Alfaeftrenonacogue (fator XI de coagulação recombinante Fc) para hemofilia B / Alfaeftrenonacogue (Fc recombinant coagulation factor XI) for hemophilia B

INTRODUÇÃO: As coagulopatias hereditárias são doenças hemorrágicas resultantes da deficiência quantitativa e/ou qualitativa de um ou mais fatores da coagulação e se caracterizam pela ocorrência de hemorragias de gravidade variável, de forma espontânea e/ou pós-traumática. Segundo dados de 2015 do Perfil das Coagulopatias Hereditárias no Brasil , o número de pacientes com Hemofilia B era de 1.948 no Brasil. Como não há cura para as hemofilias, os objetivos de tratamento são prevenir e tratar hemorragias de modo a evitar artropatias incapacitantes e dano tecidual, melhorar a qualidade de vida e a sobrevida dos pacientes. As modalidades de tratamento da hemofilia B são definidas pela periodicidade com que é realizada a reposição dos fatores de coagulação IX, podendo ser sob demanda (episódico) ou profilático. O fator IX de origem plasmática faz parte do rol de tecnologias ofertada pelo SUS para o tratamento de Hemofilia B. PERGUNTA: O uso do Alfaeftrenonacogue é mais eficaz, seguro e custo-efetivo no tratamento de pacientes com hemofilia B quando comparado ao(s) fatores IX de coagulação derivado de plasma? EVIDÊNCIAS CIENTÍFICAS: Os estudos apresentados pelo demandante demonstram a eficácia e segurança do medicamento alfaeftrenonacogue em diminuir a taxa anualizada de sangramentos, reduzir o consumo de fator IX devido a redução de infusões, menor ocorrência do desenvolvimento de inibidores e menor incidência de eventos adversos. Entretanto, não foi apresentado nenhum estudo que comparasse o fator IX plasmático ofertado pelo SUS e alfaeftrenonacogue, o que impossibilita fazer qualquer consideração de superioridade, inferioridade ou igualdade entre as tecnologias. AVALIAÇÃO ECONÔMICA: O demandante delineou em sua proposta um estudo de custo-efetividade do alfaeftrenonacogue para tratamento de hemofilia B. O estudo demonstrou uma RCEI de R$ 7.437,00 por sangramento evitado, quando comparado supostamente com fator IX plasmático. O modelo possui grandes limitações nos dados de eficácia devido a inexistência de estudos que fazem a comparação entre as tecnologias e no levantamentos dos custos, limitando a interpretação dos resultados. AVALIAÇÃO DE IMPACTO ORÇAMENTÁRIO: O impacto orçamentário apresentado pelo demandante estimou, considerando um market-share de 30% em 5 anos, que a inclusão do alfaeftrenonacogue no SUS proporcionará um valor incremental de R$ 8,7 milhões no primeiro ano e de R$ 95,2 milhões no acumulado de 5 anos. O modelo possui limitações quando à estimativa da população, estimativa de difusão da tecnologia e a previsão de custos, que podem subestimar os resultados. MONITORAMENTO DO HORIZONTE TECNOLÓGICO: No horizonte foram detectadas três tecnologias para controlar ou prevenir episódios de sangramento em pacientes com hemofilia B, duas consideradas como terapias gênicas (Estimulador do gene F9) e um inibidor de antitrombina III já em estudos fase 3 ou 4 mas sem aprovação nos orgãos de resgistro ANVISA, EMA e FDA. CONSIDERAÇÕES: São necessárias novas evidências para melhor compreensão dos benéficos clínicos do alfaeftrenonacogue quando comparado as alternativas disponíveis atualmente no SUS. RECOMENDAÇÃO PRELIMINAR DA CONITEC: O plenário, em reunião da CONITEC realizada no dia 07 de novembro de 2018, recomendou que o tema fosse submetido à consulta pública com recomendação preliminar não favorável à incorporação do alfaeftrenonacogue (Fator XI de coagulação recombinante Fc) para tratamento de pacientes com hemofilia B. Considerou-se que há grande incerteza a respeito da eficácia do medicamento quando comparado as opções de tratamento já disponíveis no SUS, além disso a análise econômica apresentada e a análise e impacto orçamentário apresentaram limitações importantes que atribuíram elevada incerteza quanto as estimativas reais de custo-efetividade e de impacto orçamentário. CONSULTA PÚBLICA: Foram recebidas 19 contribuições técnico-científicas e 289 contribuições de experiência e opinião durante o período de consulta pública, entre 29 de novembro a 18 de dezembro de 2018. Dentre as contribuições, a maioria foram contrárias à recomendação da CONITEC. Nenhuma evidência científica adicional foi encontrada nas contribuições. Os principais argumentos abordados foram a redução de dosageme das infusões, melhora na qualidade de vida, resução dos eventos adversos e maior adesão. O plenário da CONITEC entendeu que não houve argumentação suficiente para alterar a recomendação inicial. RECOMENDAÇÃO FINAL DA CONITEC: Os membros da CONITEC presentes na 74ª reunião ordinária, nos dias 06 e 07 de fevereiro de 2019, deliberaram, por unanimidade, por não recomendação a incorporação ao SUS do medicamento alfaeftrenonacogue (Fator XI de coagulação recombinante Fc) para tratamento de pacientes com hemofilia B. Foi assinado em 07 de fevereiro o registro de deliberação nº 420/2019. DECISÃO: Não incorporar o alfaeftrenonacogue para hemofilia B, no âmbito do Sistema Único de Saúde - SUS. Dada pela Portaria nº 9, de 21 de fevereiro de 2019, publicada no Diário Oficial da União nº 38, de 22/02/2019, seção 1, página 54.

