Identification of Binding Sites on Human Serum Albumin for Somapacitan, a Long-Acting Growth Hormone Derivative

Toward once-monthly insulin therapy via synergy in two pharmacokinetic protractors: Fc-conjugation and fatty acid acylation

Pharmacokinetic properties and duration of therapeutic action of a pharmaceutical agent can be significantly extended through the combination of two distinct strategies aimed at increasing plasma half-life: fatty acid acylation and Fc-conjugation. Using insulin as a case study, we demonstrate that a doubly protracted insulin analog produces a substantial prolongation of pharmacodynamic effect to lower blood glucose in STZ-treated mice when compared to the Fc-only counterparts. This enhancement is further corroborated by direct pharmacokinetic measurements in rat and dog models, demonstrating the potential for once-monthly insulin therapy. The results suggest that this approach might have broad application across a diverse spectrum of peptide- and protein-based therapeutics.

Development of Zalfermin, a Long-Acting Proteolytically Stabilized FGF21 Analog

Here, we describe the development of the FGF21 analog zalfermin (NNC0194-0499, 15), intended for once-weekly sc dosing. Protein engineering was needed to address inherent druggability issues of the natural FGF21 hormone. Thus, deamidation of Asp121 was solved by mutation to glutamine, and oxidation of Met168 was solved by mutation to leucine. N-terminal region degradation by dipeptidyl peptidase IV was prevented by alanine residue elongation. To prevent inactivating metabolism by fibroblast activation protein and carboxypeptidase-like activity in the C-terminal region, and to achieve t1/2 extension (53 h in cynomolgus monkeys), we introduced a C18 fatty diacid at the penultimate position 180. The fatty diacid binds albumin in a reversible manner, such that the free fraction of zalfermin potently activates the FGF-receptor complex and retains receptor selectivity compared with FGF21, providing strong efficacy on body weight loss in diet-induced obese mice. Zalfermin is currently being clinically evaluated for the treatment of metabolic dysfunction-associated steatohepatitis.

Utilizing Somapacitan, a Long-acting Growth Hormone Formulation, for the Treatment of Adult Growth Hormone Deficiency: A Guide for Clinicians

OBJECTIVE

Somapacitan is the first approved and currently the only long-acting growth hormone (GH) formulation in the United States for treatment of adults with growth hormone deficiency (GHD). The aim of this review was to provide a practical approach for clinicians on how to utilize somapacitan in the treatment of adults with GHD.

METHODS

Literature search was performed on PubMed using key words, including adult GHD, long-acting growth hormone, somapacitan, treatment, and management. The discussion of treatment aspects utilizing somapacitan was based on evidence from previous clinical studies and personal experience.

RESULTS

Clinical trial data demonstrated that somapacitan, a once-weekly reversible albumin-binding GH derivative, decreased truncal fat, improved visceral fat and lean body mass, increased insulin-like growth factor-I standard deviation score and exerted neutral effects on glucose metabolism. Overall, somapacitan was well-tolerated, adverse event rates were comparable with daily GH, antisomapacitan or anti-GH antibodies were not detected, and treatment satisfaction was in favor of somapacitan vs daily GH.

CONCLUSION

Somapacitan is an efficacious, safe, convenient and well-tolerated once-weekly long-acting GH formulation that reduces the treatment burden of once-daily GH injections for adults with GHD. This article provides a review of the pharmacology of somapacitan and offers practical recommendations based on previous clinical trial data on how to initiate, dose titration, monitoring and dose adjustments whilst on therapy in adults with GHD. Timing of measurement of serum insulin-like growth factor-I levels, information on administration, recommendations on missed doses, and clinical recommendations on dosing in certain sub-population of patients are also discussed.

