A post hoc analysis of PROTECT VIII kids assessing long-term efficacy and safety of damoctocog alfa pegol in adolescents with severe haemophilia A.

INTRODUCTION: The safety and efficacy of the extended half-life factor VIII (FVIII) product damoctocog alfa pegol (BAY 94-9027, Jivi®) has been demonstrated in the PROTECT VIII Kids study (NCT01775618), where male previously-treated patients (PTPs) aged <12 years old with severe haemophilia A and ≥ 50 exposure days (EDs) were treated prophylactically. The PROTECT VIII Kids extension study assessed the long-term safety and efficacy of damoctocog alfa pegol in the same population. AIM: To evaluate the long-term impact of damoctocog alfa pegol in a post hoc subgroup analysis of adolescent patients in the PROTECT VIII Kids study and its extension from 12th birthday onwards. METHODS: The current analysis included PTPs aged ≥12 years old, who remained in the extension for ≥6 months following their 12th birthday. The observation period was defined as the time from 12th birthday to the end of the extension period; all data from this birthday were included whether in the main study or extension phase. The main efficacy variable was annualised bleeding rate (ABR) and the main safety variable was the frequency of inhibitor development. RESULTS: This subgroup analysis comprised 25 patients. Median observation time after 12th birthday was 3.2 years. Median total/joint/spontaneous ABRs in the observation period were 1.7/0.7/0.3, respectively. Safety findings were consistent with those reported for the overall study population; no confirmed FVIII inhibitors or anti-drug antibodies were reported. CONCLUSIONS: Damoctocog alfa pegol is efficacious with a favourable safety profile in adolescents with haemophilia A, supporting its long-term use in children and adolescents.

Assessment of exposure to direct oral anticoagulants in elderly hospitalised patients.

It is unclear whether elderly patients established on direct oral anticoagulants (DOACs) have greater exposure to these drugs, which could subsequently increase their risk of bleeding. We assessed DOAC exposure and factors affecting it in a real-world elderly cohort of patients. For this, 151 medically stable hospital inpatients (76 established on apixaban, 61 on rivaroxaban, 14 on dabigatran) with a median [interquartile range (IQR)] age of 84 (78-89) years were recruited. Patients provided blood samples for measurement of peak and trough plasma DOAC concentrations. There was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82·9% vs. 44·3% vs. 64·3% respectively; P < 0·001). A third of the variability in DOAC plasma concentrations was attributed to the influences of DOAC dosage, renal function and gender. To what extent the observed increases in DOAC exposure in the older patients is the cause of their increased risk of bleeding, which could potentially be ameliorated by dosing titration, requires further investigation.

Characterization and treatment of congenital thrombotic thrombocytopenic purpura.

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.

PROTECT VIII kids extension study: Long-term safety and efficacy of BAY 94-9027 (damoctocog alfa pegol) in children with severe haemophilia A.

INTRODUCTION: BAY 94-9027 (damoctocog alfa pegol; an extended half-life PEGylated recombinant factor VIII [FVIII]) demonstrated efficacy and safety in previously treated paediatric patients (PTPs) aged <12 years with severe haemophilia A in the PROTECT VIII Kids study (NCT01775618). AIM: To evaluate the long-term safety of BAY 94-9027 in PTPs aged <12 years at enrolment. METHODS: In the PROTECT VIII Kids study, boys <12 years with severe haemophilia A were enrolled in two age cohorts (6-<12 years and <6 years) and treated prophylactically twice weekly, every 5 days or every 7 days, with BAY 94-9027 for ≥50 exposure days (EDs). Patients who had completed ≥50 EDs and ≥6 months in the main study or 12-week safety expansion study were eligible to participate in the extension. Primary safety variable was frequency of inhibitor development; main efficacy variable was annualised bleeding rate (ABR). RESULTS: Of 73 PTPs from the main/expansion studies, 59 (81%) entered the extension phase for a median (range) duration of 5.0 (0.4-5.9) years. Overall, 39 patients completed ≥5 years of treatment. No patients developed FVIII inhibitors/anti-PEG antibodies, and two patients aged <6 years discontinued. Median ABR for total bleeds was 1.5 (<6 years) and 1.9 (6-<12 years). Total ABR improved in the extension vs. the main study. In the last 12 months of treatment, median spontaneous ABR was 0.0 in both age groups. CONCLUSIONS: BAY 94-9027 showed long-term safety and efficacy for the prevention and treatment of bleeds in younger and older paediatric patients with severe haemophilia A.

