Pharmacokinetics, Pharmacodynamics, and Safety of a Long-Acting Human Growth Hormone (MOD-4023) in Healthy Japanese and Caucasian Adults

Stable Production of a Recombinant Single-Chain Eel Follicle-Stimulating Hormone Analog in CHO DG44 Cells

This study aimed to produce single-chain recombinant Anguillid eel follicle-stimulating hormone (rec-eel FSH) analogs with high activity in Cricetulus griseus ovary DG44 (CHO DG44) cells. We recently reported that an O-linked glycosylated carboxyl-terminal peptide (CTP) of the equine chorionic gonadotropin (eCG) β-subunit contributes to high activity and time-dependent secretion in mammalian cells. We constructed a mutant (FSH-M), in which a linker including the eCG β-subunit CTP region (amino acids 115-149) was inserted between the β-subunit and α-subunit of wild-type single-chain eel FSH (FSH-wt). Plasmids containing eel FSH-wt and eel FSH-M were transfected into CHO DG44 cells, and single cells expressing each protein were isolated from 10 and 7 clones. Secretion increased gradually during the cultivation period and peaked at 4000-5000 ng/mL on day 9. The molecular weight of eel FSH-wt was 34-40 kDa, whereas that of eel FSH-M increased substantially, with two bands at 39-46 kDa. Treatment with PNGase F to remove the N glycosylation sites decreased the molecular weight remarkably to approximately 8 kDa. The EC50 value and maximal responsiveness of eel FSH-M were approximately 1.23- and 1.06-fold higher than those of eel FSH-wt, indicating that the mutant showed slightly higher biological activity. Phosphorylated extracellular-regulated kinase (pERK1/2) activation exhibited a sharp peak at 5 min, followed by a rapid decline. These findings indicate that the new rec-eel FSH molecule with the eCG β-subunit CTP linker shows potent activity and could be produced in massive quantities using the stable CHO DG44 cell system.

A Randomized, Cross-Over Study Investigating the Comparability of Somatrogon-ghla in 2 Different Drug Product Presentations

Somatrogon-ghla is a long-acting, recombinant human growth hormone approved for the treatment of pediatric patients with growth hormone deficiency. Forty-nine healthy, adult males were enrolled in a randomized, crossover study to compare somatrogon exposure after subcutaneous doses administered using a frozen vial presentation or a prefilled, multiple dose pen. Somatrogon, insulin-like growth factor-I, and IGF-1 binding protein-3 concentrations were collected for up to 240 hours post dose to assess pharmacokinetic and pharmacodynamic responses. There was a 2-week washout between administration of the doses. Seven participants did not complete the study due to withdrawal of consent (n = 2) or loss to follow-up. Two treatment-emergent adverse events, headaches, were judged by the investigator as possibly related to study drug administration. Both were mild. Injection site reactions were observed in 6/48 participants after administration with the pen and 12/46 after administration using the vial. Drug and biomarker concentrations were assessed using validated assays and noncompartmental methods were used to determine pharmacokinetic and pharmacodynamic parameters. Bioequivalence was demonstrated for somatrogon area under the concentration-time curve, but not for the peak somatrogon concentration, where the lower limit of the 90% confidence interval for the ratio of pen/vial was 74.2%, which is less than the lower limit, 80.0%, dictated by bioequivalence criteria. The IGF-1 responses were largely within bioequivalence limits. It was concluded that the 2 formulations are comparable.

