Erythropoietin pharmacology

Role of erythropoietin in the treatment of Alzheimer's disease: the story so far

This review aims to explore the potential of erythropoietin, a glycopeptide hormone, as a treatment option for Alzheimer's disease, which is the commonest cause of dementia. Despite years of focus and research, therapeutic options for Alzheimer's disease are not yet completely satisfactory. And as people age, they are likely to develop Alzheimer's Disease, further pressuring the healthcare system. So, it is definite to develop treatment options that meet superior outcomes with minimal negative effects. A comprehensive review of the literature was conducted in PubMed and Google Scholar using a combination of keywords, including Alzheimer's disease, dementia, erythropoietin, and neuroprotection. Search results were assessed for relevance before using the data for this study. The beneficial implications of erythropoietin as a therapeutic option have been explored, along with the side effects and mechanisms of erythropoietin in Alzheimer's disease. Overall, the authors' review indicates that erythropoietin presents a promising avenue for mitigating the progression of Alzheimer's disease, with minimal associated side effects.

Clinical Pharmacokinetics and Pharmacodynamics of Roxadustat

The pharmacokinetics of roxadustat are well characterized, with an apparent volume of distribution after oral administration of 22–57 L, apparent clearance of 1.2–2.65 L/h, and renal clearance of 0.030–0.026 L/h in healthy volunteers; the elimination half-life is 9.6–16 h. Plasma binding is 99% and the fraction eliminated by hemodialysis is 2.34%. As an interpretation of the pharmacodynamics of roxadustat, we proposed a concept with a hypothetical cascade of two subsequent effects, first on erythropoetin (EPO) and second on hemoglobin (delta Hb). The primary effect on EPO is observed within a few hours after roxadustat administration and can be modeled using the sigmoidal Hill equation. The concentration at half-maximum effect can be inferred at 10–36 µg/mL, the Hill coefficient at 3.3, and the effect bisection time at 10–17 h, corresponding to EPO half-life. The subsequent effect on hemoglobin (delta Hb) is observed after several weeks and can be interpreted as an irreversible, dose proportional, unsaturable effect, continuing in agreement with the lifespan of red blood cells of 63–112 days.

Engineered human FcγRIIa fusion: A novel strategy to extend serum half-life of therapeutic proteins

The immunoglobulin G (IgG) molecule has a long circulating serum half-life (~3 weeks) through pH- dependent FcRn binding-mediated recycling. To hijack the intracellular trafficking and recycling mechanism of IgG as a way to extend serum persistence of non-antibody therapeutic proteins, we have evolved the ectodomain of a low-affinity human FcγRIIa for enhanced binding to the lower hinge and upper CH2 region of IgG, which is very far from the FcRn binding site (CH2-CH3 interface). High-throughput library screening enabled isolation of an FcγRIIa variant (2A45.1) with 32-fold increased binding affinity to human IgG1 Fc (equilibrium dissociation constant: 9.04 × 10^-7  M for wild type FcγRIIa and 2.82 × 10^-8  M for 2A45.1) and significantly improved affinity to mouse serum IgG compared to wild type human FcγRIIa. The in vivo pharmacokinetic profile of PD-L1 fused with engineered FcγRIIa (PD-L1-2A45.1) was compared with that of PD-L1 fused with wild type FcγRIIa (PD-L1-wild type FcγRIIa) and human PD-L1 in mice. PD-L1-2A45.1 showed 11.7- and 9.7-fold prolonged circulating half-life (t_1/2 ) compared to PD-L1 when administered intravenously and intraperitoneally, respectively. In addition, the AUC_inf of PD-L1-2A45.1 was two-fold higher compared to that of PD-L1-wild type FcγRIIa. These results demonstrate that engineered FcγRIIa fusion offers a novel and successful strategy for prolonging serum half-life of therapeutic proteins.

Does recombinant human erythropoietin administration in critically ill COVID-19 patients have miraculous therapeutic effects?

