Subcutaneous diphtheria and tetanus vaccines in children with haemophilia: A pilot study and review of the literature.

INTRODUCTION: Subcutaneous (SQ) vaccination has emerged as standard of care in children with severe bleeding disorders to reduce unnecessary factor exposure and avoid provoking an intramuscular bleed, but little is known about comparative immunogenicity to intramuscular (IM) vaccination. AIM: To confirm immunogenicity of Diphtheria Tetanus acellular Pertussis (DTaP) vaccines administered SQ to individuals <6 years old with haemophilia. METHODS: We performed a retrospective and prospective pilot study of tetanus and diphtheria antibody titres among patients evaluated at our Haemophilia Treatment Centre between 2015-2016. Children with haemophilia who had received three to four doses of DTaP containing vaccine administered SQ were eligible. RESULTS: Eight children met inclusion criteria. The mean age at the time of diphtheria and tetanus antibody testing was 21.1±17.8 months. All children who received SQ diphtheria and tetanus developed a positive antibody titre to both antigens. There was no statistically significant difference in distribution of titre values. The average time between the last dose of vaccine and antibody testing was 6.6±3.9 months among SQ vaccinated subjects. Minor injection site reactions were common with SQ vaccines. CONCLUSION: SQ administration of diphtheria and tetanus vaccination appears to be immunogenic in a pilot study of Haemophilia patients and supports this practice as the standard of care for this population.

Efficacy and safety of pegylated full-length recombinant factor VIII with extended half-life for perioperative haemostasis in haemophilia A patients.

INTRODUCTION: BAX 855 is a pegylated full-length recombinant factor VIII (rFVIII) with an extended half-life, built on a licensed rFVIII (ADVATE(®) ). BAX 855 demonstrated efficacy and safety in prophylaxis and the treatment of bleeding episodes in previously treated patients (PTPs) with severe haemophilia A. AIM: This phase 3 surgery study evaluates the haemostatic efficacy and safety of BAX 855 for perioperative haemostasis in PTPs with severe haemophilia A undergoing surgery. METHODS: Elective procedures were prospectively classified as major or minor. The dose and frequency of BAX 855 administered perioperatively were to be guided by each patient's pharmacokinetic profile for major procedures or BAX 855 incremental recovery for minor procedures. Haemostatic efficacy was evaluated using a predefined scale. Blood loss was compared to the expected average and maximum blood loss predicted preoperatively. RESULTS: A total of 15 male patients (aged 19-52 years) underwent 15 procedures (11 major and four minor). The overall intra- and perioperative haemostatic efficacy of BAX 855 was 'excellent' in all 15 subjects (100%). Postoperatively, evaluated at postoperative Day 1, all treatments were 'excellent' except for one minor (dental) procedure which was rated 'good'. No related adverse events, allergic reactions, thrombotic events, nor signs of immunogenicity in terms of induction of binding antibodies to FVIII, PEG or PEG-VIII, or FVIII inhibitors were observed. CONCLUSION: These results demonstrate that BAX 855 is safe and haemostatically effective in patients with severe haemophilia A undergoing surgery.

Assessment of individual dose utilization vs. physician prescribing recommendations for recombinant activated factor VII (rFVIIa) in paediatric and adult patients with congenital haemophilia and alloantibody inhibitors (CHwI): the Dosing Observational Study in Hemophilia (DOSE).

Recent data from the Dosing Observational Study in Hemophilia diary study has described home treatment with recombinant activated factor VII (rFVIIa) in congenital haemophilia with inhibitors (CHwI). The current analysis compares prescribed and patient/caregiver-reported rFVIIa administration in paediatric and adult CHwI patients in this study. Patients with ≥ 4 bleeding episodes within a 3-month period prescribed rFVIIa as first-line therapy for bleeding episodes were eligible. Patients/caregivers completed a diary for ≥ 90 days or until the patient experienced four bleeds. Initial, total and mean rFVIIa doses reported for each bleeding episode were calculated and compared with the physician-prescribed doses. Of 52 enrolled patients (25 children; 27 adults), 39 (75%) completed the study. Children and adults had similar mean durations of bleeding episodes. Both patient groups were administered higher initial rFVIIa doses for joint bleeds than prescribed: median (range) 215.2 (74.1-400.0) mcg kg(-1) vs. 200.0 (61.0-270.0) mcg kg(-1) for children, and 231.3 (59.3-379.7) mcg kg(-1) vs. 123.0 (81.0-289.0) mcg kg(-1) for adults. The median infused dose for joint bleeds was higher in adults than children (175.2 vs. 148.0 mcg kg(-1) ), but children received significantly more doses per joint bleed than adults (median 6.5 vs. 3.0). The median total dose per joint bleed was higher in children than adults (1248.7 vs. 441.6). For children and adults, both initial and additional doses administered for bleeds were higher than prescribed. Children received higher total doses per bleed due to an increased number of infusions per bleed.