Immune tolerance induction in severe haemophilia A: A UKHCDO inhibitor and paediatric working party consensus update.

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.

Elderly people are inherently sensitive to the pharmacological activity of rivaroxaban: implications for DOAC prescribing.

According to both trial and clinical data on direct oral anticoagulants (DOACs) elderly patients are at greatest risk of bleeding. It is unclear whether age intrinsically affects anticoagulation response. To investigate the age-related sensitivity to DOACs, we compared the pharmacological activity of the direct factor Xa inhibitor, rivaroxaban, between young and elderly subjects ex-vivo. 36 fit elderly and 30 fit young subjects [median (IQR) age: 83(75-87) vs 30(26-38) years] provided a blood sample. Clotting parameters were measured in the resultant plasma samples incubated with rivaroxaban (100-500 ng/ml). Parametric, non-parametric tests and regression lines adjusted for rivaroxaban concentration and baseline values were used to compare data. Rivaroxaban produced a greater prolongation of both Prothrombin Time (PT) and modified Prothrombin Time (mPT) (both p < 0.001) in the elderly compared to young subjects (with difference in mean PT increasing from 1.6 to 6.1s and for mPT from 23.5 to 71.1s at 100 ng/ml and 500 ng/ml plasma rivaroxaban concentration, respectively). Factor X and factor II activity was significantly lower in the elderly in the presence of rivaroxaban (p < 0.001 for both). Rivaroxaban prolonged time-based parameters and suppressed the amount of thrombin generation to a significantly greater extent in the elderly compared to young subjects [%change from baseline for Endogenous Thrombin Potential (ETP): - 35.0 ± 4.4 vs - 29.8 ± 7.4 nM*min; p = 0.002]. The use of validated DOAC assays will be of considerable benefit for monitoring elderly patients who, because of their increased sensitivity to rivaroxaban, may require lower doses of the drug for therapeutic anticoagulation.

CYP2C9, VKORC1, and CYP4F2 polymorphisms and pediatric warfarin maintenance dose: a systematic review and meta-analysis.

Studies on the effect of cytochrome P450 2C9 (CYP2C9), vitamin K epoxide reductase complex subunit 1 (VKORC1), and cytochrome P450 4F2 (CYP4F2) polymorphisms on warfarin maintenance dose in children are conflicting. We conducted a systematic review and meta-analysis to evaluate the effect of these polymorphisms on warfarin maintenance dose in children. We searched relevant literature using the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trial libraries without any language restrictions from their inception to 23 July 2017. Dose differences are expressed as standardized mean difference (SMD) or mean difference (MD) with 95% confidence intervals (CI). This review was registered in the PROSPERO prospective register of systematic reviews (CRD42015016172). We included a total of nine studies (745 participants) in the meta-analysis. Patients with CYP2C9 *1/*2, *1/*3, *2/*2, *2/*3, or *3/*3 required a lower warfarin maintenance dose compared with patients with CYP2C9 *1/*1 (SMD = -0.610, 95% CI: -0.802 to -0.419, I2 = 0%). Patients with VKORC1-1639GA or AA required a lower warfarin maintenance dose compared with patients with VKORC1-1639GG (SMD = -0.666, 95% CI: -0.887 to -0.445, I2 = 33%). However, no associations were observed between CYP4F2 polymorphisms and warfarin maintenance dose (MD = 0.005 mg/kg/day, 95% CI: -0.006 to 0.015, I2 = 0%). These results were not affected by a sensitivity analysis. Our meta-analysis provides evidence that CYP2C9 and VKORC1 variant statuses affect warfarin maintenance dose in children, but not CYP4F2.

