Safety of recombinant activated factor VII for treatment of breakthrough bleeds in patients with congenital haemophilia A and inhibitors receiving emicizumab prophylaxis: Review of the real-world evidence.

BACKGROUND: Emicizumab is used as a subcutaneous prophylaxis for prevention of bleeding episodes in patients with haemophilia A (HA) with and without inhibitors. While low bleeding rates were observed in clinical trials, patients still experience breakthrough bleeds (BTBs) with emicizumab in the real-world. Current guidelines recommend use of recombinant activated factor VII (rFVIIa) for treatment of BTBs in patients with inhibitors. Due to thrombotic events observed in the HAVEN 1 study, activated prothrombin complex concentrate (aPCC) should be used with caution. OBJECTIVES: The objective of this review is to identify and discuss real-world data on the frequency of BTBs and the safety of concomitant rFVIIa use in patients with inhibitors on emicizumab prophylaxis. METHODS: A search of the following databases was conducted on 15 July 2022: BIOSIS Previews® , Current Contents Search® , Embase® , MEDLINE® . Search terms included 'real world', 'haemophilia A', and 'emicizumab'. RESULTS AND CONCLUSIONS: Eleven relevant publications were identified (seven original research articles and four congress abstracts). The frequency of BTBs specifically for HA patients with inhibitors was described in three publications with 5%-56% patients on emicizumab reporting ≥1 bleeding episode. Treatment of these BTBs appeared to be managed according to relevant guidelines. Importantly, no thrombotic complications occurred during concomitant rFVIIa use. Due to the nature of real-world studies, direct comparison of the results between studies is limited. However, real-world data show that BTBs in inhibitor patients during emicizumab prophylaxis can be safely treated with rFVIIa.

Befovacimab, an anti-tissue factor pathway inhibitor antibody: Early termination of the multiple-dose, dose-escalating Phase 2 study due to thrombosis.

INTRODUCTION: Befovacimab (formerly BAY 1093884) is a fully human monoclonal antibody able to bind to tissue factor pathway inhibitor (TFPI) and developed as a non-replacement therapy for individuals with haemophilia A/B, with or without inhibitors. AIM: To assess the safety of multiple escalating doses of befovacimab in individuals with severe haemophilia A/B with or without inhibitors. METHODS: In this non-randomised, open-label Phase 2 study (NCT03597022), adult males with <1% factor VIII or <2% factor IX and ≥4 bleeds in the previous six months were enrolled in three dose cohorts (100/225/400 mg). Participants received befovacimab subcutaneously once weekly. The primary endpoint was safety; secondary endpoints included annualised bleeding rate (ABR) and pharmacokinetics/pharmacodynamics (PK/PD) of befovacimab. RESULTS: A total of 24 participants (n = 8 in each dose cohort) were treated for 2-47 weeks. Patients treated with 100 mg and 225 mg doses of befovacimab demonstrated improved bleeding control compared with pre-study bleeding rates, with a dose-dependent effect. Dosing was suspended and the study prematurely terminated following three drug-related thrombotic serious adverse events (SAEs): two at the 225 mg dose and one at the 400 mg dose. These occurred in the absence of bleeding episodes or concomitant use of replacement/bypass therapies. No laboratory abnormalities were observed, and PK/PD data did not show correlation between SAE occurrence and levels of circulating befovacimab or free TFPI. CONCLUSION: Despite favourable initial results from preclinical and clinical studies, a positive safety profile of befovacimab was not confirmed. The lack of SAE-related laboratory abnormalities or differentiating PK/PD characteristics in participants experiencing SAEs raises concerns about the predictability of thrombosis following befovacimab treatment and emphasises the need for further investigation into the therapeutic window of anti-TFPI treatment.

Analysis of current status of antithrombotic therapy in 136 patients with nonvalvular atrial fibrillation / 中国基层医药

