The erythropoietin-derived peptide ARA 284 reduces tissue wasting and improves survival in a rat model of cancer cachexia.

BACKGROUND: Cancer cachexia (CC) is a severe complication during the last stages of the disease, which is characterized by the substantial loss of muscle and fat mass. Currently, there is no effective treatment of CC. Erythropoietin plays tissue-protective role in different tissues. Based on the structure of erythropoietin, small non-erythropoietic peptides were synthesized, which activate tissue-protective signalling pathways. METHODS: Here, we investigated the influence of the tissue-protective peptide ARA 284 on CC in rats using the Yoshida hepatoma model. RESULTS: Treatment with ARA 284 (1.7 µg/kg/day) counteracted the loss of body weight (12.46 ± 4.82% ARA 284 vs. 26.85 ± 0.88% placebo, P < 0.01), fat mass (P < 0.01), and lean mass (P < 0.01). It improved spontaneous activity of ARA 284-treated animals. Further, gastrocnemius mass was increased (13.2% ARA 284 vs. placebo, P < 0.01) in association with induced p-Akt (P < 0.01) and decreased in p-p38 MAPK, GSK-3ß, and myostatin (all P < 0.01), suggesting an induction of anabolic pathways. At the same time, we observed the significant increase in the survival of animals by high-dose ARA 284 treatment (hazard ratio: 0.46, 95% confidence interval: 0.23-0.94, P = 0.0325). CONCLUSIONS: Taken together these results suggest that ARA 284 can be considered beneficial in experimental CC and it remains to be seen, if it can have similar beneficial effects in CC patient.

A small erythropoietin derived non-hematopoietic peptide reduces cardiac inflammation, attenuates age associated declines in heart function and prolongs healthspan.

Background: Aging is associated with increased levels of reactive oxygen species and inflammation that disrupt proteostasis and mitochondrial function and leads to organism-wide frailty later in life. ARA290 (cibinetide), an 11-aa non-hematopoietic peptide sequence within the cardioprotective domain of erythropoietin, mediates tissue protection by reducing inflammation and fibrosis. Age-associated cardiac inflammation is linked to structural and functional changes in the heart, including mitochondrial dysfunction, impaired proteostasis, hypertrophic cardiac remodeling, and contractile dysfunction. Can ARA290 ameliorate these age-associated cardiac changes and the severity of frailty in advanced age? Methods: We conducted an integrated longitudinal (n = 48) and cross-sectional (n = 144) 15 months randomized controlled trial in which 18-month-old Fischer 344 x Brown Norway rats were randomly assigned to either receive chronic ARA290 treatment or saline. Serial echocardiography, tail blood pressure and body weight were evaluated repeatedly at 4-month intervals. A frailty index was calculated at the final timepoint (33 months of age). Tissues were harvested at 4-month intervals to define inflammatory markers and left ventricular tissue remodeling. Mitochondrial and myocardial cell health was assessed in isolated left ventricular myocytes. Kaplan-Meier survival curves were established. Mixed ANOVA tests and linear mixed regression analysis were employed to determine the effects of age, treatment, and age-treatment interactions. Results: Chronic ARA290 treatment mitigated age-related increases in the cardiac non-myocyte to myocyte ratio, infiltrating leukocytes and monocytes, pro-inflammatory cytokines, total NF-κB, and p-NF-κB. Additionally, ARA290 treatment enhanced cardiomyocyte autophagy flux and reduced cellular accumulation of lipofuscin. The cardiomyocyte mitochondrial permeability transition pore response to oxidant stress was desensitized following chronic ARA290 treatment. Concurrently, ARA290 significantly blunted the age-associated elevation in blood pressure and preserved the LV ejection fraction. Finally, ARA290 preserved body weight and significantly reduced other markers of organism-wide frailty at the end of life. Conclusion: Administration of ARA290 reduces cell and tissue inflammation, mitigates structural and functional changes within the cardiovascular system leading to amelioration of frailty and preserved healthspan.

