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Vadadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor for treating anemia in chronic kidney disease (CKD). Single ascending dose (SAD) and multiple ascending dose (MAD) studies assessed pharmacokinetics (PK), pharmacodynamics (PD), and safety of vadadustat in healthy volunteers. A single-dose, open-label study was conducted in patients with CKD stages 3 and 4 not on dialysis. In the SAD study, 48 healthy adult men (n = 8/cohort) received single doses of vadadustat (80-1,200 mg) or placebo. In the MAD study, 34 healthy adult men (n = 8-9/cohort) received daily vadadustat (500-900 mg) or placebo for 10 days. In the single-dose CKD study, 22 male and female patients with CKD (stage 3: n = 10; stage 4: n = 12) received single doses of vadadustat (500 mg). PK parameters included plasma vadadustat; PD biomarkers were measured, including erythropoietin (EPO) levels, reticulocytes, and others. Plasma vadadustat peaked 3-4 hours after single or multiple dosing in healthy volunteers, with a mean t 1/2 of approximately 4.5 hours. In patients with CKD, plasma vadadustat peaked at 5-6 hours, with a mean t 1/2 of 7.2 (stage 3) and 8.5 (stage 4) hours. Vadadustat AUC ∞ and C max increased dose proportionally in SAD and MAD trials. In all trials, EPO concentrations increased in a dose-related manner and returned approximately to baseline by 24 hours. Adverse events were mild and considered not study drug related. The PK and PD results of these studies were utilized for further clinical development of vadadustat for treatment of anemia in CKD patients., (© 2024 Akebia Therapeutics, Inc. and The Author(s). Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Belzutifan (Welireg, Merck & Co., Inc., Rahway, NJ, USA) is an oral, potent hypoxia-inducible factor-2α inhibitor, recently approved in the United States for the treatment of von Hippel-Lindau (VHL) disease-associated renal cell carcinoma (RCC) and other VHL disease-associated neoplasms. Safety and efficacy were investigated in two clinical studies: a Phase 1 dose escalation/expansion study in solid tumors and RCC and a Phase 2 study in VHL-RCC. A population pharmacokinetic model was used to estimate belzutifan exposures to facilitate exposure-response (E-R) analyses for efficacy and safety endpoints. Relationships between exposure and efficacy (overall response rate, disease control rate, progression-free survival, best overall tumor size response, and other endpoints), safety outcomes (Grade ≥3 anemia, Grade ≥3 hypoxia, and time to first dose reduction/dose interruption), and pharmacodynamic biomarkers (erythropoietin [EPO] and hemoglobin [Hgb]) were evaluated using various regression techniques and time-to-event analyses. Efficacy E-R was generally flat with non-significant positive trends with exposure. The safety E-R analyses demonstrated a lack of relationship for Grade ≥3 hypoxia and a positive relationship for Grade ≥3 anemia, with incidences also significantly dependent on baseline Hgb. Exposure-dependent reductions in EPO and Hgb were observed. Based on the cumulative benefit-risk assessment in VHL disease-associated neoplasms using E-R, no a priori dose adjustment is recommended for any subpopulation. These analyses supported the benefit-risk profile of belzutifan 120 mg once daily dosing in patients with VHL-RCC for labeling and the overall development program., (© 2024 Merck Sharp & Dohme LLC. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Purpose: This first-in-human trial aimed to investigate the pharmacokinetics and pharmacodynamics characteristics and safety and tolerability of single ascending doses of subcutaneous polyethylene glycol-erythropoietin (PEG-EPO) in healthy subjects., Methods: In this phase I, randomized, double-blind, placebo-controlled, dose-escalating trial, subjects were sequentially enrolled into 7 cohorts with 12 subjects in each cohort and randomized in a 5:1 ratio to receive a single dose of 0.2, 0.4, 0.8, 1.6, 2.4, 3.6, or 4.8 µg/kg PEG-EPO or matching placebo. Safety and tolerability including dose-limiting toxicities (DLTs) were assessed. Pharmacokinetics parameters, including C max , AUC 0-inf , T max , and t 1/2 , and pharmacodynamics parameters, including reticulocyte count and hemoglobin content, were evaluated., Findings: Eighty-four subjects (median age 30.4 years and 77.4% male) were enrolled. No subjects developed DLTs. Any grade treatment-related adverse events occurred in 66.7% of the subjects, but most (92.9%) were mild. No serious adverse events and no death occurred. Forty percent of the subjects receiving PEG-EPO had iron decreased, 27.1% reported ferritin decreased, 25.7% showed unsaturated iron binding capacity increased, and 17.1% had neutrophil count decreased. C max exhibited a dose-disproportionate rise from a geometric mean of 525 pg/mL with 0.2 µg/kg PEG-EPO to 23196 pg/mL with 4.8 µg/kg PEG-EPO. The mean t 1/2 ranged between 82.4 ± 21.3 h with 0.4 µg/kg PEG-EPO and 160.6 ± 65.7 h with 1.6 µg/kg PEG-EPO. AUC 0-inf displayed a largely dose-proportional rise from 226264.5 pg*h/mL with 0.2 µg/kg PEG-EPO to 5206434.0 pg*h/mL with 4.8 µg/kg PEG-EPO. The absolute reticulocyte count increased with escalating doses of PEG-EPO, with the mean maximal change from baseline between 3.2 ± 1.5*10^10/L (Q1,Q3 1.8-3.6*10^10/L) with PEG-EPO 0.2 µg/kg and 9.3 ± 4.0*10^10/L (Q1,Q3 6.2-13.5*10^10/L) with 3.6 µg/kg PEG-EPO. The mean maximal change from baseline in the mean hemoglobin content ranged between 5.9 ± 4.4 g/L (Q1,Q3 3.5,7.0) with 0.2 µg/kg PEG-EPO and 15.4 ± 8.7 g/L (Q1,Q3 10.5,20.0) with 2.4 µg/kg PEG-EPO., Implications: This trial demonstrated that PEG-EPO was safe and tolerable in healthy subjects. The subcutaneous route of administration allows outpatient treatment and the pharmacokinetics characteristics of PEG-EPO support less frequent dosing regimens and effective treatment for chronic kidney disease patients with anemia., Trial Registration: clinicaltrials.gov identifier: NCT03657238., Competing Interests: Declaration of competing interest Yuanyuan Wu, Junlong Huang, Xiangrong Zhang were full-time employees of the trial sponsor (Shenzhen Sciprogen Bio-pharmaceutical Co., Ltd.). No competing interests were reported by any other contributing authors., (Copyright © 2024. Published by Elsevier Inc.)

Our aim was to build a mechanistic full target-mediated drug disposition (TMDD) model for rhEpo to better understand rhEpo disposition, Epo receptor (EpoR) synthesis, and degradation in hematopoietic transplant patients with four distinct bone marrow conditions. All PK data were analyzed simultaneously using the nonlinear mixed effect modeling approach with NONMEM. The final model was a two-compartmental full TMDD model, which adequately characterizes rhEpo PK in patients and provides insight into the dynamics of free EpoR, rhEpo-EpoR, and total EpoR. The model predicted association rate constant (k on ), dissociation rate constant (k off ), and internalization rate constant (k int ) were 0.0276 pM -1 h -1 , 0.647 h -1 , and 0.255h -1 , respectively, which were supported by experimental data. Also, the EpoR degradation rate constant (k deg ) was estimated to be 0.461 h -1 . EpoR production rate was estimated to be 37.5 pM/h for adults at pre-ablation baseline and 5.91 pM/h, and 4.19 pM/h in the early post-transplant post-engraftment, and late post-transplant full engraftment. Our model provides extensive information on the dynamics of free EpoR, total EpoR and rhEpo-EpoR, and proven to be more robust and can provide more physiologically relevant binding parameters than previous models., Competing Interests: Conflict of Interest None., (Copyright © 2022 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.)

Neuroprotection in glaucoma using epoetin beta (EPOβ) has yielded promising results. Our team has developed chitosan-hyaluronic acid nanoparticles (CS/HA) designed to carry EPOβ into the ocular globe, improving the drug's mucoadhesion and retention time on the ocular surface to increase its bioavailability. In the present in vivo study, we explored the possibility of delivering EPOβ to the eye through subconjunctival administration of chitosan-hyaluronic acid-EPOβ (CS/HA-EPOβ) nanoparticles. Healthy Wistar Hannover rats ( n = 21) were split into 7 groups and underwent complete ophthalmological examinations, including electroretinography and microhematocrit evaluations before and after the subconjunctival administrations. CS/HA-EPOβ nanoparticles were administered to the right eye (OD), and the contralateral eye (OS) served as control. At selected timepoints, animals from each group ( n = 3) were euthanized, and both eyes were enucleated for histological evaluation (immunofluorescence and HE). No adverse ocular signs, no changes in the microhematocrits (≈45%), and no deviations in the electroretinographies in both photopic and scotopic exams were observed after the administrations ( p < 0.05). Intraocular pressure remained in the physiological range during the assays (11-22 mmHg). EPOβ was detected in the retina by immunofluorescence 12 h after the subconjunctival administration and remained detectable until day 21. We concluded that CS/HA nanoparticles could efficiently deliver EPOβ into the retina, and this alternative was considered biologically safe. This nanoformulation could be a promising tool for treating retinopathies, namely optic nerve degeneration associated with glaucoma.

