RESUMO
Emicizumab, a bispecific humanized monoclonal antibody, bridges activated factor IX (FIX) and FX to restore the function of missing activated FVIII in hemophilia A. Emicizumab prophylaxis in children with hemophilia A and FVIII inhibitors was investigated in a phase 3 trial (HAVEN 2). Participants, previously receiving episodic/prophylactic bypassing agents (BPAs), were treated with subcutaneous emicizumab: 1.5 mg/kg weekly (group A), 3 mg/kg every 2 weeks (group B), or 6 mg/kg every 4 weeks (group C). Pharmacokinetics, safety, and efficacy (including an intraindividual comparison of participants from a noninterventional study) were evaluated. Eighty-five participants aged <12 years were enrolled. In group A (n = 65), the annualized rate of treated bleeding events (ABRs) was 0.3 (95% confidence interval [CI], 0.17-0.50), and 77% had no treated bleeding events. Intraindividual comparison of 15 participants who previously took BPA prophylaxis showed that emicizumab prophylaxis reduced the ABR by 99% (95% CI, 97.4-99.4). In groups B (n = 10) and C (n = 10), ABRs were 0.2 (95% CI, 0.03-1.72) and 2.2 (95% CI, 0.69-6.81), respectively. The most frequent adverse events were nasopharyngitis and injection-site reactions; no thrombotic events occurred. Two of 88 participants developed antidrug antibodies (ADAs) with neutralizing potential, that is, associated with decreased emicizumab plasma concentrations: 1 experienced loss of efficacy, and, in the other, ADAs disappeared over time without intervention or breakthrough bleeding. All other participants achieved effective emicizumab plasma concentrations, regardless of the treatment regimen. Emicizumab prophylaxis has been shown to be a highly effective novel medication for children with hemophilia A and inhibitors. This trial was registered at www.clinicaltrials.gov as #NCT02795767.
Assuntos
Anticorpos Biespecíficos/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Hemofilia A/complicações , Hemofilia A/tratamento farmacológico , Hemorragia/etiologia , Hemorragia/prevenção & controle , Adolescente , Anticorpos Biespecíficos/administração & dosagem , Anticorpos Biespecíficos/efeitos adversos , Anticorpos Biespecíficos/farmacocinética , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/efeitos adversos , Anticorpos Monoclonais Humanizados/farmacocinética , Criança , Pré-Escolar , Fator VIII/antagonistas & inibidores , Fator VIII/imunologia , Feminino , Hemofilia A/imunologia , Humanos , Lactente , Isoanticorpos/sangue , Isoanticorpos/imunologia , Masculino , Qualidade de Vida , Resultado do TratamentoRESUMO
Congenital thrombotic thrombocytopenic purpura (cTTP) is an ultra-rare thrombomicroangiopathy caused by an inherited deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13). There are limited data on genotype-phenotype correlation; there is no consensus on treatment. We reviewed the largest cohort of cTTP cases, diagnosed in the United Kingdom, over the past 15 years. Seventy-three cases of cTTP were diagnosed, confirmed by genetic analysis. Ninety-three percent were alive at the time of review. Thirty-six percent had homozygous mutations; 64% had compound heterozygous mutations. Two presentation peaks were seen: childhood (median diagnosis age, 3.5 years) and adulthood, typically related to pregnancy (median diagnosis age, 31 years). Genetic mutations differed by age of onset with prespacer mutations more likely to be associated with childhood onset (P = .0011). Sixty-nine percent of adult presentations were associated with pregnancy. Fresh-frozen plasma (FFP) and intermediate purity factor VIII concentrate were used as treatment. Eighty-eight percent of patients with normal blood counts, but with headaches, lethargy, or abdominal pain, reported symptom resolution with prophylactic therapy. The most common currently used regimen of 3-weekly FFP proved insufficient for 70% of patients and weekly or fortnightly infusions were required. Stroke incidence was significantly reduced in patients receiving prophylactic therapy (2% vs 17%; P = .04). Long-term, there is a risk of end-organ damage, seen in 75% of patients with late diagnosis of cTTP. In conclusion, prespacer mutations are associated with earlier development of cTTP symptoms. Prophylactic ADAMTS13 replacement decreases the risk of end-organ damage such as ischemic stroke and resolved previously unrecognized symptoms in patients with nonovert disease.