Cibinetide Protects Isolated Human Islets in a Stressful Environment and Improves Engraftment in the Perspective of Intra Portal Islet Transplantation.

During intra-portal pancreatic islet transplantation (PITx), innate immune reactions such as the instant blood mediated inflammatory reaction (IBMIR) cause an immediate loss of islets. The non-hematopoietic erythropoietin analogue cibinetide has previously shown islet-protective effects in mouse PITx. Herein, we aimed to confirm cibinetide's efficacy on human islets, and to characterize its effect on IBMIR. We cultured human islets with pro-inflammatory cytokines for 18 hours with or without cibinetide. ATP content and caspase 3/7 activity were measured. Dynamic glucose perfusion assay was used to evaluate islet function. To evaluate cibinetides effect on IBMIR, human islets were incubated in heparinized polyvinyl chloride tubing system with ABO compatible blood and rotated for 60 minutes to mimic the portal vein system. Moreover, human islets were transplanted into athymic mice livers via the portal vein with or without perioperative cibinetide treatment. The mice were sacrificed six days following transplantation and the livers were analyzed for human insulin and serum for human C-peptide levels. Histological examination of recipient livers to evaluate islet graft infiltration by CD11b+ cells was performed. Our results show that cibinetide maintained human islet ATP levels and reduced the caspase 3/7 activity during culture with pro-inflammatory cytokines and improved their insulin secreting capacity. In the PVC loop system, administration of cibinetide reduced the IBMIR-induced platelet consumption. In human islet to athymic mice PITx, cibinetide treatment showed an increased amount of human insulin in the livers and higher serum human C-peptide, while histological examination of the livers showed reduced infiltration of pro-inflammatory CD11b+ cells around islets grafts compared to the controls. In summary, Cibinetide protected isolated human islets in a pro-inflammatory milieu and reduced IBMIR related platelet consumption. It improved engraftment of human islets in athymic mice. The study confirms that cibinetide is a promising agent to be used in clinical PITx.

A Phase 2 Clinical Trial on the Use of Cibinetide for the Treatment of Diabetic Macular Edema.

PURPOSE: Evaluating the effects of cibinetide in diabetic macular edema (DME). METHODS: Phase 2 trial. Naïve patients with >400 µm central retinal thickness (CRT) DME in one/both eyes were recruited (May 2016-April 2017) at the Belfast Health and Social Care Trust. The study eye was that with best vision and lowest CRT. Patients self-administered cibinetide 4 mg/day subcutaneously for 12 weeks. Primary and secondary outcomes: mean change from baseline to week 12 in best corrected visual acuity (BCVA), CRT, central retinal sensitivity, tear production, patient-reported outcomes, adverse events and antibodies to cibinetide. Descriptive statistics were used; exploratory analyses focused on non-study eyes, diabetic control, serum cytokines and albuminuria. RESULTS: Nine patients were recruited; eight completed the study. There was no improvement in mean change baseline-week 12 in BCVA (-2.9 + 5.0), CRT (10 + 94.6 microns), central retinal sensitivity (-0.53 + 1.9 dB) or tear production (-0.13 + 7.7 mm), but there was an improvement in National Eye Institute Visual Function Questionnaire (NEI VFQ-25) composite scores (2.7 + 3.1). Some participants experienced improvements in CRT, tear production, diabetic control and albuminuria. No serious adverse events/reactions or anti-cibinetide antibodies were seen. CONCLUSIONS: The cibinetide 12-week course was safe. Improvements in NEI VFQ-25 scores, CRT, tear production, diabetic control and albuminuria, observed in some participants, warrant further investigation. TRIAL REGISTRATION: EudraCT number: 2015-001940-12. ISRCTN16962255-registration date 25.06.15.

Improvement of Islet Allograft Function Using Cibinetide, an Innate Repair Receptor Ligand.

