What Is ARA-290 (Cibinetide)? Innate Repair Research

ARA-290, given the international name cibinetide, is a synthetic eleven-amino-acid peptide copied from the outward-facing surface of helix B of erythropoietin (EPO). It was engineered to keep the tissue-protective signaling attributed to EPO while leaving out EPO's red-blood-cell effect, by activating a different receptor: the innate repair receptor.

That separation, one hormone acting through two receptor systems, is the idea the whole compound rests on. ARA-290 was developed by Araim Pharmaceuticals, reached Phase 2 trials in small fiber neuropathy, and was never approved as a medicine anywhere. This guide reviews what ARA-290 is, how it acts at the innate repair receptor, what the published research record actually shows, and how laboratories verify the material they work with.

What Is ARA-290, Exactly?

ARA-290 is a designed fragment, not a piece cut from EPO itself. Researchers mapped which surface of the EPO molecule engages the tissue-protective receptor and synthesized that surface as a short standalone peptide. Its first residue is pyroglutamate, a ring-closed form of glutamate that protects the start of the chain from enzymatic trimming.

• Also written as: Cibinetide; pyroglutamate helix B surface peptide (pHBSP)
• Length: 11 amino acids, N-terminal pyroglutamate
• Sequence: pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser (ZEQLERALNSS)
• Molecular weight: Approximately 1,257.3 g/mol
• Molecular formula: C51H84N16O21
• CAS number: 1208243-50-8
• Parent molecule: Erythropoietin, helix B surface region
• Class: Innate repair receptor agonist; non-erythropoietic EPO-derived peptide

The design goal explains both halves of its profile. The classical EPO receptor is a pair of identical receptor subunits on blood-forming cells; ARA-290 does not meaningfully engage it. The receptor it does engage pairs one EPO receptor subunit with a different partner, CD131, and that pairing is what the next sections unpack.

Where Does ARA-290 Come From?

ARA-290 emerged from work by Michael Brines, Anthony Cerami, and colleagues on EPO's non-blood effects. By the 2000s, animal studies showed EPO protecting injured tissue in models where its blood effects were a liability rather than the mechanism. In 2008, the group reported that these two jobs run through different receptors, and that short peptides modeled on EPO's helix B surface could trigger the protective pathway without stimulating red cell production.

Citation: Brines M, et al. Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin. Proceedings of the National Academy of Sciences. 2008. [PubMed PMID: 18676614](https://pubmed.ncbi.nlm.nih.gov/18676614/)

Araim Pharmaceuticals advanced the compound, under the name cibinetide, into human trials, and it received orphan drug designation for sarcoidosis-associated small fiber neuropathy. Development did not proceed to Phase 3, the last human data were published in the late 2010s, and the developer has since ceased operating. The published record, not an active drug program, is what researchers work with today.

How Does ARA-290 Work at the Innate Repair Receptor?

The innate repair receptor is a heteromer: one erythropoietin receptor subunit joined with CD131, the beta common receptor shared by several immune signaling molecules. Unlike the blood receptor, which is always present on its target cells, this receptor is reported to be expressed transiently on injured or stressed tissue, which is the proposed basis for its repair role.

Engaging it is reported to initiate anti-inflammatory and cell-protective signaling in preclinical models, moderating innate immune activation around an injury site. The strongest mechanistic evidence is genetic: in nerve-injury experiments, ARA-290 reduced pain-related sensitivity in normal mice but had no effect in mice lacking the beta common receptor, an effect that disappears when its receptor is removed.

Citation: Swartjes M, et al. ARA290, a peptide derived from the tertiary structure of erythropoietin, produces long-term relief in neuropathic pain: an experimental study in rats and beta common receptor knockout mice. Anesthesiology. 2011. [PubMed PMID: 21873879](https://pubmed.ncbi.nlm.nih.gov/21873879/)

How Is ARA-290 Different From Erythropoietin?

Property	Erythropoietin (EPO)	ARA-290 (cibinetide)
Structure	165-amino-acid glycoprotein hormone	11-amino-acid synthetic peptide modeled on EPO's helix B surface
Primary receptor	Classical EPO receptor homodimer	Innate repair receptor (EPO receptor + CD131)
Red blood cell production	Yes — its defining physiological role	No erythropoietic activity reported by design
Research focus	Blood formation; tissue protection as a secondary literature	Tissue protection and small fiber nerve research
Regulatory status	Approved medicines exist (epoetins)	Not approved anywhere; Phase 2 record only

Read side by side, the two molecules answer the same question differently: which of EPO's signals can be separated from the whole hormone? ARA-290 is the test case for the protective half of that split, and its literature should be read as evidence about the receptor idea as much as about the peptide itself.

What Has the Published Research Found?

The human record centers on small fiber neuropathy, the damage to the small nerve fibers that carry pain and temperature sensation. In a randomized, double-blind pilot trial in sarcoidosis-associated small fiber neuropathy, Dahan and colleagues reported improvements in neuropathic symptom scores and physical functioning over four weeks of study treatment versus placebo.