Assuntos
Proteína ADAMTS13/genética , Púrpura Trombocitopênica Trombótica/congênito , Púrpura Trombocitopênica Trombótica/tratamento farmacológico , Proteína ADAMTS13/deficiência , Adulto , Pré-Escolar , Fator VIII/uso terapêutico , Feminino , Humanos , Masculino , Mutação , Plasma , Gravidez , Pré-Medicação/métodos , Púrpura Trombocitopênica Trombótica/complicações , Púrpura Trombocitopênica Trombótica/genética , Acidente Vascular Cerebral/prevenção & controleRESUMO
The incidence of FIX inhibitors in severe hemophilia B (SHB) is not well defined. Frequencies of 3-5% have been reported but most studies to date were small, including patients with different severities, and without prospective follow-up for inhibitor incidence. Study objective was to investigate inhibitor incidence in patients with SHB followed up to 500 exposure days (ED), the frequency of allergic reactions, and the relationship with genotypes. Consecutive previously untreated patients (PUPs) with SHB enrolled into the PedNet cohort were included. Detailed data was collected for the first 50 ED, followed by annual collection of inhibitor status and allergic reactions. Presence of inhibitors was defined by at least two consecutive positive samples. Additionally, data on factor IX gene mutation was collected. 154 PUPs with SHB were included; 75% were followed until 75 ED, and 43% until 500 ED. Inhibitors developed in 14 patients (7 high-titre). Median number of ED at inhibitor manifestation was 11 (IQR 6.5-36.5). Cumulative inhibitor incidence was 9.3% (95%CI 4.4-14.1) at 75 ED, and 10.2% (5.1-15.3) at 500 ED. Allergic reactions occurred in 4 (28.6%) inhibitor patients. Missense mutations were most frequent (46.8%) overall but not associated with inhibitors. Nonsense mutations and deletions with large structural changes comprised all mutations among inhibitor patients and were associated with an inhibitor risk of 26.9% and 33.3%, respectively. In an unselected, well-defined cohort of PUPs with SHB, cumulative inhibitor incidence was 10.2% at 500 ED. Nonsense mutations and large deletions were strongly associated with the risk of inhibitor development. The PedNet Registry is registered at clinicaltrials.gov; identifier: NCT02979119.
Assuntos
Hemofilia A , Hemofilia B , Fator VIII , Hemofilia B/tratamento farmacológico , Hemofilia B/epidemiologia , Hemofilia B/genética , Humanos , Incidência , Estudos Prospectivos , Fatores de RiscoRESUMO
INTRODUCTION: European regulatory authorities request postmarketing safety and efficacy data for factor IX (FIX) products. AIM: Collect additional clinical data from routine nonacog alfa use in children aged <6 years with haemophilia B. METHODS: The EUREKIX registry included retrospective and prospective data collection phases. Safety was assessed via adverse drug reactions (ADRs)/adverse events (AEs) and events of special interest (ESIs) as the primary objective; efficacy was evaluated via annualised bleeding rates (ABRs). RESULTS: The retrospective phase comprised 37 subjects. Of these, 25 had severe haemophilia B. One subject experienced 2 ADRs; another experienced 4 ESIs of hypersensitivity. Median ABR in subjects receiving a predominantly on-demand regimen (prophylaxis <50% of time; n = 11) was 2.0; median ABR was 3.8 in those receiving predominantly prophylactic treatment (prophylaxis ≥50% of time; n = 24). Joint bleeding was infrequent (median ABR, 0.4; n = 35). The prospective phase included 26 subjects, with 17 continuing from the retrospective phase. A total of 20 subjects had severe haemophilia B. Three subjects experienced 7 treatment-related AEs; 3 experienced 4 ESIs. Median ABR was 4.5 and 1.1 in subjects who received predominantly on-demand (n = 5) or prophylactic treatment (n = 19), respectively; the overall median ABR for joint bleeding events was 0.0. CONCLUSIONS: Overall, nonacog alfa treatment effectively controlled bleeding events, with no new safety signals identified. These data support the safety and efficacy of nonacog alfa in routine clinical settings in children aged <6 years.