Factor XI promotes hemostasis in factor IX-deficient mice.

Essentials Mice lacking factor IX (FIX) or factor XI (FXI) were tested in a saphenous vein bleeding model. FIX-deficient mice displayed a hemostatic defect and FXI-deficient mice were similar to wild type mice. Infusion of FXI or over-expression of FXI in FIX-deficient mice improved hemostasis. FXI may affect the phenotype of FIX-deficiency (hemophilia B). SUMMARY: Background In humans, deficiency of coagulation factor XI may be associated with a bleeding disorder, but, until recently, FXI-deficient mice did not appear to have a hemostatic abnormality. A recent study, however, indicated that FXI-deficient mice show a moderate hemostatic defect in a saphenous vein bleeding (SVB) model. Objectives To study the effect of FXI on bleeding in mice with normal levels of the FXI substrate FIX and in mice lacking FIX (a murine model of hemophilia B). Methods Wild-type mice and mice lacking either FIX (F9- ) or FXI (F11-/- ) were tested in the SVB model. The plasma levels of FXI in F11-/- mice were manipulated by infusion of FXI or its active form FXIa, or by overexpressing FXI by the use of hydrodynamic tail vein injection. Results F9- mice showed a significant defect in the SVB model, whereas F11-/- mice and wild-type mice were indistinguishable. Intravenous infusion of FXI or FXIa into, or overexpression of FXI in, F9- mice improved hemostasis in the SVB model. Overexpression of a FXI variant lacking a FIX-binding site also improved hemostasis in F9- mice. Conclusions Although we were unable to demonstrate a hemostatic defect in F11-/- mice in the SVB model, our results support the premise that supraphysiological levels of FXI improve hemostasis in F9- mice through FIX-independent pathways.

Successful hemostatic management of major surgery for cervical spondylotic myelopathy in a patient with severe factor XI deficiency.

Factor XI deficiency (FXID) is a rare bleeding disorder caused by mutations in the F11 gene. Spontaneous bleeding in patients with factor XI deficiency is rare, but major bleeding may occur after surgery or trauma. The basic method for hemostatic treatment is replacement of the missing factor using FXI concentrate or fresh frozen plasma (FFP). We report the case of a 72-year-old male with severe FXID who underwent a laminoplasty under sufficient, but minimal, FFP transfusion. Through detailed monitoring of activated partial thromboplastin time (APTT) and FXI activity at the perioperative period, we succeeded in hemostatic management of major surgery without significant blood loss and fluid overload. From the course of this case, we found that measuring FXI activity is superior to measuring APTT. Furthermore, we identified a novel homozygous mutation in F11 [NM_000128.3:c.1041C > A:p.(Tyr347*)] by whole exome sequencing.

The Evolving Dilemma of Factor XI in Pregnancy: Suggestions for Management.

A case of a patient with severe factor XI (FXI) deficiency who presented for her seventh labor and delivery is presented. The nature of FXI deficiency, its prevalence, and issues related to genetic screening are discussed. Published literature on the topic is reviewed, including criteria that were developed to assess bleeding, laboratory tools used to estimate bleeding risk, and available treatments. Within the context of this challenging clinical dilemma, specific recommendations are provided for the antepartum, intrapartum, and postpartum stages of pregnancy. These include recommendations that take into account both FXI levels and history of any abnormal bleeding. While there are effective treatments available, it is important to consider that institutional multidisciplinary protocols are needed to manage this complex disorder. More work is needed to define the best management protocols.

