Simoctocog alfa (Nuwiq®) in previously untreated patients with severe haemophilia A-Final efficacy and safety results from the NuProtect study.

INTRODUCTION: Simoctocog alfa (Nuwiq®) is a 4th generation recombinant FVIII with proven efficacy for the prevention and treatment of bleeding episodes (BEs) in previously treated patients with severe haemophilia A. The NuProtect study assessed the immunogenicity, efficacy and safety of simoctocog alfa in 108 previously untreated patients (PUPs). The incidence of high-titre inhibitors was 16.2% and no patients with non-null F8 mutations developed inhibitors. AIM: To report the efficacy and safety results from the NuProtect study. METHODS: PUPs received simoctocog alfa for prophylaxis, treatment of BEs, or as surgical prophylaxis. The efficacy of prophylaxis (during inhibitor-free periods) was assessed using annualised bleeding rates (ABRs). The efficacy in treating BEs and in surgical prophylaxis was assessed using a 4-point scale. Adverse events were recorded throughout the study. RESULTS: Of 108 PUPs treated with simoctocog alfa, 103 received at least one prophylactic dose and 50 received continuous prophylaxis for at least 24 weeks. In patients on continuous prophylaxis, the median ABR was 0 (mean 0.5) for spontaneous BEs and 2.5 (mean 3.6) for all BEs. In 85 patients who had BEs, efficacy of BE treatment was excellent or good for 92.9% (747/804) of rated BEs; 92.3% of BEs were treated with 1 or 2 infusions. The efficacy of surgical prophylaxis was excellent or good for 94.7% (18/19) of rated procedures. There were no safety concerns and no thromboembolic events. CONCLUSION: Simoctocog alfa was efficacious and well tolerated as prophylaxis, surgical prophylaxis and for the treatment of BEs in PUPs with severe haemophilia A.

Simoctocog Alfa (Nuwiq) in Previously Untreated Patients with Severe Haemophilia A: Final Results of the NuProtect Study.

INTRODUCTION: FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line. METHODS: The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C <1%) of any age and ethnicity were treated with simoctocog alfa for 100 exposure days or a maximum of 5 years. Patients were true PUPs without prior exposure to FVIII concentrates or blood components. Inhibitor titres were measured with the Nijmegen-modified Bethesda assay; cut-off for positivity was 0.6 BU mL-1 (≥0.6 to <5 low-titre, ≥5 high titre). RESULTS: A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0-23.5) were treated with simoctocog alfa. F8 mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null F8 mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null F8 mutations developed inhibitors. CONCLUSION: In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null F8 mutations.

ADA2 deficiency complicated by EBV-driven lymphoproliferative disease.

A 29-year old male with recurrent respiratory and skin infections, anaemia and neutropaenia during childhood required immunoglobulin replacement for antibody deficiency from age 16. He remained relatively well until age 28 when he presented with a two-week history of fatigue, sore throat, fever and productive cough. He was found to have EBV viraemia and splenomegaly and a diagnosis of EBV-driven lymphoproliferative disease was made following bone marrow trephine. Family history was notable with three siblings: a healthy sister and two brothers with anaemia and neutropaenia; one who succumbed to septicaemia secondary to neutropaenic enterocolitis age 5 and another who developed intestinal vasculitis and antibody deficiency and had a successful haemopoetic stem cell transplant. The proband's DNA underwent targeted sequencing of 279 genes associated with immunodeficiency (GRID panel). The best candidates were two ADA2 variants, p.Arg169Gln (R169Q) and p.Asn370Lys (N370K). Sanger sequencing and co-segregation of variants in the parents, unaffected sister and all three affected brothers was fully consistent with compound heterozygous inheritance. Subsequent whole genome sequencing of the proband identified no other potential causal variants. ADA2 activity was consistent with a diagnosis of ADA2 deficiency in affected family members. This is the first description of EBV-driven lymphoproliferative disease in ADA2 deficiency. ADA2 deficiency may cause susceptibility to severe EBV-induced disease and we would recommend that EBV status and viral load is monitored in patients with this diagnosis and allogeneic SCT is considered at an early stage for patients whose ADA2 deficiency is associated with significant complications.

Genotype analysis and identification of novel mutations in a multicentre cohort of patients with hereditary factor X deficiency.

: The objective was to examine the genotypic and phenotypic characteristics of individuals with hereditary factor X deficiency (FXD), a rare autosomal recessive bleeding disorder caused by mutations in the F10 gene located on chromosome 13q34-ter. To date, 149 F10 mutations have been identified as contributory to FXD. Three open-label phase 3 trials enrolled individuals with mild, moderate, or severe FXD. Individuals received plasma-derived factor X concentrate as routine prophylaxis, to treat bleeds, and/or during or after surgery. F10 genotyping was performed (studies 1 and 2) or genotype data was collected at screening (study 3), and identified F10 mutations were compared against the Human Gene Mutation Database to assess novelty. Genotype data were combined to evaluate the number, type, and novelty of the F10 mutations identified. Genotype data were available for 24 of 27 individuals with mild (n = 2), moderate (n = 2), or severe (n = 20) FXD. Analyses identified 22 separate mutations, including 15 missense mutations, 2 deletions, 4 splice site mutations, and 1 nonsense mutation. Sixteen individuals had homozygous mutations; 8 had compound heterozygous mutations. Eleven unique novel mutations (all compound heterozygous) were identified in seven individuals: six missense mutations, three splice site mutations, one exon deletion, and one nonsense mutation. In silico analyses strongly supported the pathogenicity of all novel mutations. The identification of 11 novel F10 mutations provides a substantial contribution to the mutations known to cause FXD.

