostomy, laparotomy and polypectomy. Eighteen (81.8%) major surgeries, including all arthroplasties, were managed with additional prophylactic medications (Table). Of these, 12/18 (66.7%) resulted in postoperative bleeds (including 10/13 arthroplasties), of which six (50.0%) were treated (all arthroplasties). Four (18.2%) major surgeries were managed without additional prophylactic medication, including three hemorrhoid operations in one patient, and a coronarography in a patient with acute myocardial infarction. One hemorrhoid operation resulted in a postoperative treated bleed. Major surgeries included a 55-year-old male with Grade 4 device dislocation of left knee prosthesis on Day 7, who was diagnosed with recurrent infection and prosthesis misalignment on Day 62. Amputation of the left leg above the knee was performed, with treatment including tranexamic acid and rFVIIa. A 61-year-old male with left knee prosthesis infection underwent left knee arthrodesis on Day 457, vacuum-assisted closure therapy on Day 495, skin grafting on Day 512, and left knee arthrodesis with skin flap placement on Day 527. Throughout these surgeries, the individual experienced recurrent joint bleeding and received rFVIIa. Neither of these individuals had a change in their study treatment due to these events. No thrombotic events (TEs) or thrombotic microangiopathies (TMAs) related to surgeries were observed. Conclusions: In the STASEY study of PwHA with FVIII inhibitors receiving emicizumab prophylaxis, most minor surgical procedures were performed without additional prophylactic coagulation factor and did not result in postoperative treated bleeds. Therefore, emicizumab alone provided adequate hemostatic coverage for some PwHA undergoing certain types of minor surgery, such as tooth extraction and CVAD removal. Major surgeries were safely performed with additional coagulation prophylaxis. Management of surgeries with rFVIIa did not result in TE or TMA. In case of bleeds, a bleed management plan should be in place. Effects of emicizumab on coagulation and assays may persist for up to 6 months after the last dose, which may be relevant when planning postoperative treatment. Figure 1 Figure 1. Disclosures Castaman: Uniqure: Honoraria; Bayer: Honoraria; Sobi: Honoraria; CSL Behring: Honoraria; Novo Nordisk: Honoraria; Kedrion: Honoraria; LFB: Honoraria; Grifols: Honoraria; Werfen: Honoraria; Biomarin: Honoraria; Sanofi: Honoraria; F Hoffmann-La Roche Ltd: Honoraria. Windyga: Swixx BioPharma: Honoraria; Octapharma: Honoraria, Research Funding; Sobi: Honoraria, Research Funding; Sanofi-Aventis: Honoraria, Research Funding; Werfen: Honoraria; Bayer AG: Honoraria; Aspen: Honoraria; Alfasigma: Honoraria; Takeda: Honoraria, Research Funding; Shire: Honoraria, Research Funding; Alnylam Pharmaceuticals: Research Funding; Sanofi/Genzyme: Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Honoraria, Research Funding; Alexion: Honoraria; CSL Behring: Honoraria; Rigel Pharmaceuticals: Research Funding; Novo Nordisk: Honoraria, Research Funding; Baxalta: Honoraria, Research Funding. Alzahrani: Sobi: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Bayer: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria; King Faisal Specialist Hospital and Research Centre: Current Employment. Robson: F. Hoffmann-La Roche Ltd: Current Employment, Ended employment in the past 24 months. Sanabria: F. Hoffmann-La Roche Ltd: Current Employment, Current holder of individual stocks in a privately-held company. Howard: F. Hoffmann-La Roche Ltd: Current Employment, Current equity holder in publicly-traded company. Jiménez-Yuste: Octapharma: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Sobi: Consultancy, Honoraria, Research Funding; BioMarin: Consultancy; CSL Behring: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding.

scholarly journals Gene Therapy in Hemophilia: An Assessment of Hematologists' Knowledge Gaps and Attitudes

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3485-3485 ◽  
Author(s):  
Simi Hurst ◽  
Charlotte Warren ◽  
K. John Pasi
Keyword(s):  
Gene Therapy ◽  
Research Funding ◽  
Hemophilia A ◽  
Viral Vector ◽  
Healthcare Providers ◽  
Factor Ix ◽  
Educational Activity ◽  
Knowledge Gaps ◽  
Endogenous Expression ◽  
Therapy Strategies