Objective:To analyze the current status and effectiveness of different antithrombotic regimens in patients with non-valvular atrial fibrillation.Methods:The clinical data of 136 patients with non-valvular atrial fibrillation who received treatment in The Second People's Hospital of Yongkang from May 2018 to May 2019 were retrospectively analyzed. According to the treatment plan, they were divided into no antithrombosis group ( n = 32), rivaroxaban group ( n = 41), warfarin group ( n = 42), and aspirin group ( n = 21). Based on treatment of primary disease and complications, patients in the no antithrombosis group were not given anticoagulation or antiplatelet therapy, those in the rivarxaban group were given rivarxaban (10 mg/d), those in the warfarin group were given warfarin (2.5 mg/d), and those in the aspirin group were given aspirin (0.1 g/d). The incidence of thromboembolism and bleeding, all-cause mortality and readmission rate within 1 year were compared among groups. Results:There were significant differences in age, type of atrial fibrillation, coronary heart disease, heart failure, and hypertension among groups (all P < 0.05). There were no significant differences in sex, history of stroke/transient ischemic attack, and the percentage of patients developing diabetes mellitus and hyperlipidemia among groups (all P > 0.05). The incidence of thromboembolic events within 1 year in the no antithrombosis, rivaroxaban, warfarin, and aspirin groups were 21.87% (7/32), 7.32% (3/41), 2.38% (1/42), and 19.05% (4/21), respectively, and there were significant differences among groups ( χ2 = 8.98, P < 0.05). The 1-year incidence of bleeding events in the no antithrombosis, rivaroxaban, warfarin, and aspirin groups were 18.75% (6/32), 29.27% (12/41), 4.76% (2/42), 4.76% (61/21), respectively, and there were significant differences among groups ( χ2 =11.77, P < 0.05). There were no significant differences in the 1-year incidence of thromboembolism events and bleeding events among patients aged < 65 years, 65-75 years, and > 75 years (all P > 0.05), but there were significant difference in all-cause mortality and readmission rate ( χ2 = 6.76, 7.56, both P < 0.05). Conclusion:Early antithrombotic therapy is very important for patients with non valvular atrial fibrillation. The treatment regimens should be individualized, and the risk of death increases with age.

Development of a novel fully functional coagulation factor VIII with reduced immunogenicity utilizing an in silico prediction and deimmunization approach.

BACKGROUND: Up to 30% of hemophilia A patients develop inhibitory antibodies against the infused factor VIII (FVIII). The development of a deimmunized FVIII is an unmet high medical need. Although improved recombinant FVIII (rFVIII) products evolved within the last years, the immunogenicity has not been solved. A deimmunized FVIII could reduce the probability of inhibitor development, providing safer therapy. OBJECTIVE: To develop a deimmunized FVIII molecule by modifying major histocompatibility complex (MHC) class II presentation, leading to a functional but less immunogenic molecule. METHODS: We performed (1) in silico prediction of potentially immunogenic T cell epitopes and their modification by amino acid substitutions in the FVIII sequence, (2) evaluation of functional and structural similarity of the modified rFVIII to unmodified FVIII and registered products, and (3) confirmation of the reduced immunogenicity by in vitro testing. RESULTS: A partially deimmunized fully functional FVIII molecule incorporating 19 amino acid substitutions was generated. The substitutions led to a reduction of the immunogenicity score, indicating a reduced immunogenicity based on in silico calculations. This was confirmed in an in vitro dendritic cell (DC)--T cell assay. Using this assay, cells from healthy donors proved the significantly reduced immunogenicity of the modified FVIII variant by revealing less proliferation of T helper cells to this variant than to the unmodified FVIII. CONCLUSION: In silico predictions resulted in a partially deimmunized FVIII. This FVIII is fully functional and was demonstrated to be less immunogenic in in vitro testing. This approach may result in a reduction of the inhibitor risk for patients with hemophilia A.

Clot waveform analysis for perioperative hemostatic monitoring of arthroscopic synovectomy in a pediatric patient with hemophilia A and inhibitor receiving emicizumab prophylaxis.

Emicizumab reduces bleeding in patients with hemophilia A and inhibitors (PwHA-I). Coagulation potential during the perioperative period in emicizumab-treated PwHA-I undergoing surgery remains to be evaluated. We describe a 14-year-old boy with HA-I receiving emicizumab prophylaxis who experienced arthroscopic synovectomy. He was treated with a bolus infusion of recombinant factor VIIa (rFVIIa; 80 µg/kg) immediately before surgery, and treatment continued at the same dose every 3 h on day 1, every 4 h on day 2, and every 6 h on day 3. Treatment with rFVIIa was discontinued on day 4. No perioperative bleeding or thrombotic events were observed. Coagulation potential throughout the perioperative period was retrospectively assessed with an easy-to-use clot waveform analysis (CWA). Measurements from CWA returned to within or near the normal range, suggesting successful hemostatic management. Coagulation potentials assessed by CWA showed a significant correspondence with those from a thrombin generation assay (TGA) that is already in use. CWA and TGA could both provide useful data for assessing coagulation potential in the perioperative hemostatic management of emicizumab-treated PwHA-I.

Prophylaxis Using a Mixture of Plasma-Derived Activated Factor VII and Factor X (pdFVIIa/FX) in a Patient with Hemophilia B Complicated by Inhibitors and Allergy to Factor IX Concentrates: A Case Report.

