Emicizumabe para tratamento profilático de pacientes com hemofilia A, moderada ou grave, e anticorpos inibidores do Fator VIII, sem restrição de faixa etária, conforme Protocolo do Ministério da Saúde / Emicizumab for prophylactic treatment of patients with moderate or severe hemophilia A and Factor VIII inhibitor antibodies, without age group restrictions, according to the Ministry of Health Protocol

INTRODUÇÃO: A hemofilia A é uma condição rara que afeta a habilidade de coagulação do sangue, caracterizada pela disfunção ou diminuição da produção do fator de coagulação VIII (FVIII), uma proteína chave na cascata de coagulação para uma hemostasia efetiva. Tal deficiência está associada com a ocorrência de sangramentos, sendo os principais sintomas da doença a presença de sangramentos prolongados. Os quadros podem ser classificados de acordo com a atividade coagulante endógena do fator seja 0,01 UI/ml ou < 1% (grave), 0,01 a 0,05 UI/mL ou 1% a 5% (moderada) e > 0,05 a < 0,40 IU/ml ou > 5% a < 40% (leve), respectivamente. O tratamento dos sangramentos na hemofilia requer a infusão intravenosa do fator de coagulação deficiente. A reposição deste fator pode ser feita sob demanda (tratamento do episódio hemorrágico) ou de forma profilática (manutenção dos níveis de FVIII suficientemente elevados para prevenir os episódios hemorrágicos). Entretanto, uma complicação grave na hemofilia A é o desenvolvimento de inibidores, anticorpos da classe IgG, contra o FVIII infundido, inibindo assim a atividade coagulante dos concentrados de FVIII. A presença destes inibidores tem como consequência a ausência de resposta ao tratamento ou maior frequência ou gra

Emicizumab for the treatment of acquired hemophilia A: Retrospective review of a single-institution experience.

INTRODUCTION: Acquired haemophilia A (AHA) is a rare and potentially life-threatening bleeding disorder arising from autoantibodies that inhibit coagulation factor VIII (FVIII). Treatment entails achieving haemostasis with bypassing agents or factor replacement, and eradication of the inhibitor with immunosuppressive therapy (IST). Due to the rarity of AHA, there are few prospective data to guide management. METHODS: We present a retrospective report of 11 AHA patients treated with emicizumab, a FVIII-mimetic bispecific antibody, administered at 3 mg/kg weekly for 4 weeks in conjunction with rituximab-based immunosuppressive therapy. The chromogenic FVIII inhibitor assay was used to assess for inhibitor eradication. RESULTS: The median follow-up was 13.9 months. The median number of days of additional haemostatic therapy or red blood cell transfusions after initiating emicizumab was 2 (range 0-15). The median was 0 days (range 0-8) for patients who did not require vascular embolization to achieve haemostasis. Eight patients achieved a complete remission (defined as recovery of FVIII activity to > 50% with a negative inhibitor test in the absence of haemostatic and IST); two patients achieved a partial remission (FVIII activity > 50% but with detectable inhibitor); one patient experienced refractory disease. One patient experienced rebleeding and two patients experienced inhibitor recurrence. No thrombotic, thrombotic microangiopathic or infectious complications occurred. CONCLUSION: Our observations suggest emicizumab can facilitate haemostasis for AHA patients and be combined with safer, lower-intensity immunosuppressive therapies to achieve remission.

BAFF rs9514828 gene polymorphism and the risk of the development of inhibitors in children with severe haemophilia A.

INTRODUCTION: Haemophilia A (HA) is an x-linked recessive disease due to deficiency of coagulation factor VIII (FVIII). The development of neutralizing antibodies (inhibitors) against infused FVIII is a major concern. B cell activating factor (BAFF) has been implicated in several autoimmune diseases. AIM: We aimed to evaluate the possible association of BAFF rs9514828 gene polymorphism and the risk of the development of FVIII inhibitor in children with severe HA. METHODS: This cohort study was carried out on 100 newly diagnosed boys with severe HA who were never treated before with FVIII concentrate. Assessment of serum levels of BAFF and BAFF rs9514828 genotyping at first diagnosis was performed and the patients were followed up for the completion of a total of 50 exposure days or the development of inhibitors whichever occurred first. The patients were divided as positive or negative according to the presence or absence of inhibitors. RESULTS: The risk allele for BAFF rs9514828 (T) was significantly more frequent in the inhibitor positive patients than the inhibitor negative patients (P = .003). In addition, CT+TT genotypes were associated with increased risk of FVIII inhibitor development. Receiver operating characteristics (ROC) analysis showed that BAFF levels could predict the development of FVIII inhibitors at a cut-off value of ≥ .92 with a sensitivity of 85.9% and a specificity of 80.2%. CONCLUSION: BAFF rs9514828 gene polymorphism could be independent risk factor and elevated BAFF levels might be useful prognostic marker for the development of FVIII inhibitor in newly diagnosed children with severe HA.