Developments in the Management of Growth Hormone Deficiency: Clinical Utility of Somapacitan

Growth hormone (GH) replacement therapy for growth hormone deficiency (GHD) in children and adults has for over 25 years, until recently, been administered as daily injections. This daily treatment regimen often incurs a burden to patients and caregivers, leading to high rates of non-adherence and, consequently, decreased treatment efficacy outcomes. To address this shortcoming, long-acting growth hormones (LAGHs) have been developed with the aim of reducing the burden of daily injections, thereby potentially improving treatment adherence and outcomes. Somapacitan (Sogroya®) (Novo Nordisk, Bagsværd, Denmark) is a LAGH currently approved for the treatment of adult and childhood GHD (AGHD and CGHD, respectively) in several countries. Other LAGHs, such as somatrogon (Ngenla®) (Pfizer, New York, United States) and lonapegsomatropin/TransCon GH (Skytrofa®) (Ascendis Pharma, Copenhagen, Denmark), are also currently approved and available for the treatment of CGHD in several countries. In this review, we will consider the method of protraction, pharmacokinetics (PK) and pharmacodynamics (PD), efficacy, and safety results of somapacitan in adult and pediatric trials and how these characteristics differ from those of the other aforementioned LAGHs. Additionally, the administration of somapacitan and timing of measurement of serum insulin-like growth factor-I (IGF-I) levels are summarized. Information on administration, advice on missed doses, and clinical guidelines are discussed, as well as identifying which patients are suitable for somapacitan therapy, and how to monitor and adjust dosing whilst on therapy.

Comparative studies of structure and dynamics of caprine, leporine, ovine, and equine serum albumins

Serum albumin (SA) is the most prevalent protein found in blood. Human albumin was used as an albumin substitute in hypoalbuminemia pets due to high sequence similarity. SAs from furry animals were also reported to be the major indoor allergens. Sensitizing to one of SAs coupled with high sequence identity can lead to cross-reactive antibodies in allergic individuals. Thus, understanding the structural and dynamic characters of SAs is crucial for not only albumin substitution but also allergen therapy. Herein, Molecular dynamics (MD) simulations were performed to elucidate the structural and dynamic dissimilarity and similarity of economic animals [equine (ESA), caprine (CASA), ovine (OSA), and leporine (LSA)] to albumins from human (HSA), bovine (BSA), porcine (PSA), and pets [cat (FSA) and dog (CSA)]. The aim is to explore the feasibility of HSA substitution and understand how albumins cause the cross-reactivity. Generally, all albumins studied here show the scissoring motion like other mammalian albumins. The uniqueness of each albumin is defined by different sequence identity of domain I. Also, the drug binding affinity of studied albumins differs from HSA, CSA, FSA, BSA, and PSA. Especially, LSA displays the most deviated behavior from the group. So, such albumin may not be suitable for albumin therapy for pets and humans. CASA, OSA, and ESA share similar characteristics, therefore it is possible to use them to monitor the osmotic pressure among their species, but the allergenic response must be seriously considered. An insight obtained here can be useful to develop albumin therapy and understand clinical allergy.Communicated by Ramaswamy H. Sarma.

Molecular Recognition of Moringa oleifera Active Compounds for Stunted Growth Prevention Using Network Pharmacology and Molecular Modeling Approach

In this study, network pharmacology was used to analyze the active compounds of Moringa oleifera as food supplements for stunted growth prevention. Thirty-eight important proteins were discovered that may be strongly related to stunting. Those proteins were uploaded to several online tool platforms in order to determine the shared genes' pathways. Six pathways were identified that may be correlated with human growth. Furthermore, ligands for molecular docking analysis were retrieved from the top 5 active substances discovered through experimental investigation. In the meantime, the first-degree rank based on the protein-protein interaction (PPI) topological analysis was utilized to choose albumin protein (ALB) as a receptor. Our docking results showed that every ligand binds to the receptors, indicating that they can bind to the binding site of the ALB protein to form a complex formation. Further, MD simulation was used to verify the stability of the ligand in complex with the protein in the TIP3P water model. Based on the validation parameters, our results suggested that all models achieved a stable phase along the simulation. Additionally, the MM-GBSA method was used to calculate the binding energies of all models. Ligands 2 and 4 have strong binding to the binding pocket of ALB, followed by ligands 3, 5, and 2, suggesting that those ligands could be promising food supplements that can be utilized for the prevention of stunted growth in children.

