Development of a long-acting erythropoietin by fusing the carboxyl-terminal peptide of human chorionic gonadotropin beta-subunit to the coding sequence of human erythropoietin

Single-chain human follicle-stimulating hormone with a di-N-glycosylated linker

The classic way to produce single-chain (sc) glycoprotein hormones is to fuse their two subunits through the carboxy-terminal peptide (CTP) from human Choriogonadotropin (hCG). The CTP confers a longer half-life to single-chain hormones thanks to its four O-glycosyl side chains. However, unlike syncytiotrophoblastic cells, most cells used for recombinant protein production do not transfer O-glycosyl chains efficiently. We thus choose to fuse the hFSH subunits with a linker comprising two N-glycosyl side chains (sc-hFSH LNN) or none (sc-hFSH L0N), that were generated using two expression systems, HEK293 and CHO K1 cells. Their production levels and biological activities were tested and compared. Both expression systems successfully produced biologically active sc-hFSH, but, in our hands, CHO K1 cells yielded about 30-fold higher amounts of recombinant protein than HEK293 cells. Moreover, sc-hFSH L0N was considerably less expressed than sc-hFSH LNN in both cell types. Our data show that sc-hFSH L0N and sc-hFSH LNN produced from both cell lines stimulate cAMP and progesterone production in mLTC cells expressing hFSH receptors and exhibit similar B/I (in vitro Bioactivity/Immuno activity) ratios. Finally, the ratio of in vivo/in vitro bioactivities for sc-hFSH LNN relative to natural pituitary heterodimeric hFSH increased 8-fold, most likely because of a longer half-life in the blood.

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.

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.

Fusion with CTP increases the stability of recombinant neuritin

Neuritin is a vital neurotrophin that plays an essential role in recovery from nerve injury and neurodegenerative diseases and may become a new target for treating these conditions. However, improving neuritin protein stability is an urgent problem. In this study, to obtain active and stable neuritin proteins, we added a carboxyl-terminal peptide (CTP) sequence containing four O-linked glycosylation sites to the C-terminus of neuritin and cloned it into the Chinese hamster ovary (CHO) expression system. The neuritin-CTP protein was purified using a His-Tag purification strategy after G418 screening of stable high-expression cell lines. Ultimately, we obtained neuritin-CTP protein with a purity >90%. Functional analyses showed that the purified neuritin-CTP protein promoted the neurite outgrowth of PC12 cells, and stability experiments showed that neuritin stability was increased by adding CTP. These results indicate that neuritin protein-CTP fusion effectively increases stability without affecting secretion and activity. This study offers a sound strategy for improving the stability of neuritin protein and provides material conditions for further study of the function of neuritin.

The effect of a single escalating dose of long-acting recombinant human follicle-stimulating hormone Fc fusion protein (KN015) on healthy, pituitary-suppressed women: first-in-human and randomized study on its pharmacokinetics, pharmacodynamics, and tolerability

OBJECTIVE

KN015 is a long-acting, recombinant human follicle-stimulating hormone Fc fusion protein that induces follicle development. This first-in-human study evaluated the effect of KN015 on healthy, pituitary-suppressed women and examined its pharmacokinetics, pharmacodynamics, and tolerability.

METHODS

This phase I study was a double-blind, randomized, and placebo-controlled design with a single ascending dose (20, 40, and 60 μg, respectively).

RESULTS

After subcutaneous administration of a single dose, the maximum serum KN015 concentrations reached 1.57, 2.78, and 3.62 ng/mL, respectively, after baseline adjustment. Over this dose range, the median T_max occurred at 240-312 h, and the half-life (t_½) was 752-1160 h. Dose proportionality was shown across the studied dose range. In most subjects, follicular growth was observed, and the number and diameter of the follicles increased with an increasing dose. In the 40-μg and 60-μg groups, the mean numbers of follicles with a diameter of ≥17 mm were 3 and 4, respectively. There was no significant difference in adverse events between the KN015 and placebo groups. KN015 antibody was not detected in any of the dosage groups.

CONCLUSION

The administration of a single ascending dose of KN015 was tolerated and able to induce follicular growth.

TRIAL REGISTRATION

This trial is registered at the Chinese Clinical Trials website (http://www.chinadrugtrials.org.cn/index.html # CTR20160741) and ClinicalTrials.gov (https://clinicaltrials.gov/ # NCT03192527).

