Selective functional activity measurement of a PEGylated protein with a modification-dependent activity assay.

BAX 855 (ADYNOVATE) is a PEGylated recombinant factor VIII (rFVIII) that showed prolonged circulatory half-life compared to unmodified rFVIII in hemophilic patients. Here, the development and validation of a novel assay is described that selectively measures the activity of BAX 855 as cofactor for the serine protease factor IX, which actives factor X. This method type, termed modification-dependent activity assay, is based on PEG-specific capture of BAX 855 by an anti-PEG IgG preparation, followed by a chromogenic FVIII activity assay. The assay principle enabled sensitive measurement of the FVIII cofactor activity of BAX 855 down to the pM-range without interference by non-PEGylated FVIII. The selectivity of the capture step, shown by competition studies to primarily target the terminal methoxy group of PEG, also allowed assessment of the intactness of the attached PEG chains. Altogether, the modification-dependent activity not only enriches, but complements the group of methods to selectively, accurately, and precisely measure a PEGylated drug in complex biological matrices. In contrast to all other methods described so far, it allows measurement of the biological activity of the PEGylated protein. Data obtained demonstrate that this new method principle can be extended to protein modifications other than PEGylation and to a variety of functional activity assays.

Two-Year Data from a Long-Term Phase IV Study of Recombinant Human Growth Hormone in Short Children Born Small for Gestational Age.

INTRODUCTION: This ongoing, prospective, open-label, non-comparative, multicenter phase IV study is evaluating the safety and efficacy of recombinant human growth hormone (rhGH; Omnitrope(®), Sandoz GmbH) in short children born small for gestational age (SGA). Here we report data from patients who have completed 2 years' treatment. METHODS: Eligibility criteria included prepubertal children born SGA with growth disturbances defined as current height standard deviation score (HSDS) <-2.5 and parental adjusted SDS <-1; birth weight and/or length <-2 SDS; and failure of catch-up growth [height velocity (HV) SDS <0 during the last year] by 4 years of age or later. The primary study objective is to assess the long-term effect of Omnitrope treatment on the development of diabetes in short children born SGA. Secondary objectives include evaluation of efficacy, incidence and severity of adverse events (AEs), occurrence of malignancies during treatment, and detection of anti-rhGH antibodies during treatment. RESULTS: In total, 278 children have been enrolled and received study medication; 249 have completed 2 years of treatment. No child has developed diabetes mellitus during the first 2 years; no fasting glucose or 2-h oral glucose tolerance test value exceeded the pre-defined limits of >126 or >200 mg/dL, respectively. No adverse alterations in body mass were noted. Treatment-emergent AEs were experienced by 211 (76.2%) children; most of these were of mild-to-moderate intensity (99.3%) and considered unrelated to study medication (97.6%). Treatment with Omnitrope was effective; mean HSDS was -3.39 at baseline, -2.57 at 1 year and -2.15 at 2 years of treatment. Mean HVSDS (peak-centered) also improved, from -2.13 at baseline to +4.16 at 1 year and +2.23 at 2 years. CONCLUSION: In this second interim analysis, short children born SGA were safely and effectively treated with rhGH (Omnitrope), and 2 years' treatment had no major adverse impact on carbohydrate metabolism or body mass. FUNDING: Sandoz.

Development, Validation, and Application of a Novel Ligand-Binding Assay to Selectively Measure PEGylated Recombinant Human Coagulation Factor VIII (BAX 855).

BAX 855 is a PEGylated recombinant factor VIII preparation that showed prolonged circulatory half-life in nonclinical and clinical studies. This paper describes the development, validation, and application of a novel ligand-binding assay (LBA) to selectively measure BAX 855 in plasma. The LBA is based on PEG-specific capture of BAX 855, followed by immunological factor VIII (FVIII)-specific detection of the antibody-bound BAX 855. This assay principle enabled sensitive measurement of BAX 855 down to the low nanomolar range without interference from non-PEGylated FVIII as demonstrated by validation data for plasma from animals typically used for nonclinical characterization of FVIII. The selectivity of an in-house-developed anti-PEG and a commercially available preparation, shown by competition studies to primarily target the terminating methoxy group of PEG, also allowed assessment of the intactness of the attached PEG chains. Altogether, this new LBA adds to the group of methods to selectively, accurately, and precisely measure a PEGylated drug in complex biological matrices. The feasibility and convenience of using this method was demonstrated during extensive nonclinical characterization of BAX 855.