Abstract BACKGROUND: Currently available treatments for hemophilia A and B require frequent intravenous infusions. Gene therapy, by contrast, offers the hope of a functional cure through endogenous expression of the factor VIII or factor IX genes. To identify and address practice gaps among healthcare providers who manage patients with hemophilia, a collaboration between the National Hemophilia Foundation (NHF), European Haemophilia Consortium (EHC), World Federation of Hemophilia (WFH), and Medscape Education was established. The objective of the current study is to assess clinicians' needs with regard to understanding the science and mechanism for gene therapy, the different technologies being proposed, identifying candidates for gene therapy, disease areas for which gene therapy is being explored, and the latest data on the potential role of gene therapy in hemophilia A and B. METHODS: A continuing medical education (CME)-certified clinical practice assessment comprising 25 multiple choice questions that measured knowledge, attitudes, and perspectives about gene therapy was developed. The survey instrument was made available online to physicians without monetary compensation or charge. Respondent confidentiality was maintained and responses were de-identified and aggregated prior to analyses. The activity launched on March 03, 2018; data through July 27, 2018 are presented, but data collection is ongoing. RESULTS: At the time of this analysis, 194 physician participants indicated that they actively manage patients with hemophilia. Demographics are presented in Table 1; confidence and attitudes about gene therapy in Table 2. Among hematologists/oncologists (n=54; hem/onc), identified knowledge gaps include, 46% could not identify the liver as the tissue/cell type that is the primary target for gene therapy in hemophilia46% thought that current approaches to gene therapy in hemophilia involved some form of host gene editing39% did not realize that gene therapy strategies only affect somatic cells and not the germline22% thought current gene therapy strategies would prevent or reduce the severity of hemophilia in subsequent generations of patients33% were unable to correctly identify adeno-associated virus (AAV) as the viral vector that is the current basis for the majority of gene therapy trials in hemophilia81% had misconceptions regarding the key characteristics of the AAV vector56% did not recognize that the AAV vector does not routinely integrate into the host genome19% were unfamiliar with the maximum gene cassette capacity of AAV57% were unfamiliar with the results from the pivotal University College London (UCL)/St Jude trial of scAAV2/8-LP1-hFIXcovector in patients with hemophilia B63% were unfamiliar with the clinical trial data for SPK-8011 in hemophilia A67% were unfamiliar with the results at the 12 month time-point for valoctocogene roxaparvovec in hemophilia A trials57% had misconceptions with regard to the causes for and treatment of ALT elevations seen in hemophilia AAV gene therapy trials CONCLUSIONS: Gene therapy has the potential to fundamentally alter the management of hemophilia. This educational activity identified clear deficits about - and attitudes toward - gene therapy among healthcare providers who currently care for patients with hemophilia. Furthermore, the great majority of healthcare providers lacked confidence in their understanding of gene therapy for hemophilia A. These findings will be used to inform the development of educational programs and to prepare providers for anticipated changes to the hemophilia treatment landscape. Disclosures Pasi: Catalyst Bio: Honoraria; Octapharma: Honoraria; NovoNordisk: Speakers Bureau; Bioverativ: Honoraria, Research Funding; Apcintex: Honoraria; Shire: Speakers Bureau; Bayer: Speakers Bureau; Pfizer: Speakers Bureau; Sobi: Honoraria; Biomarin: Honoraria, Research Funding; Alnylam: Honoraria, Research Funding.

scholarly journals Factor-mimetic and rebalancing therapies in hemophilia A and B: the end of factor concentrates?

Hematology ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 219-225
Author(s):  
Patrick Ellsworth ◽  
Alice Ma
Keyword(s):  
Hemophilia A ◽  
Treatment Options ◽  
Standard Of Care ◽  
Factor Ix ◽  
Coagulation Cascade ◽  
Coagulation System ◽  
Current Standard ◽  
Factor Viiia ◽  
Hemorrhagic Tendency ◽  
The Many

Abstract Hemophilia A (HA) and B are inherited bleeding disorders caused by a deficiency of factor VIII or factor IX, respectively. The current standard of care is the administration of recombinant or purified factor. However, this treatment strategy still results in a high economic and personal burden to patients, which is further exacerbated by the development of inhibitors—alloantibodies to factor. The treatment landscape is changing, with nonfactor therapeutics playing an increasing role in what we consider to be the standard of care. Emicizumab, a bispecific antibody that mimics the function of factor VIIIa, is the first such nonfactor therapy to gain US Food and Drug Administration approval and is rapidly changing the paradigm for HA treatment. Other therapies on the horizon seek to target anticoagulant proteins in the coagulation cascade, thus “rebalancing” a hemorrhagic tendency by introducing a thrombotic tendency. This intricate hemostatic balancing act promises great things for patients in need of more treatment options, but are these other therapies going to replace factor therapy? In light of the many challenges facing these therapies, should they be viewed as a replacement of our current standard of care? This review discusses the background, rationale, and potential of nonfactor therapies as well as the anticipated pitfalls and limitations. This is done in the context of a review of our current understanding of the many aspects of the coagulation system.