Antibodies that bind polyethylene glycol (PEG) can be induced by pegylated biomolecules and also exist in a significant fraction of healthy individuals who have never received pegylated medicines. The binding affinity of antibodies against PEG (anti-PEG antibodies) likely varies depending on if they are induced or naturally occurring. Anti-PEG antibodies can accelerate the clearance of pegylated medicines from the circulation, resulting in loss of drug efficacy, but it is unknown how accelerated blood clearance is affected by anti-PEG antibody affinity. We identified a panel of anti-PEG IgG and IgM antibodies with binding avidities ranging over several orders of magnitude to methoxy polyethylene glycol-epoetin beta (PEG-EPO), which is used to treat patients suffering from anemia. Formation of in vitro immune complexes between PEG-EPO and anti-PEG IgG or IgM antibodies was more obvious as antibody affinity increased. Likewise, high affinity anti-PEG antibodies produced greater accelerated blood clearance of PEG-EPO as compared to low affinity antibodies. The molar ratio of anti-PEG antibody to PEG-EPO that accelerates drug clearance in mice correlates with antibody binding avidity. Our study indicates that the bioactivity of PEG-EPO may be reduced due to rapid clearance in patients with either high concentrations of low affinity or low concentrations of high affinity anti-PEG IgG and IgM antibodies., (Copyright © 2021 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Jimaixin™ (Jintan Ltd, China) is a biosimilar of recombinant erythropoietin (rEPO) now authorized for therapeutic application in China. With a risk of abuse by athletes, a clear evaluation of its detection using the electrophoretic methods in use in antidoping laboratories was necessary. In a previous work, we showed that Jimaixin™ electrophoretic profile presented slight changes compared with the original drug (first generation rEPO) and that a spike of Jimaixin™ in urine and serum was well identified by SDS-PAGE but with less performance by IEF-PAGE unless a neuraminidase treatment was applied first. The aims of this research were to perform an intravenous administration of Jimaixin™ on three healthy subjects (one microdose [10 IU/kg] and three therapeutic doses [50 IU/kg]) and to evaluate the detection in urine and blood up to 7 days post administration. Analysis of the samples showed that Jimaixin™ detection was complicated by IEF-PAGE due to the loss of the most distinctive basic isoforms. In addition, a neuraminidase treatment did not improve detection (contrary to the observations from spike experiments). On the contrary, Jimaixin™ was very efficiently detected in blood and urine by SDS-PAGE: up to 40 h after a microdose and up to 7 days after the therapeutic doses. The effect of Jimaixin™ on hematological parameters was limited to a clear but transitory increase of the reticulocytes. These data give new elements to better survey a potential misuse of Jimaixin™ by athletes., (© 2021 John Wiley & Sons, Ltd.)

Recombinant human erythropoietin (rHuEPO) is effective in managing chronic kidney disease and chemotherapy-induced anemia. However, hyporesponsiveness to rHuEPO treatment was reported in about 10% of the patients. A decreased response in rats receiving a single or multiple doses of rHuEPO was also observed. In this study, we aimed to develop a quantitative systems pharmacology (QSP) model to examine hyporesponsiveness to rHuEPO in rats. Pharmacokinetic (PK) and pharmacodynamic (PD) data after a single intravenous dose of rHuEPO (100 IU/kg) was obtained from a previous study (Yan et al. in Pharm Res, 30:1026-1036, 2013) including rHuEPO plasma concentrations, erythroid precursors counts in femur bone marrow and spleen, reticulocytes (RETs), red blood cells (RBCs), and hemoglobin (HGB) in circulation. Parameter values were obtained from literature or calibrated with experimental data. Global sensitivity analysis and model-based simulations were performed to assess parameter sensitivity and hyporesponsiveness. The final QSP model adequately characterizes time courses of rHuEPO PK and nine PD endpoints in both control and treatment groups simultaneously. The model indicates that negative feedback regulation, neocytolysis, and depletion of erythroid precursors are major factors leading to hyporesponsiveness to rHuEPO treatment in rats., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Molidustat is an oral inhibitor of hypoxia-inducible factor (HIF) prolyl-hydroxylase enhancing the erythropoietin (EPO) response to HIF; it is in clinical development for the treatment of anaemia related to chronic kidney disease. The predominant role of glucuronidation for molidustat clearance (formation of N-glucuronide metabolite M1) and subsequent renal excretion was confirmed in a human mass balance study, with about 85% of the drug being excreted as M1 in urine. The inhibitory effects of 176 drugs and xenobiotics from various compound classes on the UGT-mediated glucuronidation of molidustat in human liver microsomes (HLMs) were investigated. Based on preclinical findings, glucuronidation of molidustat was predominantly mediated by the 5'-diphospho-glucuronosyltransferase (UGT) isoform UGT1A1. Therefore, atazanavir, which is a potent inhibitor of UGT1A1, was chosen for the evaluation of pharmacokinetics and EPO release following a single oral dose of 25 mg molidustat. Molidustat exposure increased about twofold upon coadministration with atazanavir when considering area under plasma concentration-time curve from zero to infinity (AUC) and maximum plasma concentration (C max ). Baseline-corrected increase of EPO was 14% and 34% for C max and AUC (calculated over 24 hours), respectively. Coadministration of molidustat and atazanavir was well tolerated., (© 2020 The Authors. Basic & Clinical Pharmacology & Toxicology published by John Wiley & Sons Ltd on behalf of Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Aim: To estimate the blood level of Erythropoietin(EPO) in neonates with anemia of prematurity (APO) and in late hypo-regenerative anemia and to clarify role of EPO in correction of anemia and reducing the number of blood transfusions., Methods: This study was carried out on 60 neonates divided into; group I (30 preterm neonates) with AOP received EPO (250 IU/kg/dose subcutaneously 3 times weekly for 4 weeks), compared to group II (30 neonates) with AOP treated only with blood transfusion. CBC parameters and transfusion requirements were followed during therapy. Serum level of EPO was measured by ELISA technique., Results: By the end of the 4th week of therapy, there was significant increase in group I post r-Hu EPO compared to group II regarding reticulocyte counts (P < 0.001) leading to rise of the Hb (P < 0.001), Hct levels (P < 0.001) with subsequent reduction in the overall number of blood transfusions (P < 0.001)., Conclusion: EPO therapy in conjunction with iron, vitamin E and folic acid, stimulated erythropoiesis and significantly reduced the need for blood transfusion in AOP., Competing Interests: Declaration of Competing Interest The authors declared that there is no conflict of interest., (Copyright © 2019 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.)

Recombinant human erythropoietin (rhEpo) can improve human performance, but misuse remains difficult to detect. C-terminal fibroblast growth factor 23 (cFGF23) was recently demonstrated to increase following injection of a single high dose rhEpo, but the effect of more frequent low doses is unknown. Using a randomized double-blind placebo-controlled design, we investigated whether 2 weeks of subcutaneous injections three times a week of 50 IU/kg Eprex (low-dose) or 20 IU/kg Eprex (micro-dose) increase cFGF23 levels compared with saline (placebo) injections in 24 healthy males. Venous blood was sampled at day -3, 0, 1, 3, 11, 14, 18, and 25 of the treatment and analyzed for cFGF23 and erythropoietin concentration ([EPO]). The level of cFGF23 was similar at days -3, 0, 1, 3, 11, 14, 18, and 25 with the low-dose (23 ± 4, 26 ± 5, 23 ± 7, 27 ± 6, 25 ± 8, 24 ± 10, 22 ± 5, and 24 ± 7 RU/mL, respectively), micro-dose (23 ± 6, 25 ± 5, 23 ± 8, 28 ± 9, 27 ± 7, 25 ± 9, 25 ± 5, and 23 ± 6 RU/mL, respectively) and placebo (23 ± 6, 24 ± 6, 26 ± 7, 26 ± 6, 31 ± 6, 31 ± 7, 24 ± 4, and 27 ± 8 RU/mL, respectively) treatment. The correlation coefficient between plasma [EPO] and plasma cFGF23 levels was R 2 = 0.01 and insignificant. The results demonstrate that cFGF23 is not sensitive to low doses of subcutaneous rhEpo injections in healthy males., (© 2020 John Wiley & Sons, Ltd.)