An 80‐year‐old man with multiple comorbidities presented to the emergency department with tachypnea, tachycardia, fever, and critically low O₂ saturation and definitive chest computerized tomography scan findings in favor of COVID‐19 and positive PCR results in 48 hours. He received antiviral treatment plus recombinant human erythropoietin (rhEPO) due to his severe anemia. After 7 days of treatment, he was discharged with miraculous improvement in his symptoms and hemoglobin level. We concluded that rhEPO could attenuate respiratory distress syndrome and confront the severe acute respiratory syndrome coronavirus 2 virus through multiple mechanisms including cytokine modulation, antiapoptotic effects, leukocyte release from bone marrow, and iron redistribution away from the intracellular virus.

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Recombinant human erythropoietin can rapidly correct anemia and symptoms associated with COVID‐19

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Through cytokine modulation, rhEPO exerts its cytoprotective and anti‐apoptotic effects in COVID pneumonia.

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rhEPO takes iron away from intracellular virus into the bone marrow, undermining the viral enzymatic requirements.

Current strategies in extending half-lives of therapeutic proteins

Macromolecular protein and peptide therapeutics have been proven to be effective in treating critical human diseases precisely. Thanks to biotechnological advancement, a huge number of proteins and peptide therapeutics were made their way to pharmaceutical market in past few decades. However, one of the biggest challenges to be addressed for protein therapeutics during clinical application is their fast degradation in serum and quick elimination owing to enzymatic degradation, renal clearance, liver metabolism and immunogenicity, attributing to the short half-lives. Size and hydrophobicity of protein molecules make them prone to kidney filtration and liver metabolism. On the other hand, proteasomes responsible for protein destruction possess the capability of specifically recognizing almost all kinds of foreign proteins while avoiding any unwanted destruction of cellular components. At present almost all protein-based drug formulations available in market are administered intravenously (IV) or subcutaneously (SC) with high dosing at frequent interval, eventually creating dose-fluctuation-related complications and reducing patient compliance vastly. Therefore, artificially increasing the therapeutic half-life of a protein by attaching to it a molecule that increases the overall size (eg, PEG) or helps with receptor mediated recycling (eg, albumin), or manipulating amino acid chain in a way that makes it more prone towards aggregate formation, are some of the revolutionary approaches to avoid the fast degradation in vivo. Half-life extension technologies that are capable of dramatically enhancing half-lives of proteins in circulation (2-100 folds) and thus improving their overall pharmacokinetic (PK) parameters have been successfully applied on a wide range of protein therapeutics from hormones and enzymes, growth factor, clotting factor to interferon. The focus of the review is to assess the technological advancements made so far in enhancing circulatory half-lives and improving therapeutic potency of proteins.

Neuroprotective Agents in the Intensive Care Unit: -Neuroprotective Agents in ICU

Neuroprotection or prevention of neuronal loss is a complicated molecular process that is mediated by various cellular pathways. Use of different pharmacological agents as neuroprotectants has been reported especially in the last decades. These neuroprotective agents act through inhibition of inflammatory processes and apoptosis, attenuation of oxidative stress and reduction of free radicals. Control of this injurious molecular process is essential to the reduction of neuronal injuries and is associated with improved functional outcomes and recovery of the patients admitted to the intensive care unit. This study reviews neuroprotective agents and their mechanisms of action against central nervous system damages.