HCV infection in hemophilia A patients is associated with altered cytokines and chemokines profile and might modulate the levels of FVIII inhibitor.

Prevalence of hepatitis C virus (HCV) is high in hemophilia A patients and the development of FVIII inhibitor is another challenge in the management of these individuals. The influence of HCV infection in the occurrence of inhibitors was investigated by the comparison of clinical and laboratory data from noninfected (NI, n = 96) and chronically HCV-infected (HCV, n = 58) hemophilia A patients. Concentrations of plasmatic cytokines (IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17A) and chemokines (CCL2, CCL5, CXCL8, CXCL9, and CXCL10) were quantified from patients' samples. The results showed that older age, use of cryoprecipitate and fresh frozen plasma, and severe hemophilia were associated with HCV infection, whereas exclusive use of virus inactivated clotting factors was a protector factor to acquiring HCV infection. HCV infection was strongly associated with low levels of inhibitor (OR = 20.53, p < 0.001). Patients with a history of inhibitor (INB+) presented a mixed immune profile characterized by higher levels of pro-and anti-inflammatory cytokines than those without a history of inhibitor (INB-). The highest levels of CCL2 and CXCL8 were seen in HCVINB- , whereas CXCL9 and CXCL10 in HCVINB+ . Heatmap analysis of the set of cytokines and chemokines concentration distributed HCV patients into two distinct clusters, HCVINB+ and HCVINB- , both characterized by low concentrations of IL-4, while noninfected patients were grouped in a single block regardless of inhibitor development history (NIINB-/INB+ ). This finding suggests that the strong association between HCV infection and low levels of factor VIII inhibitors might be due to the modulation of the cytokine and chemokine network established by the antiviral response.

Real-world experience on the tolerability and safety of emicizumab prophylaxis in paediatric patients with severe haemophilia A with and without FVIII inhibitors.

BACKGROUND: Emicizumab is a bispecific monoclonal antibody that bridges activated factor (F) IX and FX, and maintains haemostasis in patients with haemophilia A (PwHA). As a novel agent, many questions remain unanswered about the loss of emicizumab efficacy due to anti-drug antibody (ADA) development, the incidence of inhibitor recurrence in previously tolerized patients, and the risk of de novo inhibitor development. AIM: To present real-world experience regarding tolerability, side effects, and outcomes of adverse events of emicizumab prophylaxis in paediatric PwHA. METHODS: Data on tolerability, compliance, adverse events, and laboratory results of paediatric patients receiving emicizumab prophylaxis, treated at the Haemophilia Comprehensive Care Centre, at Birmingham Children's Hospital between March 2018 and June 2021, were collected. RESULTS: Our results showed that out of 52 patients, four experienced minor adverse events, two developed headaches, one developed abdominal pain and nausea, and one developed injection site reactions. Moreover, four patients experienced major adverse events, including severe headaches, major bleeding events, development of ADAs, and recurrence of inhibitors. Emicizumab prophylaxis was discontinued in three patients (5.7% of the cohort) due to adverse events. In addition, emicizumab was discontinued in one patient because of poor compliance. No adverse events were reported in previously untreated/minimally treated patients, represented by four patients in our cohort. CONCLUSIONS: The real-world experience of emicizumab prophylaxis in our cohort showed that emicizumab was safe and well tolerated in paediatric PwHA with and without inhibitors. Long-term assessment is crucial to monitor major adverse events, recurrence of inhibitors, and development of ADAs.

Structure of Blood Coagulation Factor VIII in Complex With an Anti-C2 Domain Non-Classical, Pathogenic Antibody Inhibitor.