Physiologically-based pharmacokinetic (PBPK) modelling provides an integrated framework to predict the disposition of small molecule drugs in children and is increasingly being used for dose recommendation and optimal design of paediatric studies and in regulatory submissions. Existing paediatric PBPK models can be adopted to describe the disposition of therapeutic proteins (TPs) in children by incorporating information on age-related changes of additional physiological and biological parameters (e.g. endogenous IgG, neonatal Fc receptor, lymph flow). In this study, physiological parameters were collated from literature and evaluated for any age-dependent trends. The age-dependent physiological parameters were used to construct a paediatric PBPK model for TPs. The model was then used to predict the pharmacokinetics of recombinant human erythropoietin (EPO), infliximab, etanercept, basiliximab, anakinra and enfuvirtide in paediatric subjects. The developed paediatric PBPK model predicted the drug concentration-time profiles reasonably well in full-term neonates (clinical PK data only available for EPO), infants, children and adolescents with the ratios of predicted over observed clearance values within 1.5-fold and 25 out of 26 clearance predictions were within 0.8- to 1.25-fold of the observed values. The clinically reported data are required to further assess the predictive accuracy of PK for Fc-containing proteins in term-born children younger than 2 months. This study demonstrates the ability of PBPK models accounting for age-dependent changes in relevant parameters to predict the pharmacokinetics of different types of TPs in paediatrics. The information gained from the PBPK models described here can facilitate our understanding of the complexities of TPs' disposition during growth and development.

High-dose human recombinant erythropoietin (rEPO) is a promising potential neuroprotective treatment in preterm and full-term neonates with hypoxic-ischemic encephalopathy (HIE). There are limited data on the pharmacokinetics of high-dose rEPO in neonates. We examined the effects of body weight, gestation age, global asphyxia, cerebral ischemia, hypothermia and exogenous rEPO on the pharmacokinetics of high-dose rEPO in fetal sheep. Near-term fetal sheep on gestation day 129 (0.87 gestation) (full term 147 days) received sham-ischemia ( n = 5) or cerebral ischemia for 30 min followed by treatment with vehicle ( n = 4), rEPO ( n = 8) or combined treatment with rEPO and hypothermia ( n = 8). Preterm fetal sheep on gestation day 104 (0.7 gestation) received sham-asphyxia ( n = 1) or complete umbilical cord occlusion for 25 min followed by i.v. infusion of vehicle ( n = 8) or rEPO ( n = 27) treatment. rEPO was given as a loading bolus, followed by a prolonged continuous infusion for 66 to 71.5 h in preterm and near-term fetuses. A further group of preterm fetal sheep received repeated bolus injections of rEPO ( n = 8). The plasma concentrations of rEPO were best described by a pharmacokinetic model that included first-order and mixed-order elimination with linear maturation of elimination with gestation age. There were no detectable effects of therapeutic hypothermia, cerebral ischemia, global asphyxia or exogenous treatment on rEPO pharmacokinetics. The increase in rEPO elimination with gestation age suggests that to maintain target exposure levels during prolonged treatment, the dose of rEPO may have to be adjusted to match the increase in size and growth. These results are important for designing and understanding future studies of neuroprotection with high-dose rEPO., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

This study aimed to develop a method for implementing dose correction in a Michaelis-Menten (M-M) approximation of a target-mediated drug disposition (TMDD) model with multiple intravenous (IV) bolus administrations. We derived the formula of a correction factor (Fcorr) for each dose in a multiple IV bolus dosing regimens for M-M model. Fcorr depends on the residual free drug amount prior IV bolus dosing event and dose amount. We conducted a stochastic simulation and estimation (SSE) exercise based on therapeutic antibody PK parameters to evaluate the effect of Fcorr on parameter estimation. Previously published clinical PK data of recombinant human erythropoietin (rHuEPO) from four clinical trials in healthy subjects receiving multiple IV bolus doses were analyzed by both M-M model with and without dose correction (MMC and MMNC) as well as the rapid-binding/quasi-steady-state (RB/QSS) TMDD models. Our results showed that MMNC introduced bias to fixed-effect parameter estimates and overestimated random-effect variables. Compared with MMC, MMNC was not able to adequately characterize the nonlinearity in the PK data of antibody and rHuEPO. The MMC-based simulation demonstrated that thricely weekly 10 IU/kg rHuEPO dosing regimen yielded Fcorr = 0.5. This result suggested that the lower-than-expected exposure for rHuEPO at low dose is due to target binding. An M-M approximation of the TMDD model should include a dose correction to avoid model misfitting and potential bias in the estimated PK parameters.

Routine erythropoietin (Epo) therapy for neonatal anemia is presently controversial due to its modest response. We speculate that an important contributor to this modest response is that previous clinical study designs were not driven by rigorous mechanistic and kinetic insights into the complex pharmacokinetics (PK) and pharmacodynamics (PD) of Epo in this population. To address this therapeutic opportunity, we conducted a prospective clinical study to investigate the PK of Epo in very-low-birth-weight (VLBW) premature neonates using a unique Epo dosing algorithm that accounts for complex neonatal erythropoietic physiology. Twenty-seven subjects received up to 10 intravenous or subcutaneous exogenous doses of Epo (600 or 1200 U/kg) during the first 4 weeks of life. Subjects were administered two doses of Epo 1200 U/kg on days 2 and 16, and eight doses of Epo 600 U/kg on days 4, 5, 6, 7, 9, 14, 15, and 28 following birth. We have developed for the first time a mechanistic, target-mediated disposition model that provides novel insights into the mechanisms driving Epo PK in VLBW neonates. Epo association rate, k on , was estimated to be 0.00610 pM -1 h -1 , and the dissociation rate k off was 0.112 h -1 . Internalization of the Epo-target complex (k int ) and the total receptor concentration (R max ) were estimated to be 0.118 h -1 and 133 pM, respectively. Following s.c. administration, the absorption rate (k a ) of Epo was 0.0738h -1 and bioavailability was 78.0%. Our mechanism-based population pharmacokinetic analysis provided quantitative insight into Epo kinetics in VLBW neonates; the information gained will assist in deriving dosing strategies for neonatal anemia and for neuroprotection efficacy studies., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Erythropoietin (EPO) is a potential therapeutic for Alzheimer's disease (AD); however, limited blood-brain barrier (BBB) penetration reduces its applicability as a CNS therapeutic. Antibodies against the BBB transferrin receptor (TfRMAbs) act as molecular Trojan horses for brain drug delivery, and a fusion protein of EPO and TfRMAb, designated TfRMAb-EPO, is protective in a mouse model of AD. TfRMAbs have Fc effector function side effects, and removal of the Fc N-linked glycosylation site by substituting Asn with Gly reduces the Fc effector function. However, the effect of such Fc mutations on the pharmacokinetics (PK) of plasma clearance of TfRMAb-based fusion proteins, such as TfRMAb-EPO, is unknown. To examine this, the plasma PK of TfRMAb-EPO (wild-type), which expresses the mouse IgG1 constant heavy chain region and includes the Asn residue at position 292, was compared to the mutant TfRMAb-N292G-EPO, in which the Asn residue at position 292 is mutated to Gly. Plasma PK was compared following IV, IP, and SQ administration for doses between 0.3 and 3 mg/kg in adult male C57 mice. The results show a profound increase in clearance (6- to 8-fold) of the TfRMAb-N292G-EPO compared with the wild-type TfRMAb-EPO following IV administration. The clearance of both the wild-type and mutant TfRMAb-EPO fusion proteins followed nonlinear PK, and a 10-fold increase in dose resulted in a 7- to 11-fold decrease in plasma clearance. Following IP and SQ administration, the C max values of the TfRMAb-N292G-EPO mutant were profoundly (37- to 114-fold) reduced compared with the wild-type TfRMAb-EPO, owing to comparable increases in plasma clearance of the mutant fusion protein. The wild-type TfRMAb fusion protein was associated with reticulocyte suppression, and the N292G mutation mitigated this suppression of reticulocytes. Overall, the beneficial suppression of effector function via the N292G mutation may be offset by the deleterious effect this mutation has on the plasma levels of the TfRMAb-EPO fusion protein, especially following SQ administration, which is the preferred route of administration in humans for chronic neurodegenerative diseases including AD.