Assuntos
Hemofilia A , Hemofilia B , Criança , Fator IX/uso terapêutico , Hemofilia B/tratamento farmacológico , Hemorragia/etiologia , Hemorragia/prevenção & controle , Humanos , Sistema de Registros , Estudos RetrospectivosRESUMO
INTRODUCTION: In good risk patients (historic inhibitor peak < 200BU), the International Immune Tolerance Study demonstrated equal efficacy to induce tolerance between high (200iu/kg/day) and low dose (50iu/kg ×3 times/week) immune tolerance induction (ITI) regimens. However, the trial stopped early on account of the excessive bleed rate in the low dose ITI arm. METHODS: United Kingdom Haemophilia Centre Doctors' Organization (UKHCDO) Paediatric and Inhibitor working parties considered available ITI data alongside the bi-phenotypic antibody emicizumab (Hemlibra®) efficacy and safety data to develop a consensus guideline for the future UK ITI guideline. RESULTS: This revision of UKHCDO ITI guidance incorporates the recommendation to use emicizumab as a prophylaxis haemostatic agent to reduce bleeding rates and to facilitate low dose and reduced frequency of FVIII CFC for ITI in the majority of children. CONCLUSION: This consensus protocol will facilitate future evaluation of ITI outcomes in the evolving landscape of haemophilia therapeutics and ITI strategies.
Assuntos
Hemofilia A , Criança , Fator VIII , Hemofilia A/tratamento farmacológico , Hemorragia/prevenção & controle , Humanos , Tolerância Imunológica , Reino UnidoRESUMO
AIMS: Population pharmacokinetic (PK) models are increasingly applied to perform individualized dosing of factor VIII (FVIII) concentrates in haemophilia A patients. To guarantee accurate performance of a population PK model in dose individualization, validation studies are of importance. However, external validation of population PK models requires independent data sets and is, therefore, seldomly performed. Therefore, this study aimed to validate a previously published population PK model for FVIII concentrates administrated perioperatively. METHODS: A previously published population PK model for FVIII concentrate during surgery was validated using independent data from 87 children with severe haemophilia A with a median (range) age of 2.6 years (0.03-15.2) and body weight of 14 kg (4-57). First, the predictive performance of the previous model was evaluated with MAP Bayesian analysis using NONMEM v7.4. Subsequently, the model parameters were (re)estimated using a combined dataset consisting of the previous modelling data and the data available for the external validation. RESULTS: The previous model underpredicted the measured FVIII levels with a median of 0.17 IU mL-1 . Combining the new, independent and original data, a dataset comprising 206 patients with a mean age of 7.8 years (0.03-77.6) and body weight of 30 kg (4-111) was obtained. Population PK modelling provided estimates for CL, V1, V2, and Q: 171 mL h-1 68 kg-1 , 2930 mL 68 kg-1 , 1810 mL 68 kg-1 , and 172 mL h-1 68 kg-1 , respectively. This model adequately described all collected FVIII levels, with a slight median overprediction of 0.02 IU mL-1 . CONCLUSIONS: This study emphasizes the importance of external validation of population PK models using real-life data.