Factor VIII (fVIII) is a procoagulant protein that binds to activated factor IX (fIXa) on platelet surfaces to form the intrinsic tenase complex. Due to the high immunogenicity of fVIII, generation of antibody inhibitors is a common occurrence in patients during hemophilia A treatment and spontaneously occurs in acquired hemophilia A patients. Non-classical antibody inhibitors, which block fVIII activation by thrombin and formation of the tenase complex, are the most common anti-C2 domain pathogenic inhibitors in hemophilia A murine models and have been identified in patient plasmas. In this study, we report on the X-ray crystal structure of a B domain-deleted bioengineered fVIII bound to the non-classical antibody inhibitor, G99. While binding to G99 does not disrupt the overall domain architecture of fVIII, the C2 domain undergoes an ~8 Å translocation that is concomitant with breaking multiple domain-domain interactions. Analysis of normalized B-factor values revealed several solvent-exposed loops in the C1 and C2 domains which experience a decrease in thermal motion in the presence of inhibitory antibodies. These results enhance our understanding on the structural nature of binding non-classical inhibitors and provide a structural dynamics-based rationale for cooperativity between anti-C1 and anti-C2 domain inhibitors.

B cell-activating factor modulates the factor VIII immune response in hemophilia A.

Inhibitors of factor VIII (FVIII) remain the most challenging complication of FVIII protein replacement therapy in hemophilia A (HA). Understanding the mechanisms that guide FVIII-specific B cell development could help identify therapeutic targets. The B cell-activating factor (BAFF) cytokine family is a key regulator of B cell differentiation in normal homeostasis and immune disorders. Thus, we used patient samples and mouse models to investigate the potential role of BAFF in modulating FVIII inhibitors. BAFF levels were elevated in pediatric and adult HA inhibitor patients and decreased to levels similar to those of noninhibitor controls after successful immune tolerance induction (ITI). Moreover, elevations in BAFF levels were seen in patients who failed to achieve FVIII tolerance with anti-CD20 antibody-mediated B cell depletion. In naive HA mice, prophylactic anti-BAFF antibody therapy prior to FVIII immunization prevented inhibitor formation and this tolerance was maintained despite FVIII exposure after immune reconstitution. In preimmunized HA mice, combination therapy with anti-CD20 and anti-BAFF antibodies dramatically reduced FVIII inhibitors via inhibition of FVIII-specific plasma cells. Our data suggest that BAFF may regulate the generation and maintenance of FVIII inhibitors and/or anti-FVIII B cells. Finally, anti-CD20/anti-BAFF combination therapy may be clinically useful for ITI.

Long-term outcomes with emicizumab prophylaxis for hemophilia A with or without FVIII inhibitors from the HAVEN 1-4 studies.

Prophylaxis with emicizumab, a subcutaneously administered bispecific humanized monoclonal antibody, promotes effective hemostasis in persons with hemophilia A (PwHAs). The primary efficacy, safety, and pharmacokinetics of emicizumab were reported previously, but long-term data were limited. Here, data from 401 pediatric and adult PwHAs with/without factor VIII (FVIII) inhibitors who were enrolled in the phase 3 HAVEN 1, HAVEN 2, HAVEN 3, and HAVEN 4 studies (NCT02622321, NCT02795767, NCT02847637, NCT03020160) have been pooled to establish a long-term efficacy, safety, and pharmacokinetics profile. Across a median efficacy period of 120.4 weeks (interquartile range, 89.0-164.4) (data cutoff 15 May 2020), the model-based treated annualized bleed rate (ABR) was 1.4 (95% confidence interval [CI], 1.1-1.7). ABRs declined and then stabilized at <1 in an analysis of 24-week treatment intervals; at weeks 121 to 144 (n = 170), the mean treated ABR was 0.7 (95% CI, 0-5.0). During weeks 121 to 144, 82.4% of participants had 0 treated bleeds, 97.6% had ≤3 treated bleeds, and 94.1% reported no treated target joint bleeds. Bleeding into target joints decreased substantially. Emicizumab was well tolerated, and no participant discontinued because of adverse events beyond the 5 previously described. This data cutoff includes the previously reported 3 thrombotic microangiopathies (one in the PwHA with fatal rectal hemorrhage) and 2 thromboembolic events, all associated with activated prothrombin complex concentrate use, as well as a myocardial infarction and a venous device occlusion. With 970.3 patient-years of exposure, emicizumab prophylaxis maintained low bleed rates in PwHAs of all ages with/without FVIII inhibitors and remains well tolerated, with no new safety concerns identified.

