Definitions of clinical events and end points of care are important for disease characterization as well as documentation of outcomes in clinical practice and trials. Until recently, the only ...definitions in hemophilia that were provided through an international scientific organization related to disease severity and levels of inhibitors. Recently, the Scientific and Standardization Committee (SSC) of the International Society on Thrombosis and Haemostasis, through its Factor VIII and IX subcommittee, published consensus definitions for several other aspects of hemophilia management, including classification of disease severity; inhibitors; bleeding (and rebleeding) into muscles and joints; target joints; different forms of factor replacement therapy; and response to therapy for joint bleeding and surgical hemostasis. These definitions should help to bring greater uniformity in the documentation of critical clinical events and laboratory data that are reported both from clinical trials as well as real-world practice. This article describes these definitions in greater detail than the SSC short report and also addresses some of the unresolved issues. Wide dissemination of these concepts and definitions and their acceptance by relevant leading scientific societies, drug regulators, industry, and patient organizations will go a long way in ensuring their acceptance and use globally.
Summary Background The thrombopoietin receptor agonist romiplostim could be an effective treatment in symptomatic children with persistent or chronic immune thrombocytopenia. We aimed to assess ...whether romiplostim is safe and effective in children with immune thrombocytopenia of more than 6 months' duration. Methods In this phase 3 double-blind study, eligible participants were children with immune thrombocytopenia aged 1 year to 17 years and mean platelet counts 30 × 109 /L or less (mean of two measurements during the screening period) with no single count greater than 35 × 109 /L, and were recruited from 27 sites in the USA, Canada, and Australia. Participants were randomly assigned (2:1) through the interactive voice response system to receive weekly romiplostim or placebo for 24 weeks stratified by age (1 year to <6 years, 6 years to <12 years, 12 years to <18 years), adjusting the dose weekly from 1 μg/kg to 10 μg/kg to target platelet counts of 50–200 × 109 /L. Patients and investigators were blinded to the treatment assignment. The primary analysis included all randomised patients and the safety analysis included all randomised patients who received at least one dose of investigational product. The primary endpoint, durable platelet response, was defined as achievement of weekly platelet responses (platelet counts ≥50 × 109 /L without rescue drug use in the preceding 4 weeks) in 6 or more of the final 8 weeks (weeks 18–25). This study is registered with ClinicalTrials.gov , NCT 01444417. Findings Between Jan 24, 2012, and Sept 3, 2014, 62 patients were randomly assigned; 42 to romiplostim and 20 to placebo. Durable platelet response was seen in 22 (52%) patients in the romiplostim group and two (10%) in the placebo group (p=0·002, odds ratio 9·1 95% CI 1·9–43·2). Durable platelet response rates with romiplostim by age were 38% (3/8) for 1 year to younger than 6 years, 56% (10/18) for 6 years to younger than 12 years, and 56% (9/16) for 12 years to younger than 18 years. One (5%) of 19 patients in the placebo group had serious adverse events compared with 10 (24%) of 42 patients in the romiplostim group. Of these serious adverse events, headache and thrombocytosis, in one (2%) of 42 patients in the romiplostim group, were considered treatment related. No patients withdrew due to adverse events. Interpretation In children with chronic immune thrombocytopenia, romiplostim induced a high rate of platelet response with no new safety signals. Ongoing romiplostim studies will provide further information as to long-term efficacy, safety, and remission in children with immune thrombocytopenia. Funding Amgen Inc.
Previously published guidelines for the diagnosis and management of primary immune thrombocytopenia (ITP) require updating largely due to the introduction of new classes of therapeutic agents, and a ...greater understanding of the disease pathophysiology. However, treatment-related decisions still remain principally dependent on clinical expertise or patient preference rather than high-quality clinical trial evidence. This consensus document aims to report on new data and provide consensus-based recommendations relating to diagnosis and treatment of ITP in adults, in children, and during pregnancy. The inclusion of summary tables within this document, supported by information tables in the online appendices, is intended to aid in clinical decision making.