The objective of the current study was to develop a population pharmacokinetics (PK) model for erythropoietin (Epo) in premature infants and healthy adults to characterize the variation in PK, and to study the differences in Epo PK in these 2 populations. Thirteen very low-birth-weight premature infants (<1500 g at birth), and 10 healthy adults received up to 4 intravenous doses of Epo that ranged from 10 to 500 U/kg. The final model had a target-mediated saturable, nonlinear, elimination pathway that incorporated the mechanism of Epo binding to its receptors along with a parallel linear, central elimination pathway. Epo clearance was found to be significantly higher in preterm infants compared to adults. Epo clearance via the nonlinear pathway was found to be much higher in infants; they had an Epo receptor capacity of 133 pM vs 86.6 pM in adults, which is most likely due to the higher erythroid progenitor cell mass per kilogram of body weight in infants. The parallel linear elimination was found to be more dominant in adults, reaching 91% of the total clearance with a 500-U/kg dose compared to just 6.1% of the total clearance following the same dose in preterm infants. Thus, this mechanism-based population PK model revealed that receptor-based nonlinear elimination is the dominant Epo elimination pathway in premature infants, and parallel linear elimination is dominant in adults., (© 2019, The American College of Clinical Pharmacology.)

Excessive fluid intake, that is, hyperhydration, may be adopted by athletes as a masking method during antidoping sample collection to influence the excretion patterns of doping agents and, therefore, manipulate their detection. The aim of this exploratory study was to assess the hyperhydration effect on the detection sensitivity of recombinant human erythropoietin (rHuEPO) by sodium N-lauroyl sarcosinate ("sarkosyl") polyacrylamide gel electrophoresis analysis. The influence of hyperhydration on the serum and urinary pharmacokinetic (PK) profiles of rHuEPO was also investigated. Seven healthy physically active nonsmoking Caucasian males participated in a 31-day clinical study comprising a baseline (days 0, 1-3, and 8-10) and a drug phase (days 15-17, 22-24, and 29-31). Epoetin beta was administered subcutaneously at a single dose of 3000 IU on days 15, 22, and 29. Hyperhydration was applied in the morning on 3 consecutive days (days 1-3, 8-10, 22-24, and 29-31), that is, 0, 24, and 48 h after first fluid ingestion. Water and a commercial sports drink were used as hyperhydration agents (20 mL/kg body weight). Serum and urinary concentration-time profiles were best described by a one-compartment PK model with zero-order absorption. Delayed absorption was observed after hyperhydration and, therefore, lag time was introduced in the PK model. Results showed no significant difference (p > 0.05) on serum or urinary erythropoietin concentrations under hyperhydration conditions. A trend for decreasing volume of distribution and increasing clearance after hyperhydration was observed, mainly after sports drink consumption. However, no significant differences (p > 0.05) due to hyperhydration for any of the serum PK parameters calculated by noncompartmental PK analysis were observed. Renal excretion of endogenous erythropoietin and rHuEPO, as reflected on the urinary cumulative amount, was increased approximately twice after hyperhydration and this supports the nonsignificant difference on the urinary concentrations. Analysis of serum and urine samples was able to detect rHuEPO up to 72 h after drug administration. The detection window of rHuEPO remained unaffected after water or sports drink ingestion. Hyperhydration had no effect on the detection sensitivity of EPO either in serum or urine samples., (Copyright © 2019 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Background: Paraplegia remains a significant complication of thoracoabdominal aortic intervention. We previously reported that diazoxide (DZ), enhances the neuroprotective efficacy of erythropoietin (EPO). We hypothesized that DZ and EPO combined treatment attenuates spinal cord ischemic injury through upregulation of nerve growth factor (NGF)., Methods: DZ (pretreatment) was given to adult male C57/BL6 mice by oral gavage and EPO (before surgery) was intraperitoneally injected 32 h after administration of DZ. Spinal cords were harvested 0, 2, 4, and 6 h after injection of EPO. NGF expression was analyzed by western blot. After determining the optimal time, NGF expression was compared between DZ (pretreatment) + EPO (before surgery), DZ + PBS, PBS + EPO, and PBS + PBS (ischemic control). Four groups were studied to compare the motor function after ischemia: DZ + EPO (n = 11), ischemic control (n = 9), DZ + EPO + tropomyosin receptor kinase A receptor inhibitor (n = 9), and sham (without cross-clamp, n = 4). Spinal cord ischemia was induced by a 4-min thoracic aortic cross-clamp. Functional scoring (Basso Mouse Score) was done at 12-h intervals until 48 h, and spinal cords were harvested for evaluation of NGF expression and histological changes., Results: NGF expression was significantly upregulated 4 h after administration of EPO. At 4 h after injection of EPO, NGF expression in the DZ + EPO group was significantly higher than that in the other groups. DZ + EPO significantly preserved motor function compared with all other groups. At 48 h after reperfusion, the level of NGF expression in the DZ + EPO group, was significantly higher than in all other groups., Conclusions: DZ + EPO attenuates spinal cord ischemic injury through upregulation of NGF. Better understanding of this mechanism may serve to further prevent ischemic complications for aortic intervention., (Published by Elsevier Inc.)

Hosseini M, Azampour H, Raeisi S, Behtari M, Valizadeh H, Saboohi R. The effects of enteral artificial amniotic fluid-containing erythropoietin on short term outcomes of preterm infants. Turk J Pediatr 2019; 61: 392-398. Necrotizing Enterocolitis (NEC) is a common devastating gastrointestinal disease, which usually develops in premature infants. Erythropoietin (EPO) as a hematopoietic hormone produced by the kidney can also be naturally found in amniotic fluid and breast milk. There is some evidence that supports the contribution of EPO in the prevention of inflammation and intestinal tissue repair. This study was aimed to determine if oral administration of artificial amniotic fluid with or without EPO would protect preterm infants against NEC and improve the certain neonatal outcomes. In this study, 150 preterm infants with gestational age 28 weeks or less and birth weight 1250 grams or less were enrolled. The infants were divided randomly into 3 groups: 1) Control group (n=50) with routine feeding protocol without any administration; 2) Amniotic fluid group (n=50) with 5mL/kg synthetic amniotic fluid; 3) EPO group (n=50) with RhuEPO dissolved in the synthetic amniotic fluid. The administrations of the study solution were started 3 days after the birth and were continued for 3 weeks (21 days). The infants in the study groups were followed up until discharge and the frequency of NEC, mortality, and other complications of the disease among the groups were compared. The mortality rate in preterm infants of the amniotic fluid and EPO groups were significantly lower than in the control group (p=0.027). We couldn`t find any significant differences in the frequency of NEC and other complications among the three study groups. The administration of synthetic amniotic fluid (with or without EPO) in preterm infants may decrease the mortality rate. Use of EPO in synthetic amniotic fluid did not affect the frequency of NEC.

Erythropoietin (EPO), a glycoprotein cytokine essential to hematopoiesis, has neuroprotective effects in rodent models of Alzheimer's disease (AD). However, high therapeutic doses or invasive routes of administration of EPO are required to achieve effective brain concentrations due to low blood-brain barrier (BBB) penetrability, and high EPO doses result in hematopoietic side effects. These obstacles can be overcome by engineering a BBB-penetrable analog of EPO, which is rapidly cleared from the blood, by fusing EPO to a chimeric monoclonal antibody targeting the transferrin receptor (cTfRMAb), which acts as a molecular Trojan horse to ferry the EPO into the brain via the transvascular route. In the current study, we investigated the effects of the BBB-penetrable analog of EPO on AD pathology in a double transgenic mouse model of AD. Five and a half month old male APPswe/PSEN1dE9 (APP/PS1) transgenic mice were treated with saline ( n = 10) or the BBB-penetrable EPO ( n = 10) 3 days/week intraperitoneally for 8 weeks, compared to same-aged C57BL/6J wild-type mice treated with saline ( n = 8) with identical regiment. At 9 weeks following treatment initiation, exploration and spatial memory were assessed with the open-field and Y-maze test, mice were sacrificed, and brains were evaluated for Aβ peptide load, synaptic loss, BBB disruption, microglial activation, and microhemorrhages. APP/PS1 mice treated with the BBB-penetrable cTfRMAb-EPO fusion protein had significantly lower cortical and hippocampal Aβ peptide number ( p < 0.05) and immune-positive area ( p < 0.05), a decrease in hippocampal synaptic loss ( p < 0.05) and cortical microglial activation ( p < 0.001), and improved spatial memory ( p < 0.05) compared with APP/PS1 saline controls. BBB-penetrating EPO was not associated with microhemorrhage development. The cTfRMAb-EPO fusion protein offers therapeutic benefits by targeting multiple targets of AD pathogenesis and progression (Aβ load, synaptic loss, microglial activation) and improving spatial memory in the APP/PS1 mouse model of AD.