A high-throughput sequencing test for diagnosing inherited bleeding, thrombotic, and platelet disorders.

Inherited bleeding, thrombotic, and platelet disorders (BPDs) are diseases that affect ∼300 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.

Human phenotype ontology annotation and cluster analysis to unravel genetic defects in 707 cases with unexplained bleeding and platelet disorders.

BACKGROUND: Heritable bleeding and platelet disorders (BPD) are heterogeneous and frequently have an unknown genetic basis. The BRIDGE-BPD study aims to discover new causal genes for BPD by high throughput sequencing using cluster analyses based on improved and standardised deep, multi-system phenotyping of cases. METHODS: We report a new approach in which the clinical and laboratory characteristics of BPD cases are annotated with adapted Human Phenotype Ontology (HPO) terms. Cluster analyses are then used to characterise groups of cases with similar HPO terms and variants in the same genes. RESULTS: We show that 60% of index cases with heritable BPD enrolled at 10 European or US centres were annotated with HPO terms indicating abnormalities in organ systems other than blood or blood-forming tissues, particularly the nervous system. Cases within pedigrees clustered closely together on the bases of their HPO-coded phenotypes, as did cases sharing several clinically suspected syndromic disorders. Cases subsequently found to harbour variants in ACTN1 also clustered closely, even though diagnosis of this recently described disorder was not possible using only the clinical and laboratory data available to the enrolling clinician. CONCLUSIONS: These findings validate our novel HPO-based phenotype clustering methodology for known BPD, thus providing a new discovery tool for BPD of unknown genetic basis. This approach will also be relevant for other rare diseases with significant genetic heterogeneity.

Non-irradiated female survivors of childhood acute lymphoblastic leukaemia are at risk of long-term increases in weight and body mass index.

We report long-term, including final height, auxological data from our retrospective study of non-irradiated survivors of childhood acute lymphoblastic leukaemia (ALL). Body mass index (BMI) standard deviation score (SDS) increases in females, due to increased weight-SDS, persisted to final height, with probable adverse long-term health outcomes. In contrast, males demonstrated increased BMI-SDS in follow-up, due to reduced height-SDS, not increased weight-SDS, but such changes had resolved by final height. Childhood ALL survivors, particularly females, are therefore at potential increased risk of developing the metabolic syndrome during follow-up. We recommend that strategies to minimize weight gain should be implemented during ALL treatment.

Acquired, noncongenital thrombotic thrombocytopenic purpura in children and adolescents: clinical management and the use of ADAMTS 13 assays.

Thrombotic thrombocytopenic purpura (TTP) in children is rare and is often thought to be due to congenital ADAMTS13 deficiency. We report seven new cases of noncongenital TTP in children and adolescents and perform a review of the literature where ADAMTS13 assays have been performed in paediatric acquired TTP. All new cases were female and the median age was 13 years. Presenting clinical features included bruising/petechiae or bleeding, fever, neurological, and renal impairment. Median Hb and platelet counts on admission were 66 g/l and 10 x 10(9)/l respectively. Two cases had raised Troponin T levels and one had an abnormal ECG. All cases had ADAMTS13 activity less than 5% and an inhibitor to ADAMTS13. The median number of plasma exchange to remission was 22.5. Six cases received rituximab. Three achieved normal ADAMTS13 activity and remain in remission. Two had persistently low ADAMTS13 activity with high anti-ADAMTS13 IgG levels and one of these relapsed. One had moderately reduced levels of ADAMTS13 in remission with no inhibitor, however, a fall in ADAMTS13 activity and increase in anti-ADAMTS13 IgG heralded clinical relapse. The literature review identified 12 acquired cases showing low ADAMTS13 activity and inhibition of ADAMTS13 (in 95%). In children and adolescents TTP may be due to acquired deficiency of ADAMTS13, associated with an inhibitor/Anti-ADAMTS13 IgG antibodies. Treatment of acquired disease requires PEX and usually immunosuppressive treatment. Rituximab appears to be an effective adjunctive treatment modality.

The use of intermediate purity factor VIII concentrate BPL 8Y as prophylaxis and treatment in congenital thrombotic thrombocytopenic purpura.

This report presents seven children with congenital thrombotic thrombocytopenic purpura (TTP). Six had a history of severe neonatal unconjugated hyperbilirubinaemia and thrombocytopenia. The seventh child had no neonatal problems but has suffered three episodes of acute TTP. The subsequent clinical course of the children varied. Five had a relapsing-remitting course and one had chronic microangiopathic haemolytic anaemia. The five oldest children initially received plasma infusions but, because of viral safety issues and easier administration, they now receive intermediate purity US-sourced plasma-derived factor VIII concentrate: BPL 8Y. Effective prophylaxis and treatment is possible in congenital TTP using BPL 8Y.