Erythropoietin for cancer-associated malignant anemia: A meta-analysis

The present study aimed to evaluate the effectiveness of erythropoietin (EPO) for improving cancer-associated malignant anemia. A search was performed for randomized clinical trials, conducted according to the Cochrane manual, using electronic databases including PubMed, EMBASE, the Cochrane Library and ClinicalTrails.gov up to 15 August 2015. A total of 6 eligible studies from 5 articles enrolling a total of 453 patients were entered into the current meta-analysis. Upon EPO treatment, there were significant differences in the change in hemoglobin (HB) levels compared with the placebo at short-term follow-up [mean difference (MD)=0.66; 95% confidence interval (CI), 0.14-1.18; I2=Not applicable; P=0.01) and long-term follow-up (MD=0.10; 95% CI, 0.02-0.18; I2=Not applicable; P=0.01) under the random effects model. For changes in hematocrit (HCT) compared with the placebo, the results revealed there were significant differences at short-term follow-up (MD=2.47; 95% CI, 0.75-4.19; I2=Not applicable; P=0.005) and long-term follow-up (MD=7.60; 95% CI, 6.15-9.05; I2=Not applicable; P<0.00001) under the random effects model. Compared with the placebo in short-term follow-up under the fixed effects model with homogeneity, the result was a significant difference for the transfusion ratio [relative risk (RR)=0.81; 95% CI, 0.67- 0.97; I2=34%; P=0.02) and the transfusion requirements (MD=-0.45; 95% CI, -0.92, 0.03; I2=6%; P=0.07). Funnel plots did not detect any publication bias. These results suggest that EPO was beneficial to alleviate cancer-associated anemia and improve survival outcomes for patients with cancer.

Hormones as doping in sports

Though we may still sing today, as did Pindar in his eighth Olympian Victory Ode, "… of no contest greater than Olympia, Mother of Games, gold-wreathed Olympia…", we must sadly admit that today, besides blatant over-commercialization, there is no more ominous threat to the Olympic games than doping. Drug-use methods are steadily becoming more sophisticated and ever harder to detect, increasingly demanding the use of complex analytical procedures of biotechnology and molecular medicine. Special emphasis is thus given to anabolic androgenic steroids, recombinant growth hormone and erythropoietin as well as to gene doping, the newly developed mode of hormones abuse which, for its detection, necessitates high-tech methodology but also multidisciplinary individual measures incorporating educational and psychological methods. In this Olympic year, the present review offers an update on the current technologically advanced endocrine methods of doping while outlining the latest procedures applied-including both the successes and pitfalls of proteomics and metabolomics-to detect doping while contributing to combating this scourge.

Insertion of an NPVY sequence into the cytosolic domain of the erythropoietin receptor selectively affects erythropoietin-mediated signalling and function

EPO (erythropoietin), the major hormone regulating erythropoiesis, functions via activation of its cell-surface receptor (EPO-R) present on erythroid progenitor cells. One of the most striking properties of EPO-R is its low expression on the cell surface, as opposed to its high intracellular levels. The low cell-surface expression of EPO-R may thus limit the efficacy of EPO that is routinely used to treat primary and secondary anaemia. In a recent study [Nahari, Barzilay, Hirschberg and Neumann (2008) Biochem. J. 410, 409–416] we have shown that insertion of an NPVY sequence into the intracellular domain of EPO-R increases its cell-surface expression. In the present study we demonstrate that this NPVY EPO-R insert has a selective effect on EPO-mediated downstream signalling in Ba/F3 cells expressing this receptor (NPVY-EPO-R). This is monitored by increased phosphorylation of the NPVY-EPO-R (on Tyr479), Akt, JAK2 (Janus kinase 2) and ERK1/2 (extracellular-signal-regulated kinase 1/2), but not STAT5 (signal transducer and activator of transcription 5), as compared with cells expressing wild-type EPO-R. This enhanced signalling is reflected in augmented proliferation at low EPO levels (0.05 units/ml) and protection against etoposide-induced apoptosis. Increased cell-surface levels of NPVY-EPO-R are most probably not sufficient to mediate these effects as the A234E-EPO-R mutant that is expressed at high cell-surface levels does not confer an augmented response to EPO. Taken together, we demonstrate that insertion of an NPVY sequence into the cytosolic domain of the EPO-R confers not only improved maturation, but also selectively affects EPO-mediated signalling resulting in an improved responsiveness to EPO reflected in cell proliferation and protection against apoptosis.