Objective: Doping control is an important and indispensable aspect of fair horse racing; genetic doping has been recently included to this. In this study, we aimed to develop a detection method of gene doping. A plasmid cloned with human erythropoietin gene (p.hEPO, 250 μg/head) was intramuscularly injected into a microminipig. Subsequently, p.hEPO was extracted from 1 mL of plasma and detected by droplet digital polymerase chain reaction., Results: The results confirmed that the maximum amount of plasmid was detected at 15 min after administration and the majority of the plasmid was degraded in the bloodstream within 1-2 days after administration. In contrast, low amounts of p.hEPO were detected at 2-3 weeks after administration. These results suggest that the proposed method to detect gene doping can help obtain information for experiments using horses.

Oral delivery of protein drugs is greatly limited by low hydrophobicity, an important determinant for intestinal epithelial permeation and bioavailability. Herein, surface properties of recombinant erythropoietin were investigated using the fluorescent dye bis-ANS to monitor relative hydrophobicity for correlation with permeabilities with Caco-2 cells. At various pHs, bis-ANS fluorescence intensity indicated different surface hydrophobicities of erythropoietin molecules. Erythropoietin incorporated in chitosan or chitosan-trimethylchitosan (CS-TMC) nanoparticles prepared by polyelectrolyte complexation and ionotropic gelation with tripolyphosphate also showed different surface hydrophobicities. Chitosan nanoparticles with erythropoietin provided the most hydrophobic surface, followed by free erythropoietin (in water) and that loaded into CS-TMC nanoparticles. Chitosan nanoparticles were more effective than CS-TMC nanoparticles for permeation of erythropoietin across Caco-2 cell monolayers; the lowest permeability was shown by erythropoietin itself. Thus, hydrophilic protein molecules complexed with polyelectrolytes can provide more hydrophobic surfaces that enhance transepithelial permeability. This bis-ANS method also provides valuable information for the design of polyelectrolyte nanoparticules for oral delivery of protein drugs.

Marketed formulations of erythropoietin (EPO) ior®EPOCIM, MIRCERA® and two newly developed pegylated-EPO analogues (PEG-EPO 32 and 40 kDa) formulations were intravenously administered to New Zealand rabbits. A semi-mechanistic Pharmacokinetic/Pharmacodynamic (PK/PD) model describing in a simultaneous and integrated form the time course of reticulocytes, red blood cells and hemoglobin was built to account for the time course of hematopoiesis stimulation after erythropoietin administration. Data analysis was performed based on the population approach with the software NONMEM version 7.3. Erythropoietin disposition of each of the administered formulations was best described with a two compartment model and linear elimination. Different formulations show different clearance and apparent volume of distribution of the central compartment but share estimates of inter-compartmental clearance and apparent peripheral volume of distribution. A semi-mechanistic model including cell proliferation, maturation, and homeostatic regulation provided a good description of the data regardless the type of erythropoietin formulation administered. The system-, and drug-related parameters showed consistency and differed across formulations, respectively. A single IV administration of PEG-EPO 32 and 40 kDa formulations in New Zealand rabbits achieves a median change of 27% and 22% on RET levels, and of 47% and 63% on RBC and HGB levels, respectively compared to MIRCERA®. The administration of new branched PEG-chains formulations improves PK and PD properties of EPO, in terms of increasing elimination half-lives and pharmacological activity on RET, RBC and HGB compared to commercially available formulations (ior®EPOCIM and MIRCERA®)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The current study aimed to enhance the efficacy of peripheral nerve regeneration using an electrically conductive biodegradable porous neural guidance conduit for transplantation of allogeneic Schwann cells (SCs). The conduit was produced from polylactic acid (PLA), multiwalled carbon nanotubes (MWCNTs), and gelatin nanofibrils (GNFs) coated with the recombinant human erythropoietin-loaded chitosan nanoparticles (rhEpo-CNPs). The PLA/MWCNTs/GNFs/rhEpo-CNPs conduit had the porosity of 85.78 ± 0.70%, the contact angle of 77.65 ± 1.91° and the ultimate tensile strength and compressive modulus of 5.51 ± 0.13 MPa and 2.66 ± 0.34 MPa, respectively. The conduit showed the electrical conductivity of 0.32 S cm -1 and lost about 11% of its weight after 60 days in normal saline. The produced conduit was able to release the rhEpo for at least 2 weeks and exhibited favorable cytocompatibility towards SCs. For functional analysis, the conduit was seeded with 1.5 × 10 4 SCs and implanted into a 10 mm sciatic nerve defect of Wistar rat. After 14 weeks, the results of sciatic functional index, hot plate latency, compound muscle action potential amplitude, weight-loss percentage of wet gastrocnemius muscle and Histopathological examination using hematoxylin-eosin and Luxol fast blue staining demonstrated that the produced conduit had comparable nerve regeneration to the autograft, as the gold standard to bridge the nerve gaps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1463-1476, 2018., (© 2017 Wiley Periodicals, Inc.)

Introduction: Biopharmaceuticals are large protein based drugs which are heterogeneous by nature due to post translational modifications resulting from cellular production, processing and storage. Changes in the abundance of different variants over time are inherent to biopharmaceuticals due to their sensitivity to subtle process differences and the necessity for regular manufacturing changes. Product variability must thus be carefully controlled to ensure that it does not result in changes in safety or efficacy., Areas Covered: The focus of this manuscript is to provide improved understanding of the science and strategies used to maintain the quality and clinical performance of biopharmaceuticals, including biosimilars, throughout their lifecycle. This review summarizes rare historical instances where clinically relevant changes have occurred, defined here as clinical drift, and discusses modern tools used to prevent such changes, including improved analytics, quality systems and regulatory frameworks., Expert Opinion: Despite their size complexity and heterogeneity, modern analytics, manufacturing quality systems and comparability requirements for the evaluation of manufacturing changes cumulatively help to ensure the consistent quality and clinical performance of biopharmaceuticals throughout their product lifecycle. Physicians and patients can expect the same safety and efficacy from biopharmaceuticals and their respective biosimilars irrespective of batch or production history.

Background: While protein therapeutics are invaluable in managing numerous diseases, many require frequent injections to maintain therapeutically effective concentrations, due to their short half-life in circulation. PolyXen™, a platform and patented technology employing biodegradable, non-immunogenic and hydrophilic Polysialic Acids (PSA) for drug delivery, is being utilized to overcome such limitations, thereby potentially enabling the clinical utility of a broad range of protein therapeutics. Here, we report the recent progress on two development candidates, polysialylated deoxyribonuclease I (PSA-DNase) and polysialylated erythropoietin (PSA-EPO)., Methods and Results: Chemical polysialylation of DNase I (DNase) using PSA with different chain length at various conjugation sites led to improved stability against proteases and thermal stress, and slightly reduced enzymatic activity. Polysialylation of EPO resulted in retention of protein structure and PSA-EPO remained biologically active. PSA-EPO had a significantly prolonged circulating half-life (e.g. t1/2 of PSA-EPO = ~400 h in patients after subcutaneous administration, aimed for once monthly administration, vs. t1/2 of EPO = ~22 h; administered twice or thrice weekly), and retained in vivo efficacy., Conclusion: This approach has been clinically validated in phase I (in healthy volunteers) and II studies of PSA-EPO [for managing anemia in patients with chronic kidney disease (CKD)]., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The aim of this study is to test the permeation of human recombinant erythropoietin (rHuEPO) across conjunctiva, cornea, and sclera in an ex vivo model. Thirty fresh pig eyes were collected from a slaughterhouse. Conjunctivas (n = 10), corneas (n = 10), and scleras (n = 10) were surgically dissected from surrounding tissues. Ocular membranes were placed into Franz diffusion cells and rHuEPO was administered into the donor phase of each cell, except for control samples. Samples were collected from the receptor phase at seven time points, from 30 min to 6 h of incubation. Erythropoietin (EPO) was quantified by enzyme-linked immunosorbent assay (ELISA) technique. Ocular membranes immunohistochemistry was also performed at the end of the study. EPO was detected in all test samples. After 6 h of incubation, conjunctiva was the most permeable membrane to rHuEPO (509.3 ± 89.8 mIU/cm 2 , corresponding to 0.52% of the total rHuEPO administered on the donor phase), followed by sclera (359.1 ± 123.7 mIU/cm 2 , corresponding to 0.35%) and finally cornea (71.0 ± 31.8 mIU/cm 2 , corresponding to 0.07%). Differences between ocular membranes' permeation were statistically significant (p < 0.001). EPO immunostaining signal was positive for the three ocular membranes. We have demonstrated in an ex vivo model that porcine conjunctiva, cornea, and sclera are permeable to rHuEPO protein. These are promising results concerning ocular EPO administration.