IgG subclasses as biomarkers for persistence of factor VIII inhibitors in previously untreated patients with severe haemophilia A.

We investigated longitudinally the behaviour of anti-factor VIII (anti-FVIII) IgG subclasses for 6 months from inhibitor development in 43 patients from the Survey of Inhibitors in Plasma-Products Exposed Toddlers (SIPPET) trial who developed persistent or transient inhibitors. We first analysed 43 patients within 60 days post inhibitor detection. Then, 14 of these 43 patients were studied at five time points over 6 months. Our study showed that during the first 60 days, the risk of inhibitor persistence increased with the concomitant presence of an increasing number of IgG subclasses. Over the 6-month period post inhibitor detection, only the IgG2 subclass could be considered a hallmark of inhibitor persistence.

Pharmacokinetics and Pharmacodynamics of Emicizumab in Persons with Hemophilia A with Factor VIII Inhibitors: HAVEN 1 Study.

Emicizumab, a bispecific monoclonal antibody, bridges activated factor IX (FIXa) and FX, replacing the function of missing FVIIIa to restore effective hemostasis in persons with hemophilia A (PwHA). Here we assess pharmacokinetic (PK) and pharmacodynamic (PD) biomarkers in PwHA with FVIII inhibitors in the Phase III HAVEN 1 study (NCT02622321). Blood samples from 112 PwHA receiving 1.5 mg/kg once-weekly subcutaneous emicizumab were analyzed at central laboratories. Emicizumab concentrations for PK analysis were measured via validated immunoassay. PD effects were assessed using FVIII chromogenic activity assay containing human factors (Hyphen Biophen FVIII:C), and by FXIa-triggered thrombin generation (TG). Activated partial thromboplastin time (aPTT), prothrombin time (PT), antigen levels of FIX and FX, fibrinogen, D-dimer, and prothrombin fragment 1.2 (PF1.2) levels were determined. Emicizumab trough concentrations ≥ 50 µg/mL were maintained throughout the study. FVIII-like activity and TG (peak height) correlated with emicizumab concentrations and remained above 20 U/dL and 100 nM, respectively, with a weekly maintenance dose, theoretically converting persons with severe hemophilia A to a mild disease phenotype. aPTT was normalized at subtherapeutic concentrations of emicizumab. Plasma concentrations of target antigens FIX and FX were not significantly affected by emicizumab treatment; nor were fibrinogen, PT (international normalized ratio), D-dimer, or PF1.2. The PK profile of once-weekly emicizumab in HAVEN 1 provides sustained therapeutic plasma levels, consistent with population PK models. Both the PK profile and the PD and safety biomarkers are consistent with the established efficacy of emicizumab prophylaxis in PwHA with FVIII inhibitors.

Treatment of acquired hemophilia A, a balancing act: results from a 27-year Dutch cohort study.

Acquired hemophilia A (AHA) is a severe auto-immune bleeding disorder. Treatment of AHA is burdensome and optimal management is still unresolved. Therefore a retrospective nationwide multi-center cohort study (1992-2018) was performed to evaluate clinical presentation and treatment efficacy and safety of AHA in the Netherlands. Multivariate logistic and Cox regression analysis was used to study independent associations between patient characteristics and clinical outcomes. A total of 143 patients (median age 73 years; 52.4% male) were included with a median follow-up of 16.8 months (IQR 3.6-41.5 months). First-line immunosuppressive treatment was mostly steroid monotherapy (67.6%), steroids/cyclophosphamide (11.9%) and steroids/rituximab (11.9%), with success rates of 35.2%, 80.0% and 66.7% respectively, P < .05. Eventually 75% of patients achieved complete remission (CR). A high anti-FVIII antibody titer, severe bleeding and steroid monotherapy were associated with lower CR rates. Infections, the most important adverse event, occurred significantly more often with steroid combination therapy compared to steroids alone (38.7% vs 10.6%; P = .001). Overall mortality was 38.2%, mostly due to infections (19.2%) compared to 7.7% fatal bleeds. Advanced age, underlying malignancy and ICU admission were predictors for mortality. This study showed that AHA is characterized by significant disease-related and treatment-related morbidity and mortality. A high anti-FVIII titer, severe bleeding and steroid monotherapy were associated with a lower CR rate. The efficacy of steroid combination therapies however, was overshadowed by higher infection rates and infections represented the most important cause of death. The challenging and delicate balance between treatment effectivity and safety requires ongoing monitoring of AHA and further identification of prognostic markers.