Uneventful cesarean delivery with administration of factor XI concentrate in a patient with severe factor XI deficiency.

Factor XI (FXI) is a procoagulant factor and antifibrinolytic agent, and its absence causes a bleeding tendency. FXI deficiency is autosomal in inheritance, with severe FXI deficiency in homozygotes and partial deficiency in heterozygotes. A 24-year-old primigravida with an uneventful pregnancy and no history of bleeding manifestations was admitted to our department at 38 weeks of gestation. Her blood count and serum biochemistry findings were normal except for a coagulation screen, which revealed a prolonged activated partial thromboplastin time (APTT) of 63 seconds (normal range, 24-35 seconds). The measured FXI coagulant activity of 8 IU/dL (reference range, 70-150 IU/dL) established a diagnosis of severe FXI deficiency. The breech presentation of the fetus prompted the decision for cesarean delivery under general anesthesia. We administered a single dose of FXI concentrate (15 IU/kg), which corrected the APTT to 34 seconds. The cesarean delivery was uncomplicated, and postpartum recovery of the mother and her baby was uneventful with no bleeding complications. The finding of an isolated prolonged APTT should prompt obstetricians to consider FXI deficiency. The appropriate use of factor FXI concentrate in managing obstetric patients with FXI deficiency can minimize potential bleeding complications and ensure an optimal outcome for both mother and neonate.

Management of factor XI inhibitor for cardiac intervention: successful treatment with immunosuppressive therapy and plasma exchange.

Two cases with congenital homozygous factor XI deficiency developed a factor XI inhibitor following repeated plasma transfusions. Case 1 was given cyclophosphamide, intravenous immunoglobulin, and steroids. The factor XI inhibitor disappeared on day 103 and cardiac catheterization was performed without complications after giving fresh frozen plasma. Case 2 was effectively managed by plasma exchange for cardiac catheterization and surgery. However, after five plasma exchange procedures, the same plasma volume exchange was not effective in shortening the activated partial thromboplastin time (APTT). A significant heparin rebound occurred 4 h after heparin neutralization with protamine sulphate for which the patient needed to have a blood clot evacuated from around the heart.

In vivo coagulation activation following infusion of highly purified factor XI concentrate.

The use of factor XI concentrates has been associated with thrombosis. Plasma markers of coagulation activation were measured before and 30, 60, 120 and 240 min after six infusions of the BPL factor XI concentrate. Five studies were completed before surgical intervention, one was undertaken in a patient with an intracerebral haemorrhage. Significant elevation of levels of fibrinopeptide A (FpA) (P < 0.05) and thrombin-antithrombin (TAT) were demonstrated following six infusions and prothrombin fragment F1.2 following four. Levels of all three markers had risen 60 min following concentrate administration and FpA levels remained elevated throughout the study period. Levels of D-dimer rose in four patients at 240 min. These results indicate significant thrombin generation by 60 min and subsequent plasmin generation consistent with coagulation activation by the factor XI concentrate. The greatest elevation of activation markers was seen in those subjects with pre-existing coagulation activation. We advise caution in the use of these products and awareness of the risks in patients who may already have activated coagulation states.

Activation of the coagulation cascade after infusion of a factor XI concentrate in congenitally deficient patients.

Virally inactivated, high-purity factor XI concentrates are available for treatment of patients with factor XI deficiency. However, preliminary experience indicates that some preparations may be thrombogenic. We evaluated whether a highly purified concentrate produced signs of activation of the coagulation cascade in two patients with severe factor XI deficiency infused before and after surgery. Signs of heightened enzymatic activity of the common pathway of coagulation (elevated plasma levels of prothrombin fragment 1 + 2 and fibrinopeptide A) developed in the early post-infusion period, accompanied by more delayed signs of fibrin formation with secondary hyperfibrinolysis (elevated D-dimer and plasmin-antiplasmin complex). These changes occurred in both patients, but were more severe in the older patient with breast cancer when she underwent surgery, being accompanied by fibrinogen and platelet consumption. There were no concomitant signs of heightened activity of the factor VII-tissue factor mechanism on the factor Xase complex (plasma levels of activated factor VII and of factor IX and X activation peptides did not increase). The observed changes in biochemical markers of coagulation activation indicate that concentrate infusions increased thrombin generation and activity and that such changes were magnified by malignancy and surgery. Because some factor XI concentrates may be thrombogenic, they should be used with caution, especially in patients with other risk factors for thrombosis.