Treating patients with hemophilia and inhibitors is often problematic. The presence of inhibitors negatively impacts the effectiveness of treatment to achieve hemostasis especially in patients with hemophilia B, owing mainly to allergic reactions to factor IX (FIX) concentrates and the low success rate of immune tolerance therapy. A 9-month-old boy had intracranial hemorrhage and was diagnosed with hemophilia B. After replacement therapy, he developed inhibitors and an allergic reaction to FIX. Prophylactic therapy was initiated with recombinant activated factor VII (rFVIIa) and later switched to pdFVIIa/factor X (FX; 120 µg/kg as the FVII dose, every other day) because of a recurrence of intracranial hemorrhage. Since then, he remained well without life-threatening bleeding for more than 2 years. Our case suggests that pdFVIIa/FX may be useful for prophylactic therapy in hemophilia B complicated by inhibitors and allergic reaction to FIX concentrates.

Factors Involved in the Development of Inhibitory Antibodies in Patients with Hemophilia in Colombia: A Case-Control Study.

BACKGROUND: The appearance of inhibitory antibodies against antihemophilic factors is one of the most serious complications related to hemophilia. OBJECTIVE: The objective of this study was to identify variables and factors related to the development of inhibitory antibodies in a group of patients undergoing antihemophilic therapy in Colombia. METHODS: A case-control study in patients with hemophilia treated in Specialized Healthcare Provider Institutions (IPS-E) in 21 cities of Colombia of any age and with a diagnosis of inhibitory antibodies against factor VIII or IX during 2016. Four controls per case paired by age and type of hemophilia were used. Sociodemographic, clinical, and pharmacological variables were identified and analyzed. RESULTS: Seventeen patients with inhibitory antibodies and 68 controls with hemophilia were identified. The mean age was 28.3 ± 17.8 years. A total of 94.1% had hemophilia A, and 88.2% of the cases and 50.0% of the controls had severe hemophilia; 47.1% of the cases and 54.4% of the controls were receiving prophylaxis with coagulation factors. Multivariate analysis showed that having severe hemophilia (OR:17.0, 95%CI:1.32-219.60) and lack of knowledge of the coagulation factor with which the patient was treated before entering the care program in the IPS-E (OR:8.9, 95%CI:1.82-43.75) were significantly associated with a higher probability of developing inhibitory antibodies. CONCLUSION AND RELEVANCE: Coagulation factors associated with the development of inhibitory antibodies were severe hemophilia and lack of knowledge of the type of factor used prior to entering the follow-up cohort.

Outcomes in children with hemophilia A with inhibitors: Results from a noninterventional study.

BACKGROUND: Data regarding management of pediatric persons with hemophilia A (PwHA) with factor VIII (FVIII) inhibitors are limited. This prospective noninterventional study (NCT02476942) evaluated annualized bleeding rates (ABRs), safety, and health-related quality of life (HRQoL) in pediatric PwHA with FVIII inhibitors. PROCEDURE: PwHA aged <12 years with current FVIII inhibitors and high-titer inhibitor history were enrolled. Participants remained on usual treatment; no interventions were applied. Outcomes included ABR, safety, and HRQoL. RESULTS: Twenty-four PwHA aged 2-11 years (median 7.5) were enrolled and monitored for 8.7-44.1 weeks (median 23.4). In the episodic (n = 10) and prophylactic (n = 14) groups, respectively, 121 of 185 (65.4%) and 101 of 186 (54.3%) bleeds were treated using activated prothrombin complex concentrate (aPCC) and/or recombinant activated FVII (rFVIIa). ABRs (95% confidence interval) were 19.4 (13.2-28.4) and 18.5 (14.2-24.0) for treated bleeds, and 32.7 (20.5-52.2) and 33.1 (22.4-48.9) for all bleeds, respectively. Most prophylactic group participants (92.9%) were prescribed aPCC; 50% adhered to their prescribed treatment regimen. Adherence to prophylactic rFVIIa was not assessed. Serious adverse events included hemarthrosis (12.5%) and mouth hemorrhage (12.5%); the most common nonserious adverse event was viral upper respiratory tract infection (12.5%). HRQoL showed functional impairment at baseline; scores remained stable throughout, with little intergroup variation. CONCLUSIONS: ABRs remained high in pediatric PwHA with inhibitors receiving standard treatment. This study demonstrates the need for more effective treatments, with reduced treatment burden, to prevent bleeds, increase prophylaxis adherence, and improve patient outcomes.

Clinical Care of Bone Health in Patients on the Immune Tolerance Induction's Protocols With an Immunosuppressive Agent for Inhibitor Eradication in Hemophilia.