Oral Corticosteroid Therapy as an Adjuvant Treatment for Acute Bleeding in Hemophilia Patients With High Titer Inhibitors.

Treatment options exist for patients with severe hemophilia and high titer factor VIII inhibitors but is often inadequate. Few studies have been conducted to evaluate the utility of short-term corticosteroid therapy for improvement in bleeding complications and temporary or sustained resolution of inhibitors in these patients. We describe 2 patients with acute muscular hematomas successfully treated with 4 to 5 days of oral adjuvant corticosteroid therapy resulting in improvement in their acute bleeds and temporary reduction of inhibitors. Thus, the addition of corticosteroids to traditional therapy of hemophilia with inhibitors may be beneficial in some patients. In those with impending compartment syndrome steroids may improve edema and bleeding symptoms preventing the need for surgical interventions.

Rituximab en combinación con agentes «bypass» hemostáticos para hemofilia adquirida con inhibidor, a propósito de un caso / Rituximab in combination with hemostatic «bypass» agents for hemophilia acquired with an inhibitor, in the event of a case

La hemofilia adquirida es un trastorno hemorrágico producido por anticuerpos del propio organismo que actúan frente al factor VIII. Posee una incidencia estimada 1-1,5 casos/millón/año, con predominio en sujetos de edad avanzada. Es considerada una enfermedad rara pero su impacto puede verse infraestimado por la falta de registros adecuados, la falta de conocimiento por el facultativo y su complejidad para diagnosticarla. No hay establecido un protocolo fijo en el manejo de la patología, por ello la mayoría de las recomendaciones se basan en las opiniones de expertos en el tratamiento de otras coagulopatías. (AU)

Acquired hemophilia is a bleeding disorder caused by the body’s own antibodies to factor VIII. It has an estimated incidence of 1-1.5 cases/million/year, with a predominance of elderly subjects. It is considered a rare disease but its impact may be underestimated due to the lack of adequate records, the lack of knowledge by the specialists and its complexity in diagnosing it. There is no fixed protocol in the management of the pathology, so the majority of recommendations are based on the opinions of experts in the treatment of other coagulopathies.

Primera experiencia de tratamiento con emicizumab en un paciente con hemofilia A severa e inhibidor de alto título en Uruguay / First report of emicizumab use in a patient with severe haemophilia A and high-titer inhibitor in Uruguay / Primeira experiência de tratamento com emicizumab em paciente com hemofilia A grave e inibidor de alto título no Uruguai

La hemofilia A es una coagulopatía congénita causada por la deficiencia o el mal funcionamiento del factor VIII de la coagulación. Una de las complicaciones más graves del tratamiento de la hemofilia A es el desarrollo de inhibidores que hacen que la terapia de reemplazo con FVIII sea ineficaz, dificultando la prevención y el control de los sangrados. El emicizumab es un anticuerpo monoclonal humanizado biespecífico dirigido contra los factores FIXa y FX, que imita la función de cofactor del FVIII. El tratamiento profiláctico con emicizumab es seguro y eficaz para prevenir hemorragias en los pacientes con hemofilia A con y sin inhibidores. Se presenta el caso del primer paciente tratado con emicizumab en Uruguay.

Haemophilia A is a congenital coagulopathy caused by a deficiency or malfunction of coagulation factor VIII. One of the most serious complications of haemophilia A treatment is the development of inhibitors that render FVIII replacement therapy ineffective, making it difficult to prevent and control bleeding. Emicizumab is a humanized bispecific monoclonal antibody directed against factors FIXa and FX, which mimics the cofactor function of FVIII. Emicizumab has been shown to be safe and effective as prophylaxis to prevent bleeding in haemophilia A patients with or without inhibitors to FVIII. We report the first patient treated with emicizumab in Uruguay.