Patient/caregiver-reported recombinant factor VIIa (rFVIIa) dosing: home treatment of acute bleeds in the Dosing Observational Study in Hemophilia (DOSE).

Patients with congenital haemophilia with inhibitors experience acute bleeds managed with bypassing agents, such as recombinant FVIIa (rFVIIa). Home-based treatment and dosing patterns in the US remain poorly described. This study aimed to assess the prescribed and actual rFVIIa dosing in frequently bleeding inhibitor patients (≥4 bleeds in 3 months) prescribed first-line therapy with rFVIIa. Patients or caregivers recorded daily diaries, including the details of all bypassing agent infusions for 3-6 months. Median (range) initial rFVIIa dose prescribed for joint, muscle and other bleeds was 167.5 (61.0-289.0) mcg kg(-1). Additional rFVIIa doses prescribed were 90 (61-270) mcg kg(-1) at an interval of 2.5-3 (1-24) h. The actual initial rFVIIa dose reported by patients/caregivers for 158 bleeds was 212 (59-400) mcg kg(-1), with total dose per episode of 695 (74-21257) mcg kg(-1). Patient/caregiver-reported average dose per bleed was 146 (40-400) mcg kg(-1) across 5 (1-106) infusions. The initial rFVIIa dose was higher for haemarthrosis (223 [59-400] mcg kg(-1)) than muscle bleeds (148 [74-300] mcg kg(-1); P = 0.07). Initial and mean dose per day changed as treatment progressed. The DOSE study indicates that frequently bleeding inhibitor patients are prescribed and use higher rFVIIa dosing for all bleed types than recommended in the package insert (90 mcg kg(-1)). The rFVIIa dosing was highly variable within and across bleed types, with higher initial doses used for joint bleeds than muscle and other bleed types, particularly in the first days of treatment. This suggests that patients/caregivers have adopted home treatment strategies based on physician discretion and individual responses and experience.

BDDrFVIII (Moroctocog alfa [AF-CC]) for surgical haemostasis in patients with haemophilia A: results of a pivotal study.

SUMMARY: Moroctocog alfa (AF-CC) (Xyntha, BDDrFVIII) is manufactured by a process designed to enhance the theoretical viral safety profile relative to ReFacto, its predecessor, and to provide alignment with clinical monitoring by the one-stage clotting assay. To evaluate the efficacy and safety of B-domain-deleted recombinant factor VIII (BDDrFVIII) was given as bolus injection (BI) or continuous infusion (CI) in haemophilia patients undergoing major surgery. BDDrFVIII was administered by BI or CI per investigator discretion peri-operatively for at least 6 days. Thirty patients enrolled and were treated with at least one dose of BDDrFVIII. Twenty-five patients were evaluable for efficacy. Outcomes were favourable against a background of multiple major surgical procedures. All haemostatic efficacy ratings were 'excellent' or 'good'. End-of-surgery haemostasis ratings, the primary efficacy endpoint, were excellent for 72% (18/25) and good for 28% (7/25) of patients. Haemostasis ratings following the initial postoperative period were excellent for 92% (23/25) and good for 8% (2/25) of patients. Intra-operative blood loss was rated as normal in all patients. Thirteen patients had postoperative blood loss; in 10, this was rated as normal. A low frequency of transfusion was reported in both the intra-operative and postoperative settings. Adverse events (AEs) were consistent with surgery; three were considered related to BDDrFVIII. One patient had a related AE of postoperative haemorrhage. A clinically silent low-titre inhibitor was detected in one patient, and one patient had a false-positive inhibitor titre. This study demonstrates that BDDrFVIII is safe and efficacious for surgical prophylaxis in haemophilia A patients undergoing major surgery.