Nowadays, the development of factor VIII and IX inhibitors in patients with hemophilia is considered as the most challenging in the treatment of hemophilia. Immune tolerance induction (ITI) therapy is an approach for eradication of inhibitors. Some ITI protocols are routinely in use for the eradication of inhibitors in patients with hemophilia. Moreover, such a therapeutic regimen may facilitate the tendency to reduced bone density in patients with inhibitor. This study scheduled to investigate whether that predisposing role of ITI protocols with an immunosuppressive agent has considered or not. By a literature review, published ITI protocols in hemophilia with inhibitors were evaluated. Among them, 51 papers found and studied thoroughly. None of them had performed the bone mineral examination in patients with hemophilia and inhibitor under treatment. Since there are 2 coexisting facilitating factors in these protocols, considering the bone mineral density study for patients with inhibitor who are undergoing ITI protocols with an immunosuppressive agent is recommended.

Non-additive effect on thrombin generation when a plasma-derived factor VIII/von Willebrand factor (FVIII/VWF) is combined with emicizumab in vitro.

BACKGROUND: Emicizumab is an alternative non-factor approach for treating patients with hemophilia A. However, there is a potential risk of thrombotic events when emicizumab is concomitantly administered with pro-hemostatic therapies. OBJECTIVES: To assess the hemostatic effect in vitro when a plasma-derived factor VIII concentrate containing von Willebrand factor (pdFVIII/VWF) was added to hemophilia A plasma (HAp) in combination with emicizumab. METHODS: HAp and HAp with FVIII inhibitors (HAp-i) samples with different concentrations of emicizumab (50 and 100 µg/mL) were combined with activated prothrombin complex concentrate at 0.5 to 1 U/mL, recombinant activated factor VII (rFVIIa) at 0.5 to 7 µg/mL, and pdFVIII/VWF at 0.1 to 4.5 IU/mL. Thrombin generation (TG; thrombin peak and endogenous thrombin potential) was determined using a Calibrated Automated Thrombogram assay. RESULTS: When activated prothrombin complex concentrate was added to HAp and HAp-i with emicizumab, TG dramatically increased (multiplier effect > 4.5×). Addition of rFVIIa to HAp or HAp-i with emicizumab moderately increased TG in a concentration-related manner compared with rFVIIa alone. Addition of pdFVIII/VWF to HAp or HAp-i with emicizumab induced a TG response equivalent to those samples without emicizumab. In an in vitro model of immune tolerance induction with bleeds (HAp-i 15 Bethesda units), combination of pdFVIII/VWF, emicizumab, and rFVIIa did not trigger a multiplying effect on TG. CONCLUSIONS: pdFVIII/VWF showed a non-additive effect on TG when combined in vitro with emicizumab. This finding suggests that emicizumab has limited ability to promote factor X activation in the presence of pdFVIII/VWF, thus reducing the risk of thrombotic events.

Prediction of the haemostatic effects of bypassing therapy using comprehensive coagulation assays in emicizumab prophylaxis-treated haemophilia A patients with inhibitors.

In emicizumab prophylaxis, the concomitant therapy using bypassing agents (BPAs) is required for breakthrough bleeding and invasive procedures with attention to thrombotic complications. To predict coagulant effects of BPAs in emicizumab-treated patients with haemophilia A (PwHA) with inhibitor (PwHAwI), blood samples from emicizumab-treated PwHAwI (n = 8) and PwHA without inhibitor (n = 2) in phase 1/2 and HAVEN 1 study, spiked with activated prothrombin complex concentrates (aPCC) or recombinant factor VIIa (rFVIIa) ex vivo, and blood samples from emicizumab-treated PwHAwI-receiving BPAs were analysed by Ca2+ -triggered rotational thromboelastometry (ROTEM) and ellagic acid/tissue factor-triggered clot waveform analysis (CWA). Spiked aPCC, corresponded to 10-100 U/kg, markedly shortened ROTEM parameters beyond the normal range, while spiked rFVIIa, corresponded to 90-270 µg/kg, shortened them within near-normal range. Each of the spiked BPA-improved adjusted maximum coagulation velocity of CWA to within or near the normal range. In blood samples at post-infusion of aPCC (44-73 U/kg) or rFVIIa (79-93 µg/kg), the parameters of both assays improved to approximately the normal range. Taken together, ex vivo results of spiking tests in ROTEM and CWA, except aPCC spiking test in ROTEM, were relatively consistent with in vivo ones, and could usefully predict the coagulant effects of concomitant bypassing therapy for emicizumab-treated PwHAwI.

Quantitative HLA-class-II/factor VIII (FVIII) peptidomic variation in dendritic cells correlates with the immunogenic potential of therapeutic FVIII proteins in hemophilia A.