Embryo Selection and Mate Choice: Can 'Honest Signals' Be Trusted?

When a measure becomes a target, it often ceases to be a good measure - an effect familiar from the declining usefulness of standardized testing in schools. This economic principle also applies to mate choice and, perhaps surprisingly, pregnancy. Just as females screen potential mates under many metrics, human mothers unconsciously screen embryos for quality. 'Examinees' are under intense selection to improve test performance by exaggerating formerly 'honest' signals of quality. Examiners must change their screening criteria to maintain useful information (but cannot abandon old criteria unilaterally). By the resulting 'proxy treadmill', new honest indicators arise while old degraded indicators linger, resulting in trait elaboration and exaggeration. Hormone signals during pregnancy show extreme evolutionary escalation (akin to elaborate mating displays).

Recent Advances in Half-life Extension Strategies for Therapeutic Peptides and Proteins

Peptides and proteins are two classes of molecules with attractive possibilities for therapeutic applications. However, the bottleneck for the therapeutic application of many peptides and proteins is their short halflives in vivo, typically just a few minutes to hours. Half-life extension strategies have been extensively studied and many of them have been proven to be effective in the generation of long-acting therapeutics with improved pharmacokinetic and pharmacodynamic properties. In this review, we summarize the recent advances in half-life extension strategies, illustrate their potential applications and give some examples, highlighting the strategies that have been used in approved drugs and for drugs in clinical trials. Meanwhile, several novel strategies that are still in the process of discovery or at a preclinical stage are also introduced. In these strategies, the two most frequently used half-life extension methods are the reduction in the rate of renal clearance or the exploitation of the recycling mechanism of FcRn by binding to the albumin or IgG-Fc. Here, we discuss half-life extension strategies of recombinant therapeutic protein via genetic fusion, rather than chemical conjugation such as PEGylation. With the rapid development of genetic engineering and protein engineering, novel strategies for half-life extension have been emerged consistently. Some of these will be evaluated in clinical trials and may become viable alternatives to current strategies for making next-generation biodrugs.

Effect of ANITVNITV peptide fusion on the bioactivity and pharmacokinetics of human IFN-α2b and a hyper-N-glycosylated variant

Different strategies have been developed and successfully applied to biotherapeutics in order to improve their in vivo efficacy. The genetic fusion to natural or synthetic glycosylated peptides constitutes a promising strategy since it conserves the protein sequence and results in the improvement of the pharmacokinetic properties. The ANITVNITV peptide described by Perlmann and coworkers presents 9 amino acids and 2 potential N-glycosylation sites. Its fusion to FSH resulted in the increase of the molecular mass and negative charge of the protein. Consequently, the pharmacokinetics was considerably improved. The aim of the present study was to compare the influence of ANITVNITV peptide fusion on the physicochemical, biological and pharmacokinetic properties of native hIFN-α2b (IFNwt), which contains a single O-glycosylation site, and a hyperglycosylated variant (IFN4N), that bears, in addition, 4 N-linked glycans. The resulting molecules, IFNwtNter and IFN4NNter, evidenced a higher molecular mass and negative charge compared to IFNwt and IFN4N, respectively. Therefore, the pharmacokinetic properties of the new molecules were significantly improved. The molecules obtained by the synthetic peptide fusion strategy evidenced a decrease in their in vitro antiviral specific biological activities (SBA). However, in vitro antiproliferative SBA was differentially modified for IFNwtNter and IFN4NNter in comparison with the parental molecules. For IFNwtNter, a reduction in the antiproliferative SBA was also observed. Remarkably, the addition of the ANITVNITV peptide to the N-terminus of IFN4N had a positive impact on its growth-inhibitory activity. This feature together with its improved pharmacokinetics encourages the development of IFN4NNter as an IFN-α based biobetter.