Erythropoietin (EPO) has been well known as a hematopoietic cytokine over the past decades. However, recent reports have demonstrated that EPO plays a neuroprotective role in the central nervous system, and EPO has been considered as a therapeutic target in neurodegenerative diseases such as ischemic stroke. Despite the neuroprotective effect of EPO, clinical trials have shown its unexpected side effects, including undesirable proliferative effects such as erythropoiesis and tumor growth. Therefore, the development of EPO analogs that would confer neuroprotection without adverse effects has been attempted. In this study, we examined the potential of a novel EPO-based short peptide, MK-X, as a novel drug for stroke treatment in comparison with EPO. We found that MK-X administration with reperfusion dramatically reduced brain injury in an in vivo mouse model of ischemic stroke induced by middle cerebral artery occlusion, whereas EPO had little effect. Similar to EPO, MK-X efficiently ameliorated mitochondrial dysfunction followed by neuronal death caused by glutamate-induced oxidative stress in cultured neurons. Consistent with this effect, MK-X significantly decreased caspase-3 cleavage and nuclear translocation of apoptosis-inducing factor induced by glutamate. MK-X completely mimicked the effect of EPO on multiple activation of JAK2 and its downstream PI3K/AKT and ERK1/2 signaling pathways, and this signaling process was involved in the neuroprotective effect of MK-X. Furthermore, MK-X and EPO induced similar changes in the gene expression patterns under glutamate-induced excitotoxicity. Interestingly, the most significant difference between MK-X and EPO was that MK-X better penetrated into the brain across the brain-blood barrier than did EPO. In conclusion, we suggest that MK-X might be used as a novel drug for protection from brain injury caused by ischemic stroke, which penetrates into the brain faster in comparison with EPO, even though MK-X and EPO have similar protective effects against excitotoxicity.

Background: High-dose erythropoietin (Epo) is a promising neuroprotective treatment in neonates with hypoxic-ischemic encephalopathy (HIE) receiving hypothermia. We evaluated the pharmacokinetics and dose-exposure relationships of high-dose Epo in this population to inform future dosing strategies., Methods: We performed a population pharmacokinetic analysis of 47 neonates with HIE treated with hypothermia who received up to six doses of Epo in two previous clinical trials. We compared the ability of different dosing regimens to achieve the target neuroprotective Epo exposure levels determined from animal models of hypoxic-ischemia (i.e., area under the curve during the first 48 h of treatment (AUC 48 h ) 140,000 mU*h/ml)., Results: Birth weight scaled via allometry was a significant predictor of Epo clearance and volume of distribution (P < 0.001). After accounting for birth weight, variation in Epo pharmacokinetics between neonates was low (CV% 20%). All 23 neonates who received 1,000 U/kg every 24 h for the first 2 d of therapy achieved the target AUC 48 h 140,000 mU*h/ml. No neonate who received a lower dosing regimen achieved this target., Conclusion: In neonates with HIE receiving hypothermia, Epo 1,000 U/kg every 24 h for the first 2 d of therapy resulted in consistent achievement of target exposures associated with neuroprotection in animal models.

Vesicular phospholipid gels (VPGs) are depot formulations for the sustained release of drugs which are characterized by a high amount of phospholipids in the formulation. They consist of physiological excipients only and therefore display high biocompatibility. Their manufacture is simple, cheap, solvent free, and ideal for the processing of proteins and peptides because of the low stress on the molecule, for example, by elevated temperatures. One major hurdle of VPGs is their high viscosity which makes them hard to almost impossible to inject with conventional, thin needles used for subcutaneous administration. However, so far no data are published to overcome this administration challenge. In the present study, needle-free injection was investigated and successfully applied as a technology for the easy and elegant administration of VPGs. VPGs with different phospholipid content were injected with a Biojector 2000 into gelatin blocks and full thickness pig skin postmortem as in vitro models and the injection depth was determined after injection. The release behavior was tested after shearing the VPG with the device to evaluate the effect of shearing on the drug release from the formulation. No differences were observed when compared to an ejection with needle and syringe., (Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Erythropoietin (EPO) is the principal hormone which, has somewhat short half-life involved in the differentiation and regulation of circulating red blood cells. The present study was carried out to evaluate the capability of a polyethylene glycol mimetic technology as a biological alternative to improve pharmaceutical properties of human recombinant EPO. In silico models of EPO fused to 200 amino acids of proline, alanine, and serine (PAS) were initially generated and assessed by molecular dynamic (MD) simulation. The fluctuations of the modeled structure reached a plateau after 6000 ps of MD simulation. The Phi and psi analysis showed >99.2% of residues were located in the allowed regions. An expression vector consisting of EPO cDNA tagged to PAS coding sequences was synthesized and expressed in CHO-K1 Cells. The produced PASylated molecule was purified and characterized by standard analytical methods. The molecular weight of fusion protein was expanded to 70 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis method. Analytical size exclusion chromatography revealed an approximately sevenfold increase in apparent size of produced protein. Although the in vitro potency of the fusion protein was significantly reduced (1.26 ± 0.05 vs. 0.24 ± 0.03 ng/ml) but, the in vivo activity was considerably increased up to 1.58 × 10 5 IU/ml in normocythemic mice assay. Pharmacokinetic animal studies revealed strongly 15.6-fold plasma half-life extension for the PASylated EPO (83.16 ± 13.28 h) in comparison to epoetin α (8.5 ± 2.4 h) and darbepoetin α (25.3 ± 2.2h).

Erythropoietin (EPO), recognized early as a tissue protective agent, can trigger antiinflammatory and anti-apoptotic processes to delimit injury and promote repair by binding tissueprotective receptor (TPR). However, only at a high dosage can EPO exert tissue protective effect, which may elicit severe side-effects at the meantime. Helix B surface peptide (HBSP), a 11-amnio acid sequence derived from the non-erythropoietic helix B of EPO, not only shows higher affinity to TPR but also plays a more specific and powerful role in tissue protection without erythropoietic side-effects. While it has obvious merits, the 2-min plasma half-life of HBSP restricts its application in vivo. Therefore, based on the amino acid sequence of HBSP, we originally designed and synthesized thioethercyclized helix B peptide (CHBP) for an increased resistance to proteolytic degradation as well as an improved tissue protective potency, implying a brighter prospective for translational application. In this review, we will mainly discuss the development from EPO to CHBP, the merits and limitation of CHBP and the probable mechanism mediating tissue protection., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Unlabelled: The development of chemoselective, site-specific chemistries for proteins/peptides is essential for biochemistry, pharmaceutical chemistry, and other fields. In this work, we found that catechol, which has been extensively utilized as an adhesive molecule for material-independent surface chemistry and as a crosslinker in hydrogel preparation, specifically reacts with N-terminal α-amines, avoiding the ε-amine group in lysine. A conjugate of methoxy-poly(ethylene glycol)-catechol called mPEG-cat chemoselectively reacts with N-terminal amine groups at neutral pH resulting in site-specific PEGylation. To demonstrate the versatility of this catechol chemoselective reaction, we used four proteins (lysozyme, basic-fibroblast growth factor (bFGF), granulocyte-colony stimulating factor (G-CSF), insulin, and erythropoietin (EPO)) as well as two peptides (hinge-3 and laminin-derived peptide (LDP)). All the tested macromolecules showed N-terminal site-specific modifications. Furthermore, we prepared another catechol grafted conjugate called hyaluronic acid-catechol (HA-cat) to demonstrate that this catechol-involved chemoselective chemistry is not specific for PEG conjugates. This new catechol chemoselective chemistry could be a new platform for the functionalization of proteins and peptides for a variety of purposes., Statement of Significance: Considering the fact that biological activities of proteins or peptides depend largely on their 3-dimensional conformation, the orientation-controllable reaction is very important for preserving the intrinsic functionality of them. In addition to PEG, many other bio-polymers such as oligonucleotides, antibodies, and oligosaccharides have been conjugated with proteins or peptides for various biomedical applications. Although several chemoselective conjugation chemistries have been reported, conjugation efficiencies are different depending on types of proteins or polymers, and thus there've been strong needs for the development of alternative strategy of chemoselective conjugation that can be applied for a variety of therapeutic proteins towards high biological activities. We are certain this new catechol chemoselective chemistry could be a new platform for the functionalization of proteins and peptides for various purposes., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Erythropoiesis-stimulating agents (ESAs) are widely used for treating chronic kidney disease (CKD)-associated anemia. The biological activity of ESAs is mainly regulated by the number of sialic acid-containing carbohydrates on the erythropoietin (EPO) peptide. Sialidase, a sialic acid-metabolizing enzyme that accumulates in CKD patients, is suspected of contributing to shortening the circulation half-life of ESAs. Epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.), is an EPO integrated with methoxypolyethylene glycol (PEG). It has been suggested that C.E.R.A. may exert a favorable therapeutic effect, even under conditions of elevated sialidase; however, no detailed investigation of the pharmacological profile of C.E.R.A. in the presence of sialidase has been reported. In the present study, we injected C.E.R.A. or EPO pre-incubated with sialidase into rats, and assessed the hematopoietic effect by reticulocyte count. The hematopoietic effect of C.E.R.A., but not EPO, was preserved after sialidase treatment, despite the removal of sialic acid. Proliferation of EPO-dependent leukemia cells (AS-E2) was significantly increased by desialylated C.E.R.A. and EPO compared to non-treated C.E.R.A. or EPO. In conclusion, we show that C.E.R.A. exerts a favorable hematopoietic effect even under conditions of elevated sialidase. Our findings may contribute to a better understanding of CKD and more effective therapeutic approaches based on a patient's profile of anemia.