Assuntos
Hemofilia A , Teorema de Bayes , Peso Corporal , Criança , Pré-Escolar , Estudos de Coortes , Fator VIII , Hemofilia A/tratamento farmacológico , HumanosRESUMO
Inhibitor development is a major complication of treatment with factor VIII concentrates in nonsevere haemophilia A. It has been suggested that plasma-derived factor VIII (FVIII) concentrates elicit fewer inhibitors than recombinant FVIII concentrates, but studies in severe haemophilia A patients have shown conflicting results. We designed a case-control study to investigate the clinical and genetic risk factors for inhibitor development in nonsevere haemophilia A patients. We investigated whether the type of FVIII concentrate was associated with inhibitor development in nonsevere haemophilia A patients. This nested case-control study includes 75 inhibitor patients and 223 controls, from a source population of the INSIGHT study, including all nonsevere haemophilia A patients (FVIII:C 2-40%) that were treated with FVIII concentrates in 33 European and one Australian centre. Cases and controls were matched for date of birth and cumulative number of exposure days (CED) to FVIII concentrate. A conditional logistic regression model was used to calculate unadjusted and adjusted odds ratios. No increased risk for inhibitor development was found for any type of FVIII concentrate; either when comparing recombinant FVIII concentrates to plasma-derived FVIII concentrates (adjusted odds ratio 0·96, 95% confidence interval (CI) 0·36-2·52) or for specific types of FVIII concentrates.
Assuntos
Inibidores dos Fatores de Coagulação Sanguínea/sangue , Fator VIII , Hemofilia A , Adolescente , Adulto , Criança , Pré-Escolar , Fator VIII/administração & dosagem , Fator VIII/antagonistas & inibidores , Fator VIII/metabolismo , Hemofilia A/sangue , Hemofilia A/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de RiscoRESUMO
INTRODUCTION: As a result of the new treatment paradigm that the haemophilia community will face with the availability of novel (non-factor) therapies, an updated consensus on ITI recommendations and inhibitor management strategies is needed. AIM: The Future of Immunotolerance Treatment (FIT) group was established to contemplate, determine and recommend the best management options for patients with haemophilia A and inhibitors. DISCUSSION AND CONCLUSIONS: Despite the considerable success of emicizumab in the management of inhibitor patients, the FIT group still sees the importance of eradicating inhibitors. However, the availability of emicizumab and other non-factor therapies in the future might impact greatly on how ITI is undertaken. Theoretically, concomitant use of emicizumab and FVIII might allow emicizumab to effectively prevent bleeding with lower dose ITI regimens. This might allow for the greater adoption of low-dose/low-frequency FVIII ITI regimens, which may result in a reduced need for central venous access devices while still maintaining a reasonable likelihood of ITI success. The FIT group proposes a new management algorithm for current ITI (without emicizumab) and a hypothetical new approach with the availability of emicizumab. As there are no published data regarding the concomitant use of emicizumab and FVIII for ITI, the FIT Expert group encourages the undertaking of properly conducted prospective studies to explore these approaches further.
Assuntos
Anticorpos Biespecíficos/farmacologia , Anticorpos Monoclonais Humanizados/farmacologia , Fator VIII/imunologia , Hemofilia A/imunologia , Tolerância Imunológica/efeitos dos fármacos , Anticorpos Neutralizantes/imunologia , Relação Dose-Resposta a Droga , Hemofilia A/tratamento farmacológico , Humanos , Medição de RiscoRESUMO
Inherited bleeding, thrombotic, and platelet disorders (BPDs) are diseases that affect â¼300 individuals per million births. With the exception of hemophilia and von Willebrand disease patients, a molecular analysis for patients with a BPD is often unavailable. Many specialized tests are usually required to reach a putative diagnosis and they are typically performed in a step-wise manner to control costs. This approach causes delays and a conclusive molecular diagnosis is often never reached, which can compromise treatment and impede rapid identification of affected relatives. To address this unmet diagnostic need, we designed a high-throughput sequencing platform targeting 63 genes relevant for BPDs. The platform can call single nucleotide variants, short insertions/deletions, and large copy number variants (though not inversions) which are subjected to automated filtering for diagnostic prioritization, resulting in an average of 5.34 candidate variants per individual. We sequenced 159 and 137 samples, respectively, from cases with and without previously known causal variants. Among the latter group, 61 cases had clinical and laboratory phenotypes indicative of a particular molecular etiology, whereas the remainder had an a priori highly uncertain etiology. All previously detected variants were recapitulated and, when the etiology was suspected but unknown or uncertain, a molecular diagnosis was reached in 56 of 61 and only 8 of 76 cases, respectively. The latter category highlights the need for further research into novel causes of BPDs. The ThromboGenomics platform thus provides an affordable DNA-based test to diagnose patients suspected of having a known inherited BPD.