The generation and biological activity of a long-lasting recombinant human interferon-λ1

The previously generated recombinant human (rh) interferon (IFN)-λ1 protein has a short half-life, and this feature makes it challenging to conduct studies on potential clinical applications for rhIFN-λ1. In an attempt to overcome this difficulty, we constructed a 'long-life' version of rhIFN-λ1. This modified rhIFN-λ1, named rhIFN-λ1-CTPON, has a human chorionic gonadotropin β subunit carboxyl-terminal peptide (CTP) and an N-glycosylation sequence linked to its C-terminus. We confirmed the sequence of rhIFN-λ1-CTPON by mass spectrometry and then measured its biological activities. The results show that rhIFN-λ1-CTPON had antiviral activity and anti-proliferation activity in vitro that were similar to those of rhIFN-λ1 and that it similarly promoted natural killer cell cytotoxicity. Notably, the in vivo half-life of rhIFN-λ1-CTPON was determined to be 3-fold higher than that of rhIFN-λ1. We also assessed the anti-hepatitis B virus activity of rhIFN-λ1-CTPON; it was able to inhibit the production of the antigens HBs-Ag and HBe-Ag and induce antiviral gene expression. In conclusion, rhIFN-λ1-CTPON has a longer half-life than rhIFN-λ1 and has similar biological activities, so rhIFN-λ1-CTPON is an appropriate substitute for rhIFN-λ1 in the further study of potential clinical applications for rhIFN- λ1.

Development of long-acting recombinant glycoprotein hormones by increasing the carbohydrate content

Therapeutic recombinant glycoproteins are important for both the biotechnological industry and clinical purposes. Given the rapid clearance of these proteins from the circulation, they have to be injected frequently to obtain optimal therapy. Several strategies have been developed to overcome this limitation, aiming to increase the half-life of such proteins in the circulation. These strategies included chemical attachment of polyethylene glycol, nanocapsulation, fusion to immunoglobulins or to albumin as protein carriers, or enrichment of the carbohydrate content. Here, we describe a strategy for increasing the half-life of recombinant proteins using gene fusion to increase the carbohydrate content of the protein backbone.

Construction, Purification, and Characterization of a Homodimeric Granulocyte Colony-Stimulating Factor

Granulocyte colony-stimulating factor (G-CSF) has found widespread clinical application, and modified forms with improved biopharmaceutical properties have been marketed as well. PEGylation, the covalent modification of G-CSF with polyethylene glycol (PEG), has a beneficial effect on drug properties, but there are concerns connected to the immunogenicity of PEGylated compounds and bioaccumulation of the synthetic polymer. To overcome challenges connected with chemical modifications, we developed fusion proteins composed of two G-CSF molecules connected via different peptide linkers. Three different homodimeric G-CSF proteins were purified, and their in vitro and in vivo activities were determined. A G-CSF dimer, GCSF-Lα, was constructed using an alpha-helix-forming peptide linker, and it demonstrated an extended half-life in serum with a stronger neutrophil response as compared to the monomeric G-CSF protein. The GCSF-Lα protein, therefore, might be selected for further studies as a potential drug candidate.

Erythropoietin mimetic peptides and erythropoietin fusion proteins for treating anemia of chronic kidney disease

PURPOSE OF REVIEW

First generation erythropoiesis stimulating agents (ESAs) have short duration of action which requires administration once weekly or greater. Second generation ESAs were developed which have longer duration of action and can be administered one to two times monthly. Erythropoietin (EPO) mimetic peptides (EMPs) activate the EPO receptor but have no structural analogy to EPO, offering the potential for lower cost as they are not biologic drugs. The first approved EMP, peginesatide, was withdrawn from the market within a year of its approval because of fatal anaphylactic reactions. In this review, we summarize recent progress regarding the development of newer, possibly less toxic, EMPs. We also summarize the development of EPO fusion proteins which fuse EPO with a portion of an immunoglobulin molecule or another EPO molecule, achieving a longer duration of action and less frequent dosing.

RECENT FINDINGS

AGEM400(hydroxyethyl starch) and pegolsihematide are EMPs in phase II clinical trials. Three EPO fusion proteins are under development, two in phase I and one in phase II.

SUMMARY

The future success of EMPs is limited by the prior experience with peginesatide and EPO fusion proteins do not offer cost savings or longer duration of action than currently available ESAs.

Half-life extended biotherapeutics

INTRODUCTION

Many of the biotherapeutics approved or under development suffer from a short half-life necessitating frequent applications in order to maintain a therapeutic concentration over an extended period of time. The implementation of half-life extension strategies allows the generation of long-lasting therapeutics with improved pharmacokinetic and pharmacodynamic properties.

AREAS COVERED

This review gives an overview of the different half-life extension strategies developed over the past years and their application to generate next-generation biotherapeutics. It focuses on srategies already used in approved drugs and drugs that are in clinical development. These strategies include those aimed at increasing the hydrodynamic radius of the biotherapeutic and strategies which further implement recycling by the neonatal Fc receptor (FcRn).