BACKGROUND: During intraportal pancreatic islet transplantation (PITx), early inflammatory reactions cause an immediate loss of more than half of the transplanted graft and potentiate subsequent allograft rejection. Previous findings suggest that cibinetide, a selective innate repair receptor agonist, exerts islet protective and antiinflammatory properties and improved transplant efficacy in syngeneic mouse PITx model. In a stepwise approach toward a clinical application, we have here investigated the short- and long-term effects of cibinetide in an allogeneic mouse PITx model. METHODS: Streptozotocin-induced diabetic C57BL/6N (H-2) mice were transplanted with 320 (marginal) or 450 (standard) islets from BALB/c (H-2) mice via the portal vein. Recipients were treated perioperative and thereafter daily during 14 d with cibinetide (120 µg/kg), with or without tacrolimus injection (0.4 mg/kg/d) during days 4-14 after transplantation. Graft function was assessed using nonfasting glucose measurements. Relative gene expressions of proinflammatory cytokines and proinsulin of the graft-bearing liver were assessed by quantitative polymerase chain reaction. Cibinetide's effects on dendritic cell maturation were investigated in vitro. RESULTS: Cibinetide ameliorated the local inflammatory responses in the liver and improved glycemic control immediately after allogeneic PITx and significantly delayed the onset of allograft loss. Combination treatment with cibinetide and low-dose tacrolimus significantly improved long-term graft survival following allogeneic PITx. In vitro experiments indicated that cibinetide lowered bone-marrow-derived-immature-dendritic cell maturation and subsequently reduced allogeneic T-cell response. CONCLUSIONS: Cibinetide reduced the initial transplantation-related severe inflammation and delayed the subsequent alloreactivity. Cibinetide, in combination with low-dose tacrolimus, could significantly improve long-term graft survival in allogeneic PITx.

Corneal confocal microscopy: ready for prime time.

Corneal confocal microscopy is a non-invasive ophthalmic imaging modality, which was initially used for the diagnosis and management of corneal diseases. However, over the last 20 years it has come to the forefront as a rapid, non-invasive, reiterative, cost-effective imaging biomarker for neurodegeneration. The human cornea is endowed with the densest network of sensory unmyelinated axons, anywhere in the body. A robust body of evidence shows that corneal confocal microscopy is a reliable and reproducible method to quantify corneal nerve morphology. Changes in corneal nerve morphology precede or relate to clinical manifestations of peripheral and central neurodegenerative conditions. Moreover, in clinical intervention trials, corneal nerve regeneration occurs early and predicts functional gains in trials of neuroprotection. In view of these findings, it is timely to summarise the knowledge in this area of research and to explain why the case for corneal confocal microscopy is sufficiently compelling to argue for its inclusion as a Food and Drug Administration endpoint in clinical trials of peripheral and central neurodegenerative conditions.

The vasoreparative potential of endothelial colony-forming cells in the ischemic retina is enhanced by cibinetide, a non-hematopoietic erythropoietin mimetic.