PROTECT VIII Kids: BAY 94-9027 (PEGylated Recombinant Factor VIII) safety and efficacy in previously treated children with severe haemophilia A.

INTRODUCTION: BAY 94-9027, a site-specifically PEGylated, B-domain-deleted recombinant factor VIII (FVIII) with extended half-life, demonstrated efficacy for bleed prevention and treatment in previously treated adolescents and adults with severe haemophilia A. AIM: To assess BAY 94-9027 in children with severe haemophilia A. METHODS: In the two-part PROTECT VIII Kids study, boys <12 years with <1% FVIII and >50 exposure days (EDs) to FVIII were enrolled in two cohorts (<6 years; 6-<12 years) and treated with BAY 94-9027 prophylaxis twice-weekly, every 5 days, or every 7 days at physician discretion for ≥50 EDs (Part 1) or twice-weekly for 12-weeks (Part 2). Annualized bleeding rate (ABR) was a primary efficacy endpoint; FVIII inhibitor development was the primary safety variable. RESULTS: At study completion, 25 patients had been treated twice-weekly, 28 in the every-5-day group, and 8 in the every-7-day group. Median ABR for all bleeds was 2.9 (Part 1) and 2.4 (Part 2) and similar in younger and older patients; median ABR for joint bleeds was 0 for both cohorts. In the last 90 days' treatment, median ABR was 0 for younger and older patients (Part 1). Of 149 reported bleeds, 93% were treated with ≤2 infusions. Twelve patients, the majority <6 years (n = 11), discontinued due to apparent loss of efficacy or hypersensitivity. No FVIII inhibitors developed. CONCLUSIONS: In PROTECT VIII Kids, which allowed tailoring of prophylaxis to individual clinical response, BAY 94-9027 was efficacious for bleed prevention and treatment in previously treated children with severe haemophilia A.

Therapeutic metamorphosis: Findings from a grounded theory study of the impact of low-dose prophylaxis in children living with haemophilia in India.

INTRODUCTION: The clinical benefits of administering low-dose prophylaxis in children with haemophilia are well established. Qualitative research describing the impact of prophylaxis on quality of life is comparatively rare in this area. AIM: The aim of this study was to investigate in children the experiences of living and becoming adjusted to haemophilia before prophylaxis, by collecting information directly from children and their parents or guardians. A further goal was to evaluate whether and how the use of low-dose prophylaxis impacts the disease experience. METHODS: A grounded theory design according to Strauss and Corbin was chosen for this study. The study was conducted in the Haemophilia Treatment Centre at Aluva, Kerala, India and involved nineteen participants (children, mothers, father and grandmothers) who were selected by theoretical sampling. Data were collected through audiotaped interviews, which included demographic and semi-structured interview questions. Data were coded and evolved into concepts and categories that lead to the emergence of theory. RESULTS: The study resulted in the construction of 'Theory of Therapeutic Metamorphosis'. It comprised two stages: stage of bondage (enduring hardships), experienced during the absence of prophylaxis or on-demand treatment and stage of freedom (deliverance/reductions, energized life/improvements and behaviour to seek prophylaxis) experienced during low-dose prophylaxis. CONCLUSION: This study illustrates the challenges faced by children with haemophilia and their families and the positive impact of low-dose prophylaxis. Further prospective research studies are required to add to the growing knowledge in this area.

Presenting ADAMTS13 antibody and antigen levels predict prognosis in immune-mediated thrombotic thrombocytopenic purpura.

