ARA-290

ARA-290, known by the International Nonproprietary Name cibinetide, is a synthetic 11-amino-acid peptide derived from the helix-B region of erythropoietin (EPO). Its molecular formula is C51H84N16O21, with a molecular weight of approximately 1,257.31 g/mol, PubChem CID 91810664, and CAS number 1208243-50-8. Despite being structurally derived from erythropoietin, ARA-290 was specifically engineered to be non-erythropoietic — meaning it does not stimulate red blood cell production the way EPO does.

At Verified Peptides, we describe ARA-290 to researchers as a selective agonist of the Innate Repair Receptor (IRR), a heterodimer receptor complex formed from the erythropoietin receptor (EPOR) subunit and CD131 (the beta-common receptor subunit shared with several cytokine receptors). This is the key structural distinction from erythropoietin itself, which acts primarily through a homodimeric EPOR complex that drives erythropoiesis. By selectively engaging the IRR heterodimer rather than the classical homodimeric EPOR, ARA-290 is studied for activating EPO's cytoprotective, anti-inflammatory, and tissue-repair signaling pathways while avoiding the erythropoietic effects (and associated cardiovascular/thrombotic risk profile) that limit EPO's own use outside of anemia treatment.

ARA-290 was developed by Araim Pharmaceuticals and has been studied primarily in small-fiber neuropathy associated with sarcoidosis, an orphan-disease research context, as well as in early-stage metabolic and endothelial-function research.

At Verified Peptides, we consider ARA-290 one of the more thoroughly studied IRR-agonist peptides for a genuine orphan-disease application: small fiber neuropathy (SFN) associated with sarcoidosis. An early randomized, double-blind, placebo-controlled pilot study (Molecular Medicine, 2012; PMID 23168581) enrolled 22 sarcoidosis patients with SFN symptoms, dosing ARA-290 intravenously at 2 mg three times weekly for four weeks against placebo (12 treated, 10 placebo). The treated group showed a statistically significant (p<0.05) improvement at week 4 in the Small Fiber Neuropathy Screening List (SFNSL) score compared with placebo, along with significant improvement in the pain and physical-functioning dimensions of the SF-36 quality-of-life questionnaire.

A larger, more rigorous Phase 2b trial followed (Investigative Ophthalmology & Visual Science, 2017; PMID 28475703; Culver DA, Dahan A, et al.), randomizing 64 sarcoidosis patients with painful small-fiber neuropathy to daily subcutaneous ARA-290 at 1 mg, 4 mg, or 8 mg, or placebo, for 28 days. This trial used corneal nerve fiber abundance — measured objectively via corneal confocal microscopy — as a quantifiable regeneration endpoint, rather than relying on symptom scores alone. The 4 mg dose group showed a statistically significant 23% increase in corneal nerve fiber abundance compared with placebo, alongside reported reductions in pain and improvements in functional capacity, representing one of the more objective nerve-regeneration signals reported for any peptide in this class.

Separately, a registered trial (ClinicalTrials.gov identifier NCT01933529) examined ARA-290's effects on glucose homeostasis, insulin sensitivity, and inflammatory/gluco-regulatory hormone levels in patients with prediabetes or early, diet-controlled type 2 diabetes, reflecting the broader hypothesis that IRR-mediated anti-inflammatory and endothelial effects may extend beyond peripheral-nerve applications. We have not located a peer-reviewed publication with a confirmable PMID for this specific trial's results and are citing it narratively rather than including it in this page's formal citation list.

Despite these positive Phase 2 and Phase 2b signals, ARA-290's clinical development did not advance to a Phase 3 confirmatory trial. Araim Pharmaceuticals, the peptide's original developer, ceased operations, and no multicenter Phase 3 replication study was completed. As of this writing, no active clinical trials for ARA-290/cibinetide are registered, and it has not been approved by the FDA or any other regulatory agency for any indication. Research-grade ARA-290 sold here is intended exclusively for laboratory research, not for human or animal use.

