Tissue Distribution and Receptor Activation by Somapacitan, a Long Acting Growth Hormone Derivative.

Somapacitan is a long-acting, once-weekly, albumin-binding growth hormone (GH) derivative. The reversible albumin-binding properties leads to prolonged circulation half-life. Here, we investigated and compared somapacitan with human GH on downstream receptor signaling in primary hepatocytes and hepatocellular models and using isothermal titration calorimetry to characterize receptor binding of somapacitan in the presence or absence of human serum albumin (HSA). With non-invasive fluorescence imaging we quantitatively visualize and compare the temporal distribution and examine the tissue-specific growth hormone receptor (GHR) activation at distribution sites. We found that signaling kinetics were slightly more rapid and intense for GH compared with somapacitan. Receptor binding isotherms were characterized by a high and a low affinity interaction site with or without HSA. Using in vivo optical imaging we found prolonged systemically biodistribution of somapacitan compared with GH, which correlated with plasma pharmacokinetics. Ex vivo mouse organ analysis revealed that the temporal fluorescent intensity in livers dosed with somapacitan was significantly increased compared with GH-dosed livers and correlated with the degree of downstream GHR activation. Finally, we show that fluorescent-labeled analogs distributed to the hypertrophic zone in the epiphysis of proximal tibia of hypophysectomized rats and that somapacitan and GH activate the GHR signaling in epiphyseal tissues.

Turoctocog alfa (NovoEight®)--from design to clinical proof of concept.

Turoctocog alfa (NovoEight®) is a recombinant factor VIII (rFVIII) with a truncated B-domain made from the sequence coding for 10 amino acids from the N-terminus and 11 amino acids from the C-terminus of the naturally occurring B-domain. Turoctocog alfa is produced in Chinese hamster ovary (CHO) cells without addition of any human- or animal-derived materials. During secretion, some rFVIII molecules are cleaved at the C-terminal of the heavy chain (HC) at amino acid 720, and a monoclonal antibody binding C-terminal to this position is used in the purification process allowing isolation of the intact rFVIII. Viral inactivation is ensured by a detergent inactivation step as well as a 20-nm nano-filtration step. Characterisation of the purified protein demonstrated that turoctocog alfa was fully sulphated at Tyr346 and Tyr1664, which is required for optimal proteolytic activation by thrombin. Kinetic assessments confirmed that turoctocog alfa was activated by thrombin at a similar rate as seen for other rFVIII products fully sulphated at these positions. Tyr1680 was also fully sulphated in turoctocog alfa resulting in strong affinity (low nm Kd ) for binding to von Willebrand factor (VWF). Half-lives of 7.2 ± 0.9 h in F8-KO mice and 8.9 ± 1.8 h haemophilia A dogs supported that turoctocog alfa bound to VWF after infusion. Functional studies including thromboelastography analysis of human haemophilia A whole blood with added turoctocog alfa and effect studies in mice bleeding models demonstrated a dose-dependent effect of turoctocog alfa. The non-clinical data thus confirm the haemostatic effect of turoctocog alfa and, together with the comprehensive clinical evaluation, support the use as FVIII replacement therapy in patients with haemophilia A.

Psychometric Validation of the Growth Hormone Deficiency-Child Impact Measure (GHD-CIM).

OBJECTIVE: The aim of this study was to perform psychometric testing of the Growth Hormone Deficiency-Child Impact Measure (GHD-CIM): a patient-reported outcome (PRO) for children with GHD aged 9 to < 13 years and an observer-reported outcome (ObsRO) for parents/guardians of children who are unable to answer for themselves. METHODS: A non-interventional, multicenter, clinic-based study was conducted in 30 private-practice and large institutional sites in the US and the UK. Psychometric analyses were conducted following an a priori validation statistical analysis plan. RESULTS: A preliminary examination of the data determined a PRO version for children aged 9 to < 13 years was not psychometrically sound and therefore the decision was made to have only an ObsRO measure of the GHD-CIM, which would be suitable for children aged 4 to < 13 years. The GHD-CIM ObsRO validity analyses included 98 parents/guardians. Factor analyses identified three domains: Physical Functioning (PHYS), Social Well-Being (SWB), and Emotional Well-Being (EWB). Internal consistency reliability was acceptable for all domains and for the overall score (Cronbach's alpha > 0.70), as was test-retest reliability for the SWB, EWB and overall (above 0.70). At least one convergent validity hypotheses for each domain and overall was proven (r > 0.40). Known-groups validity hypotheses for the EWB and SWB domains were significant (p < 0.05). Associated effect sizes ranged from - 0.40 to - 0.58, indicating that the GHD-CIM is sensitive to change. Anchor-based patient and clinician ratings of severity of disease suggest a preliminary minimally important difference of 5 points for the overall score, and 5 for PHYS, 7 for EWB, and 5 for SWB. CONCLUSIONS: The GHD-CIM ObsRO was found to be a reliable and valid measure to assess disease-specific functioning, which will provide a more complete patient-centric picture to the growth hormone therapy experience in children. TRIAL REGISTRATION: ClinicalTrials.gov NCT02580032, first posted 20 October 2015.