EXPERT OPINION

Half-life extension strategies have become an integral part of development for many biotherapeutics. A diverse set of these strategies is available for the fine-tuning of half-life and adaption to the intended treatment modality and disease. Currently, half-life extension is dominated by strategies utilizing albumin binding or fusion, fusion to an immunoglobulin Fc region and PEGylation. However, a variety of alternative strategies, such as fusion of flexible polypeptide chains as PEG mimetic substitute, have reached advanced stages and offer further alternatives for half-life extension.

Improvement of in vitro stability and pharmacokinetics of hIFN-α by fusing the carboxyl-terminal peptide of hCG β-subunit

Improving in vivo half-life and in vitro stability of protein-based therapeutics is a current challenge for the biopharmaceutical industry. In particular, recombinant human interferon alpha-2b (rhIFN-α2b), which belongs to a group of cytokines extensively used for the treatment of viral diseases and cancers, shows a poor stability in solution and an extremely short plasma half-life which determines a strict therapeutic regimen comprising high and repeated doses. In this work, we have used a strategy based on the fusion of the carboxyl-terminal peptide (CTP) of human chorionic gonadotropin (hCG) β-subunit, bearing four O-linked oligosaccharide recognition sites, to each or both N- and C-terminal ends of rhIFN-α2b. Molecules containing from 5 (CTP-IFN and IFN-CTP) to 9 (CTP-IFN-CTP) O-glycosylation sites were efficiently expressed and secreted to CHO cells supernatants, and exhibited antiviral and antiproliferative bioactivities in vitro. Significant improvements in pharmacokinetics in rats were achieved through this approach, since the doubly CTP-modified IFN variant showed a 10-fold longer elimination half-life and a 19-fold decreased plasma apparent clearance compared to the wild-type cytokine. Moreover, CTP-IFN-CTP demonstrated a significant increase in in vitro thermal resistance and a higher stability against plasma protease inactivation, both features attributed to the stabilizing effects of the O-glycans provided by the CTP moiety. These results constitute the first report that postulates CTP as a tag for improving both the in vitro and in vivo stability of rhIFN-α2b which, in turn, would positively influence its in vivo bioactivity.

Fusion Proteins for Half-Life Extension of Biologics as a Strategy to Make Biobetters

The purpose of making a "biobetter" biologic is to improve on the salient characteristics of a known biologic for which there is, minimally, clinical proof of concept or, maximally, marketed product data. There already are several examples in which second-generation or biobetter biologics have been generated by improving the pharmacokinetic properties of an innovative drug, including Neulasta(®) [a PEGylated, longer-half-life version of Neupogen(®) (filgrastim)] and Aranesp(®) [a longer-half-life version of Epogen(®) (epoetin-α)]. This review describes the use of protein fusion technologies such as Fc fusion proteins, fusion to human serum albumin, fusion to carboxy-terminal peptide, and other polypeptide fusion approaches to make biobetter drugs with more desirable pharmacokinetic profiles.

Combination of apolipoprotein A1-modi liposome-doxorubicin with autophagy inhibitors overcame drug resistance in vitro

Multidrug resistance (MDR) represents the major drawback in chemotherapy. Liposome-based approaches could reverse MDR to some extent through circumventing the active efflux effect of P-glycoprotein. However, the reverse power of liposome is very limited because the nontargeting liposome is inefficient to deliver drugs to tumor actively. Besides, autophagy could reinforce the resistance of tumor cells to the cytotoxicity of intracellular drugs. Here, liposomal doxorubicin (Lipodox) that was conjugated with apolipoprotein A1-apo-Lipodox, was employed in tumor targeting delivery of doxorubicin. In the experiments, apo-Lipodox could enter cells effectively and reverse MDR more efficiently than their nontargeting counterpart. Autophagy occurred in this process and contributed to the survival of tumor cells. Combination use of autophagy inhibitors could enhance the cytotoxicity of apo-Lipodox and reverse drug resistance to a higher degree. We propose that this strategy holds promise to overcome MDR in human cancer.

New treatment approaches in chronic kidney disease-associated anaemia

INTRODUCTION

Erythropoiesis-stimulating agents (ESA) and iron are the main tools for treating anaemia associated with chronic kidney disease (CKD). Pharmaceutical research has focused on modified epoetins or different strategies to stimulate erythropoiesis with the idea of improving relative disadvantages of the molecules already available in the market.