Clinical Immunogenicity of rHuPH20, a Hyaluronidase Enabling Subcutaneous Drug Administration.

Recombinant human PH20 hyaluronidase (rHuPH20) is used to facilitate dispersion of subcutaneously delivered fluids and drugs. This report summarizes rHuPH20 immunogenicity findings from clinical trials where rHuPH20 was co-administered with SC human immunoglobulin, trastuzumab, rituximab, or insulin. Plasma samples were obtained from evaluable subjects participating in ten different clinical trials as well as from healthy plasma donors. A bridging immunoassay and a modified hyaluronidase activity assay were used to determine rHuPH20-reactive antibody titers and neutralizing antibodies, respectively. rHuPH20-binding antibody populations from selected subjects with positive titers were affinity-purified and subjected to further characterization such as cross-reactivity with endogenous PH20. Among individual trials, the prevalence of pre-existing rHuPH20-reactive antibodies varied between 3 and 12%, excepting the primary immunodeficiency (PID) studies. Incidence of treatment-induced rHuPH20 antibodies was 2 to 18%, with the highest titers (81,920) observed in PID. No neutralizing antibodies were observed. Within most trials, the kinetics of antibody responses were comparable between pre-existing and treatment-induced antibody responses, although responses classified as persistent were more common in subjects with pre-existing titers. There was no association between antibody positivity and either local or systemic adverse events. Pre-existing and treatment-induced antibody populations were of similar immunoglobulin isotypes and cross-reacted to endogenous PH20 to similar extents. No cross-reactivity to PH20 paralogs was detected. rHuPH20 induces only modest immunogenicity which has no association with adverse events. In addition, antibodies purified from baseline-positive individuals are qualitatively similar to those purified from individuals developing rHuPH20-reactive antibodies following exposure to the enzyme.

Integration of adult patients with phenylketonuria into professional life: long-term follow-up of 27 patients in a single centre in Switzerland.

BACKGROUND: Neonatal screening and treatment of phenylketonuria (PKU) prevent the development of neurocognitive impairment. The degree of dysfunction may be related to metabolic control and responsible for a hampered school career. METHODS: This was a retrospective study from a single metabolic unit of a Swiss University Hospital. The time point of diagnosis and all Phenylalanin (Phe) concentrations during the follow-up were recorded. The primary outcome was integration into professional life defined as no professional studies versus accomplished apprenticeship versus high school diploma/university. Phe levels were correlated with professional outcome. The control group consisted of the patients' healthy parents and siblings. RESULTS: A total of 27 patients (13 females, 14 males) were included in the study. The mean (SD) follow-up period was 25.1 (7.6) years. The control group consisted of 57 subjects. Overall, 23 patients were diagnosed by neonatal screening, and 4 patients were diagnosed later. All 4 were in the non-professional study group. Compared with the controls there were significantly more patients in the non-professional study group (26% vs 9%, p <0.05) and significantly less in the accomplished apprenticeship group (59% vs 82%; p <0.04). After exclusion of the patients with late diagnosis no significant differences were found with regard to the professional integration between patients and controls. Significant differences in Phe-levels between the three groups could be documented between 2-10 years of age with the highest levels in the non-professional study followed by the accomplished apprenticeship and the high school diploma group (p <0.01). CONCLUSION: Patients who are diagnosed by neonatal screening and are consequently cared for are able to accomplish an apprenticeship or a high school diploma.

Sexual difference in bone geometry of adult patients with classical congenital adrenal hyperplasia: data using peripheral quantitative computed tomography.