scholarly journals Bridging the Missing Link with Emicizumab: A Bispecific Antibody for Treatment of Hemophilia A

2020 ◽  
Vol 120 (10) ◽  
pp. 1357-1370
Author(s):  
Georg Gelbenegger ◽  
Christian Schoergenhofer ◽  
Paul Knoebl ◽  
Bernd Jilma
Keyword(s):  
Clinical Trials ◽  
Hemophilia A ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Coagulation Cascade ◽  
Factor Vii ◽  
Factor X ◽  
Current Standard ◽  
Bleeding Events ◽  
Recombinant Activated Factor Vii

AbstractHemophilia A, characterized by absent or ineffective coagulation factor VIII (FVIII), is a serious bleeding disorder that entails severe and potentially life-threatening bleeding events. Current standard therapy still involves replacement of FVIII, but is often complicated by the occurrence of neutralizing alloantibodies (inhibitors). Management of patients with inhibitors is challenging and necessitates immune tolerance induction for inhibitor eradication and the use of bypassing agents (activated prothrombin complex concentrates or recombinant activated factor VII), which are expensive and not always effective. Emicizumab is the first humanized bispecific monoclonal therapeutic antibody designed to replace the hemostatic function of activated FVIII by bridging activated factor IX and factor X (FX) to activate FX and allow the coagulation cascade to continue. In the majority of hemophilic patients with and without inhibitors, emicizumab reduced the annualized bleeding rate to almost zero in several clinical trials and demonstrated a good safety profile. However, the concurrent use of emicizumab and activated prothrombin complex concentrate imposes a high risk of thrombotic microangiopathy and thromboembolic events on patients and should be avoided. Yet, the management of breakthrough bleeds and surgery remains challenging with only limited evidence-based recommendations being available. This review summarizes published clinical trials and preliminary reports of emicizumab and discusses the clinical implications of emicizumab in treatment of hemophilia A.

Aptamer ARC19499 mediates a procoagulant hemostatic effect by inhibiting tissue factor pathway inhibitor

Blood ◽  
2011 ◽  
Vol 117 (20) ◽  
pp. 5514-5522 ◽  
Author(s):  
Emily K. Waters ◽  
Ryan M. Genga ◽  
Michael C. Schwartz ◽  
Jennifer A. Nelson ◽  
Robert G. Schaub ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Hemophilia A ◽  
Factor Viia ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Intrinsic Pathway ◽  
Extrinsic Pathway ◽  
Tissue Factor Pathway

Abstract Hemophilia A and B are caused by deficiencies in coagulation factor VIII (FVIII) and factor IX, respectively, resulting in deficient blood coagulation via the intrinsic pathway. The extrinsic coagulation pathway, mediated by factor VIIa and tissue factor (TF), remains intact but is negatively regulated by tissue factor pathway inhibitor (TFPI), which inhibits both factor VIIa and its product, factor Xa. This inhibition limits clot initiation via the extrinsic pathway, whereas factor deficiency in hemophilia limits clot propagation via the intrinsic pathway. ARC19499 is an aptamer that inhibits TFPI, thereby enabling clot initiation and propagation via the extrinsic pathway. The core aptamer binds tightly and specifically to TFPI. ARC19499 blocks TFPI inhibition of both factor Xa and the TF/factor VIIa complex. ARC19499 corrects thrombin generation in hemophilia A and B plasma and restores clotting in FVIII-neutralized whole blood. In the present study, using a monkey model of hemophilia, FVIII neutralization resulted in prolonged clotting times as measured by thromboelastography and prolonged saphenous-vein bleeding times, which are consistent with FVIII deficiency. ARC19499 restored thromboelastography clotting times to baseline levels and corrected bleeding times. These results demonstrate that ARC19499 inhibition of TFPI may be an effective alternative to current treatments of bleeding associated with hemophilia.