Assuntos
Transtornos Plaquetários/genética , Predisposição Genética para Doença , Hemorragia/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Trombose/genética , Estudos de Casos e Controles , Variações do Número de Cópias de DNA , Feminino , Estudos de Associação Genética/métodos , Humanos , Masculino , Mutação , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA/métodosRESUMO
The discussion of prophylactic therapy in haemophilia is largely focused on joint outcomes. The impact of prophylactic therapy on intracranial haemorrhage (ICH) is less known. This study aimed to analyse ICH in children with haemophilia, with a focus on different prophylaxis regimens and sequelae of ICH. We conducted a multicentre retrospective and prospective study that included 33 haemophilia centres from 20 countries. Inclusion criteria were children and adolescents born between 1993 and 2014, with severe haemophilia A or B without inhibitors. Participants were categorized by prophylaxis regimen: full, partial or none, based on dose and dose frequency of regular infusions. The cohort study included 1515 children: 29 cases of ICH over 8038 patient years were reported. The incidence of ICH in the prophylaxis group, 0·00033 cases of ICH/patient year, was significantly lower compared to the no prophylaxis group, 0·017 cases of ICH/patient year (RR 50·06; P < 0·001) and the partial prophylaxis group, 0·0050 cases of ICH/patient year (RR 14·92; P = 0·007). In the on-demand-group, 8% (2/24) children with ICH died and 33% had long-term sequelae, including intellectual and behavioural problems, paresis and epilepsy. Children on regular, frequent prophylaxis have a low risk of ICH compared to those using non-frequent or no prophylaxis.
Assuntos
Hemofilia A , Hemofilia B , Hemorragias Intracranianas , Índice de Gravidade de Doença , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Hemofilia A/complicações , Hemofilia A/mortalidade , Hemofilia A/terapia , Hemofilia B/complicações , Hemofilia B/mortalidade , Hemofilia B/terapia , Humanos , Lactente , Hemorragias Intracranianas/etiologia , Hemorragias Intracranianas/mortalidade , Hemorragias Intracranianas/prevenção & controle , Masculino , Estudos Prospectivos , Estudos RetrospectivosRESUMO
The effect of recombinant factor VIII (rFVIII) brand on inhibitor development was investigated in all 407 severe hemophilia A previously untreated patients born in the United Kingdom (UK) between 1 January 2000 and 31 December 2011. Eighty-eight (22%) had been in the RODIN study. Information was extracted from the National Haemophilia Database. Because exposure days (EDs) were not known for some patients, time from first treatment was used as a surrogate for rFVIII exposure. An inhibitor developed in 118 (29%) patients, 60 high and 58 low titer, after a median (interquartile range) of 7.8 (3.3-13.5) months from first exposure and 16 (9-30) EDs. Of 128 patients treated with Kogenate Bayer/Helixate NexGen, 45 (35.2%, 95% confidence interval [CI] 27.4-43.8) developed an inhibitor compared with 42/172 (24.4%, 95% CI 18.6% to 31.4%) with Advate (P = .04). The adjusted hazard ratio (HR) (95% CI) for Kogenate Bayer/Helixate NexGen compared with Advate was 2.14 (1.12-4.10) (P = .02) for high titer and 1.75 (1.11-2.76) (P = .02) for all inhibitors. When excluding UK-RODIN patients, the adjusted HR (95% CI) for high-titer inhibitors was 2.00 (0.93-4.34) (P = .08). ReFacto AF was associated with a higher incidence of all, but not high-titer, inhibitors than Advate. These results will help inform debate around the relative immunogenicity and use of rFVIII brands.