Factor VIII (FVIII) pharmacokinetic (PK) properties show high interpatient variability in hemophilia A patients. Although previous studies have determined that age, body mass index, von Willebrand ...factor antigen (VWF:Ag) levels, and ABO blood group status can influence FVIII PK, they do not account for all observed variability. In this study, we aim to describe the genetic determinants that modify the FVIII PK profile in a population of 43 pediatric hemophilia A patients. We observed that VWF:Ag and VWF propeptide (VWFpp)/VWF:Ag, but not VWFpp, were associated with FVIII half-life. VWFpp/VWF:Ag negatively correlated with FVIII half-life in patients with non-O blood type, but no correlation was observed for type O patients, suggesting that von Willebrand factor (VWF) half-life, as modified by the ABO blood group, is a strong regulator of FVIII PK. The FVIII-binding activity of VWF positively correlated with FVIII half-life, and the rare or low-frequency nonsynonymous VWF variants p.(Arg826Lys) and p.(Arg852Glu) were identified in patients with reduced VWF:FVIIIB but not VWF:Ag. Common variants at the VWF, CLEC4M, and STAB2 loci, which have been previously associated with plasma levels of VWF and FVIII, were associated with the FVIII PK profile. Together, these studies characterize the mechanistic basis by which VWF clearance and ABO glycosylation modify FVIII PK in a pediatric population. Moreover, this study is the first to identify non-VWF and non-ABO variants that modify FVIII PK in pediatric hemophilia A patients.
•VWF gene variants that modify FVIII binding influence FVIII PK.•Variants in clearance receptors for VWF-FVIII influence FVIII PK.
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Comparison of the pharmacokinetics (PK) of a coagulation factor between groups of patients can be biased by differences in study protocols, in particular between blood sampling schedules. This could ...affect clinical dose tailoring, especially in children. The aim of this study was to describe the relationships of the PK of factor VIII (FVIII) with age and body weight by a population PK model. The potential to reduce blood sampling was also explored. A model was built for FVIII PK from 236 infusions of recombinant FVIII in 152 patients (1-65 years of age) with severe hemophilia A. The PK of FVIII over the entire age range was well described by a 2-compartment model and a previously reported problem, resulting from differences in blood sampling, to compare findings from children and adults was practically abolished. The decline in FVIII clearance and increase in half-life with age could be described as continuous functions. Retrospective reduction of blood sampling from 11 to 5 samples made no important difference to the estimates of PK parameters. The obtained findings can be used as a basis for PK-based dose tailoring of FVIII in clinical practice, in all age groups, with minimal blood sampling.
Children with immune thrombocytopenia for ≥6 months completing a romiplostim study received weekly subcutaneous romiplostim (1-10 μg/kg targeting platelet counts of 50-200×10
/L) in this extension to ...examine romiplostim's long-term safety and efficacy. Sixty-five children received romiplostim for a median of 2.6 years (range: 0.1-7.0 years). Median baseline age was 11 years (range: 3-18 years) and platelet count was 28×10
/L (range: 2-458×10
/L). No patient discontinued treatment for an adverse event. Median average weekly dose was 4.8 mg/kg (range: 0.1-10 mg/kg); median platelet counts remained >50×10
/L, starting at week 2. Nearly all patients (94%) had ≥1 platelet response (≥50×10
/L, no rescue medication in the previous 4 weeks), 72% had responded at ≥75% of visits, and 58% had responded at ≥90% of visits. Treatment-free response (platelets ≥50×10
/L ≥24 weeks without immune thrombocytopenia treatment) was seen in 15 of 65 patients while withholding romiplostim doses. At onset of treatment-free response, the nine girls and six boys had a median immune thrombocytopenia duration of four years (range: 1-12 years) and had received romiplostim for two years (range: 1-6 years). At last observation, treatment-free responses lasted for a median of one year (range: 0.4-2.1 years), with 14 of 15 patients still in treatment-free response. Younger age at first dose and platelet count >200×10
/L in the first four weeks were associated with treatment-free responses. In this 7-year open-label extension, three-quarters of the patients responded ≥75% of the time, and romiplostim was well tolerated, with no substantial treatment-related adverse events. Importantly, 23% of children maintained treatment-free platelet responses while withholding romiplostim and all other immune thrombocytopenia medications for ≥6 months. (Registered at
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Summary
Hereditary spherocytosis (HS) is a common inherited haemolytic anaemia attributed to disturbances in five different red cell membrane proteins. We performed a retrospective study of 166 ...children with HS and describe the clinical phenotype according to the genotype. In 160/166 (97%) children with HS a disease‐causing mutation was identified. Pathogenic variants in ANK1, SPTB, SLC4A1 and SPTA1 were found in 49%, 33%, 13% and 5% of patients. Children with SLC4A1‐HS had the mildest phenotype, showing the highest haemoglobin (P < 0·001), lowest reticulocyte counts (P < 0·001) and lowest unconjugated bilirubin levels (P = 0·006), and none required splenectomy in childhood (P < 0·001). Conversely, children with autosomal recessive SPTA1‐HS had the most severe clinical phenotype, with almost all patients undergoing splenectomy in early childhood. Patients with ANK1 and SPTB variants showed a similar clinical phenotype. Within each gene, variant type or location did not predict disease severity or likelihood of splenectomy. Among patients with a genetic diagnosis, 47 (29%) underwent splenectomy (23 partial; 24 total) while 57 (36%) underwent cholecystectomy. Total splenectomy led to greater improvements in haemoglobin (P = 0·02). Select use of genetic testing (especially in patients without a family history) may help predict clinical phenotype in childhood and guide family counselling.