BACKGROUND/AIMS: Glucocorticoid treatment may influence bone and muscle development in patients with congenital adrenal hyperplasia (CAH). This study evaluated bone mineral density (BMD), bone geometry and muscle mass. METHODS: 73 adult patients with classical CAH were followed. BMD, bone geometry and muscle mass were measured using peripheral quantitative computed tomography (pQCT). Glucocorticoid-equivalent doses throughout life were calculated and at the time pQCT androgen levels were measured. RESULTS: In males the mean standard deviation (SD) score for trabecular BMD (-0.33 ± 0.71) was reduced, whereas mean cortical BMD (1.05 ± 1.11) was elevated. Mean total (0.86 ± 1.12) and medullary cross-sectional area (CSA; 1.12 ± 1.17) were significantly increased (p < 0.001). In all patients SD scores for cortical thickness (-0.65 ± 0.91) and muscle CSA (-0.83 ± 0.91) were reduced. Treatment duration was associated with lower trabecular BMD in males (r = -0.63, p < 0.001). Suppressed androgens and simple virilizing CAH had an adverse effect on the muscle CSA SD score (OR 0.58 and 0.46, respectively, p < 0.05). CONCLUSION: There was a sexual difference with enlarged total and medullary CSA in females, whereas in males trabecular BMD was reduced and cortical BMD elevated. Cortical thickness and muscle CSA were reduced in all CAH patients with a possible long-term impact on bone development and stability. Monitoring of bone and muscle development might be warranted.

Blood pressure, fludrocortisone dose and plasma renin activity in children with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency followed from birth to 4 years of age.

INTRODUCTION: Infants with congenital adrenal hyperplasia (CAH) require higher doses of fludrocortisone (FC) due to physiological mineralocorticoid resistance. The adequacy of mineralocorticoid replacement should be closely monitored to avoid hypertension. OBJECTIVE: To evaluate blood pressure (BP) in infants with CAH due to 21-hydroxylase deficiency. PATIENTS AND METHODS: Thirty-three patients (18f/15 m) diagnosed by newborn screening were followed until the age of 4 years. Mean start of HC and FC treatment was day 9·8 ± 9·2 postnatally. Mean daily HC dose ranged from 8·6 to 12·3 mg/m(2) /day. RESULTS: During the first year of life prevalence of systolic hypertension was up to 45·5%. At 12 and at 18 months, BP was highest. Prevalence of systolic hypertension was up to 57·6% at 18 months of age. After 24 months BP levels were lower and at 48 months prevalence of hypertension decreased to 15·2%. Systolic and diastolic BP correlated significantly with the administered fludrocortisone dose (r = 0·3, P = 0·005), but not with body mass index. Hypertensive children received significantly higher FC doses and had significantly lower plasma renin activity during the study period. CONCLUSION: High prevalence of transient, most likely FC induced hypertension was found in young children with classic CAH diagnosed by newborn screening. The changing mineralocorticoid sensitivity in infants is a risk factor for the development of hypertension in patients with CAH, who are treated with FC. Therefore suppressed plasma renin activity should be avoided to prevent arterial hypertension.

One-Year Data from a Long-Term Phase IV Study of Recombinant Human Growth Hormone in Short Children Born Small for Gestational Age.

BACKGROUND: This prospective, open-label, non-comparative, multicentre, long-term phase IV study is examining the efficacy and safety of somatropin [recombinant human growth hormone (rhGH)] in short children born small for gestational age (SGA) and its impact on the incidence of diabetes. This report is the first interim analysis of patients who have completed 1 year of treatment. METHODS: A total of 278 pre-pubertal patients were enrolled. Key eligibility criteria included height standard deviation score (HSDS) <-2.5; parental adjusted SDS <-1; birth weight and/or length <-2 SD and failure to show catch-up growth by ≥4 years of age. Patients were treated with rhGH 0.035 mg/kg/day. The primary objective was to evaluate the long-term effect of rhGH on carbohydrate metabolism [including fasting glucose, stimulated glucose (2-h oral glucose tolerance test, OGTT) and glycated haemoglobin (HbA1c)]. Secondary objectives included evaluation of height parameters [body height, HSDS, height velocity (HV), HVSDS]; insulin-like growth factor 1 (IGF-I) and insulin-like growth factor-binding protein 3 (IGFBP-3) serum levels during treatment; and incidence and severity of adverse events (AEs). RESULTS: None of the children developed diabetes mellitus within the first year of treatment. Mean levels of fasting glucose, HbA1c and 2-h OGTT values remained stable during the study period. Treatment with rhGH was effective, as documented by all height parameters. Mean HSDS improved from -3.39 at baseline to -2.57 at Year 1. Mean HV increased markedly from 4.25 cm/year at baseline to 8.99 cm/year during the first year. Similarly, mean peak-centred HVSDS increased from -2.13 at baseline to +4.16 at Year 1. Mean IGF-I SDS and IGFBP-3 SDS also increased within the first year (by +1.80 and +0.41, respectively). 13 patients (4.7%) did not respond adequately to treatment (HVSDS <1); they were withdrawn from the study. In total, 192 children (69.3%) experienced treatment-emergent AEs; most (98.7%) were mild-to-moderate, and the majority (96.5%) were unrelated to study treatment. CONCLUSION: This interim analysis shows that short children born SGA can be effectively and safely treated with rhGH and that rhGH treatment has no major impact on carbohydrate metabolism after the first year of treatment.