AREAS COVERED

Following a literature search on PubMed using anaemia, haemoglobin, erythropoietin (EPO), hypoxia-inducible transcription factor (HIF) inhibitors and chronic kidney disease as keywords, we critically analysed new strategies for increasing erythropoiesis, looking in depth at their peculiar characteristics and possible advantages in the clinical setting.

EXPERT OPINION

In recent years the ESA market is facing a number of hurdles making it less appealing than before. Economic recession or stagnation has raised the need of sustainability of medical treatment. New treatments must bring clear benefits compared to existing drugs. In addition to this, ESA consumption has been progressively reduced, fearing possible risks of increased cardiovascular events especially when given at excessive doses. New drugs may also undergo premature stopping because of unexpected adverse reactions as for peginesatide. At present, the most promising approach to anaemia treatment in CKD patients is the manipulation of the HIF system. The regulation of activin A pathway is another option with good potential, also considering the additional advantage of increasing bone mass.

The role of the 3' region of mammalian gonadotropin β subunit gene in the luteinizing hormone to chorionic gonadotropin evolution

CGβ subunits comprise a unique carboxyl-terminal peptide (CTP) that has multiple O-linked glycans and extends serum half-life of the protein. It has evolved by incorporating a previously untranslated region of the LHβ gene into the reading frame. Although CTP-like sequences are encrypted in the LHβ genes of several mammals, the CGβ subunit developed only in primates and equids. To study this restriction in evolution, we examined whether the cryptic CTP decoded from the bovine LHβ gene (boCTP) possesses key characteristics of the human (h) CGβ-CTP. The boCTP does not impede several crucial aspects of hormone biosynthesis, but compared to the hCGβ-CTP, the stretch lacks O-glycans and determinants for circulatory survival. O-glycan deficiency and the associated incapacity to extend serum half-life is a major drawback of the boCTP. This may explain why LH did not evolve into CG in ruminants and consequently alternative mechanisms evolved to delay luteolysis early in gestation.

Impact of physiochemical properties on pharmacokinetics of protein therapeutics

Physicochemical properties, such as molecular weight, size, partition coefficient, acid dissociation constant and solubility have a great impact on pharmacokinetics of traditional small molecule drugs and substantially used in development of small drugs. However, predicting pharmacokinetic fate (absorption, distribution, metabolism and elimination) of protein therapeutics from their physicochemical parameters is extremely difficult due to the macromolecular nature of therapeutic proteins and peptides. Their structural complexity and immunogenicity are other contributing factors that determine their biological fate. Therefore, to develop generalized strategies concerning development of therapeutic proteins and peptides are highly challenging. However, reviewing the literature, authors found that physiochemical properties, such as molecular weight, charge and structural modification are having great impact on pharmacokinetics of protein therapeutics and an attempt is made to provide the major findings in this manuscript. This manuscript will serve to provide some bases for developing protein therapeutics with desired pharmacokinetic profile.

Erythropoietin and erythropoiesis stimulating agents

Erythropoietin (EPO) is the main hormonal regulator of red blood cell production. Recombinant EPO has become the leading drug for treatment of anaemia from a variety of causes; however, it is sometimes misused in sport with the aim of improving performance and endurance. This paper presents an introductory overview of EPO, its receptor, and a variety of recombinant human EPOs/erythropoiesis stimulating agents (ESAs) available on the market (e.g. epoetins and their long acting analogs--darbepoetin alfa and continuous erythropoiesis receptor activator). Recent efforts to improve on EPO's pharmaceutical properties and to develop novel replacement products are also presented. In most cases, these efforts have emphasized a reduction in frequency of injections or complete elimination of intravenous or subcutaneous injections of the hormone (biosimilars, EPO mimetic peptides, fusion proteins, endogenous EPO gene activators and gene doping). Isoelectric focusing (IEF) combined with double immunoblotting can detect the subtle differences in glycosylation/sialylation, enabling differentiation among endogenous and recombinant EPO analogues. This method, using the highly sensitive anti-EPO monoclonal antibody AE7A5, has been accepted internationally as one of the methods for detecting misuse of ESAs in sport.