Assuntos
Fator VIII/imunologia , Fator VIII/uso terapêutico , Hemofilia A/tratamento farmacológico , Hemofilia A/epidemiologia , Isoanticorpos/sangue , Formação de Anticorpos , Criança , Pré-Escolar , Estudos de Coortes , Fator VIII/antagonistas & inibidores , Hemofilia A/imunologia , Humanos , Incidência , Lactente , Recém-Nascido , Índice de Gravidade de Doença , Reino Unido/epidemiologiaAssuntos
Hemofilia A/complicações , Hemorragias Intracranianas/etiologia , Criança , Seguimentos , Humanos , Recém-Nascido , MasculinoRESUMO
The objective of this study was to examine the association of the intensity of treatment, ranging from high-dose intensive factor VIII (FVIII) treatment to prophylactic treatment, with the inhibitor incidence among previously untreated patients with severe hemophilia A. This cohort study aimed to include consecutive patients with a FVIII activity < 0.01 IU/mL, born between 2000 and 2010, and observed during their first 75 FVIII exposure days. Intensive FVIII treatment of hemorrhages or surgery at the start of treatment was associated with an increased inhibitor risk (adjusted hazard ratio [aHR], 2.0; 95% confidence interval [CI], 1.3-3.0). High-dose FVIII treatment was associated with a higher inhibitor risk than low-dose FVIII treatment (aHR, 2.3; 95% CI, 1.0-4.8). Prophylaxis was only associated with a decreased overall inhibitor incidence after 20 exposure days of FVIII. The association with prophylaxis was more pronounced in patients with low-risk F8 genotypes than in patients with high-risk F8 genotypes (aHR, 0.61, 95% CI, 0.19-2.0 and aHR, 0.85, 95% CI, 0.51-1.4, respectively). In conclusion, our findings suggest that in previously untreated patients with severe hemophilia A, high-dosed intensive FVIII treatment increases inhibitor risk and prophylactic FVIII treatment decreases inhibitor risk, especially in patients with low-risk F8 mutations.
Assuntos
Inibidores dos Fatores de Coagulação Sanguínea/metabolismo , Fator VIII/administração & dosagem , Fator VIII/antagonistas & inibidores , Hemofilia A/tratamento farmacológico , Hemofilia A/epidemiologia , Hemorragia/prevenção & controle , Adolescente , Adulto , Inibidores dos Fatores de Coagulação Sanguínea/sangue , Quimioprevenção/efeitos adversos , Criança , Estudos de Coortes , Relação Dose-Resposta a Droga , Hemofilia A/sangue , Hemofilia A/metabolismo , Hemorragia/sangue , Hemorragia/epidemiologia , Hemorragia/metabolismo , Humanos , Fatores de Risco , Índice de Gravidade de Doença , Adulto JovemRESUMO
Neutralizing antibodies (inhibitors) toward factor VIII form a severe complication in nonsevere hemophilia A, profoundly aggravating the bleeding pattern. Identification of high-risk patients is hampered by lack of data that take exposure days to therapeutic factor VIII concentrates into account. In the INSIGHT study, we analyzed the association between F8 mutation and inhibitor development in patients with nonsevere hemophilia A (factor VIII 2-40 IU/dL). This analysis included 1112 nonsevere hemophilia A patients from 14 centers in Europe and Australia that had genotyped at least 70% of their patients. Inhibitor risk was calculated as Kaplan-Meier incidence with cumulative number of exposure days as the time variable. During 44 800 exposure days (median, 24 exposure days per patient; interquartile range [IQR], 7-90), 59 of the 1112 patients developed an inhibitor; cumulative incidence of 5.3% (95% confidence interval [CI], 4.0-6.6) after a median of 28 exposure days (IQR, 12-71). The inhibitor risk at 50 exposure days was 6.7% (95% CI, 4.5-8.9) and at 100 exposure days the risk further increased to 13.3% (95% CI, 9.6-17.0). Among a total of 214 different F8 missense mutations 19 were associated with inhibitor development. These results emphasize the importance of F8 genotyping in nonsevere hemophilia A.