Stable Production of a Tethered Recombinant Eel Luteinizing Hormone Analog with High Potency in CHO DG44 Cells

We produced a recombinant eel luteinizing hormone (rec-eel LH) analog with high potency in Chinese hamster ovary DG44 (CHO DG44) cells. The tethered eel LH mutant (LH-M), which had a linker comprising the equine chorionic gonadotropin (eLH/CG) β-subunit carboxyl-terminal peptide (CTP) region (amino acids 115 to 149), was inserted between the β-subunit and α-subunit of wild-type tethered eel LH (LH-wt). Monoclonal cells transfected with the tethered eel LH-wt and eel LH-M plasmids were isolated from five to nine clones of CHO DG44 cells, respectively. The secreted quantities abruptly increased on day 3, with peak levels of 5000-7500 ng/mL on day 9. The molecular weight of tethered rec-eel LH-wt was 32-36 kDa, while that of tethered rec-eel LH-M increased to approximately 38-44 kDa, indicating the detection of two bands. Treatment with the peptide N-glycanase F decreased the molecular weight by approximately 8 kDa. The oligosaccharides at the eCG β-subunit O-linked glycosylation sites were appropriately modified post-translation. The EC50 value and maximal responsiveness of eel LH-M increased by approximately 2.90- and 1.29-fold, respectively, indicating that the mutant exhibited more potent biological activity than eel LH-wt. Phosphorylated extracellular regulated kinase (pERK1/2) activation resulted in a sharp peak 5 min after agonist treatment, with a rapid decrease thereafter. These results indicate that the new tethered rec-eel LH analog had more potent activity in cAMP response than the tethered eel LH-wt in vitro. Taken together, this new eel LH analog can be produced in large quantities using a stable CHO DG44 cell system.

Somatrogon injection for the treatment of pediatric growth hormone deficiency with comparison to other LAGH products

INTRODUCTION

Somatrogon (NGENLA™) is a long-acting GH (LAGH) formulation that was approved in Canada in October 2021 for the treatment of pediatric growth hormone deficiency (GHD). Somatrogon has also received approval in Australia, Japan, the European Union, the USA, and the UK. Somatrogon is a glycoprotein that utilizes three copies of the C-terminal peptide of human chorionic gonadotropin to delay its clearance allowing for once-weekly administration.

AREAS COVERED

The purpose of this article is to describe the development of somatrogon for treatment of individuals with GHD. Trials of somatrogon demonstrated positive efficacy results in adults (Phase 2) and children (Phase 2 and 3) with GHD including non-inferiority of height velocity compared to daily GH, with no concerning side effects. Growth responses, pharmacodynamics and safety data are compared to other LAGH products, lonapegsomatropin and somapacitan, in Phase 3 trials in pediatric GHD.

EXPERT OPINION

New LAGH products, including somatrogon, have the potential to increase patient adherence as well as improve quality of life and clinical outcomes. Clinicians will need to identify the best candidates for LAGH therapy and understand how to safely monitor and adjust therapy. Long-term surveillance studies are necessary to demonstrate adherence, efficacy, cost-effectiveness, and safety of LAGH preparations.

An open-label extension of a phase 2 dose-finding study of once-weekly somatrogon vs. once-daily Genotropin in children with short stature due to growth hormone deficiency: results following 5 years of treatment

OBJECTIVES

Somatrogon is a long-acting recombinant human growth hormone (GH) employed as a once-weekly treatment for children with GH deficiency (GHD). A 12-month, phase 2 study of once-weekly somatrogon vs. once-daily GH (Genotropin^®) was initiated, after which participants could enroll into an open-label extension (OLE) evaluating the safety and efficacy of long-term somatrogon treatment.

METHODS

There were five study periods, Periods I and II were 6 months each while Periods III, IV, and V were 12 months each. In the main study (Periods I and II), 53 prepubertal children with GHD were randomized to once-weekly somatrogon (0.25, 0.48, or 0.66 mg/kg/week) or once-daily Genotropin (0.034 mg/kg/day); 48 continued into the OLE, consisting of Period III (original somatrogon dose; Genotropin recipients randomized to one of three somatrogon doses), Period IV (somatrogon 0.66 mg/kg/week), and Period V (prefilled somatrogon pen [0.66 mg/kg/week]).

RESULTS

At the end of Period III, the mean ± SD annual height velocity (HV) for 0.25, 0.48, and 0.66 mg/kg/week somatrogon groups was 7.73 ± 1.89, 7.54 ± 1.28, and 8.81 ± 1.12 cm/year, respectively; HV was sustained during Periods IV/V. Height SD scores (SDS) showed progressive improvement throughout the OLE, regardless of initial cohort assignment, approaching the normal range (-0.69 ± SD 0.87) at the end of Period V Year 1. Mild or moderate treatment-emergent adverse events were reported in 81.3% of participants, most unrelated to study drug.