The model-independent estimation of physiological steady-state volume of distribution ([Formula: see text]), often referred to non-compartmental analysis (NCA), is historically based on the linear compartment model structure with central elimination. However the NCA-based steady-state volume of distribution ([Formula: see text]) cannot be generalized to more complex models. In the current paper, two-compartment models with simultaneous first-order and Michaelis-Menten elimination are considered. In particular, two indistinguishable models [Formula: see text] and [Formula: see text], both having central Michaelis-Menten elimination, while first-order elimination exclusively either from central or peripheral compartment, are studied. The model-based expressions of the steady-state volumes of distribution [Formula: see text] and their relationships to NCA-based [Formula: see text] are derived. The impact of non-linearity and peripheral elimination is explicitly delineated in the formulas. Being concerned with model identifiability and indistinguishability issues, an interval estimate of [Formula: see text] is suggested.

Purpose: The present study aimed to determine whether the subconjunctival administration of recombinant human erythropoietin (rHuEPO) reached the retina in glaucoma conditions. After subconjunctival rHuEPO administration, in a rat glaucoma model, erythropoietin (EPO) distribution in the rat's retina was studied by immunohistochemistry., Methods: Female Wistar Hannover albino rats (n = 15) were divided into 2 groups, control (n = 3) and treated (n = 12). The animals' unilateral glaucoma was induced by coagulation of episcleral veins, under general anaesthesia. After vein coagulation, 1,000 IU of rHuEPO were administered by the subconjunctival route to the treated group (n = 12). The control group (n = 3) received only a subconjunctival saline injection. The contralateral eye of each animal remained untouched. Treated group animals were euthanized at different time points, i.e. days 1, 3, 7 and 14. Bilateral enucleation was performed, and EPO distribution in the rat's retina was assessed by immunohistochemistry., Results: Glaucoma was confirmed by results of repeated intraocular pressure measurements over the experimental period. In the test group, EPO was identified in different neuroretinal cells, showing a stronger immunostaining signal during the first 2 time points in the retinal ganglion cell (RGC) layer. EPO protein was still present on day 14 after the subconjunctival injection. EPO was not detected in any of the control eyes or in any contralateral eye of the treated group., Conclusion: When administered subconjunctivally to glaucomatous eyes, rHuEPO reached the RGC layer and was still present at least 14 days after administration. The subconjunctival route was shown to be a promising alternative for ocular EPO delivery in glaucomatous conditions in a rat animal model., (© 2016 S. Karger AG, Basel.)

Purpose: To test the efficacy of systemic gene delivery of a mutant form of erythropoietin (EPO-R76E) that has attenuated erythropoietic activity, in a mouse model of autosomal dominant retinitis pigmentosa., Methods: Ten-day old mice carrying one copy of human rhodopsin with the P23H mutation and both copies of wild-type mouse rhodopsin (hP23H RHO+/-,mRHO+/+) were injected into the quadriceps with recombinant adeno-associated virus (rAAV) carrying either enhanced green fluorescent protein (eGFP) or EpoR76E. Visual function (electroretinogram) and retina structure (optical coherence tomography, histology, and immunohistochemistry) were assessed at 7 and 12 months of age., Results: The outer nuclear layer thickness decreased over time at a slower rate in rAAV.EpoR76E treated as compared to the rAAV.eGFP injected mice. There was a statistically significant preservation of the electroretinogram at 7, but not 12 months of age., Conclusions: Systemic EPO-R76E slows death of the photoreceptors and vision loss in hP23H RHO+/-,mRHO+/+ mice. Treatment with EPO-R76E may widen the therapeutic window for retinal degeneration patients by increasing the number of viable cells. Future studies might investigate if co-treatment with EPO-R76E and gene replacement therapy is more effective than gene replacement therapy alone.

The design of cell-targeted protein therapeutics can be informed by natural protein-protein interactions that use cooperative physical contacts to achieve cell type specificity. Here we applied this approach in vivo to the anemia drug erythropoietin (EPO), to direct its activity to EPO receptors (EPO-Rs) on red blood cell (RBC) precursors and prevent interaction with EPO-Rs on nonerythroid cells, such as platelets. Our engineered EPO molecule was mutated to weaken its affinity for EPO-R, but its avidity for RBC precursors was rescued via tethering to an antibody fragment that specifically binds the human RBC marker glycophorin A (huGYPA). We systematically tested the impact of these engineering steps on in vivo markers of efficacy, side effects, and pharmacokinetics. huGYPA transgenic mice dosed with targeted EPO exhibited elevated RBC levels, with only minimal platelet effects. This in vivo selectivity depended on the weakening EPO mutation, fusion to the RBC-specific antibody, and expression of huGYPA. The terminal plasma half-life of targeted EPO was ∼28.3 h in transgenic mice vs. ∼15.5 h in nontransgenic mice, indicating that huGYPA on mature RBCs acted as a significant drug sink but did not inhibit efficacy. In a therapeutic context, our targeting approach may allow higher restorative doses of EPO without platelet-mediated side effects, and also may improve drug pharmacokinetics. These results demonstrate how rational drug design can improve in vivo specificity, with potential application to diverse protein therapeutics.

Purpose: The purpose of this study was to evaluate the pharmacodynamic (PD) and pharmacokinetic (PK) equivalences of multiple doses of the proposed biosimilar Epoetin Hospira to the reference product Epogen(⁎), when each is administered three times per week over 28 days to healthy male subjects, Methods: This single center, open-label, randomized, parallel group study was conducted in 129 healthy male subjects. Subjects were randomized to receive 100 U/kg Epoetin Hospira or 100 U/kg Epogen, each administered subcutaneously 3 times per week over 28 days. Blood was collected for determination of hemoglobin (Hb) concentrations for PD properties and for determination of epoetin concentrations for PK properties. The primary PD end point was the geometric mean ratio (GMR) of the 2 treatments for area under the effect curve for Hb from day 1 through 48 hours after the final dose of study drug administration on day 26, and the primary PK end point was the GMR of the 2 treatments for AUC0-48 and Cmax for epoetin after the final dose of study drug on day 26., Findings: The GMR (Epoetin Hospira/Epogen) for the area under the effect curve for Hb from day 1 through 48 hours after the final dose of study drug administration on day 26 was 1.006 with a 95% CI of 0.996 to 1.016, which was contained within the prespecified equivalence margin of 0.965 to 1.035. The GMRs (Epoetin Hospira/Epogen) for the epoetin-derived PK parameters were 0.974 for AUC0-48 with a 90% CI of 0.896 to 1.059, and 0.938 for Cmax with a 90% CI of 0.839 to 1.049, with both 90% CIs contained within the prespecified equivalence margin of 0.80 to 1.25. The incidence (21.2% and 23.8% for Epoetin Hospira and Epogen, respectively) and severity of adverse events were similar between the 2 groups. One subject in each treatment group had a positive recombinant human erythropoietin antibody result by radioimmunoprecipitation assay before dosing and throughout study conduct with negative immunoglobulin M and neutralizing antibodies and with no evidence of clinical deterioration or of impact on PD, PK, or safety profile., Implications: The results of this study established PD and PK equivalences of multiple subcutaneous doses of the proposed biosimilar Epoetin Hospira to the reference product Epogen in healthy male subjects, and supported the overall demonstration of biosimilarity of Epoetin Hospira and Epogen., (Copyright © 2016. Published by Elsevier Inc.)