Preclinical safety and efficacy of a new recombinant FIX drug product for treatment of hemophilia B.

Baxter has developed a new recombinant factor IX (rFIX) drug product (BAX326) for treating patients with hemophilia B, or congenital FIX deficiency. An extensive preclinical program evaluated the pharmacokinetics, efficacy, and safety of BAX326 in different species. The efficacy of BAX326 was tested in three mouse models of primary pharmacodynamics: tail-tip bleeding, carotid occlusion, and thrombelastography. The pharmacokinetics was evaluated after a single intravenous bolus injection in mice, rats, and macaques. Toxicity was assessed in rats and macaques, safety pharmacology in rabbits and macaques, and immunogenicity in mice. BAX326 was shown to be efficacious in all three primary pharmacodynamic studies (P ≤ 0.0076). Hemostatic efficacy was dose related and similar for the three lots tested. Pharmacokinetic results showed that rFIX activity and rFIX antigen concentrations declined in a bi-phasic manner, similar to a previously licensed rFIX product. BAX326 was well tolerated in rabbits and macaques at all dose levels; no thrombogenic events and no adverse clinical, respiratory, or cardiovascular effects occurred. BAX326 was also shown to have a similar immunogenicity profile to the comparator rFIX product in mice. These results demonstrate that BAX326 has a favorable preclinical safety and efficacy profile, predictive of a comparable effect to that of the previously licensed rFIX in humans.

Testicular adrenal rest tumors develop independently of long-term disease control: a longitudinal analysis of 50 adult men with congenital adrenal hyperplasia due to classic 21-hydroxylase deficiency.

CONTEXT: Testicular adrenal rest tumors (TARTs) and hypogonadotropic hypogonadism are the two most common causes for male infertility in classic 21-hydroxylase deficiency. Current hypotheses suggest the quality of disease control to be one of the main pathogenic factors for TART development. OBJECTIVE: The aim was to study long-term predictors for TART development in a retrospective longitudinal study. DESIGN: Fifty men with classic 21-hydroxylase deficiency (31 salt wasting, 19 simple virilizing) were investigated. Testicular ultrasound at a median age at investigation of 27 years detected TARTs in 28 of 50 subjects (19 salt wasting, 9 simple virilizing). TART presence was correlated with long-term parameters of disease control during childhood and adolescence obtained from patients' charts: 24-hour urine pregnanetriol, serum 17-hydroxyprogesterone, onset and stage of pubic hair development, testicular growth, and bone age in relation to chronological age. RESULTS: There was no difference in pregnanetriol excretion over lifetime between patients with and without TARTs. Similarly, neither development of pubic hair and testicular volume (Tanner) nor bone age in relation to chronological age differed between the two groups. Furthermore, the two groups had the same body mass index and the same impairment of final height in relation to midparental target height. CONCLUSION: Our longitudinal analysis demonstrates no association between TART presence and parameters of disease control. These data, therefore, argue for other mechanisms more relevant for TART induction including those occurring during fetal development.

Development of a transgenic mouse model with immune tolerance for human coagulation factor VIIa.