Protein-based Nanoparticles: From Drug Delivery to Imaging, Nanocatalysis and Protein Therapy

Proteins and enzymes are versatile biomaterials for a wide range of medical applications due to their high specificity for receptors and substrates, high degradability, low toxicity, and overall good biocompatibility. Protein nanoparticles are formed by the arrangement of several native or modified proteins into nanometer-sized assemblies. In this review, we will focus on artificial nanoparticle systems, where proteins are the main structural element and not just an encapsulated payload. While under natural conditions, only certain proteins form defined aggregates and nanoparticles, chemical modifications or a change in the physical environment can further extend the pool of available building blocks. This allows the assembly of many globular proteins and even enzymes. These advances in preparation methods led to the emergence of new generations of nanosystems that extend beyond transport vehicles to diverse applications, from multifunctional drug delivery to imaging, nanocatalysis and protein therapy.

The role of surface activity on the amyloid fibrillation pathway of bovine serum albumin upon interaction with glyphosate

As an active ingredient in its derivative products, glyphosate has emerged as the most widespread herbicide in recent decades. Bovine serum albumin (BSA) as a carrier protein may be adversely affected by structural changes due to binding affinity with glyphosate, which may lead to dysfunctionality or metabolic disorders. This study aimed to investigate the interaction of glyphosate with BSA and its thermal fibrillation pathway employing techniques such as dynamic surface tension, fluorescence quenching, ThT binding, circular dichroism spectroscopy, and reactive oxygen species (ROS) measurement, as well as molecular dynamics (MD) studies. The adsorption dynamic analysis suggested hydrophobic moiety at higher concentrations of glyphosate upon interaction with BSA. MD results suggested a slight fluctuation due to glyphosate interaction with protein molecules. The carboxy group presented in glyphosate made a hydrogen bond with the hydroxyl group of TYR¹⁴⁷. The fluorescence quenching and diffusion studies approved BSA's increased unfolding and hydrophobicity resulting from glyphosate interaction, which would induce fibrillation/aggregation, according to our fibrillation kinetics data. The surface activity of glyphosate at higher concentrations and its approved involvement in structural changes of BSA through hydrogen bonding may raise concerns about its potential side effect on farm animals and the food cycle.

Derivatization with fatty acids in peptide and protein drug discovery

Peptides and proteins are widely used to treat a range of medical conditions; however, they often have to be injected and their effects are short-lived. These shortcomings of the native structure can be addressed by molecular engineering, but this is a complex undertaking. A molecular engineering technology initially applied to insulin - and which has now been successfully applied to several biopharmaceuticals - entails the derivatization of peptides and proteins with fatty acids. Various protraction mechanisms are enabled by the specific characteristics and positions of the attached fatty acid. Furthermore, the technology can ensure a long half-life following oral administration of peptide drugs, can alter the distribution of peptides and may hold potential for tissue targeting. Due to the inherent safety and well-defined chemical nature of the fatty acids, this technology provides a versatile approach to peptide and protein drug discovery.

Biophysical Characterization of the Interaction between a Transport Human Plasma Protein and the 5,10,15,20-Tetra(pyridine-4-yl)porphyrin

The interaction between human serum albumin (HSA) and the non-charged synthetic photosensitizer 5,10,15,20-tetra(pyridine-4-yl)porphyrin (4-TPyP) was evaluated by in vitro assays under physiological conditions using spectroscopic techniques (UV-vis, circular dichroism, steady-state, time-resolved, synchronous, and 3D-fluorescence) combined with in silico calculations by molecular docking. The UV-vis and steady-state fluorescence parameters indicated a ground-state association between HSA and 4-TPyP and the absence of any dynamic fluorescence quenching was confirmed by the same average fluorescence lifetime for HSA without (4.76 ± 0.11 ns) and with 4-TPyP (4.79 ± 0.14 ns). Therefore, the Stern-Volmer quenching (K_SV) constant reflects the binding affinity, indicating a moderate interaction (10⁴ M^-1) being spontaneous (ΔG°= -25.0 kJ/mol at 296 K), enthalpically (ΔH° = -9.31 ± 1.34 kJ/mol), and entropically (ΔS° = 52.9 ± 4.4 J/molK) driven. Binding causes only a very weak perturbation on the secondary structure of albumin. There is just one main binding site in HSA for 4-TPyP (n ≈ 1.0), probably into the subdomain IIA (site I), where the Trp-214 residue can be found. The microenvironment around this fluorophore seems not to be perturbed even with 4-TPyP interacting via hydrogen bonding and van der Waals forces with the amino acid residues in the subdomain IIA.