PURPOSE: Retinal ischemia remains a common sight threatening end-point in blinding diseases such as diabetic retinopathy and retinopathy of prematurity. Endothelial colony forming cells (ECFCs) represent a subpopulation of endothelial progenitors with therapeutic utility for promoting reparative angiogenesis in the ischaemic retina. The current study has investigated the potential of enhancing this cell therapy approach by the dampening of the pro-inflammatory milieu typical of ischemic retina. Based on recent findings that ARA290 (cibinetide), a peptide based on the Helix-B domain of erythropoietin (EPO), is anti-inflammatory and tissue-protective, the effect of this peptide on ECFC-mediated vascular regeneration was studied in the ischemic retina. METHODS: The effects of ARA290 on pro-survival signaling and function were assessed in ECFC cultures in vitro. Efficacy of ECFC transplantation therapy to promote retinal vascular repair in the presence and absence of ARA290 was studied in the oxygen induced retinopathy (OIR) model of retinal ischemia. The inflammatory cytokine profile and microglial activation were studied as readouts of inflammation. RESULTS: ARA290 activated pro-survival signaling and enhanced cell viability in response to H2O2-mediated oxidative stress in ECFCs in vitro. Preconditioning of ECFCs with EPO or ARA290 prior to delivery to the ischemic retina did not enhance vasoreparative function. ARA290 delivered systemically to OIR mice reduced pro-inflammatory expression of IL-1ß and TNF-α in the mouse retina. Following intravitreal transplantation, ECFCs incorporated into the damaged retinal vasculature and significantly reduced avascular area. The vasoreparative function of ECFCs was enhanced in the presence of ARA290 but not EPO. DISCUSSION: Regulation of the pro-inflammatory milieu of the ischemic retina can be enhanced by ARA290 and may be a useful adjunct to ECFC-based cell therapy for ischemic retinopathies.

Cibinetide dampens innate immune cell functions thus ameliorating the course of experimental colitis.

Two distinct forms of the erythropoietin receptor (EPOR) mediate the cellular responses to erythropoietin (EPO) in different tissues. EPOR homodimers signal to promote the maturation of erythroid progenitor cells. In other cell types, including immune cells, EPOR and the ß-common receptor (CD131) form heteromers (the innate repair receptor; IRR), and exert tissue protective effects. We used dextran sulphate sodium (DSS) to induce colitis in C57BL/6 N mice. Once colitis was established, mice were treated with solvent, EPO or the selective IRR agonist cibinetide. We found that both cibinetide and EPO ameliorated the clinical course of experimental colitis in mice, resulting in improved weight gain and survival. Correspondingly, DSS-exposed mice treated with cibinetide or EPO displayed preserved tissue integrity due to reduced infiltration of myeloid cells and diminished production of pro-inflammatory disease mediators including cytokines, chemokines and nitric oxide synthase-2. Experiments using LPS-activated primary macrophages revealed that the anti-inflammatory effects of cibinetide were dependent on CD131 and JAK2 functionality and were mediated via inhibition of NF-κB subunit p65 activity. Cibinetide activation of the IRR exerts potent anti-inflammatory effects, especially within the myeloid population, reduces disease activity and mortality in mice. Cibinetide thus holds promise as novel disease-modifying therapeutic of inflammatory bowel disease.

Cibinetide Improves Corneal Nerve Fiber Abundance in Patients With Sarcoidosis-Associated Small Nerve Fiber Loss and Neuropathic Pain.

Purpose: Sarcoidosis frequently is complicated by small nerve fiber loss (SNFL), which can be quantified using corneal confocal microscopy (CCM). Prior studies suggest that the innate repair receptor agonist cibinetide reverses corneal nerve loss. This phase 2b, 28-day, randomized trial of 64 subjects with sarcoid-associated SNFL and neuropathic pain assessed the effect of cibinetide on corneal nerve fiber area (CNFA) and regenerating intraepidermal fibers (GAP-43+) as surrogate endpoints for disease modification, pain severity, and functional capacity (6-minute walk test [6MWT]). Methods: Cibinetide (1, 4, or 8 mg/day) was compared to placebo. The primary study endpoint was a change in CNFA at 28 days. Results: The placebo-corrected mean change from baseline CNFA (µm2) at day 28 was 109 (95% confidence interval [CI], -429, 647), 697 (159, 1236; P = 0.012), and 431 (-130, 992) in the 1, 4, and 8 mg groups, respectively. Intraepidermal GAP-43+ fibers increased in the 4 mg group (P = 0.035). Further, changes in CNFA correlated with changes in GAP-43+ (ρ = 0.575; P = 0.025) and 6MWT (ρ = 0.645; P = 0.009). Pain improved significantly in all groups, with subjects having moderate-severe pain reporting a clinically meaningful placebo-corrected decrease in pain intensity in the 4 mg group (P = 0.157). Conclusions: Cibinetide significantly increased small nerve fiber abundance in the cornea and skin, consistent with a disease modifying effect. The relationships between CNFA and other clinical measures of disease support its use as a surrogate endpoint to assess potential disease modifying therapies for neuropathy.