Cysteine PEGylation includes several steps, and is difficult to manage in practice. In the current investigation, the cysteine PEGylation of erythropoietin analogs was examined using computational and nonglycosylated systems to define a simpler approach for specific PEGylation. Two model analogs (E31C and E89C) were selected for PEGylation based on lowest structural deviation from the native form, accessibility, and nucleophilicity of the free thiol group. The selected analogs were cloned and the expression was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot using Coomassie blue staining and anti-His monoclonal antibody, respectively. PEGylation with 20 kDa mPEG-maleimide resulted in 79% and 82% conjugation yield for E31C and E89C nonglycosylated erythropoietin (ngEPO) analogs, respectively. The size distribution and charge analysis showed an increase in size and negative charge of the PEGylated forms compared with nonconjugated ones. Biological assay revealed that E31C and E89C mutations and subsequent PEGylation of ngEPO analogs have no deleterious effects on in vitro biological activity when compared to CHO-derived recombinant human erythropoietin. In addition, PEG-conjugated ngEPOs showed a significant increase in plasma half-lives after injection into rats when compared to nonconjugated ones. The development of the cysteine-PEGylated proteins using nonglycosylated expression system and in silico technique can be considered an efficient approach in terms of optimization of PEGylation parameters, time, and cost.

The recombinant human erythropoietins epoetin alfa (Eprex®), darbepoetin (Aranesp®) and methoxy polyethylene glycol-epoetin beta (Mircera®) were administered to greyhounds for 7, 10 and 14 days respectively. Blood and urine samples were collected and analysed for erythropoietin by ELISA, LC-MS/MS and western blotting. Limits of confirmation in plasma for western blotting and LC-MS/MS methods ranged from a low of 2.5mIU/mL, and closely matched the sensitivity of ELISA screening., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: Adequately powered studies directly comparing hard clinical outcomes of darbepoetin alfa (DPO) versus epoetin alfa (EPO) in patients undergoing dialysis are lacking., Study Design: Observational, registry-based, retrospective cohort study; we mimicked a cluster-randomized trial by comparing mortality and cardiovascular events in US patients initiating hemodialysis therapy in facilities (almost) exclusively using DPO versus EPO., Setting & Participants: Nonchain US hemodialysis facilities; each facility switching from EPO to DPO (2003-2010) was matched for location, profit status, and facility type with one EPO facility. Patients subsequently initiating hemodialysis therapy in these facilities were assigned their facility-level exposure., Intervention: DPO versus EPO., Outcomes: All-cause mortality, cardiovascular mortality; composite of cardiovascular death, nonfatal myocardial infarction (MI), and nonfatal stroke., Measurements: Unadjusted and adjusted HRs from Cox proportional hazards regression models., Results: Of 508 dialysis facilities that switched to DPO, 492 were matched with a similar EPO facility; 19,932 (DPO: 9,465 [47.5%]; EPO: 10,467 [52.5%]) incident hemodialysis patients were followed up for 21,918 person-years during which 5,550 deaths occurred. Almost all baseline characteristics were tightly balanced. The demographics-adjusted mortality HR for DPO (vs EPO) was 1.06 (95% CI, 1.00-1.13) and was materially unchanged after adjustment for all other baseline characteristics (HR, 1.05; 95% CI, 0.99-1.12). Cardiovascular mortality did not differ between groups (HR, 1.05; 95% CI, 0.94-1.16). Nonfatal outcomes were evaluated among 9,455 patients with fee-for-service Medicare: 4,542 (48.0%) in DPO and 4,913 (52.0%) in EPO facilities. During 10,457 and 10,363 person-years, 248 and 372 events were recorded, respectively, for strokes and MIs. We found no differences in adjusted stroke or MI rates or their composite with cardiovascular death (HR, 1.10; 95% CI, 0.96-1.25)., Limitations: Nonrandom treatment assignment, potential residual confounding., Conclusions: In incident hemodialysis patients, mortality and cardiovascular event rates did not differ between patients treated at facilities predominantly using DPO versus EPO., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Epoetin alfa (EPO) and darbepoetin alfa (DPO) are erythropoiesis-stimulating agents that are widely and interchangeably used for the treatment of anemia in patients with advanced chronic kidney disease and end-stage renal disease. No study has specifically compared the risks of hard study outcomes between EPO and DPO, including mortality., Study Design: Systematic review of the literature and meta-analysis., Setting & Population: Patients enrolled in randomized trials comparing EPO versus DPO for the treatment of anemia in adults with chronic kidney disease, including those requiring dialysis., Selection Criteria for Studies: We conducted a systematic search of the literature (PubMed, CENTRAL, SCOPUS, and EMBASE, all years) and industry resources, using predefined search terms and data abstraction tools. We then summarized key characteristics and findings of these trials and performed a random-effects meta-analysis of trials with at least 3 months' duration to identify the summary OR of mortality between patients randomly assigned to DPO versus EPO., Intervention: DPO versus EPO., Outcome: All-cause mortality., Results: We identified 9 trials that met the stated inclusion criteria. Overall, 2,024 patients were included in the meta-analysis, of whom 126 died during follow-up, which ranged from 20 to 52 weeks. We found no significant difference in mortality between patients randomly assigned to DPO versus EPO (OR, 1.33; 95% CI, 0.88-2.01). No treatment heterogeneity across studies was detected (Q statistic=4.60; P=0.8)., Limitations: Generalizability to nontrial populations is uncertain., Conclusions: Few trials directly comparing DPO and EPO have been conducted and follow-up was limited. In aggregate, no effect of specific erythropoiesis-stimulating agent on mortality was identified, but the confidence limits were wide and remained compatible with considerable harm from DPO. Absent adequately powered randomized trials, observational postmarketing comparative effectiveness studies comparing these erythropoiesis-stimulating agents are required to better characterize the long-term safety profiles of these agents., (Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Objective: Bioequivalence and comparability studies are necessary for changing formulations of large-molecule drugs, such as antibody drugs and protein products, and in the development of their biosimilars. This study is the first application of modeling and simulation (M&S) in the design of bioequivalence and comparability studies of erythropoietin as an example of a large-molecule drug., Methods: A novel population pharmacokinetic and pharmacodynamic (PPK/PD) model was developed for erythropoietin. Based on this PPK/PD model, the probabilities of success of bioequivalence and comparability studies were simulated with various numbers of subjects and samples., Results: The simulation indicated that the minimum numbers of subjects and samples required to satisfy the criteria for bioequivalence and comparability studies were as follows: fewest for the area under the serum concentration-time curve, more for the area under the efficacy-time curve, and most for the maximum serum concentration of erythropoietin., Conclusion: These results suggested that M&S could be successfully applied in the design of bioequivalence and comparability studies of large-molecule drugs.

Anemia is a frequent complication in patients with chronic kidney disease. However, human recombinant erythropoietin (rHu-EPO) has revolutionized the management of anemia in chronically dialyzed patients. Epomax ® is a new rHu-EPO alfa manufactured in Tunisia (Medis Laboratories). The aim of this study was to evaluate the efficacy and tolerance of Epomax ® in chronic hemodialysis (HD) patients in a phase-III, multicenter, clinical trial. Fiftythree HD patients (mean age 47.7 ± 13 years) who received a stable dose of rHu-EPO (Hemax ® , a rHu-EPO alfa manufactured by Biosidus Laboratories) subcutaneously were switched to Epomax ® via the same route of administration. At baseline, the mean systolic pressure was 132 ± 18 mm Hg and the mean diastolic pressure was 79 ± 8 mm Hg. The mean blood hemoglobin was 10.2 g/dL and the median ferritin level was 667 ng/mL. After a follow-up of 43 days, the mean blood hemoglobin was 10.5 g/dL under the effect of Epomax ® . There was no significant difference in the mean hemoglobin levels between the treatments with both drugs. Few adverse events were reported during the study. We conclude that Epomax ® was effective at maintaining the hemoglobin levels at target concentrations and was well tolerated in HD patients.

Introduction: In the TREAT and RED-HF trials, patients who received a high darbepoetin dose had an increased risk of adverse events. To find an explanation, the published literature was analyzed on the pharmacokinetics and pharmacodynamics of darbepoetin., Areas Covered: Based on the sigmoid Emax model, the concentration producing 50% of the maximum erythropoietin effect is reported as CE50 = 0.41 ng/ml and the Hill coefficient as H = 3.0 for darbepoetin. Accordingly, a pharmacodynamics-based threshold concentration can be estimated with CE05 = 0.153 ng/ml producing 5% of Emax and a ceiling concentration with CE95 = 1.098 ng/ml producing 95% of Emax, respectively., Expert Opinion: Darbepoetin trough levels should not be less than the threshold concentration but peak levels above the ceiling concentration could be associated with an increased risk of adverse events. The time span associated with the concentration fluctuation between the ceiling and the threshold concentration is estimated with 236 h (= 2.84 times elimination half-life of 83 h) and shorter than the 336 h when dosing every other week. According to such time-dependent pharmacodynamics, a weekly dosing regimen might be more effective and associated with less adverse events than higher doses every other week in patients with suboptimal response to a normal darbepoetin dose.