BACKGROUND: Plasma-derived (pd) or recombinant (r) therapeutic factor VIII proteins (FVIIIs) are infused to arrest/prevent bleeding in patients with hemophilia A (PWHA). However, FVIIIs are neutralized if anti-FVIII-antibodies (inhibitors) develop. Accumulating evidence suggests that pdFVIIIs with von Willebrand factor (VWF) are less immunogenic than rFVIIIs and that distinct rFVIIIs are differentially immunogenic. Since inhibitor development is T-helper-cell-dependent, human leukocyte antigen (HLA)-class-II (HLAcII) molecules constitute an important early determinant. OBJECTIVES: Use dendritic cell (DC)-protein processing/presentation assays with mass-spectrometric and peptide-proteomic analyses to quantify the DP-bound, DQ-bound, and DR-bound FVIII-derived peptides in individual HLAcII repertoires and compare the immunogenic potential of six distinct FVIIIs based on their measured peptide counts. PATIENTS/METHODS: Monocyte-derived DCs from normal donors and/or PWHA were cultured with either: Mix-rFVIII, a VWF-free equimolar mixture of a full-length (FL)-rFVIII [Advate® (Takeda)] and four distinct B-domain-deleted (BDD)-rFVIIIs [Xyntha® (Pfizer), NovoEight® (Novo-Nordisk), Nuwiq® (Octapharma), and Afstyla® (CSL Behring GmBH)]; a pdFVIII + pdVWF [Beriate® (CSL Behring GmBH)]; Advate ± pdVWF; Afstyla ± pdVWF; and Xyntha + pdVWF. RESULTS: We showed that (i) Beriate had a significantly lower immunogenic potential than Advate ± pdVWF, Afstyla - pdVWF, and Mix-rFVIII; (ii) distinct FVIIIs differed significantly in their immunogenic potential in that, in addition to (i), Afstyla + pdVWF had a significantly lower immunogenic potential than Beriate, while the immunogenic potential of Beriate was not significantly different from that of Xyntha + pdVWF; and (iii) rFVIIIs with pdVWF had significantly lower immunogenic potentials than the same rFVIIIs without pdVWF. CONCLUSIONS: Our results provide HLAcII peptidomic level explanations for several important clinical observations/issues including the differential immunogenicity of distinct FVIIIs and the role of HLAcII genetics in inhibitor development.

Life-threatening hemorrhage secondary to acquired deficiency of coagulation factors VIII and XI related to systemic lupus erythematosus: case report / Hemorragia severa secundaria a deficiencia adquirida de factores VIII y XI de la coagulación relacionada con lupus eritematoso sistémico: reporte de caso

ABSTRACT In patients with autoimmune diseases, the simultaneous occurrence of lupus anticoagulant and blood coagulation factors inhibitors is infrequent and is associated with hemorrhagic events. In these cases, the initial approach requires a thorough interpretation of coagulation laboratory tests and mixing studies to reach a definitive diagnosis. We report the case of a patient with systemic lupus erythematosus and Sjögren's syndrome who presented with hemorrhagic diathesis caused by circulating inhibitors against factors VIII and XI coexisting with lupus anticoagulant. The inhibitors eradication was made with rituximab, achieving good results.

RESUMEN La ocurrencia simultánea de anticoagulante lúpico e inhibidores circulantes contra los factores de la coagulación es infrecuente en los pacientes con enfermedad autoinmune, y está relacionada con eventos hemorrágicos. El abordaje inicial requiere una adecuada interpretación de los tiempos de coagulación y prueba de mezcla con plasma para alcanzar el diagnóstico definitivo. Se reporta el caso de una paciente con lupus eritematoso sistémico y síndrome de Sjögren, quien se presentó con trastorno hemorrágico amenazante de la vida ocasionado por inhibidores circulantes contra los factores VIII y XI de la coagulación en coexistencia con anticoagulante lúpico. El tratamiento de erradicación de los inhibidores se realizó con rituximab, con buenos resultados.