ARA290, a Specific Agonist of Erythropoietin/CD131 Heteroreceptor, Improves Circulating Endothelial Progenitors' Angiogenic Potential and Homing Ability.

BACKGROUND: Alternate erythropoietin (EPO)-mediated signaling via the EPOR/CD131 heteromeric receptor exerts the tissue-protective actions of EPO in a wide spectrum of injuries, especially ischemic diseases. Circulating endothelial progenitor cells contribute to endothelial repair and post-natal angiogenesis after chronic ischemic injury. This work aims to investigate the effects of ARA290, a specific agonist of EPOR/CD131 complex, on a subpopulation of endothelial progenitor cells named endothelial colony-forming cells (ECFCs) and to characterize its contribution to ECFCs-induced angiogenesis after peripheral ischemia. METHODS: ARA290 effects on ECFCs properties were studied using cell cultures in vitro. We injected ARA290 to mice undergoing chronic hindlimb ischemia (CLI) in combination with ECFC transplantation. The homing of transplanted ECFC to ischemic tissue in vivo was assessed by SPECT/CT imaging. RESULTS: In vitro, ARA290 enhanced the proliferation, migration, and resistance to H2O2-induced apoptosis of ECFCs. After ECFC transplantation to mice with CLI, a single ARA290 injection enhanced the ischemic/non-ischemic ratio of hindlimb blood flow and capillary density after 28 days and the homing of radiolabeled transplanted cells to the ischemic leg 4 h after transplantation. Prior neutralization of platelet-endothelial cell adhesion molecule-1 (CD31) expressed by the transplanted cells inhibited ARA290-induced improvement of homing. DISCUSSION: ARA290 induces specific improvement of the biological activity of ECFCs. ARA290 administration in combination with ECFCs has a synergistic effect on post-ischemic angiogenesis in vivo. This potentiation appears to rely, at least in part, on a CD31-dependent increase in homing of the transplanted cells to the ischemic tissue.

ARA290 Improves Insulin Release and Glucose Tolerance in Type 2 Diabetic Goto-Kakizaki Rats.

Effects of ARA290 on glucose homeostasis were studied in type 2 diabetic Goto-Kakizaki (GK) rats. In GK rats receiving ARA290 daily for up to 4 wks, plasma glucose concentrations were lower after 3 and 4 wks, and hemoglobin A1c (Hb A1c) was reduced by ~20% without changes in whole body and hepatic insulin sensitivity. Glucose-stimulated insulin secretion was increased in islets from ARA290-treated rats. Additionally, in response to glucose, carbachol and KCl, islet cytoplasmic free Ca2+ concentrations, [Ca2+]i, were higher and the frequency of [Ca2+]i oscillations enhanced compared with placebo. ARA290 also improved stimulus-secretion coupling for glucose in GK rat islets, as shown by an improved glucose oxidation rate, ATP production and acutely enhanced glucose-stimulated insulin secretion. ARA290 also exerted an effect distal to the ATP-sensitive potassium (KATP) channel on the insulin exocytotic pathway, since the insulin response was improved following islet depolarization by KCl when KATP channels were kept open by diazoxide. Finally, inhibition of protein kinase A completely abolished effects of ARA290 on insulin secretion. In conclusion, ARA290 improved glucose tolerance without affecting hematocrit in diabetic GK rats. This effect appears to be due to improved γ-cell glucose metabolism and [Ca2+]i handling, and thereby enhanced glucose-induced insulin release.

A Nonhematopoietic Erythropoietin Analogue, ARA 290, Inhibits Macrophage Activation and Prevents Damage to Transplanted Islets.