Immune-mediated thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder caused by antibodies against ADAMTS13. From the United Kingdom TTP registry, we undertook a prospective study investigating the impact of the presenting anti-ADAMTS13 IgG antibody and ADAMTS13 antigen on mortality. A total of 312 episodes involving 292 patients over 87 months were included; 68% were female, median age 46 (range, 11-88 years), and median presenting ADAMTS13 of <5% (range, <5%-18%). The mortality rate was 10.3% (n = 32); 68% of patients had a raised troponin at presentation conferring a sixfold increase in mortality compared with those with normal troponin levels (12.1% vs 2.0%, P = .04). Twenty-four percent had a reduced Glasgow Coma Score (GCS) at presentation with a ninefold increase in mortality (20% vs 2.2% for normal GCS at presentation, P < .0001). Mortality increased with higher anti-ADAMTS13 antibody levels and lower ADAMTS13 antigen levels. Those with antibody levels in the upper quartile (antibody >77%) had a mortality of 16.9% compared with 5.0% for the lowest quartile (antibody <20%) (P = .004). Those with an antigen level in the lowest quartile (antigen <1.5%) had a mortality of 18% compared with 3.8% for the highest quartile (antigen >11%) (P = .005). The synergistic effect of anti-ADAMTS13 IgG antibody in the upper quartile and ADAMTS13 antigen in the lowest quartile had the highest mortality of 27.3%. We conclude that both anti-ADAMTS13 IgG antibody and ADAMTS13 antigen levels correlate with outcome in TTP with increased cardiac and neurological involvement and increased mortality.

Myeloproliferative Neoplasms in Children and Adolescents and Thrombosis at Unusual Sites: The Role of Driver Mutations.

Myeloproliferative neoplasms (MPNs) in childhood and adolescence are rare and seldom complicated by thrombosis. We describe 3 cases of thrombosis at unusual sites in young patients with MPNs. In the pediatric MPN population, unlike in adult MPNs, a clonal mutation is identifiable in only a minority of cases (22% to 26%). All 3 of these individuals had JAK2 mutations driving the disease process. A literature search identified 19 cases of MPN-associated thrombosis in children. Seventeen of the 19 children (89.5%) had a driver mutation. These cases suggest that identifiable driver mutations may confer an increased thrombotic risk in children with MPNs.

Severity and Features of Epistaxis in Children with a Mucocutaneous Bleeding Disorder.

OBJECTIVE: To use standardized bleeding questionnaires to compare the severity and patterns of epistaxis in children with a mucocutaneous bleeding disorder and control children. STUDY DESIGN: The epistaxis sections of the Pediatric Bleeding Questionnaire (PBQ) administered to pediatric patients with von Willebrand disease or a platelet function disorder and healthy control children were reviewed. Scores and features of epistaxis (frequency, duration, onset, site, seasonal correlation, and need for medical/surgical intervention) were recorded. A PBQ epistaxis score ≥2 was defined as clinically significant. The Katsanis epistaxis scoring system was administered to eligible patients, ie, with ≥5 episodes of epistaxis per year. RESULTS: PBQ epistaxis scores were obtained for 66 patients, median age 12 years (range 0.6-18.3 years), and 56 control children. The median PBQ epistaxis score in patients was 2 vs 0 in control children (P <.0001). All of the features of epistaxis, except spontaneous onset, occurred in a significantly greater proportion of patients than control children with epistaxis. A total of 50% of the patients were graded as having severe epistaxis by the Katsanis epistaxis scoring system, and 30 of these (91%) had a clinically significant PBQ epistaxis score. CONCLUSION: Standardized bleeding questionnaires are useful in the assessment of epistaxis severity and pattern and may help to distinguish children with and without a mucocutaneous bleeding disorder.

Clinical presentation and therapeutic management of venous thrombosis in young children: a retrospective analysis.