Conversion of TSH heterodimer to a single polypeptide chain increases bioactivity and longevity

TSH is a dimeric glycoprotein hormone composed of a common α-subunit noncovalently linked to a hormone-specific β-subunit. Previously, the TSH heterodimer was successfully converted to an active single-chain hormone by genetically fusing α and β genes with [TSHβ- carboxyl-terminal peptide (CTP)-α] or without (TSHβ-α) the CTP of human chorionic gonadotropin β-subunit as a linker. In the present study, TSH variants were expressed in Chinese hamster ovarian cells. The results indicated that TSHβ-α single chain has the highest binding affinity to TSH receptor and the highest in vitro bioactivity. With regard to the in vivo bioactivity, all TSH variants increased the levels of T(4) in circulation after 2 and 4 h of treatment. However, the level of T(4) after treatment with TSH-wild type was significantly decreased after 6 and 8 h, compared with the levels after treatment with the other TSH variants. TSHβ-α and TSHβ-CTP-α single chains exhibited almost the same bioactivity after 8 h of treatment. Evaluating the half-life of TSH variants, TSHβ-CTP-α single chain revealed the longest half-life in circulation, whereas TSH-wild type exhibited the shortest serum half-life. These findings indicate that TSH single-chain variants with or without CTP as a linker may display conformational structures that increase binding affinity and serum half-life, thereby, suggesting novel attitudes for engineering and constructing superagonists of TSH, which may be used for treating different conditions of defected thyroid gland activity. Other prominent potential clinical use of these variants is in a diagnostic test for metastasis and recurrence of thyroid cancer.

Aberrant phenotypes of transgenic mice expressing dimeric human erythropoietin

BACKGROUND

Dimeric human erythropoietin (dHuEPO) peptides are reported to exhibit significantly higher biological activity than the monomeric form of recombinant EPO. The objective of this study was to produce transgenic (tg) mice expressing dHuEPO and to investigate the characteristics of these mice.

METHODS

A dHuEPO-expressing vector under the control of the goat beta-casein promoter, which produced a dimer of human EPO molecules linked by a 2-amino acid peptide linker (Asp-Ile), was constructed and injected into 1-cell fertilized embryos by microinjection. Mice were screened using genomic DNA samples obtained from tail biopsies. Blood samples were obtained by heart puncture using heparinized tubes, and hematologic parameters were assessed. Using the microarray analysis tool, we analyzed differences in gene expression in the spleens of tg and control mice.

RESULTS

A high rate of spontaneous abortion or death of the offspring was observed in the recipients of dHuEPO embryos. We obtained 3 founder lines (#4, #11, and #47) of tg mice expressing the dHuEPO gene. However, only one founder line showed stable germline integration and transmission, subsequently establishing the only transgenic line (#11). We obtained 2 F1 mice and 3 F2 mice from line #11. The dHuEPO protein could not be obtained because of repeated spontaneous abortions in the tg mice. Tg mice exhibited symptoms such as short lifespan and abnormal blood composition. The red blood cell count, white blood cell count, and hematocrit levels in the tg mice were remarkably higher than those in the control mice. The spleens of the tg mice (F1 and F2 females) were 11- and -21-fold larger than those of the control mice. Microarray analysis revealed 2,672 spleen-derived candidate genes; more genes were downregulated than upregulated (849/764). Reverse transcriptase-polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qRT-PCR) were used for validating the results of the microarray analysis of mRNA expression.

CONCLUSIONS

In conclusion, dHuEPO tg mice caused excessive erythrocytosis that led to abnormal blood composition, short lifespan, and abnormal splenomegaly. Further, we identified 2,672 genes associated with splenomegaly by microarray analysis. These results could be useful in the development of dHuEPO-producing tg animals.

Designing a Long Acting Erythropoietin by Fusing Three Carboxyl-Terminal Peptides of Human Chorionic Gonadotropin β Subunit to the N-Terminal and C-Terminal Coding Sequence

A new analog of EPO was designed by fusing one and two CTPs to the N-terminal and C-terminal ends of EPO (EPO-(CTP)₃), respectively. This analog was expressed and secreted efficiently in CHO cells. The in vitro test shows that the activity of EPO-(CTP)₃ in TFI-1 cell proliferation assay is similar to that of EPO-WT and commercial rHEPO. However, in vivo studies indicated that treatment once a week with EPO-(CTP)₃ (15 μg/kg) dramatically increased (~8 folds) haematocrit as it was compared to rHuEPO. Moreover, it was found that EPO-(CTP)₃ is more effective than rHuEPO and Aranesp in increasing reticulocyte number in mice blood. The detected circulatory half-lives of rHuEPO, Aranesp, and EPO-(CTP)₃ following IV injection of 20 IU were 4.4, 10.8, and 13.1 h, respectively. These data established the rational for using this chimera as a long-acting EPO analog in clinics. The therapeutic efficacy of EPO-CTP analog needs to be established in higher animals and in human clinical trials.