PURPOSE: Human factor VIIa (FVIIa) is commonly used as bypassing therapy to treat bleeding episodes in hemophilia patients with neutralizing antibodies to factors VIII (FVIII) or IX (FIX). There is a need for a suitable animal model to assess the immunogenicity of new FVIIa products during preclinical development. The aim of this study was the design of a novel transgenic mouse model with immune tolerance to human FVIIa. METHODS: The model was generated by transgenic expression of human F7 cDNA. FVIIa-specific immune responses after treatment with human FVIIa were assessed by analyzing circulating antibodies, antibody producing plasma cells and CD4(+) T cells. RESULTS: In contrast to wild-type mice, human FVII transgenic mice did not develop antibodies when treated with human FVIIa. The immune tolerance was specific and could be broken by application of human FVIIa together with a strong stimulus of the innate immune system. Break of tolerance was associated with increased numbers of pro-inflammatory FVIIa-specific CD4(+) T cells. CONCLUSIONS: The new mouse model is suitable to study the influence of the innate immune system on maintenance and break of immune tolerance against FVIIa and could be used to assess the immunogenicity of new FVIIa products during pre-clinical development.

A novel gain-of-function IKBA mutation underlies ectodermal dysplasia with immunodeficiency and polyendocrinopathy.

PURPOSE: This study reports the identification of a novel heterozygous IKBA missense mutation (p.M37K) in a boy presenting with ectodermal dysplasia with immunodeficiency (EDA-ID) who had wild type IKBKG gene encoding NEMO. Our aim was to characterize the clinical course of this IκB-α gain-of-function mutant and to investigate if the p.M37K substitution affects NF-κB activation by interfering with IκB-α degradation, thus impairing NF-κB signaling and causing the EDA-ID phenotype. METHODS: NF-κB signaling was evaluated by measuring IκB-α degradation in patient fibroblasts. In addition, transiently transfected HeLa cells expressing either the M37K-mutant IκB-α allele, the previously characterized S36A-mutant IκB-α allele, or wild type IκB-α were evaluated for IκB-α degradation and NF-κB nuclear translocation following stimulation with TNF-α. RESULTS: Clinical findings revealed a classical ectodermal dysplasia phenotype complicated by recurrent mucocutaneous candidiasis, hypothyroidism, hypopituitarism, and profound combined immunodeficiency with decreased numbers of IL-17 T cells. IκB-α degradation after TNF-α and TLR agonist stimulation was abolished in patient fibroblasts as well as in HeLa cells expressing M37K-IκB-α similar to cells expressing S36A-IκB-α resulting in impaired nuclear translocation of NF-κB and reduced NF-κB dependent luciferase activity compared to cells expressing wild type IκB-α. Patient whole blood cells failed to secrete IL-6 in response to IL-1ß, Pam2CSK4, showed reduced responses to LPS and PMA/Ionomycin, and lacked IL-10 production in response to TNF-α. CONCLUSION: The novel heterozygous mutation p.M37K in IκB-α impairs NF-κB activation causing autosomal dominant EDA-ID with an expanded clinical phenotype.

Human anti-macrophage migration inhibitory factor antibodies inhibit growth of human prostate cancer cells in vitro and in vivo.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine, originally discovered for its eponymous effect and now known for pleiotropic biologic properties in immunology and oncology. Circulating MIF levels are elevated in several types of human cancer including prostate cancer. MIF is released presumably by both stromal and tumor cells and enhances malignant growth and metastasis by diverse mechanisms, such as stimulating tumor cell proliferation, suppressing apoptotic death, facilitating invasion of the extracellular matrix, and promoting angiogenesis. Recently described fully human anti-MIF antibodies were tested in vitro and in vivo for their ability to influence growth rate and invasion of the human PC3 prostate cancer cell line. In vitro, the selected candidate antibodies BaxG03, BaxB01, and BaxM159 reduced cell growth and viability by inhibiting MIF-induced phosphorylation of the central kinases p44/42 mitogen-activated protein kinase [extracellular signal-regulated kinase-1 and -2 (ERK1/2)] and protein kinase B (AKT). Incubation of cells in the presence of the antibodies also promoted activation of caspase-3/7. The antibodies furthermore inhibited MIF-promoted invasion and chemotaxis as transmigration through Matrigel along a MIF gradient was impaired. In vivo, pharmacokinetic parameters (half-life, volume of distribution, and bioavailability) of the antibodies were determined and a proof-of-concept was obtained in a PC3-xenograft mouse model. Treatment with human anti-MIF antibodies blunted xenograft tumor growth in a dose-dependent manner. We therefore conclude that the anti-MIF antibodies described neutralize some of the key tumor-promoting activities of MIF and thus limit tumor growth in vivo.

Distinct characteristics of antibody responses against factor VIII in healthy individuals and in different cohorts of hemophilia A patients.