A hemofilia A é uma coagulopatia congênita que se caracteriza pela ausência ou mau funcionamento do factor VIII da coagulação. Uma das complicações mais sérias do tratamento da hemofilia A é o desenvolvimento de inibidores que tornam a terapia de reposição do FVIII ineficaz, dificultando a prevenção e o controle do sangramento. O emicizumab é um anticorpo monoclonal biespecífico humanizado dirigido contra os fatores FIXa e FX, que imita a função de cofator do FVIII. O tratamento profilático com emicizumab é seguro e eficaz na prevenção de sangramento em pacientes com hemofilia A com e sem inibidores. É apresentado o caso do primeiro paciente tratado com emicizumabe no Uruguai.

Health-related quality of life and caregiver burden of emicizumab in children with haemophilia A and factor VIII inhibitors-Results from the HAVEN 2 study.

INTRODUCTION: Persons with haemophilia A (PwHA) with factor (F)VIII inhibitors, including children, have impaired health-related quality of life (HRQoL). The HAVEN 2 study (NCT027955767) of paediatric PwHA with FVIII inhibitors demonstrated that subcutaneous emicizumab prophylaxis resulted in low annualizedbleed rates. AIM: We assessed the impact of emicizumab prophylaxis on the HRQoL of children and their caregivers participating in HAVEN 2. METHODS: Children aged 8-11 years self-reported HRQoL using the Haemophilia-Specific Quality of Life Assessment Instrument for Children and Adolescents Short Form (Haemo-QoL SF II). Caregivers of children aged 0-11 years completed the Adapted Inhibitor-Specific Quality of Life Assessment with Aspects of Caregiver Burden. All scores were transformed to a 0-100 scale, where lower scores reflect a better HRQoL. The number of missed days from school/day care and hospitalizations was also recorded. RESULTS: In HAVEN 2 (n = 88), the median age was 6.5 years (range: 1-15 years); 85 participants were aged < 12 years and included in this analysis, and 34 participants were aged 8-11 years, thereby eligible to complete the Haemo-QoL SF II questionnaire. The mean (standard deviation, n) baseline Haemo-QoL SF II 'Total' score was 30.2 (14.9, 30), indicating moderate impairment; with emicizumab, mean score decreased by -9.62 (7.73, 17) points to 23.0 (13.93, 20) by Week 49. The most improved domains were 'Sports & School' and 'Physical Health'. Caregivers reported similar improvements. CONCLUSION: Prophylactic emicizumab is accompanied by substantial and sustained improvements in HRQoL of paediatric PwHA with FVIII inhibitors and their caregivers.

An 89-Year-Old Man with COVID-19-Associated Coagulopathy Presenting with a Prolonged Partial Thromboplastin Time, Lupus Anticoagulant, and a High Titer of Factor VIII Inhibitor.

BACKGROUND Coagulation abnormalities are frequently encountered in patients with coronavirus disease 2019 (COVID-19), especially in those with more severe disease. These hematologic abnormalities are suspected to occur in the context of underlying immune dysregulation and endothelial dysfunction. Elevated D-dimer levels, COVID-19-associated coagulopathy (CAC), disseminated intravascular coagulation (DIC), and positive lupus anticoagulants are the most common findings to date. Current guidelines suggest that all patients with COVID-19 should receive pharmacologic thromboprophylaxis. CASE REPORT An 89-year-old man with a medical history of hypertension, type 2 diabetes, and advanced prostate cancer in remission presented with generalized weakness. At our center, a reverse transcription-polymerase chain reaction test was positive for severe acute respiratory syndrome coronavirus 2, but the patient did not have symptoms of COVID-19. He was also found to have a prolonged activated partial thromboplastin time, secondary to both a high titer of factor VIII inhibitor and a lupus anticoagulant. He eventually developed respiratory compromise, during which his disease manifested as a bleeding rather than a prothrombotic state. CONCLUSIONS This report highlights the importance of a comprehensive evaluation of prolonged partial thromboplastin time, rather than making an assumption based on a positive lupus anticoagulant result. In the case presented, the concomitant factor VIII inhibitor caused the patient to have a greater bleeding tendency. It is imperative that physicians balance the risk of bleeding and clotting in patients with COVID-19 because patients seem to have varying presentations based on disease severity and level of immune dysregulation.