ABSTRACT
INTRODUCTION: Factor VIII inhibitor development is currently the most serious complication of the treatment of haemophilia A. Differences in manufacturing and the molecular structure of brands of recombinant factor VIII have led to speculation that concentrates may differ in immunogenicity. This has led to a regulatory focus on the immunogenicity of factor VIII concentrates both before and after licensure. AIM: To investigate the immunogenicity of ReFacto AF post licensure in a real-world setting in previously untreated patients (PUPs) treated exclusively with this product until at least 50 exposure days (EDs). METHODS: The United Kingdom Haemophilia Centre Doctors' Organisation (UKHCDO) National Haemophilia Database (NHD) identified a consecutive cohort of patients with severe haemophilia A (<0.01 IU/L) whose first treatment was with ReFacto AF, monitored time to inhibitor development and described associated risk factors. RESULTS: One hundred and three boys reached 50 EDs within the study period, of whom 35 developed an inhibitor (P(t ≤ 50) = 0.33, [95% CI: 0.25-0.43]), of which 15 (P(t ≤ 50) = 0.16, [95% CI: 0.10-0.25]) were high titre. Inhibitors arose after a median (interquartile range) 11 (7-16) EDs. Inhibitors were significantly associated with high-risk mutations and non-significantly associated with non-white ethnicity. Inhibitors were negatively associated with a family history of haemophilia A. High-titre inhibitors were significantly associated with a family history of inhibitors. CONCLUSION: Inhibitor incidence in a single country population of ReFacto AF PUPs was similar to that previously described. Low- and high-titre inhibitors were detected after a similar number of EDs, contrasting with previous data, probably reflecting standardized inhibitor monitoring within the United Kingdom.
Subject(s)
Factor VIII/immunology , Hemophilia A/immunology , Adolescent , Child , Child, Preschool , Factor VIII/therapeutic use , Female , Genotype , Hemophilia A/drug therapy , Hemophilia A/genetics , Humans , Infant , Male , Time Factors , United KingdomABSTRACT
INTRODUCTION: Intracranial haemorrhage in children with inherited bleeding disorders is a potentially life-threatening complication and presents a significant therapeutic challenge. AIM: To define the characteristics, management and outcomes of intracranial haemorrhage presenting in UK children ≤16 years of age with inherited bleeding disorders from 2003 to 2015. METHOD: Retrospective analysis of children treated at UK haemophilia centres. RESULTS: Of 66 children presenting with Intracranial haemorrhage (ICH), 82% had haemophilia A or B, 3% VWD and 15% a rare IBD. The IBD was a severe phenotype in 91%. The rates of ICH were 6.4 and 4.2 per 1000 patient years for haemophilia A and B, respectively. Median age at presentation was 4 months (33% neonates; 91% children <2 years of age). In neonates, delivery was spontaneous vaginal (SV) in 11, instrumental in 6, caesarean in 4 and unknown in 1. In children with haemophilia, the risk of ICH after instrumental delivery was 10.6 times greater than after SV delivery. Trauma was more common in children >2 years (67%) than in children 1 month to 2 years (18%; P = .027). Prior to ICH, only 4.5% of children were on prophylaxis. 6% of haemophiliacs had an inhibitor. The median duration of initial replacement therapy was 15 days. Mortality was 13.5%. Neurological sequelae occurred in 39% of survivors, being more common following intracerebral bleeding. In haemophilia survivors, 52% subsequently developed a FVIII inhibitor. CONCLUSION: Intracranial haemorrhage occurs most frequently in children with severe IBDs, during the first 2 years of life and in children not receiving prophylaxis. Intracranial haemorrhage often occurs without documented trauma.
Subject(s)
Hemophilia A/complications , Hemophilia B/complications , Intracranial Hemorrhages/complications , Cohort Studies , Delivery, Obstetric , Female , Humans , Infant , Infant, Newborn , Male , Phenotype , Recurrence , Risk Factors , United KingdomSubject(s)
Exons/genetics , Factor IX/genetics , Gene Duplication , Hemophilia B/genetics , Child , Humans , Male , Multiplex Polymerase Chain ReactionABSTRACT
BACKGROUND: Effective treatment of acute bleeding episodes in patients with hemophilia B relies on factor IX recovery, with higher levels being more desirable, whereas prevention of bleeds with a prophylactic regimen depends on the half-life of the product. Lower recovery values have been reported following administration of recombinant FIX (rFIX) than following administration of plasma-derived FIX (pdFIX). OBJECTIVES: To compare the pharmacokinetic and pharmacodynamic properties of rFIX and pdFIX in patients with hemophilia B. METHODS: A prospective crossover study of nine patients with moderate to severe hemophilia B was performed. Following a washout period, 50 U kg(-1) FIX was administered, and blood samples were taken as per protocol up to 48 h postinfusion. Paired data were analyzed with the Wilcoxon signed rank test. RESULTS: Mean peak recovery at 10 min postinfusion was 62.14 IU dL(-1) with pdFIX and 52.7 IU dL(-1) with rFIX (P = 0.08). Mean half-life was 16.6 h with pdFIX and 17.5 h with rFIX (P = 0.55). Maximum peak thrombin generation (PTG) was 35.9 nm with pdFIX and 28.9 nm with rFIX (P = 0.21). Administration of rFIX resulted in early PTG, whereas administration of pdFIX resulted in slightly later and sustained PTG. At 48 h, PTG was similar with pdFIX (19.0 nm) and rFIX (19.4 nm) (P = 0.91). CONCLUSIONS: Patients experienced better recovery with pdFIX than with rFIX. pdFIX and rFIX had similar half-lives. Maximum PTG was higher for pdFIX; however, this difference did not reach statistical significance. The clinical impact of the slightly increased, delayed and sustained PTG with pdFIX requires further investigation.