Neutralizing antibodies against factor VIII (FVIII) remain the major complication in the replacement therapy of hemophilia A patients. To better understand the evolution of these antibodies it is important to generate comprehensive datasets which include both neutralizing and nonneutralizing antibodies, their isotypes, and IgG subclasses. We developed sensitive ELISAs to analyze FVIII-binding antibodies in different cohorts of hemophilia A patients and in healthy individuals. Our data reveal the prevalence of FVIII-binding antibodies among healthy individuals (n = 600) to be as high as 19%, with a prevalence of antibody titers > or =1:80 of 2%. The prevalence of FVIII-binding antibodies was 34% (5% for titers > or =1:80) in patients without FVIII inhibitors (n = 77), 39% (4% for titers > 1:80) in patients after successful immune tolerance induction therapy (n = 23), and 100% (n = 20, all titers > or =1:80) in patients with FVIII inhibitors. We found significant differences for IgG subclasses of FVIII-binding antibodies between the different study cohorts. IgG4 and IgG1 were the most abundant IgG subclasses in patients with FVIII inhibitors. Strikingly, IgG4 was completely absent in patients without FVIII inhibitors and in healthy subjects. These findings point toward a distinct immune regulatory pathway responsible for the development of FVIII-specific IgG4 associated with FVIII inhibitors.

Overestimation of final height prediction in patients with classical congenital adrenal hyperplasia using the Bayley and Pinneau method.

BACKGROUND: A typical growth pattern with decreased pubertal growth spurt has been identified in patients with classical congenital adrenal hyperplasia (CAH). OBJECTIVE: To evaluate the accuracy of final height predictions in patients with CAH using the Bayley and Pinneau (B&P) method. PATIENTS AND METHODS: Using growth and final height data of 92 patients (57 F/35 M) with CAH due to 21-hydroxylase deficiency (38 SV/54 SW), final height predictions with the B&P method were compared to actual final heights. RESULTS: In females, mean final height was 159.9 +/- 5.3 cm (-1.0 +/- 0.7 SDS) compared to predicted mean final height of 167.9 +/- 10.7 cm (+0.5 +/- 1.7 SDS), p < 0.001, overestimation 7.3 +/- 9.5 cm. In males, mean final height was 170.1 +/- 6 cm (-1.2 +/- 0.8 SDS) compared to predicted mean final height of 185.6 +/- 13.4 cm (+1.2 +/- 1.9 SDS), p < 0.001, overestimation 13.9 +/- 10.8 cm. CONCLUSION: In classical CAH, final height prediction using the B&P method results in significant overestimation of final height.

Frequency and causes of adrenal crises over lifetime in patients with 21-hydroxylase deficiency.

OBJECTIVE: To study adrenal crisis (AC) in patients with congenital adrenal hyperplasia due to classical 21-hydroxylase deficiency (21-OHD). AC was defined as an acute state of health impairment requiring i.v. glucocorticoid administration and hospital admission. DESIGN AND METHODS: In a cross-sectional study with detailed retrospective assessment, AC was studied following two approaches: i) questionnaire based: 122 adult 21-OHD patients (50 men, 72 women, median age 35 years, range 18-69 years) completed a disease-specific questionnaire; and ii) patient chart based: charts of 67 21-OHD patients (32 males, 35 females, median age 31 years, range 20-66 years) were analyzed from diagnosis to last follow-up with regard to frequency and causes of AC since diagnosis. RESULTS: Evaluation of questionnaires revealed 257 ACs in 4456 patient years (py; frequency 5.8 crises/100 py), while patient charts documented 106 ACs in 2181 py (4.9 crises/100 py). The chart-based evaluation showed that gastrointestinal infections (29%) and salt-wasting crisis (18%) were the main causes of AC. In 14%, the cause remained uncertain. There was no difference in the overall frequency of AC in males and females. AC mostly occurred during childhood, with more than 70% of AC in the first 10 years of life and one-third of AC in the first year of life. Still, 20% of cases of AC were observed in adults (>18 years). CONCLUSION: Our data demonstrate a significant risk of AC in patients with 21-OHD over lifetime. Specific age-adapted and repeated crisis prevention training may help to reduce morbidity due to AC in 21-OHD.