BACKGROUND: Venous thromboembolism (VTE) in young children is not well documented. METHODS: Clinicians from 12 institutions retrospectively evaluated the presentation, therapeutic management, and outcome of VTE in children younger than 2 years seen in 2011-2016. Feasibility of recruiting these children in EINSTEIN-Jr. phase III, a randomized trial evaluating rivaroxaban versus standard anticoagulation for VTE, was assessed. RESULTS: We identified 346 children with VTE, of whom 227 (65.6%) had central venous catheter-related thrombosis (CVC-VTE), 119 (34.4%) had non-CVC-VTE, and 156 (45.1%) were younger than 1 month. Of the 309 children who received anticoagulant therapy, 86 (27.8%) had a short duration of therapy (i.e. < 6 weeks for CVC-VTE and < 3 months for non-CVC-VTE) and 17 (5.5%) had recurrent VTE during anticoagulation (n = 8, 2.6%) or shortly after its discontinuation (n = 9, 2.9%). A total of 37 (10.7%) children did not receive anticoagulant therapy and 4 (10.5%) had recurrent VTE.The average number of children aged < 0.5 years and 0.5-2 years who would have been considered for enrolment in EINSTEIN-Jr is approximately 1.0 and 0.9 per year per site, respectively. CONCLUSIONS: Young children with VTE most commonly have CVC-VTE and approximately one-tenth and one-fourth received no or only short durations of anticoagulant therapy, respectively. Recurrent VTE rates without anticoagulation, during anticoagulation or shortly after its discontinuation seem comparable to those observed in adults. Short and flexible treatment durations could potentially increase recruitment in EINSTEIN-Jr. phase III.

Assessment of the efficacy of a novel tailored vitamin K dosing regimen in lowering the International Normalised Ratio in over-anticoagulated patients: a randomised clinical trial.

Current guidelines advocate using fixed-doses of oral vitamin K to reverse excessive anticoagulation in warfarinised patients who are either asymptomatic or have minor bleeds. Over-anticoagulated patients present with a wide range of International Normalised Ratio (INR) values and response to fixed doses of vitamin K varies. Consequently a significant proportion of patients remain outside their target INR after vitamin K administration, making them prone to either haemorrhage or thromboembolism. We compared the performance of a novel tailored vitamin K dosing regimen to that of a fixed-dose regimen with the primary measure being the proportion of over-anticoagulated patients returning to their target INR within 24 h. One hundred and eighty-one patients with an index INR > 6·0 (asymptomatic or with minor bleeding) were randomly allocated to receive oral administration of either a tailored dose (based upon index INR and body surface area) or a fixed-dose (1 or 2 mg) of vitamin K. A greater proportion of patients treated with the tailored dose returned to within target INR range compared to the fixed-dose regimen (68·9% vs. 52·8%; P = 0·026), whilst a smaller proportion of patients remained above target INR range (12·2% vs. 34·0%; P < 0·001). Individualised vitamin K dosing is more accurate than fixed-dose regimen in lowering INR to within target range in excessively anticoagulated patients.

Association between CYP4F2 genotype and circulating plasma vitamin K concentration in children on chronic warfarin therapy: Possible long-term implications for bone development and vascular health.

Vitamin K is essential, for the activation of clotting proteins, as well as the biosynthesis of osteocalcin in bones and the activation of matrix-Gla protein needed in maintaining vasculature health. Cytochrome p450 4F2 (CYP4F2) enzyme is involved in vitamin K catabolism. Genetic polymorphism in CYP4F2 is thus likely to affect vitamin K systemic availability. We show that children on chronic warfarin therapy have low levels of vitamin K and vitamin K levels are linked to CYP4F2 genotype. Long-term low levels of vitamin K, influenced by CYP4F2 genotype, might affect bone development and vascular health in children on chronic warfarin therapy.

Venous Thromboembolism in Children: Is It Preventable?

The incidence of venous thromboembolism (VTE) in children is increasing. Hospitalized infants and adolescents are at highest risk, and most individuals who have VTE have multiple thrombotic risk factors. The presence of a central venous catheter (CVC) is the most frequent risk factor for childhood thrombosis. Childhood VTE has significant consequences in relation to the thrombotic event and the anticoagulant therapy used for its treatment. Identification of the most prevalent risk factors for VTE, particularly among adolescents, has moved the focus toward prevention of thrombosis. Risk assessment models have been developed to identify individuals who are at higher risk with a view to employing preventative strategies such as mechanical and chemical thromboprophylaxis (TP). There is currently little evidence to support the efficacy of such strategies for preventing either CVC-associated thrombosis or thrombosis at other sites. In addition, there are concerns about adverse consequences of mechanical and chemical TP in a population where the overall incidence of VTE remains low.