Molecular analysis and therapeutic applications of human serum albumin-fatty acid interactions

Human serum albumin (hSA) is the major carrier protein for fatty acids (FAs) in plasma. Its ability to bind multiple FA moieties with moderate to high affinity has inspired the use of FA conjugation as a safe and natural platform to generate long-lasting therapeutics with enhanced pharmacokinetic properties and superior efficacy. In this frame, the choice of the FA is crucial and a comprehensive elucidation of the molecular interactions of FAs with hSA cannot be left out of consideration. To this intent, we report here a comparative analysis of the binding mode of different FA moieties with hSA. The choice among different albumin-binding FAs and how this influence the pharmacokinetics properties of a broad spectrum of therapeutic molecules will be discussed including a critical description of some clinically relevant FA conjugated therapeutics.

Effective GH Replacement With Once-weekly Somapacitan vs Daily GH in Children with GHD: 3-year Results From REAL 3

CONTEXT

Current GH therapy requires daily injections, which can be burdensome. Somapacitan is a long-acting GH derivative in development for treatment of GH deficiency (GHD).

OBJECTIVE

Evaluate the efficacy, safety, and tolerability of once-weekly somapacitan after 3 years of treatment.

DESIGN

A multicenter, randomized, controlled, phase 2 study comparing somapacitan and once-daily GH for 156 weeks (NCT02616562).

SETTING

Twenty-nine sites in 11 countries.

PATIENTS

Fifty-nine children with GHD randomized (1:1:1:1) and exposed to treatment. Fifty-three children completed the 3-year period.

INTERVENTIONS

Patients received somapacitan (0.04 [n = 14], 0.08 [n = 15], or 0.16 [n = 14] mg/kg/wk) or daily GH (n = 14) (0.034 mg/kg/d, equivalent to 0.238 mg/kg/wk) subcutaneously during the first year, after which all patients on somapacitan received 0.16 mg/kg/wk.

MAIN OUTCOME MEASURES

Height velocity (HV) at year 3; changes from baseline in height SD score (HSDS), HVSDS, and IGF-I SDS.

RESULTS

The estimated treatment difference (95% CI) in HV for somapacitan 0.16/0.16 mg/kg/wk vs daily GH at year 3 was 0.8 cm/y (-0.4 to 2.1). Change in HVSDS from baseline to year 3 was comparable between somapacitan 0.16/0.16 mg/kg/wk, the pooled somapacitan groups, and daily GH. A gradual increase in HSDS from baseline was observed for all groups. At year 3, mean HSDS was similar for the pooled somapacitan groups and daily GH. Change from baseline to year 3 in mean IGF-I SDS was similar across treatments.

CONCLUSIONS

Once-weekly somapacitan in children with GHD showed sustained efficacy over 3 years in all assessed height-based outcomes with similar safety and tolerability to daily GH. A plain language summary (1) is available for this study.

CLINICAL TRIAL INFORMATION

This study has been registered at ClinicalTrials.gov, number NCT02616562 (REAL 3).

Molecular Engineering of Efficacious Mono-Valent Ultra-Long Acting Two-Chain Insulin-Fc Conjugates

Here, we describe molecular engineering of monovalent ultra-long acting two-chain insulin-Fc conjugates. Insulin-Fc conjugates were synthesized using trifunctional linkers with one amino reactive group for reaction with a lysine residue of insulin and two thiol reactive groups used for re-bridging of a disulfide bond within the Fc molecule. The ultra-long pharmacokinetic profile of the insulin-Fc conjugates was the result of concertedly slowing insulin receptor-mediated clearance by (1) introduction of amino acid substitutions that lowered the insulin receptor affinity and (2) conjugating insulin to the Fc element. Fc conjugation leads to recycling by the neonatal Fc receptor and increase in the molecular size, both contributing to the ultra-long pharmacokinetic and pharmacodynamic profiles.