Prevalence of inversions in introns 1 and 22 of the factor VIII gene and inhibitors in patients from southern Brazil / Prevalência das inversões nos íntrons 1 e 22 do gene do fator VIII e inibidores em pacientes do sul do Brasil

ABSTRACT Objectives: The development of antibodies (inhibitors) against exogenous factors is the main complication in the treatment of hemophilia. Both genetic and non-genetic factors are related to inhibitor development. Among the genetic factors, the type of mutation that caused the disease is one of the most important. The objectives of the present study were to establish the prevalence of inversions in introns 1 and 22 of the factor VIII gene in patients with severe hemophilia A, correlating these with inhibitor development, and to compare the results with data from the literature. Method: Unrelated severe hemophilia A patients were analyzed for the presence of inversions in intron 1 (n = 77) and intron 22 (n = 39) by polymerase chain reaction (PCR). Detection of the inhibitor was performed by the mixing test and its quantification was performed by the Bethesda method. Results: The prevalence of inversions in introns 1 and 22 was 2.6% and 41%, respectively. No patient with inversions in intron 1 had inhibitors, whereas 26.3% of patients with inversions in intron 22 developed inhibitors. Conclusion: Due to the small number of patients with inversions in intron 1, it was not possible to perform a statistical test for the correlation with risk of inhibitor development. Inversions in intron 22 of the factor VIII gene were not associated with an increased risk of inhibitor development in the analyzed samples (p = 1).

RESUMEN Introducción: El desarrollo de anticuerpos (inhibidores) contra elfactor exógeno es la principal complicación del tratamiento de hemofilias. Tanto factores genéticos como no genéticos están relacionados con la aparición de los inhibidores. Entre los factores genéticos, el tipo de mutación que originó la enfermedad es uno de los más importantes. El objetivo de este estudio fue establecer laprevalencia de las inversiones en los intrones 1 y 22 del gen del factor VIII en pacientes con hemofilia A severa, relacionándola con el desarrollo de inhibidores, así como comparar los resultados encontrados con datos de la literatura en el mundo. Método: Pacientes con hemofilia A severa no emparentados fueron analizados cuanto a la presencia de inversión en el intrón 1 (n = 77) y de la inversión en el intrón 22 (n = 39), usando la técnica de reacción en cadena de lapolimerasa. La detección del inhibidor fue realizada por el estudio de mezclas; su cuantificación, por el método Bethesda. Resultados: La prevalencia de las inversiones en los intrones 1 y 22 fueron 2,6% y 41%, respectivamente. Ningúnpaciente con la inversión en el intrón 1 presentó inhibidores, mientras 26,3% de los pacientes con la inversión en el intrón 22 desarrollaron anticuerpos. Conclusión: El pequeno número de pacientes con inversión en el intrón 1 no permitió la aplicación de la prueba estadística para correlación con el riesgo de desarrollo de inhibidores. La inversión en el intrón 22 del gen del factor VIII no se asoció a un mayor riesgo de desarrollo de inhibidores en la muestra analizada (p = 1).

RESUMO Introdução: O desenvolvimento de anticorpos (inibidores) contra o fator exógeno é a principal complicação do tratamento de hemofilias. Tanto fatores genéticos quanto não genéticos estão relacionados com o surgimento dos inibidores. Entre os fatores genéticos, o tipo de mutação que originou a doença é um dos mais importantes. Os objetivos do presente estudo foram estabelecer a prevalência das inversões nos íntrons 1 e 22 do gene do fator VIII em pacientes com hemofilia A grave, correlacionando-a com o desenvolvimento de inibidores, bem como comparar os resultados encontrados com dados da literatura mundial. Método: Foram analisados pacientes hemofílicos A graves não aparentados quanto à presença da inversão no íntron 1 (n = 77) e da inversão no íntron 22 (n = 39), utilizando a técnica de reação em cadeia dapolimerase (PCR). A detecção do inibidor foi realizada pelo teste de mistura; a sua quantificação, pelo método de Bethesda. Resultados: As prevalências das inversões nos íntrons 1 e 22 foram de 2,6% e 41%, respectivamente. Nenhum paciente com a inversão no íntron 1 apresentou inibidores, enquanto 26,3% dos pacientes com a inversão no íntron 22 desenvolveram os anticorpos. Conclusão: O número reduzido de pacientes com a inversão no íntron 1 não permitiu a aplicação de teste estatístico para a correlação com o risco de desenvolvimento de inibidores. A inversão no íntron 22 do gene do fator VIII não se associou ao maior risco de desenvolvimento de inibidores na amostra analisada (p = 1).

Leveraging Human Genetics to Estimate Clinical Risk Reductions Achievable by Inhibiting Factor XI.