Phase 1, single-dose escalating study of marzeptacog alfa (activated), a recombinant factor VIIa variant, in patients with severe hemophilia.

Essentials Marzeptacog alfa (activated) [MarzAA] is a novel variant of activated human factor VII. A phase 1 dose escalation trial of MarzAA was conducted in subjects with severe hemophilia. MarzAA was safe and tolerated at intravenous doses up to 30 µg kg-1 Data observed support further trials for hemophilia patients with inhibitors to factors VIII/IX. SUMMARY: Background Marzeptacog alfa (activated) (MarzAA), a new recombinant activated human factor VII (rFVIIa) variant with four amino acid substitutions, was developed to provide increased procoagulant activity and a longer duration of action in people with hemophilia. Objectives To investigate the safety, tolerability, immunogenicity, pharmacokinetics (PK) and pharmacodynamics (PD) of single ascending intravenous bolus doses of MarzAA in non-bleeding patients with congenital hemophilia A or B with or without inhibitors. Methods This international, phase 1, open-label study (NCT01439971) enrolled males aged 18-64 years with severe hemophilia A or B, with or without FVIII or FIX inhibitors. Subjects were assigned to single-dose MarzAA cohorts (0.5, 4.5, 9, 18 or 30 µg kg-1 ). Blood sampling was performed predose and postdose, and subjects were monitored for 60 days postdose. Safety endpoints included adverse events, vital sign changes, electrocardiograms, laboratory abnormalities, and immunogenicity; secondary endpoints included evaluation of PK and PD. Results Overall, in 25 patients, MarzAA was well tolerated at all dose levels tested, and was not associated with dose-limiting toxicity. No treatment-emergent severe or serious adverse events occurred. MarzAA showed linear dose-response PK across the 4.5-30 µg kg-1 dose range, with a terminal half-life of ⁓ 3.5 h. Dose-dependent shortening of the activated partial thromboplastin time and prothrombin time, and evidence of an increase in peak thrombin as determined with a thrombin generation assay, were observed at all doses. Conclusions MarzAA was tolerated at doses up to 30 µg kg-1 . The safety profile and pharmacological effects observed support further clinical trials for the treatment of hemophilic patients with inhibitors.

Sensitivity, specificity and predictive value of modified assays for activated protein C resistance in children.

Very little data is available assessing the clinical utility of coagulation-based APC resistance assays compared to DNA-based analysis for the factor V Leiden mutation in children. Therefore, the clinical utility of four aPTT-based assays for APC resistance was evaluated in 169 children, ages 3 months through 16 years. The prevalence of the Arg506 to Gln mutation was 7/169 (4.1%). Using cutoff points derived from the normal PCR-screened population (n = 162), two assays for APC resistance (APC-SR and n-APC-SR) gave poor concordance with the PCR assay (sensitivity 29% and 57%, respectively). Two modified assays (FDAPC-SR and n-FDAPC-SR), in which patient plasma was prediluted 1:5 in factor V deficient plasma, gave excellent concordance (sensitivity 100%). The predictive value of a positive test was 0.25, 0.44, 1.00 and 0.88 for the APC-SR, n-APC-SR, FDAPC-SR and n-FDAPC-SR, respectively. The FDAPC-SR and n-FDAPC-SR tests gave excellent discrimination using cutoff values derived from the total population (n = 169) without regard to previous PCR screening results.

Distinct domains of alphaIIbbeta3 support different aspects of outside-in signal transduction and platelet activation induced by LSARLAF, an alphaIIbbeta3 interacting peptide.

The peptide LSARLAF causes alphaIIbeta3-dependent platelet activation exemplified by secretion, aggregation, spreading and adhesion on fibrinogen, and tyrosine phosphorylation. alphaIIIbeta3-dependent outside-in signal transduction induced by LSARLAF was investigated in variant thrombasthenic platelets which lack most of the cytoplasmic domain of the integrin beta3 subunit (alphaIIbbeta3 delta724). These studies revealed that only certain aspects of this alphaIIbbeta3-dependent outside-in signaling were affected by the beta3 truncation. Specifically, alphaIIbbeta3 delta724 supported LSARLAF-induced platelet aggregation, agglutination and secretion, but failed to trigger cytoskeletal reorganization and platelet spreading on fibrinogen, despite the fact that PMA-induced non alphaIIbbeta3 mediated signaling caused spreading of these platelets on fibrinogen. Thus, distinct domains of alphaIIbbeta3 are required to support different aspects of LSARLAF-induced platelet activation. Furthermore, these studies suggest that not all alphaIIbbeta3-dependent platelet responses require an intact beta3 cytoplasmic tail.