Assuntos
Anticorpos Neutralizantes/imunologia , Fator VIII/genética , Fator VIII/imunologia , Hemofilia A/genética , Hemofilia A/imunologia , Mutação de Sentido Incorreto , Adolescente , Adulto , Fator VIII/uso terapêutico , Seguimentos , Genótipo , Hemofilia A/tratamento farmacológico , Humanos , Estimativa de Kaplan-Meier , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Adulto JovemRESUMO
The quantification of residual plasmatic ADAMTS13 activity in congenital thrombotic thrombocytopenic purpura (TTP) patients is constrained by limitations in sensitivity and reproducibility of commonly used assays at low levels of ADAMTS13 activity, blunting efforts to establish genotype-phenotype correlations. In the present study, the residual plasmatic activity of ADAMTS13 was measured centrally by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (limit of detection = 0.5%) in 29 congenital TTP patients. The results were used to study correlations among ADAMTS13 genotype, residual plasmatic activity, and clinical phenotype severity. An ADAMTS13 activity above 0.5% was measured in 26 (90%) patients and lower levels of activity were associated with earlier age at first TTP episode requiring plasma infusion, more frequent recurrences, and prescription of fresh-frozen plasma prophylaxis. Receiver operating characteristic curve analysis showed that activity levels of less than 2.74% and 1.61% were discriminative of age at first TTP episode requiring plasma infusion < 18 years, annual rate of TTP episodes > 1, and use of prophylaxis. Mutations affecting the highly conserved N-terminal domains of the protein were associated with lower residual ADAMTS13 activity and a more severe phenotype in an allelic-dose dependent manner. The results of the present study show that residual ADAMTS13 activity is associated with the severity of clinical phenotype in congenital TTP and provide insights into genotype-phenotype correlations.
Assuntos
Proteínas ADAM/sangue , Proteínas ADAM/deficiência , Púrpura Trombocitopênica Trombótica/sangue , Púrpura Trombocitopênica Trombótica/congênito , Proteínas ADAM/genética , Proteína ADAMTS13 , Adolescente , Adulto , Fatores Etários , Idoso , Análise Química do Sangue , Transfusão de Sangue , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Estudos de Associação Genética , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Plasma , Púrpura Trombocitopênica Trombótica/genética , Púrpura Trombocitopênica Trombótica/terapia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Adulto JovemRESUMO
BACKGROUND: Standard leucodepleted blood transfusions can induce the production of human leukocyte antigen (HLA)-specific antibodies, which are associated with longer transplant waiting times and poorer graft outcomes. We hypothesized that additional washing of leucodepleted red cells might reduce antigenic stimulus by removal of residual leukocytes and soluble HLA. METHODS: A retrospective review of HLA antibodies in children with chronic kidney disease stage 4-5 who had ≥ two HLA antibody screens between 2000 and 2009, pre- and post-transfusion, and were HLA antibody-negative at first testing. Patients were divided according to whether they received standard leucodepleted blood or "washed cells". To assess the efficacy of washing methods, total leukocytes were enumerated pre- and post- manual and automated washing of standard leucodepleted red cells that had been supplemented with whole blood to achieve measurable leukocyte levels pre-washing. RESULTS: A total of 106 children were included: 23 received no blood transfusions (group 1), six had washed cells only (group 2), 59 had standard transfusions only (group 3), and 18 had both standard and washed cells (group 4). Sensitization rates were 26, 17, 44, and 44 % in groups 1-4 (p = 0.32). Patients in groups 3 and 4 had more transfusions with red cells, platelets, and plasma products. There was no difference in HLA sensitization risk with washed or standard red cells on analysis of co-variance controlling for platelets and plasma transfusions. The red cell washing study showed no significant reduction in leukocytes using manual methods. Although there was a statistically significant reduction (33 %) from baseline pre-washing using the automated method, from 6.54 ± 0.84 × 10(6) to 4.36 ± 0.67 × 10(6) leukocytes per unit, the majority of leukocytes still remained. CONCLUSIONS: There was no evidence that using washed leucodepleted red cells reduced patient HLA sensitization rates. Washing leucodepleted red cells is unlikely to reduce the risk of HLA sensitization due to the limited effect on residual leukocytes.