Strategies for extended serum half-life of protein therapeutics

With a growing number of protein therapeutics being developed, many of them exhibiting a short plasma half-life, half-life extension strategies find increasing attention by the biotech and pharmaceutical industry. Extension of the half-life can help to reduce the number of applications and to lower doses, thus are beneficial for therapeutic but also economic reasons. Here, a comprehensive overview of currently developed half-life extension strategies is provided including those aiming at increasing the hydrodynamic volume of a protein drug but also those implementing recycling processes mediated by the neonatal Fc receptor.

Effects of recombinant human LH and hCG on serum and urine LH and androgens in men

CONTEXT

The administration of gonadotrophins is prohibited in sport but the effect in men of recently available recombinant hCG and LH on serum and urine concentrations of gonadotrophins and androgens has not been systematically evaluated in the antidoping context.

OBJECTIVE

To determine the time-course of recombinant LH (rhLH) and hCG (rhCG) on blood and urine hormone profiles in men to develop effective tests to detect rhLH and rhCG doping.

DESIGN

Two randomized controlled studies with a 2 x 2 factorial design.

SETTING

Academic research centre.

PARTICIPANTS

Healthy male volunteers aged 18-45 years.

INTERVENTIONS

In the rhLH study, men were randomized into (i) either of two single doses of rhLH (75 IU or 225 IU), and (ii) suppression of endogenous LH and testosterone by nandrolone or no suppression. In the rhCG study, men were randomized into (i) either of two single doses of rhCG (250 or 750 microg), and (ii) suppression of endogenous LH and testosterone by nandrolone decanoate (ND) or no suppression. ND suppression comprised a single dose of 200 mg ND 3 days prior to, and in the rhCG study an additional dose 1 day after gonadotrophin injection.

MAIN OUTCOME MEASURES

Serum and urine hCG, LH, T, T : LH ratio, urine epitestosterone (E) and urine T : E ratio.

RESULTS

Neither rhLH dose produced a significant increase in serum or urine LH or T or in the T : E or T : LH ratios regardless of ND-induced suppression of endogenous LH and T. Nor did an even higher dose (750 IU) in three healthy men with unsuppressed gonadal axis. These findings were confirmed with two different commercial LH immunoassays together with adjustment for any influence of urine sediment and dilution. Both rhCG doses produced a steep, dose-proportional increase in serum and urine hCG with increases in serum and urine T and suppression of serum and urine LH, regardless of hCG dose. Serum but not urine T was lowered by ND suppression. The T : LH ratio showed a progressive increase unrelated to rhCG dose or ND suppression, whereas both rhCG and ND suppression minimally increased T : E ratio.

CONCLUSIONS

Both rhCG doses produce a striking increase in serum hCG and T with suppression of serum LH but, at single doses up to 750 IU, rhLH has no influence on serum or urine LH or T. Effective rhLH doping, which relies on a sustained increases in endogenous T, would require much higher and more frequent daily rhLH doses. Use of LH immunoassays optimized for serum to detect rhLH doping by urine LH measurement requires more standardization and validation and, at present, is unreliable. The T : LH ratio is, however, a useful screening test for hCG doping although its utility requires further evaluation.

Optimizing the management of renal anemia: challenges and new opportunities

Erythropoiesis stimulating agents (ESAs) are the main tool to achieve anemia correction in CKD patients. At present six different ESAs are available: epoetin alpha, epoetin beta, epoetin omega, epoetin delta, darbepoetin alpha, and very recently CERA. From one side the patent of older ESAs have expired, and biosimilars (for the moment only of epoetin alpha) have been approved for use in Europe by the European Medicines Agency. However, a number of issues about bioequivalence and how to test it are still to be solved completely. In the mean time pharmaceutical research has kept on working, developing new ESAs and alternative strategies for stimulating erythropoiesis. In this review we present and discuss these points.