The relationship of mutations in the MTHFR, prothrombin, and PAI-1 genes to plasma levels of homocysteine, prothrombin, and PAI-1 in children and adults.

Studies in adults have demonstrated that the genetic mutations C677T methylenetetrahydrofolate reductase (MTHFR), prothrombin 20210A, and the 4G polymorphism of the plasminogen activator inhibitor-1 (PAI-1) gene are associated with elevated plasma levels of homocysteine. prothrombin and PAI-1, respectively and with an increased risk of thrombosis. No similar data is available in children. Therefore, we assessed the relationship of plasma levels of homocysteine, prothrombin and PAI-1 with their respective mutations in 197 normal children, compared to 40 adults. By stepwise multiple regression, homocysteine was positively associated with age, PAI-1 activity was negatively associated with age, while PAI-1 antigen and prothrombin levels were associated with gender, being higher in girls than boys. When the genotypes were added to the regression model as additional explanatory variables, the MTHFR genotype accounted for 2.9% of the variance of homocysteine (p = 0.024), and the PAI-1 gene accounted for 2.7% of the variance of PAI-1 antigen levels (p = 0.023). Of children homozygous for the MTHFR mutation, 35% had homocysteine levels > or = the age-specific 95th percentile, compared to 2% heterozygotes and 5% wild type normals (p = 0.0001). The mean homocysteine level was higher in children homozygous for the MTHFR gene (8.4 micromol/1) than in heterozygotes (5.5 micromol/l), p <0.05. Of children homozygous for the 4G polymorphism of the PAI-1 gene, 19% had PAI-1 activity levels > or = the age-specific 95th percentile, compared to 2% of heterozygotes and 3% of wild type normals (p = 0.003). Studies of the incidence of the MTHFR, prothrombin, and PAI-1 4G/5G genotypes in children with thrombosis, when compared to these healthy normals, will provide evidence as to which of these genes are associated with thrombophilia.

Antithrombin-III for the treatment of chemotherapy-induced organ dysfunction following bone marrow transplantation.

A hypercoaguable state has been shown to follow high-dose chemotherapy for bone marrow transplantation (BMT). Deficiency of the natural anticoagulants, antithrombin III (AT-III), protein C and protein S correlate with organ dysfunction following BMT. We treated 10 patients with severe post-BMT organ dysfunction with AT-III concentrate. Indications for treatment included AT-III anticoagulant level less than 88% and life-threatening single or multiorgan dysfunction. All patients were loaded with 50 units/kg AT-III every 8 h for three doses followed by 50 units/kg/day each day for 3-12 days. Clinical improvement was seen within 1-5 days of start of therapy in all patients. Patients with veno-occlusive disease (VOD) showed a decrease in platelet consumption in nine of nine patients, resolution of hepatic tenderness in six of eight patients, and reduction of severe ascites and weight gain in four of five patients. The probability of death due to VOD and life-threatening organ dysfunction was significantly less in the AT-III-treated group when compared to a historical control group receiving the same preparative regimen (P = 0.047 and P = 0.034, respectively). Significant improvements in organ dysfunction following AT-III treatment in this small study supports a causal relationship between AT-III deficiency and post-BMT chemotherapy-induced organ dysfunction.

Heritable thrombophilia and hypofibrinolysis. Possible causes of retinal vein occlusion.