Background and Purpose- Coagulation factor XI (FXI) is a novel target for antithrombotic therapy addressed by various therapeutic modalities currently in clinical development. The expected magnitude of thrombotic event reduction mediated by targeting FXI is unclear. Methods- We analyzed the association of 2 common genetic variants, which alter levels of FXI, with a range of human phenotypes. We combined variants into a genetic score standardized to a 30% increase in relative activated partial thromboplastin time, equivalent to what can be achieved with pharmacological FXI reduction. Using data from 371 695 participants in the United Kingdom Biobank and 2 large-scale genome-wide association studies, we examined the effect of this FXI score on thrombotic and bleeding end points. Results- Genetic disposition to lower FXI levels was associated with reduced risks of venous thrombosis (odds ratio, 95% CI; P value; odds ratio=0.1, 0.07-0.14; P=3×10-43) and ischemic stroke (odds ratio=0.47, 0.36-0.61; P=2×10-8) but not with major bleeding (odds ratio=0.7, 0.45-1.04; P=0.0739). The observed relative risk reductions were consistent within a range of subgroups that were at high risk for thrombosis. Consistently, we observed higher absolute risk reductions conferred by genetically lower FXI levels in high-risk subgroups, such as patients with atrial fibrillation. Conclusions- Human genetic data suggest that pharmacological inhibition of FXI may achieve considerable reductions in ischemic stroke risk without clear evidence for an associated risk of major bleeding. The quantitative framework developed can be used to support the estimation of achievable risk reductions with pharmacological modulation of FXI.

Successful use of emicizumab in a patient with refractory acquired hemophilia A and acute coronary syndrome requiring percutaneous coronary intervention.

ABSTRACT: We report a patient with a high-titer factor VIII inhibitor refractory to immunosuppression. He initially presented with myocardial infarction requiring percutaneous coronary intervention (PCI) with bare metal stent placement. Despite Feiba prophylaxis, inadequate hemostasis prompted premature discontinuation of dual antiplatelet therapy (DAPT). Fifteen weeks later, the patient presented with a left anterior descending artery in-stent restenosis. This case report examines the Key Clinical Question of how to manage in-stent restenosis in a patient with acquired hemophilia A (AHA). After multidisciplinary discussions including hematology, cardiology, cardiac surgery, laboratory medicine, and pharmacy, emicizumab was initiated to facilitate PCI. Four weeks after emicizumab initiation, the patient underwent successful PCI with drug-eluting stent placement. Five months after discharge, he remains without signs or symptoms of cardiac disease or bleeding on DAPT and emicizumab. This case provides evidence of the potential of emicizumab for bleeding prophylaxis in AHA.

Recombinant factor VIII products and inhibitor development in previously untreated patients with severe haemophilia A: Combined analysis of three studies.

INTRODUCTION: Standard treatment of congenital haemophilia A is based on replacement therapy with coagulation factor VIII (FVIII) products. A major complication of FVIII therapy is the occurrence of IgG alloantibodies (inhibitors) that neutralize FVIII activity. AIM: The aim of the analysis was estimating the risk of high-titre inhibitor associated with the second-generation full-length product compared to third-generation full-length product and other recombinant FVIII (rFVIII). METHODS: We conducted a combined analysis of individual patient data from three large studies in previously untreated patients (PUPs) with severe haemophilia A. RESULTS: A total of 1109 PUPs were treated from 1993 to 2013 including 787 PUPs treated from 2004 onwards (primary analysis cohort). A total of 322 patients (29.0%) developed an inhibitor, of which 192 (17.3%) a high-titre inhibitor. In the primary analysis set, 29.9% of patients developed an inhibitor and 17.2% a high-titre inhibitor. The combined analysis indicated a lower risk of high-titre inhibitor development for the third-generation rFVIII product compared to the second-generation rFVIII product (primary analysis: adjusted hazard ratio (HR) = 0.72, 95% CI: 0.49 to 1.06). Adjusted HR for all inhibitor development was significantly lower for the third-generation product compared to the second-generation product. CONCLUSION: The trend of an increased risk of inhibitor development in PUPs for one recombinant product illustrates that extrapolation from one recombinant factor VIII product to other products might not be justified.

Bleeding and safety outcomes in persons with haemophilia A without inhibitors: Results from a prospective non-interventional study in a real-world setting.

INTRODUCTION: Prospectively collected real-world data on bleeds, haemophilia treatment and safety in persons with haemophilia A (PwHA) without factor VIII (FVIII) inhibitors are limited. A global, non-interventional study (NIS; NCT02476942) prospectively collected real-world data in PwHA who were treated per local routine clinical practice. AIM: Assess annualized bleeding rate (ABR), haemophilia treatment practices and adverse events (AEs) in adult/adolescent PwHA without inhibitors. METHODS: Eligible participants aged ≥12 years with severe HA without history of inhibitors prospectively collected bleeding and treatment information. RESULTS: Ninety-four participants were enrolled (median [range] age, 34 [12-76] years) and monitored for a median (range) of 29.8 (12.4-47.7) weeks. In the episodic (n = 45) and prophylactic (n = 49) treatment groups, respectively, 872/1066 (81.8%) and 151/189 (79.9%), bleeds were treated; ABRs (95% confidence interval) were 36.1 (30.8-42.3) and 5.0 (3.3-7.5), respectively, for treated bleeds and 43.1 (36.5-50.9) and 6.2 (4.2-9.2), respectively, for all bleeds, and median (interquartile range) ABRs were 31.1 (19.8-51.6) and 1.9 (0.0-8.2), respectively, for treated bleeds and 35.3 (21.7-62.9) and 2.7 (0.0-9.4), respectively, for all bleeds. Half of the participants on FVIII prophylaxis had relatively high adherence to treatment, using 2.9 and 2.1 median doses/wk of standard and extended half-life FVIII, respectively. Serious AEs included gastrointestinal polyp haemorrhage and haemarthrosis; the most common AE was viral upper respiratory tract infection. CONCLUSION: PwHA without inhibitors continue to bleed on prophylaxis, consistent with the literature, and require treatment for breakthrough bleeds. This prospective NIS demonstrates the need for more efficacious haemostatic approaches.