BACKGROUND: Erythropoietin exerts anti-inflammatory, antiapoptotic, and cytoprotective effects in addition to its hematopoietic action. A nonhematopoietic erythropoietin analogue, ARA 290, has similar properties. The efficacy of pancreatic islet transplantation (PITx) is reduced due to islet damage that occurs during isolation and from the severe inflammatory reactions caused by the transplantation procedure. We investigated whether ARA 290 protects islets and ameliorates inflammatory responses following PITx thus improving engraftment. METHODS: The effects of ARA 290 on pancreatic islets of C57BL/6J (H-2) mice and on murine macrophages were investigated using an in vitro culture model. As a marginal PITx, 185 islets were transplanted into the liver of streptozotocin-induced diabetic mice (H-2) via the portal vein. Recipients were given ARA 290 (120 µg/kg) intraperitoneally just before and at 0, 6, and 24 hours after PITx. Liver samples were obtained at 12 hours after PITx, and expression levels of proinflammatory cytokines were assessed. RESULTS: ARA 290 protected islets from cytokine-induced damage and apoptosis. Secretion of pro-inflammatory cytokines (IL-6, IL-12, and TNF-α) from macrophages was significantly inhibited by ARA 290. After the marginal PITx, ARA 290 treatment significantly improved the blood glucose levels when compared to those of control animals (P < 0.001). Upregulation of monocyte chemoattractant protein-1, macrophage inflammatory protein-1ß, IL-1ß, and IL-6 messenger RNA expression within the liver was suppressed by ARA 290 treatment. CONCLUSIONS: ARA 290 protected pancreatic islets from cytokine-induced damage and apoptosis and ameliorated the inflammatory response after PITx. ARA 290 appears to be a promising candidate for improvement of PITx.

Targeting the innate repair receptor to treat neuropathy.

The innate repair receptor (IRR) is a heteromer of the erythropoietin receptor and the ß-common (CD131) receptor, which simultaneously activates anti-inflammatory and tissue repair pathways. Experimental data suggest that after peripheral nerve injury, the IRR is upregulated in the spinal cord and modulates the neurogenic inflammatory response. The recently introduced selective IRR agonist ARA290 is an 11-amino acid peptide initially tested in animal models of neuropathy. After sciatic nerve injury, ARA290 produced a rapid and long-term relief of mechanical and cold allodynia in normal mice, but not in animals with a ß-common receptor knockout phenotype. In humans, ARA290 has been evaluated in patients with small fiber neuropathy associated with sarcoidosis or type 2 diabetes (T2D) mellitus. In patients with sarcoidosis, ARA290 significantly improved neuropathic and autonomic symptoms, as well as quality of life as assessed by the small fiber neuropathy screening list questionnaire. In addition, ARA290 treatment for 28 days initiated a regrowth of small nerve fibers in the cornea, but not in the epidermis. In patients with T2D, the results were similar to those observed in patients with sarcoidosis along with an improved metabolic profile. In both populations, ARA290 lacked significant adverse effects. These experimental and clinical studies show that ARA290 effectively reprograms a proinflammatory, tissue-damaging milieu into one of healing and tissue repair. Further clinical trials with long-term treatment and follow-up are needed to assess the full potential of IRR activation by ARA290 as a disease-modifying therapy in neuropathy of various etiologies.

Flipping the molecular switch for innate protection and repair of tissues: Long-lasting effects of a non-erythropoietic small peptide engineered from erythropoietin.