Employing Factor IX Variants to Avoid Limitations Imposed by Immune Recognition of AAV Vector in Hemophilia B Gene Therapy

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3124-3124 ◽  
Author(s):  
Paul E. Monahan ◽  
Junjiang Sun ◽  
Tong Gui ◽  
David G Wichlan ◽  
Scott W McPhee ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Gene Therapy ◽  
Board Of Directors ◽  
Research Funding ◽  
Specific Activity ◽  
Factor Ix ◽  
Hemophilia B ◽  
Ongoing Clinical Trial ◽  
Advisory Committees

Abstract Abstract 3124 Persistent factor IX expression and phenotypic improvement have been achieved in a human clinical trial for hemophilia B using liver-directed adeno-associated virus (AAV) gene therapy vectors. An ongoing clinical trial uses a vector incorporating self-complementing AAV (scAAV) genome form, factor IX codon optimization (FIXopt) and AAV serotype 8 capsid. As was seen in a previous single-strand AAV serotype 2 trial, dose escalation has been associated with apparent immune-mediated transient inflammation of vector-transduced liver, although in contrast to the previous trial persistent FIX expression has been maintained for the first time. Taken together, these important trials define a consistent threshold load of AAV capsid that has stimulated capsid-specific cytotoxic lymphocyte recognition and potential transaminitis. To advance the successes achieved in these trials while providing a clear margin of safety so that this immunogenic threshold need not be approached, we have pursued steps to limit further the AAV capsid load. Single amino acid substitutions at arginine 338 in the FIX catalytic domain generate FIX variants with increased specific activity. We separately substituted either R338A, R338Q, or R338L (FIX Padua) into a codon optimized human factor IX cDNA and evaluated F.IX expression in tissue culture following plasmid DNA transfection of HEK 293t cells. Each R338 substitution improved FIX specific activity, up to 10 times increased over wild type using the R338LFIXopt cDNA. We next generated scAAV8 vectors incorporating a liver-specific transthyretin (TTR) promoter to express optimized codon F.IX cDNA with or without the R338L substitution. FIX−/− mice receiving portal vein injection of 1 × 1010 vg/animal (4 ×1011 vg/kg) expressed 86.5% of normal FIX activity at 2 months post-transduction from the WTopt vector and 330% normal from the R338LFIXopt. Incorporation of R338Lopt variant resulted in at least 6 to 10 fold increase in FIX specific activity over a follow-up of > 40 weeks. At ten months following FIX gene delivery, mice underwent a tail transection bleeding challenge. FIX vector mice demonstrated therapeutic protection from this major bleeding challenge and furthermore all survived with no late rebleeding (a hallmark of hemophilic phenotype). Greater than 100% normal human FIX activity was maintained for >40 weeks following treatment with the R338LFIX vector (v. 26.3% at euthanasia in WTopt vector group). The prolonged follow-up permitted extended safety evaluation. Factor IX inhibitor antibodies were not detected in any mice throughout the follow-up; FIX-binding IgG1 and IgG2 were negative also. Thrombin/antithrombin III complexes (TAT) examined at 12 weeks and at >30 weeks of age in R338LFIXopt vector mice did not differ from levels in WTFIXopt vector-treated or age-matched C57Bl/6 hemostatically normal mice. Necropsy at 40–44 weeks after vector (1 year of age) showed only age-related changes with no microvascular or macrovascular thrombosis on H&E staining or specific immunostaining for fibrin/fibrinogen deposition; specific staining for fibrosis within myocardium or other sites was negative. We next synthesized a R338LFIXopt expression cassette containing the LP1 promoter/enhancer/intron sequence being used in the ongoing clinical trial and demonstrated equivalent FIX activity from either promoter construct. We then established that the R338LFIXopt vector gives a predictable dose-response across a range of doses as low as 1x 1010 vg/kg I.V. and as high as 4 × 1012 vg/kg I.V. Hemarthrosis is the most common bleeding complication in hemophilia and leads to chronic joint destruction. Bleeding was induced in the joint of FIX−/− mice that had been transduced 4 weeks earlier with the R338LFIX vector. Joints were collected at 2 weeks after induced bleed and the bleeding-induced joint damage was graded using an established histologic score. I.V. R338LFIXopt vector pretreatment resulted in protection against joint degeneration in a dose-dependent fashion in this most relevant clinical scenario. These preclinical studies demonstrate a safety :efficacy profile to advance hemophilia gene therapy using the scAAV8.R338LFIXopt vector. Disclosures: Monahan: Baxter: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Asklepios BioPharmaceutical: Patents & Royalties, Research Funding; CSL Behring: Honoraria; NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees; PharmaIN: Research Funding; Prolor-Biotech: Research Funding. McPhee:Asklepios Biopharmaceutical: Employment. Samulski:Asklepios Biopharmaceutical: Employment, Patents & Royalties.

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