Glycosylation of therapeutic proteins: an effective strategy to optimize efficacy

During their development and administration, protein-based drugs routinely display suboptimal therapeutic efficacies due to their poor physicochemical and pharmacological properties. These innate liabilities have driven the development of molecular strategies to improve the therapeutic behavior of protein drugs. Among the currently developed approaches, glycoengineering is one of the most promising, because it has been shown to simultaneously afford improvements in most of the parameters necessary for optimization of in vivo efficacy while allowing for targeting to the desired site of action. These include increased in vitro and in vivo molecular stability (due to reduced oxidation, cross-linking, pH-, chemical-, heating-, and freezing-induced unfolding/denaturation, precipitation, kinetic inactivation, and aggregation), as well as modulated pharmacodynamic responses (due to altered potencies from diminished in vitro enzymatic activities and altered receptor binding affinities) and improved pharmacokinetic profiles (due to altered absorption and distribution behaviors, longer circulation lifetimes, and decreased clearance rates). This article provides an account of the effects that glycosylation has on the therapeutic efficacy of protein drugs and describes the current understanding of the mechanisms by which glycosylation leads to such effects.

Pharmacokinetic and toxicity study of intravitreal erythropoietin in rabbits

AIM

To study the pharmacokinetics and toxicity of intravitreal erythropoietin (EPO) for potential clinical use.

METHODS

For toxicity study, 4 groups (60 rabbits) with intravitreal injection (IVit) of EPO were studied (10 U, 100 U, or 1,000 U) per eye for single injection and 0.6 U/eye (the designed therapeutic level in rabbits) for monthly injections (6X). Eye examination, flash electroretinogram (ERG), and fluorescein angiography (FA) were carried out before and after injection. The rabbits were killed for histological study at different intervals. For the pharmacokinetic study, after IVit of 5 U EPO into left eyes, 44 rabbits were killed at different intervals, and the EPO levels in vitreous, aqueous, retina and serum were analyzed by enzyme-linked immunosorbent assay.

RESULTS

At all of the time points examined, the eyes were within normal limits. No significant ERG or FA change was observed. The histology of retina remained unchanged. The pharmacokinetic profile of EPO in ocular compartments was summarized as follows. The half-life times of EPO in vitreous, aqueous and serum were 2.84, 3.24 and 2.12 d, respectively; and Cmax were 4615.75, 294.31 and 1.60 U/L, respectively. EPO concentrations in the retina of the injected eye peaked at 1.36 U/g protein at 6 h following injection, with the half-life observed to be 3.42 d.

CONCLUSIONS

IVit of EPO in a wide range is well tolerated and safe for rabbit eyes. At doses up to 10-fold higher than therapeutic levels, EPO has a pharmacokinetic profile with faster clearance, which is favorable for episodic IVit.

Conditions associated with hypertension in a high-risk premature infant

Hypertension is an uncommon but significant problem in high-risk neonates and infants, and the spectrum of potential causes is broad. Here, we describe an extremely premature infant (birth weight, 728 g; gestational age, 27 weeks) with multiple complications and hypertension. During admission, umbilical artery catheters were used for a period of time, and he suffered from respiratory distress syndrome, intraventricular hemorrhage, pulmonary hemorrhage, patent ductus arteriosus, pericardial effusion, heart failure, repeated sepsis, anemia, thrombocytopenia, chronic lung disease, and progressive liver damage. He was treated with multiple medications, including erythropoietin, indomethacin, epinephrine, dopamine, aminophylline, multiple antibiotics, amphotericin B, and total parenteral nutrition. Hypertension was first noted when he was 41 days old, with spontaneous remission. It then recurred, reaching higher than 100 mmHg when he was almost 4 months old. After stopping erythropoietin, hypertension subsided for a short period of time and went up again. Multiple factor-related hypertension in this premature infant was considered. Related literature on hypertension in premature infants is reviewed. In conclusion, multiple factors can influence blood pressure and may induce hypertension in high-risk premature infants. Thus, blood pressure should be closely monitored in high-risk premature infants. Judicious use of all medications and interventions are crucial to decrease the incidence of hypertension in high-risk premature infants.