Bleeding events and safety outcomes in persons with haemophilia A with inhibitors: A prospective, multi-centre, non-interventional study.

INTRODUCTION: Prospectively collected, real-world data on bleeds, haemophilic treatment and safety outcomes in persons with haemophilia A (PwHA) with factor VIII (FVIII) inhibitors are limited. A prospective, global, multi-centre, non-interventional study (NIS; NCT02476942) collected detailed real-world data in PwHA treated per local routine clinical practice. AIM: To characterize bleeding rates, haemophilic treatment practices, prophylaxis adherence and adverse events (AEs) in adult/adolescent PwHA with inhibitors in the NIS. METHODS: Participants aged ≥12 years with congenital haemophilia A/documented high-titre FVIII inhibitor history were enrolled. Participants remained on their usual treatment; no interventions were applied. RESULTS: Overall, 103 PwHA with inhibitors enrolled, (median [range] age 31 [12-75] years) and were monitored for median (range) 26.0 (4.1-69.6) weeks. In the episodic (n = 75) and prophylactic (n = 28) treatment groups, respectively, 1244 and 325 bleeds were reported, and 528 (42.4%) and 104 (32.0%) were not treated; annualized bleeding rates (ABRs; 95% confidence interval) were 18.6 (15.2-22.8) and 14.9 (10.5-21.2) for treated bleeds, and 32.7 (27.3-39.1) and 25.0 (18.4-34.0) for all bleeds. Coagulation products used included activated prothrombin complex concentrate (aPCC) and/or recombinant activated FVII. Among participants prescribed aPCC prophylaxis, 35.0% adhered to both prescribed frequency of aPCC administration and prescribed dose. Serious AEs of haemarthrosis and muscle haemorrhage were reported; most common AEs were arthralgia, viral upper respiratory tract infection and pyrexia. CONCLUSIONS: ABRs (treated bleeds and all bleeds) remain high on standard treatment; this prospective NIS demonstrates the need for more effective treatments for PwHA with inhibitors to reduce/prevent bleeds, with potential to improve prophylaxis adherence and further improve outcomes.

Clinical and laboratory diagnosis of autoimmune factor V inhibitors: A single institutional experience.

BACKGROUND: Coagulation factor V inhibitors (FV-i) may occur in patients with congenital FV deficiency or previously hemostatically normal patients (autoimmune (AI)-FV-i). Most of the published literature is confined to case reports. OBJECTIVE: Describe clinical and laboratory features of AI-FV-i identified through the Special Coagulation Laboratory at Mayo Clinic, Rochester, Minnesota. METHODS: In this retrospective study individuals with FV-i screens performed from January 1999 to February 2017 were identified through the special coagulation laboratory database. Clinical presentation, management, and outcomes were collected for our institutional patients while detailed laboratory data was collected for all tested patients. RESULTS: Of patients with FV-i managed at our institution, 2/8 (25%) patients experienced no bleeding. There was no correlation between inhibitor titers and/or FV activity (FV:C) levels and clinical bleeding. Hemostatic management included fresh frozen plasma, platelet transfusion, activated prothrombin complex concentrates, and recombinant factor VIIa. Only 2 patients received immunomodulatory treatment. FV-i mixing studies with normal pooled plasma (n = 26) demonstrated inhibition on immediate mix but progressive inhibition after 1 h of incubation could not be demonstrated. 71% of platelet neutralization procedures were falsely positive while 59% of DRVVT assays were indeterminate. CONCLUSION: FV-i demonstrates immediate inhibition on mixing studies; however our limited data does not support a time dependent inhibition. Our clinical cohort confirms the variable clinical phenotype for individuals with FV-i and supports the notion that management of FV-i should be guided by clinical symptoms and not FV:C or FV-i titer.