CONCLUSIONS

Up to 5 years of once-weekly somatrogon was well tolerated and resulted in sustained improvement in height SDS and delta height SDS in prepubertal short children with GHD.

Pharmacokinetics and pharmacodynamics of once-weekly administration of JR-142, a long-acting albumin-fused human growth hormone: A rondemized, placebo-controlled phase 1 study

OBJECTIVE

Under clinical development for patients with growth hormone deficiency, JR-142 is a long-acting growth hormone with a half-life extended by fusion with modified serum albumin. We conducted a Phase 1 study to investigate the safety, tolerability, and pharmacokinetic (PK) and pharmacodynamic (PD) profiles of once-weekly subcutaneous administrations of JR-142. The study consisted of two parts: an open-label single ascending dosing study (Part 1), and a randomized, placebo-controlled, assessor-blinded multiple ascending dosing study (Part 2).

DESIGN

A total of 31 healthy Japanese male participants were enrolled. In Part 1, seven of them received a single subcutaneous injection of JR-142 each at dosages of 0.15 mg/kg (n = 1), 0.25 mg/kg (n = 2), 0.5 mg/kg (n = 2), or 1.0 mg/kg (n = 2). In Part 2, one weekly subcutaneous injection of JR-142 at 0.25 mg/kg, 0.5 mg/kg, 1.0 mg/kg or a placebo were given for four weeks to each of the other 24 participants (six in each group). Plasma JR-142 and serum insulin-like growth factor-1 (IGF-1) concentrations were measured for PK and PD assessments. Safety was evaluated on the basis of adverse events (AEs), laboratory tests, and other measures.

RESULTS

JR-142 induced dose-dependent increases in the maximum plasma JR-142 concentration (C_max) and the area under the plasma concentration-time curve from time 0 to τ (AUC_0-τ). A similar dose-response relationship was observed in serum IGF-1 concentrations. All trough IGF-1 levels were well sustained one week after the final administrations of JR-142 at the three dosages, while the peak concentrations of IGF-1 remained mildly elevated. No serious AEs were observed, and laboratory tests, including assessment of anti-drug antibodies, uncovered no significant safety issues.

CONCLUSIONS

Once-weekly subcutaneous injections of JR-142 produced positive dose-dependent PK and PD profiles over the dosage range. Drug accumulation was observed after the four-week administration period but did not raise safety concerns, indicating that JR-142 is well-tolerated in healthy participants. The PD profiles observed in terms of IGF-1 concentrations were also positive, and we believe the encouraging results of this study warrant substantiation in further clinical trials in patients with GHD.

ETHICS

This clinical study was conducted at one investigational site in Osaka, Japan, where the clinical study and the non-clinical data of JR-142 were reviewed and approved by its Institutional Review Board on 9th May 2019. The study was conducted in compliance with the approved study protocol, the Declaration of Helsinki, 1964, as revised in 2013, and Good Clinical Practice.

Efficacy and Safety of Once-Weekly Somatrogon Compared with Once-Daily Somatropin (Genotropin®) in Japanese Children with Pediatric Growth Hormone Deficiency: Results from a Randomized Phase 3 Study

INTRODUCTION

Somatrogon is a long-acting recombinant human growth hormone being developed as a once-weekly treatment for children with growth hormone deficiency (GHD). The objective of this phase 3 study (NCT03874013) was to compare the efficacy and safety of once-weekly somatrogon with once-daily Genotropin in Japanese children with GHD.