A later dose-ranging Phase 2b trial used an objective structural endpoint, corneal nerve fiber area measured by confocal microscopy, and reported a statistically significant placebo-corrected increase in one dose arm. That kind of measurable nerve-fiber endpoint is uncommon in the neuropathy literature, which is why the result is frequently cited.

Read carefully, the record also has clear limits: the trials enrolled between a few dozen and 64 participants, ran for weeks rather than years, were largely run by the developer and its academic collaborators, and no Phase 3 trial was ever conducted. The literature supports continued research interest in the innate repair receptor. It does not establish an approved or proven therapy, and this guide does not present it as one.

How Is ARA-290 Used in Laboratory Research Today?

With no drug approval and no active development program, ARA-290's present-day role is as a research compound. Laboratories use it in several defined ways:

• Receptor pharmacology: a selective probe for the innate repair receptor that does not confound experiments with erythropoietic signaling.
• Nerve-injury models: studying small fiber behavior and repair signaling in preclinical neuropathy systems.
• Inflammation models: examining innate immune modulation attributed to CD131-containing receptor complexes.
• Peptide-design reference: a worked example of extracting one receptor-selective surface from a multifunctional protein.

In each role, the experimental variable is receptor signaling, so the identity and purity of the material are part of the experimental design rather than an afterthought, which leads directly to the verification question below.

How Do Researchers Verify ARA-290 Material?

Two analytical checks are standard, and ARA-290 has a signature detail both should catch. Mass spectrometry should confirm a molecular identity consistent with the eleven-residue peptide at approximately 1,257.3 g/mol, including the closed pyroglutamate ring at its start; an uncyclized variant beginning with glutamine is about 17 mass units heavier and is not the same compound. Reversed-phase HPLC is the standard purity method, quantifying the main peak against deletion sequences and other synthesis-related impurities.

Because the pyroglutamate closure is part of what defines cibinetide, researchers look for a batch-specific Certificate of Analysis documenting HPLC purity and mass spectrometry identity for the exact batch supplied. NUPEPS PEPTIDES publishes batch Certificates of Analysis for its research materials, available at nupeps.com/coas, and our guide to reading a peptide COA explains how to check one line by line. NUPEPS PEPTIDES tests every batch for purity, quantity, and sterility.

ARA-290 Research Material at NUPEPS PEPTIDES

NUPEPS PEPTIDES supplies ARA-290 as a lyophilized research material, ARA-290 16MG, for laboratory and in vitro research use only. Each batch is accompanied by its Certificate of Analysis, so the material can be matched to its analytical record before it enters an experiment. ARA-290 is supplied strictly as a research chemical; it is not a drug, and it is not for human or veterinary use.

Frequently Asked Questions

What is ARA-290 made of?

ARA-290 is a synthetic eleven-amino-acid peptide, pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser, modeled on the outward-facing surface of helix B of erythropoietin. Its first residue is pyroglutamate, a ring-closed glutamate that protects the chain start. It is a designed fragment, not a piece physically cut from the EPO protein.

Is ARA-290 the same as EPO?

No. EPO is a 165-amino-acid glycoprotein whose defining role is stimulating red blood cell production through the classical EPO receptor. ARA-290 is a small peptide modeled on one EPO surface that activates the innate repair receptor instead and was specifically designed to have no erythropoietic activity.

What is the innate repair receptor?

It is a receptor complex formed by one erythropoietin receptor subunit paired with CD131, the beta common receptor. It differs from the paired identical subunits that drive blood formation, is reported to appear on injured tissue, and is the proposed route for EPO's tissue-protective signaling in preclinical models.

Is ARA-290 an approved drug?

No. Cibinetide completed Phase 2 trials, held orphan drug designation for sarcoidosis-associated small fiber neuropathy, and was never approved by the FDA, the EMA, or any other regulator. No Phase 3 trial was conducted, and the compound is sold only as a research chemical for laboratory use.

How can a researcher check ARA-290 quality before an experiment?

Ask for the batch-specific Certificate of Analysis and check two things: mass spectrometry identity matching the expected molecular weight of about 1,257.3 g/mol with the N-terminal pyroglutamate ring closed, and HPLC purity of at least 99 percent for the batch actually supplied. A generic specification sheet that is not tied to the batch is not a substitute.

Conclusion

ARA-290 is a clean test of an elegant idea: that one surface of a multifunctional hormone can carry its protective signal to a separate receptor while leaving its blood effects behind. Its published record, from the 2008 receptor work to small Phase 2 trials with an objective nerve-fiber endpoint, is genuinely informative and genuinely limited, and both halves of that sentence matter.

For laboratories sourcing ARA-290 today, the standard that matches its literature is documentation: identity confirmed by mass spectrometry, including the defining pyroglutamate closure, purity of at least 99 percent by HPLC, and a Certificate of Analysis issued for the specific batch in hand. Material verified that way can be used with confidence in the experiments the compound was characterized for. This article is educational material about a research compound and is not medical advice.