[Advances in chromatography in the study of drug-plasma protein interactions]

After entering human blood circulation, small-molecule drugs interact extensively with various plasma proteins, such as human serum albumin and α1-acid glycoprotein. These interactions profoundly affect the distribution of drugs in vivo and the binding of drugs to targets, thus affecting the efficacy of drugs. In-depth investigation of drug-plasma protein interactions is of great significance for the optimization of drug properties, the development of new drugs, risk assessment, and combination therapy of drugs. Therefore, it is essential to develop highly efficient, sensitive, and accurate methods for elucidating drug-plasma protein interactions. Chromatography is a powerful tool with high throughput, high separation performance, and high sensitivity in the characterization of drug-protein interactions. High-performance affinity chromatography (HPAC) and capillary electrophoresis (CE) have been widely utilized in this field. These methods include the determination of the effects of the posttranslational modification of proteins on binding and the competitive binding of multiple drugs. In addition, various chromatographic methods are used to obtain interaction information such as the binding constant, binding-site number, and dissociation rate constant. In this review, the common strategies and recent advances in HPAC and CE in the study of drug-plasma protein interactions are briefly reviewed. The immobilization methods of proteins, the principles and applications of frontal analysis, zonal elution, ultrafast affinity extraction, peak profiling, and peak decay analysis are discussed for HPAC and affinity capillary electrophoresis (ACE) and capillary electrophoresis frontal analysis (CE-FA) for CE. HPAC relies on the fixation of proteins on the surfaces of chromatographic stationary phases by covalent linking or physical adsorption, followed by obtaining the drug-protein interaction information through a variety of chromatographic methods. In the frontal chromatography analysis, mobile phases with different concentrations of drugs are passed through the HPAC column to obtain different breakthrough times. The process can determine the number of drug binding sites and the binding constant of each site in the affinity protein with high accuracy. The zonal elution method can detect the drug binding sites on proteins using site-specific probes to determine whether there is competition between drugs and probes. The sample consumption and analysis time of the zonal elution method are much less than those in frontal chromatography analysis. The ultrafast affinity extraction method can inject complex samples, such as serum, into affinity columns to determine the free drug components. It can measure the combination and dissociation constants of drug-protein interactions by changing the chromatography flow rate. Peak profiling and peak decay analyses are both effective methods for investigating the dissociation of drugs and proteins. In CE analysis, the drug and protein samples are dissolved in an electrophoresis buffer, and their interactions are measured during electrophoresis with high accuracy and low sample consumption. However, the adsorption of proteins on the capillary wall can compromise CE performance. Common CE methods in drug-protein interaction analysis are ACE and CE-FA. ACE is usually performed by changing the effective mobility of drugs via the addition of different concentrations of proteins. This method has been widely used, and several variant techniques have been developed recently. CE-FA involves the sampling of a drug premixed at a known concentration with a target protein. Compared with other CE methods, CE-FA exhibits the unique advantages of high throughput, automatic online analysis, and the ability to determine high-order drug-protein interactions. Finally, the shortcomings of current chromatography methods are summarized, and the application prospects and development direction of chromatography technology in the field of drug-plasma protein interaction research are discussed.

Development of Cagrilintide, a Long-Acting Amylin Analogue

A hallmark of the pancreatic hormone amylin is its high propensity toward the formation of amyloid fibrils, which makes it a challenging drug design effort. The amylin analogue pramlintide is commercially available for diabetes treatment as an adjunct to insulin therapy but requires three daily injections due to its short half-life. We report here the development of the stable, lipidated long-acting amylin analogue cagrilintide (23) and some of the structure-activity efforts that led to the selection of this analogue for clinical development with obesity as an indication. Cagrilintide is currently in clinical trial and has induced significant weight loss when dosed alone or in combination with the GLP-1 analogue semaglutide.

Photo-induced radical thiol-ene chemistry: a versatile toolbox for peptide-based drug design

While the global market for peptide/protein-based therapeutics is witnessing significant growth, the development of peptide drugs remains challenging due to their low oral bioavailability, poor membrane permeability, and reduced metabolic stability. However, a toolbox of chemical approaches has been explored for peptide modification to overcome these obstacles. In recent years, there has been a revival of interest in photoinduced radical thiol-ene chemistry as a powerful tool for the construction of therapeutic peptides.