METHODS

In this open-label, randomized, active-controlled study, 44 prepubertal Japanese children with GHD (boys: 3 to <11 years; girls: 3 to <10 years) were randomized 1:1 to receive once-weekly somatrogon or once-daily Genotropin (0.025 mg/kg/day) for 12 months. Dose escalation for somatrogon-treated subjects occurred in the first 6 weeks (0.25, 0.48, and 0.66 mg/kg/week; 2 weeks each) with the remaining 46 weeks at a dose of 0.66 mg/kg/week. The study's primary endpoint was annualized height velocity (HV) at 12 months.

RESULTS

Baseline characteristics were similar between treatment groups. Compared with Genotropin-treated subjects, somatrogon-treated subjects had higher least-squares mean HV at 12 months (9.65 cm/year vs. 7.87 cm/year). Once-weekly somatrogon was concluded as being comparable to once-daily Genotropin as the mean treatment difference (somatrogon-Genotropin) in HV was +1.79 cm/year (95% confidence interval, 0.97-2.61), which was greater than the preestablished margin (-1.8 cm/year). For both treatment groups, most adverse events were mild to moderate in severity and a similar proportion of subjects reported injection-site pain, although the somatrogon group reported more painful injections.

CONCLUSION

In prepubertal Japanese children with GHD, once-weekly somatrogon was comparable to once-daily Genotropin in terms of annualized (12-month) HV. Both treatments had similar safety and tolerability profiles.

Usefulness and Potential Pitfalls of Long-Acting Growth Hormone Analogs

Daily recombinant human GH (rhGH) is currently approved for use in children and adults with GH deficiency (GHD) in many countries with relatively few side-effects. Nevertheless, daily injections can be painful and distressing for some patients, often resulting in non-adherence and reduction of treatment outcomes. This has prompted the development of numerous long-acting GH (LAGH) analogs that allow for decreased injection frequency, ranging from weekly, bi-weekly to monthly. These LAGH analogs are attractive as they may theoretically offer increased patient acceptance, tolerability, and therapeutic flexibility. Conversely, there may also be pitfalls to these LAGH analogs, including an unphysiological GH profile and differing molecular structures that pose potential clinical issues in terms of dose initiation, therapeutic monitoring, incidence and duration of side-effects, and long-term safety. Furthermore, fluctuations of peak and trough serum GH and IGF-I levels and variations in therapeutic efficacy may depend on the technology used to prolong GH action. Previous studies of some LAGH analogs have demonstrated non-inferiority compared to daily rhGH in terms of increased growth velocity and improved body composition in children and adults with GHD, respectively, with no significant unanticipated adverse events. Currently, two LAGH analogs are marketed in Asia, one recently approved in the United States, another previously approved but not marketed in Europe, and several others proceeding through various stages of clinical development. Nevertheless, several practical questions still remain, including possible differences in dose initiation between naïve and switch-over patients, methodology of dose adjustment/s, timing of measuring serum IGF-I levels, safety, durability of efficacy and cost-effectiveness. Long-term surveillance of safety and efficacy of LAGH analogs are needed to answer these important questions.

Long-Acting Growth Hormone Preparations - Current Status and Future Considerations

CONTEXT

Long-acting GH (LAGH) preparations are currently being developed in an attempt to improve adherence. The profile of GH action following administration of LAGH raises practical questions about clinical monitoring and long-term safety and efficacy of these new therapeutic agents.

METHODS

Recent literature and meeting proceedings regarding LAGH preparations are reviewed.

RESULTS

Multiple LAGH preparations are currently at various stages of development, allowing for decreased GH injection frequency from daily to weekly, biweekly, or monthly. Following administration of LAGH, the serum peak and trough GH and IGF-I levels vary depending upon the mechanism used to prolong GH action. Randomized, controlled clinical trials of some LAGH preparations have reported non-inferiority compared with daily recombinant human GH (rhGH) for improved growth velocity and body composition in children and adults with GH deficiency (GHD), respectively. No significant LAGH-related adverse events have been reported during short-term therapy.