Assuntos
Transfusão de Eritrócitos/efeitos adversos , Transfusão de Eritrócitos/métodos , Antígenos HLA/imunologia , Isoanticorpos/sangue , Leucaférese/métodos , Insuficiência Renal Crônica/terapia , Criança , Feminino , Humanos , MasculinoRESUMO
The age-adjusted incidence of new factor VIII inhibitors was analyzed in all United Kingdom patients with severe hemophilia A between 1990 and 2009. Three hundred fifteen new inhibitors were reported to the National Hemophilia Database in 2528 patients with severe hemophilia who were followed up for a median (interquartile range) of 12 (4-19) years. One hundred sixty (51%) of these arose in patients ≥ 5 years of age after a median (interquartile range) of 6 (4-11) years' follow-up. The incidence of new inhibitors was 64.29 per 1000 treatment-years in patients < 5 years of age and 5.31 per 1000 treatment-years at age 10-49 years, rising significantly (P = .01) to 10.49 per 1000 treatment-years in patients more than 60 years of age. Factor VIII inhibitors arise in patients with hemophilia A throughout life with a bimodal risk, being greatest in early childhood and in old age. HIV was associated with significantly fewer new inhibitors. The inhibitor incidence rate ratio in HIV-seropositive patients was 0.32 times that observed in HIV-seronegative patients (P < .001). Further study is required to explore the natural history of later-onset factor VIII inhibitors and to investigate other potential risk factors for inhibitor development in previously treated patients.
Assuntos
Inibidores dos Fatores de Coagulação Sanguínea/sangue , Fator VIII/antagonistas & inibidores , Hemofilia A/sangue , Adolescente , Adulto , Fatores Etários , Criança , Pré-Escolar , Bases de Dados Factuais , Feminino , Soropositividade para HIV/sangue , Soropositividade para HIV/epidemiologia , Soropositividade para HIV/terapia , Hemofilia A/epidemiologia , Hemofilia A/terapia , Humanos , Incidência , Masculino , Estudos Retrospectivos , Fatores de Risco , Reino UnidoRESUMO
Haemophilia A is caused by a reduction in clotting factor VIII (FVIII). FVIII coagulant activity (FVIII:C) can be measured by three methods; the one-stage activated partial thromboplastin time-based clotting assay, the two-stage Xa generation-based clotting assay and the chromogenic Xa generation-based assay. The FVIII:C of most patients with haemophilia A are concordant regardless of the assay method employed. Up to a third of patients show assay discrepancy, usually with the two-stage and chromogenic assays being much lower than the one-stage assay. Very rarely, patients have been reported with lower one-stage compared to two-stage and chromogenic assays, but here we report that the mutation p.Tyr365Cys accounts for most of these patients and, at least in the UK, is not rare. We have identified this mutation in 23 different families. Affected male index individuals had a lower mean one-stage FVIII:C of 27 iu/dl compared to two-stage FVIII:C mean of 77 iu/dl. Affected individuals had minimal or absent bleeding symptoms and when these were present they were usually in patients with another co-inherited bleeding disorder. Affected individuals often had surgery without the need to correct the one-stage FVIII:C.
Assuntos
Fator VIII/genética , Hemofilia A/genética , Mutação de Sentido Incorreto , Coagulação Sanguínea/genética , Família , Feminino , Hemofilia A/epidemiologia , Hemorragia/genética , Humanos , Masculino , Fenótipo , Reino UnidoRESUMO
Evidence-based guidelines are presented for the management of haemophilia in the fetus and neonate. This includes information regarding the management of pregnancy and delivery as well as aspects of management during the early neonatal period. Specific issues regarding the mode of delivery and the risk of intra-cranial and extra-cranial haemorrhage are discussed.