Many disease processes activate a cellular stress response that initiates a cascade of inflammation and damage. However, this process also triggers a tissue protection and repair system mediated by locally-produced hyposialated erythropoietin (hsEPO). Although recombinant EPO is used widely for treating anemia, potential use of recombinant EPO for tissue-protection is limited by rises in hematocrit, platelet activation, and selectin expression resulting in a high risk of thrombosis. Importantly, the erythropoietic and tissue-protective effects of EPO are mediated by different receptors. Whereas EPO stimulates red cell progenitors by binding to an EPO receptor (EPOR) homodimer, a heterodimer receptor complex composed of EPOR and ß common receptor (ßcR) subunits, termed the innate repair receptor (IRR), activates tissue protection and repair. The IRR is typically not expressed by normal tissues, but instead is rapidly induced by injury or inflammation. Based on this understanding, EPO derivatives have been developed which selectively activate the IRR without interacting with the EPOR homodimer. The latest generation of specific ligands of the IRR includes an 11 amino acid peptide modeled from the three dimensional structure of the EPO in the region of helix B called pyroglutamate helix B surface peptide (pHBSP; ARA-290). Despite a short plasma half-life (~2min), pHBSP activates a molecular switch that triggers sustained biological effects that have been observed in a number of experimental animal models of disease and in clinical trials. This review summarizes pharmacokinetic and pharmacodynamic data and discusses the molecular mechanisms underlying the long-lasting effects of this short-lived peptide.

Modulation of cellular stress response via the erythropoietin/CD131 heteroreceptor complex in mouse mesenchymal-derived cells.

Tissue-protective properties of erythropoietin (EPO) have let to the discovery of an alternative EPO signaling via an EPO-R/CD131 receptor complex which can now be specifically targeted through pharmaceutically designed short sequence peptides such as ARA290. However, little is still known about specific functions of alternative EPO signaling in defined cell populations. In this study, we investigated effects of signaling through EPO-R/CD131 complex on cellular stress responses and pro-inflammatory activation in different mesenchymal-derived phenotypes. We show that anti-apoptotic, anti-inflammatory effects of ARA290 and EPO coincide with the externalization of CD131 receptor component as an immediate response to cellular stress. In addition, alternative EPO signaling strongly modulated transcriptional, translational, or metabolic responses after stressor removal. Specifically, we saw that ARA290 was able to overcome a TNFα-mediated inhibition of transcription factor activation related to cell stress responses, most notably of serum response factor (SRF), heat shock transcription factor protein 1 (HSF1), and activator protein 1 (AP1). We conclude that alternative EPO signaling acts as a modulator of pro-inflammatory signaling pathways and likely plays a role in restoring tissue homeostasis. Key message: Erythropoietin (EPO) triggers an alternative pathway via heteroreceptor EPO/CD131. ARA290 peptide specifically binds EPO/CD131 but not the canonical EPO/EPO receptor. Oxidative stress and inflammation promote cell surface expression of CD131. ARA290 prevents tumor necrosis factor-mediated inhibition of stress-related genes. Alternative EPO signaling modulates inflammation and promotes tissue homeostasis.

ARA 290, a nonerythropoietic peptide engineered from erythropoietin, improves metabolic control and neuropathic symptoms in patients with type 2 diabetes.

Although erythropoietin ameliorates experimental type 2 diabetes with neuropathy, serious side effects limit its potential clinical use. ARA 290, a nonhematopoietic peptide designed from the structure of erythropoietin, interacts selectively with the innate repair receptor that mediates tissue protection. ARA 290 has shown efficacy in preclinical and clinical studies of metabolic control and neuropathy. To evaluate the potential activity of ARA 290 in type 2 diabetes and painful neuropathy, subjects were enrolled in this phase 2 study. ARA 290 (4 mg) or placebo were self-administered subcutaneously daily for 28 d and the subjects followed for an additional month without further treatment. No potential safety issues were identified. Subjects receiving ARA 290 exhibited an improvement in hemoglobin A(1c) (Hb A(1c)) and lipid profiles throughout the 56 d observation period. Neuropathic symptoms as assessed by the PainDetect questionnaire improved significantly in the ARA 290 group. Mean corneal nerve fiber density (CNFD) was reduced significantly compared with normal controls and subjects with a mean CNFD >1 standard deviation from normal showed a significant increase in CNFD compared with no change in the placebo group. These observations suggest that ARA 290 may benefit both metabolic control and neuropathy in subjects with type 2 diabetes and deserves continued clinical evaluation.