OBJECTIVE: To determine whether heritable thrombophilia and hypofibrinolysis were risk factors for retinal vein occlusion. DESIGN: Measures of thrombophilia (increased likelihood of thrombus formation) included anticardiolipin antibodies (IgG and IgM), the lupus anticoagulant (including dilute Russell viper venom clotting time), antigenic proteins C and S, and homocysteine. Polymerase chain reaction assays were performed for 3 thrombophilic gene mutations (factor V Leiden, methylenetetra-hydrofolate reductase, and prothrombin gene). Measures of hypofibrinolysis (reduced ability to lyse thrombi) included lipoprotein Lp(a), plasminogen activator inhibitor activity, and polymerase chain reaction analysis of the hypofibrinolytic 4G/5G polymorphism of the PAI1 gene. These coagulation measures were performed in 17 patients with retinal vein occlusions with comparison with serologic coagulation measures and polymerase chain reaction assays in 40 and 234 healthy normal volunteers as controls, respectively. RESULTS: Of 14 patients with retinal vein occlusion with measures of dilute Russell viper venom clotting time, a thrombophilic antiphospholipid antibody, 6 (43%) had abnormal results (> 38.8 seconds) compared with 1 (3%) of 30 controls (P = .002). Of 17 patients with vein occlusion, 3 (18%) were heterozygous for the thrombophilic factor V Leiden G1691A mutation compared with 7 (3%) of 233 controls (P = .02). Of 17 patients with vein occlusion, 2 (12%) had normal alleles (5G/5G) for the plasminogen activator inhibitor gene promoter; the other 15 (88%) were heterozygous or homozygous for the 4G polymorphism, which is associated with hypofibrinolysis. Of 234 controls, 85 (36.3%) had the 5G/5G allele; 149 (63.7%) were heterozygous or homozygous for the 4G polymorphism (P = .03). Patients with vein occlusion were more likely to have high levels of the major determinant of hypofibrinolysis, plasminogen activator inhibitor activity. These levels were high (> 22 U/L) in 6 (38%) of 16 patients with vein occlusion compared with 1 (2%) of 40 controls (chi 2 = 12.8; P = .001). Patients with vein occlusion were more likely (8/16 [50%]) to have high levels of hypofibrinolytic Lp(a) (> 35 mg/dL) than controls (5/40 [13%]; chi 2 = 9; P = .003). The median Lp(a) level in patients with vein occlusion who had the 4G/4G genotype was 62 mg/dL compared with 5.3 mg/dL in controls with the 4G/4G genotype (P = .05). CONCLUSION: Thrombophilia and hypofibrinolysis are possible causes of retinal vein occlusion.

Chromosomal anomaly of 6q in chronic myelogenous leukemia (CML).

Anomalies of chromosome 6q, along with other chromosomal anomalies, are described in the bone marrow cells of two patients with chronic myelogenous leukemia (CML). One patient a 14-year-old male, developed the karyotype 46,XY,t(1;6)(p36;q15),del(3)(q25), del(17)(p11),? inv(17)(q12q24) during blastic crisis of his disease. The other patient, a 24-year-old male, had the karyotype 46,XY,del(6)(q13),5(9;22)(q34;q11) during the early phase of his disease and evolution of i(17q) in the karyotype late in the disease.

Strokes, cutis marmorata telangiectatica congenita, and factor V Leiden.

Cutis marmorata telangiectatica congenita is an uncommon, congenital cutaneous condition typified by persistent cutis marmorata and other associated abnormalities. Progressive neurologic complications are generally not a feature of the disorder. A case is reported of cutis marmorata telangiectatica congenita associated with diffuse cerebrovascular infarcts at 7 months of age. Moyamoya-like vascular abnormalities were demonstrated in addition to the factor V Leiden mutation, a congenital hypercoagulable disorder. This novel case illustrates the importance of evaluating children with strokes for congenital thrombophilic disorders.

Pediatric hematologic and oncologic emergencies.

Acute hematologic-oncologic problems fall into two groups, those that require immediate assessment, diagnosis, and therapy, and those that require attention but are not life threatening if treated appropriately. Both types are considered in this article, which discusses hemorrhagic disorders; anemias, with special emphasis on patients with sickle cell disease; an approach to fever and infection in the immunocompromised child; and oncologic disorders that may be life threatening.

Alternative methods for anticoagulation monitoring in pediatric patients with applicability to a patient with severe hemophilia A and circulating inhibitor.