CONCLUSION

Multiple LAGH preparations are proceeding through clinical development with some showing promising evidence of short-term clinical efficacy and safety in children and adults with GHD. The relationship of transient elevations of GH and IGF-I following administration of LAGH to efficacy and safety remain to be elucidated. For LAGH to replace daily rhGH in the treatment of individuals with GHD, a number of practical questions need to be addressed including methods of dose adjustment, timing of monitoring of IGF-I, safety, efficacy, and cost-effectiveness. Long-term surveillance of efficacy and safety of LAGH preparations will be needed to answer these clinically relevant questions.

Adult growth hormone deficiency: clinical advances and approaches to improve adherence

Introduction: There have been significant clinical advances in the understanding of the diagnosis and benefits of long-term recombinant human growth hormone (rhGH) replacement in adults with GH deficiency (GHD) since its approval in 1996 by the United States Food and Drug Administration.Areas covered: We searched PubMed, Medline, CINAHL, EMBASE and PsychInfo databases between January 2000 and June 2019 for published studies evaluating adults with GHD. We reviewed the data of the oral macimorelin test compared to the GHRH plus arginine and the insulin tolerance tests that led to its approval by the United States FDA and European Medicines Agency for adult diagnostic testing. We summarize the clinical advances of long-term benefits of rhGH therapy and the potential effects of GH receptor polymorphisms on individual treatment responsiveness. We identify that non-adherence and discontinuation rates are high and recommend strategies to support patients to improve adherence. We also provide an overview of several long-acting GH (LAGH) preparations currently under development and their potential role in improving treatment adherence.Expert opinion: This article summarizes recent clinical advances in rhGH replacement therapy, the biological and molecular aspects that may influence rhGH action, and offers practical strategies to enhance adherence in adults with GHD.

A Cell-Based Strategy for Bioactivity Determination of Long-Acting Fc-Fusion Recombinant Human Growth Hormone

The long-acting growth hormone (LAGH) is a promising alternative biopharmaceutical to treat growth hormone (GH) deficiency in children, and it was developed using a variety of technologies by several pharmaceutical companies. Most LAGH preparations, such as Fc fusion protein, are currently undergoing preclinical study and clinical trials. Accurate determination of bioactivity is critical for the efficacy of quality control systems of LAGH. The current in vivo rat weight gain assays used to determine the bioactivity of recombinant human GH (rhGH) in pharmacopoeias are time-consuming, expensive, and imprecise, and there are no recommended bioassays for LAGH bioactivity in pharmacopoeias. Therefore, we developed a cell-based bioassay for bioactivity determination of therapeutic long-acting Fc-fusion recombinant human growth hormone (rhGH-Fc) based on the luciferase reporter gene system, which is involved in the full-length human GH receptor (hGHR) and the SG (SIE and GAS) response element. The established bioassay was comprehensively validated according to the International Council for Harmonization (ICH) Q2 (R1) guidelines and the Chinese Pharmacopoeia, and is highly precise, time-saving, simple, and robust. The validated bioassay could be qualified for bioactivity determination during the research, development, and manufacture of rhGH-Fc, and other LAGH formulations.

Treatment with Growth Hormone for Adults with Growth Hormone Deficiency Syndrome: Benefits and Risks

Pharmacological treatment of growth hormone deficiency (GHD) in adults began in clinical practice more than 20 years ago. Since then, a great volume of experience has been accumulated on its effects on the symptoms and biochemical alterations that characterize this hormonal deficiency. The effects on body composition, muscle mass and strength, exercise capacity, glucose and lipid profile, bone metabolism, and quality of life have been fully demonstrated. The advance of knowledge has also taken place in the biological and molecular aspects of the action of this hormone in patients who have completed longitudinal growth. In recent years, several epidemiological studies have reported interesting information about the long-term effects of GH replacement therapy in regard to the possible induction of neoplasms and the potential development of diabetes. In addition, GH hormone receptor polymorphism could potentially influence GH therapy. Long-acting GH are under development to create a more convenient GH dosing profile, while retaining the excellent safety, efficacy, and tolerability of daily GH. In this article we compile the most recent data of GH replacement therapy in adults, as well as the molecular aspects that may condition a different sensitivity to this treatment.