ARA-290 is one of several compounds researchers have grouped under the broader “tissue-protective cytokine” umbrella, alongside other engineered non-erythropoietic EPO derivatives explored in academic literature (such as carbamylated erythropoietin and various EPO-mimetic peptides), all sharing the same underlying research goal of separating EPO's protective signaling from its erythropoietic activity. ARA-290 remains among the most clinically tested compounds in this specific research category, giving its evidence base — however incomplete at the Phase 3 level — more depth than many earlier-stage compounds explored for the same mechanistic hypothesis.

ARA-290's development illustrates a specific and somewhat unusual pattern in peptide drug development: a compound with genuinely positive Phase 2 and Phase 2b data that nonetheless never reached a confirmatory Phase 3 trial, not because the drug failed, but because its small, specialized developer (Araim Pharmaceuticals) ceased operations before a larger trial could be funded and conducted. This is a meaningfully different story from a peptide that failed in trials, and researchers should not conflate the two when evaluating ARA-290's evidence base.

The CD131 (beta-common) receptor subunit that partners with EPOR to form the Innate Repair Receptor is itself shared across several unrelated cytokine receptor systems, including those for interleukin-3, interleukin-5, and GM-CSF. This shared-subunit receptor biology is part of a broader research area sometimes called “tissue-protective cytokine” signaling, in which several structurally related but functionally distinct receptor complexes are studied for isolating a cytokine's protective effects from its more classically recognized primary function — in EPO's case, separating tissue protection from erythropoiesis.

Corneal confocal microscopy, the imaging technique used to measure corneal nerve fiber density in ARA-290's pivotal Phase 2b trial, has itself become an increasingly used research tool for studying small-fiber neuropathy more broadly (including in diabetic neuropathy research), since it offers a non-invasive, objective, and quantifiable window into peripheral nerve fiber status that is otherwise difficult to measure without more invasive skin biopsy techniques.

ARA-290 is sometimes discussed alongside other erythropoietin-derived or EPO-receptor-related research compounds, but it should not be confused with erythropoietin itself or with erythropoiesis-stimulating agents used clinically for anemia — its entire research rationale is built around avoiding those hematopoietic effects.

The Innate Repair Receptor concept itself remains an area of active academic interest well beyond ARA-290 specifically, since it represents a broader model for how a single cytokine can be pharmacologically “split” into separate therapeutic activities by targeting different receptor complexes it can engage. Researchers studying receptor biology sometimes cite ARA-290 as a practical proof-of-concept example of this strategy, independent of the compound's own uncertain path to eventual clinical approval.

At Verified Peptides, we require independent third-party HPLC purity testing and mass spectrometry identity verification for every batch of research-grade ARA-290 we offer, and we make the resulting Certificate of Analysis (COA) available for each lot. As an 11-amino-acid synthetic peptide with a defined, moderately complex structure, ARA-290 requires the same rigorous quality-control standards applied to any peptide of this class to confirm both purity and correct amino acid sequence.

We work only with manufacturers operating under Good Manufacturing Practice (GMP)-aligned quality systems, and every lot is independently verified rather than accepted on the basis of a supplier's own internal documentation alone. Researchers should always request the specific COA for the lot they receive and review purity percentage, mass-spectrometry-confirmed identity, and relevant microbial or endotoxin testing before use in any experimental protocol.

Because ARA-290 research spans sensitive applications — including small-fiber neuropathy and inflammatory signaling studies — where subtle degradation products or off-target impurities could plausibly confound results, we consider independent purity and identity verification a non-negotiable baseline for any research use, not merely a best-practice recommendation.

Lyophilized (freeze-dried) ARA-290 is stable when stored at -20°C, protected from light and moisture, and can generally be expected to maintain integrity over extended periods under these conditions prior to reconstitution.

Once reconstituted with bacteriostatic water or an appropriate sterile diluent, ARA-290 solution should be stored refrigerated at 2–8°C and used within the timeframe specified in the product's documentation. Reconstituted peptide solutions are generally more susceptible to degradation than the lyophilized form, and repeated freeze-thaw cycling should be avoided; aliquoting into single-use portions where practical helps minimize unnecessary freeze-thaw exposure of any individual vial.

As with other research peptides, prolonged exposure to heat, direct light, or extended room-temperature storage will accelerate degradation and can compromise the peptide's structural integrity and relevance to research use. Following the lot-specific storage guidance provided with each order remains the most reliable way to preserve sample validity for experimental work.