Diagnosis and management of immune thrombocytopenic purpura (ITP) remain largely dependent on clinical expertise and observations more than on evidence derived from clinical trials of high scientific ...quality. One major obstacle to the implementation of such studies and in producing reliable meta-analyses of existing data is a lack of consensus on standardized critical definitions, outcome criteria, and terminology. Moreover, the demand for comparative clinical trials has dramatically increased since the introduction of new classes of therapeutic agents, such as thrombopoietin receptor agonists, and innovative treatment modalities, such as anti-CD 20 antibodies. To overcome the present heterogeneity, an International Working Group of recognized expert clinicians convened a 2-day structured meeting (the Vicenza Consensus Conference) to define standard terminology and definitions for primary ITP and its different phases and criteria for the grading of severity, and clinically meaningful outcomes and response. These consensus criteria and definitions could be used by investigational clinical trials or cohort studies. Adoption of these recommendations would serve to improve communication among investigators, to enhance comparability among clinical trials, to facilitate meta-analyses and development of therapeutic guidelines, and to provide a standardized framework for regulatory agencies.
Objective
Repeated hemarthrosis in hemophilia causes arthropathy with pain and dysfunction. The Hemophilia Joint Health Score (HJHS) was developed to be more sensitive for detecting arthropathy than ...the World Federation of Hemophilia (WFH) physical examination scale, especially for children and those using factor prophylaxis. The HJHS has been shown to be highly reliable. We compared its validity and sensitivity to the WFH scale.
Methods
We studied 226 boys with mild, moderate, and severe hemophilia at 5 centers. The HJHS was scored by trained physiotherapists. Study physicians at each site blindly determined individual and total joint scores using a series of visual analog scales.
Results
The mean age was 10.8 years. Sixty‐eight percent were severe (93% of whom were treated with prophylaxis), 15% were moderate (24% treated with prophylaxis), and 17% were mild (3% treated with prophylaxis). The HJHS correlated moderately with the physician total joint score (rs = 0.42, P < 0.0001) and with overall arthropathy impact (rs = 0.42, P < 0.0001). The HJHS was 97% more efficient than the WFH at differentiating severe from mild and moderate hemophilia. The HJHS was 74% more efficient than the WFH at differentiating subjects treated with prophylaxis from those treated on demand. We identified items on the HJHS that may be redundant or rarely endorsed and could be removed from future versions.
Conclusion
Both the HJHS and WFH showed evidence of strong construct validity. The HJHS is somewhat more sensitive for mild arthropathy; its use should be considered for studies of children receiving prophylaxis.
Introduction
The genetic variant responsible for haemophilia A (HA) significantly impacts endogenous coagulant factor VIII (FVIII:C) level, thus impacting DDAVP responsiveness. Blood group (BG) also ...impacts FVIII:C levels, but this is difficult to evaluate in a genetically heterogeneous population. Canada has a large cohort of mild‐moderate HA due to a single point variant: c.6104T>C, p.Val2035Ala—the Twillingate variant.
Aim
To evaluate the impact of BG on endogenous FVIII:C levels and DDAVP responsiveness in a single genotype of mild‐moderate HA.
Methods
This was a retrospective, single‐centre study. BG and FVIII:C levels were obtained for males with the Twillingate variant. One‐hour absolute and fold increases in FVIII:C post‐DDAVP were calculated. T‐tests and Mann–Whitney U tests were used to compare FVIII:C levels and DDAVP challenge variables between individuals according to BGs (O vs. non‐O).
Results
Twenty males were included. There were significant differences between BGs (O vs. non‐O) in their lowest FVIII:C level at age <12 years (medians: 0.05 vs. 0.08 IU/mL; P = .05). Fifteen subjects underwent DDAVP challenges. Mean 1‐h FVIII:C were 0.29 (O BG) versus 0.41 IU/mL (non‐O BG); P = .04. There were no significant differences between BGs (O vs. non‐O) in mean absolute FVIII:C increase (0.20 vs. 0.27 IU/mL; P = .10) and FVIII:C fold increase (3.3‐fold vs. 3.8‐fold; P = .51).
Conclusion
In HA subjects with an identical genotype, BG significantly impacts baseline FVIII:C levels and FVIII:C levels post‐DDAVP, but does not impact absolute and fold increases in FVIII:C with DDAVP.
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