Anticoagulation monitoring in pediatric patients can be problematic because of the immaturity of the coagulation system in this population. In addition, the hemodilution required to place a small patient on bypass can interfere with standard monitoring methods. In this institution, the Hemochron Jr. ACT (activated clotting time)+ assay has been the standard of care for anticoagulation monitoring since 1997. This assay, with a target ACT of 400 s for initiating bypass, was compared to both the Medtronic HMS system (N = 7) and the Hemochron HiTT assay (N = 6) in pediatric patients. All three assays were then employed to monitor a pediatric Hemophilia A patient (Factor VIII <1%) with high inhibitor titer. Both the HiTT clotting time and the HMS heparin level showed statistically significant correlation to the ACT+ (HiTT, N = 24, r = 0.761; HMS, N = 31, r = 0.818). An HMS target heparin level of 1.5 mg/kg and a HiTT target clotting time of 180 s were found to be clinically equivalent to the 400-s ACT+ as indicators of the need for additional heparin. When a 7-year-old male with severe hemophilia A and high inhibitor titer required tricuspid valve replacement, all three assays were used to ensure appropriate anticoagulation management. During bypass, this patient's ACT+ remained out of range (>1005 s). The HiTT was maintained at >180 s and the HMS heparin level at >1.5 mg/kg. Heparin was administered when any single parameter was below the cutoff value. The use of the combination of three distinct monitoring assays for this patient allowed the surgical team an added level of confidence that appropriate anticoagulation had been maintained.

The use of a single von Willebrand factor-containing, plasma-derived FVIII product in hemophilia A immune tolerance induction: the US experience.

BACKGROUND: Inhibitors are a serious complication for patients with severe hemophilia A. Immune tolerance induction (ITI) is the primary method for eradicating these inhibitors. The role of type of concentrate and in particular the use of von Willebrand factor-containing, plasma-derived factor VIII (VWF/pd-FVIII) concentrate in primary or rescue ITI remains unclear. OBJECTIVES: To report retrospective collection of data on the use of a single VWF/pd-FVIII concentrate in primary and rescue ITI. METHODS: Retrospective chart review of hemophilia A inhibitor patients at 11 US institutions who received VWF/pd-FVIII concentrate in primary or rescue ITI. RESULTS: Primary ITI was carried out in eight inhibitor patients with a 75% complete and partial success. Secondary ITI was carried out in 25 inhibitor patients, with 52% attaining complete or partial success. CONCLUSIONS: This report represents the largest group of primarily pediatric, high-titer inhibitor patients treated with a single VWF/pd-FVIII concentrate. It adds retrospective data to the use of VWF-containing plasma-derived factor VIII concentrate in primary and rescue ITI, particularly in those patients with characteristics of poor response to ITI.

Pulmonary metastases in neuroblastoma.

Manifestations of pulmonary metastases were reviewed in a retrospective study of 30 patients with the autopsy diagnosis of neuroblastoma seen over a 25 year period. Seven patients with histologic evidence of pulmonary metastases are reported. Radiologic manifestations included examples of direct extension, hematogenous spread, and lymphangitic spread. Two patients with lymphangitic pulmonary metastases had clinically significant respiratory distress. Pulmonary spread in neuroblastoma represents widely disseminated metastatic diseases and is a grave prognostic sign.

Induction of immune tolerance in patients with hemophilia A and inhibitors.

Infusions of factor VIII at 50-100 U/kg were administered "on demand" for bleeding episodes, or once weekly, in eight patients (aged 3-20 years) with hemophilia A and historically high titer inhibitors to factor VIII. Inhibitors were eliminated and immunologic tolerance to factor VIII occurred in five of the eight patients within 5-31 months. Four patients had minimal anamnestic responses upon starting factor VIII infusions. One patient, who continued on weekly factor VIII after appearance of the inhibitor, had a continued rise in titer for 10 weeks, followed by a gradual decrease and elimination of the inhibitor at 24 months. Three patients had marked anamnestic rises in the inhibitor levels (204-2150 BU) at the start of the factor VIII infusions, followed by a slow fall and eventual suppression of the inhibitor titers to less than 15 BU. The administration of IgG, cyclophosphamide, and prednisone was only partially successful at enhancing inhibitor suppression in two of the highest responding patients. This less intensive factor VIII infusion program appeared as effective, better tolerated, and less costly than other more intensive protocols utilizing daily factor VIII for inducing immune tolerance in hemophilia patients with inhibitors.