ARA 290, a peptide derived from the tertiary structure of erythropoietin, produces long-term relief of neuropathic pain coupled with suppression of the spinal microglia response.

BACKGROUND: Neuropathic pain is a difficult to treat disorder arising from central or peripheral nervous system lesions. The etiology of neuropathic pain consists of several overlapping pathways converging into an exaggerated pain state with symptoms such as allodynia and hyperalgesia. One of these pathways involves activation of spinal cord microglia and astrocytes, which drive and maintain the inflammatory response following the lesion. These cells are a potential target for drugs for neuropathic pain relief. In this current study, we investigated the dose-effect relationship of the tissue protective peptide ARA 290, derived from the tertiary structure of erythropoietin, on allodynia and concurrent spinal cord microglia and astrocytes. RESULTS: Following a spared nerve injury in rats, vehicle or ARA290 (administered in either one of 4 doses: 3, 10, 30 and 60 µg/kg) was administered on days 1, 3, 6, 8 and 10. ARA290 exerted a dose-response effect by significantly reducing mechanical allodynia up to 20 weeks when compared to vehicle. The reduction of cold allodynia was significant up to 20 weeks for the doses 3, 10, 30 and 60 µg/kg when compared to vehicle. The effect 10 and 30 µg/kg ARA290 and vehicle on the microglia response (iba-1-immunoreactivity, iba-1-IR) and astrocyte reaction (GFAP-immunoreactivity, GFAP-IR) was investigated in animals surviving 2 (group 1) or 20 (group 2) weeks following lesion or sham surgery. In group 1, significant microglia reactivity was observed in the L5 segment of the spinal cord of animals treated with vehicle when compared to sham operated, while animals treated with 10 or 30 µg/kg did not show a increase. In group 2, a more widespread and increased microglia reactivity was observed for animals treated with 0 and 10 µg/kg when compared to sham operated animals, indicated by involvement of more spinal cord segments and higher iba-1-IR. Animals treated with 30 µg/kg did not show increased microglia reactivity. No difference in astrocyte reaction was observed. CONCLUSIONS: The erythropoietin-analogue ARA290 dose-dependently reduced allodynia coupled to suppression of the spinal microglia response, suggestive of a mechanistic link between ARA290-induced suppression of central inflammation and relief of neuropathic pain symptoms.

ARA 290 for treatment of small fiber neuropathy in sarcoidosis.

INTRODUCTION: Painful peripheral neuropathy is a common, difficult-to-treat complication associated with a variety of diseases, including diabetes mellitus and sarcoidosis. It is caused by damage of small and autonomic nerve fibers, resulting in potentially debilitating symptoms of neuropathic pain and autonomic dysfunction. The limited efficacy of current treatment options dictates a rationalized design of novel compounds. AREAS COVERED: The authors present the recent data from two Phase II clinical trials on ARA290, an erythropoietin derivative with tissue protective and healing properties that does not stimulate erythropoiesis. ARA 290 treatment was consistently associated with a significant improvement of neuropathic pain symptoms in sarcoidosis patients, evidenced by a decrease in pain scores on validated questionnaires. Moreover, ARA 290 treatment resulted in significant increases in corneal nerve fibers, improved sensory pain thresholds, improved quality of life and physical functioning. EXPERT OPINION: Current treatment modalities of neuropathy are based on a trial-and-error approach, have limited efficacy and come with significant side effects. Given the excellent safety profile while reducing neuropathy symptoms, the prospects of ARA 290 treatment in sarcoid neuropathy seem promising. The long-lasting beneficial effects of ARA 290 on both pain-related and non-pain-related symptoms in sarcoidosis patients prompt additional studies on potential disease-modifying properties of ARA 290.