ARA-290 (Cibinetide) Research: What Published Studies Have Investigated

What is ARA-290?

What is ARA-290? It is a synthetic peptide of eleven amino acids, also known as cibinetide and, in the biophysical literature, as pHBSP — pyroglutamate helix B surface peptide. Its residues correspond to the amino acids that form the aqueous-facing surface of helix B of erythropoietin, the type 1 cytokine best known for regulating red blood cell production. The N-terminal residue is a pyroglutamate, a cyclised glutamate that caps the chain.

The naming tells the story of the molecule. “Helix B surface peptide” is a structural description: rather than copying a contiguous stretch of the erythropoietin sequence, the designers took the residues that happen to line up on one face of one helix when the protein is folded, and strung them together as a linear chain. The result is a molecule that reproduces a spatial feature of a large protein in eleven residues.

One point of clarification belongs at the top, because search engines and forums routinely blur it: ARA-290 is not erythropoietin, is not an erythropoietin analogue in the pharmacological sense of the term, and the primary literature reports it as having no erythropoietic activity. Cellworks does not list erythropoietin. EPO sits on this site’s permanent exclusion list and has no catalogue row and no article; ARA-290 is a separate synthetic peptide and is treated as one.

Discovery and origin in the literature

Two receptors, one hormone

The work that produced ARA-290 begins with an observation about erythropoietin itself. Alongside its hormonal role in erythrocyte production, locally produced erythropoietin had been described as acting in a paracrine and autocrine fashion in a range of tissues. Brines, Cerami and colleagues framed the key point as a receptor question: in their account, haematopoiesis is mediated by the erythropoietin receptor homodimer, while the tissue-directed activity is mediated by a different assembly — a heterocomplex of the erythropoietin receptor with CD131, the beta common receptor shared with several cytokine systems. Brines and Cerami later named this second assembly the innate repair receptor and reviewed the case for it in Molecular Medicine in 2012 (PMID 22183892).

Reducing a protein to eleven residues

If two activities run through two receptors, a molecule that engages only the second becomes possible in principle. Brines and colleagues reported the demonstration in PNAS in 2008 (PMID 18676614). They delimited tissue-protective domains within erythropoietin down to short peptide sequences, reported that helix B was active in their models, and then showed that an 11-amino-acid peptide composed of the adjacent residues forming the aqueous face of helix B was active in models of ischaemic stroke and renal ischaemia–reperfusion. The line that defines the molecule is the negative result stated in the same paper: neither helix B nor the 11-amino-acid peptide was erythropoietic in vitro or in vivo.

That is the whole point of ARA-290, and it is worth stating plainly because it is the opposite of how most peptides in this catalogue arrived. Most were found and then characterised. This one was designed to be missing something — a deliberate dissociation of one activity from another within a single protein. The paper carries an explicit conflict-of-interest statement noting that several authors were employees of Warren Pharmaceuticals, which was developing erythropoietin analogues and tissue-protective compounds; that disclosure is part of the record and is reported here as such.

Reference data

The molecule facts below are drawn from the public chemical record (PubChem CID 91810664). They describe identity and physical form only.

The N-terminal pyroglutamate is a chemical detail with an analytical consequence: it is a cyclised residue, so a synthesis that fails to cyclise it produces a closely related impurity with a different mass. That is a matter for the certificate of analysis, discussed further below. No reconstitution procedure, quantity or route is given or implied anywhere on this page.

Mechanisms researchers have examined

The ARA-290 mechanism literature is organised around the receptor hypothesis above. Each point below is what studies characterise in model systems:

• Selective engagement of the EPOR/CD131 heterocomplex — the founding account (Brines 2008, PMID 18676614; Brines & Cerami 2012, PMID 22183892) is that ARA-290 interacts with the erythropoietin-receptor/beta-common-receptor heterocomplex rather than the erythropoietin receptor homodimer, and that this is why erythropoietic activity is absent.
• Absence of erythropoietic signalling — reported as a measured negative in the same 2008 paper, in vitro and in vivo. A negative result is a finding, and in this molecule’s case it is the primary one.
• Modulation of innate immune cell activity — Collino and colleagues (2015, Pharmacol Ther, PMID 25728128) review the peptide as antagonising inflammatory processes while being associated with repair-directed signalling, and describe effects the authors characterise as long-lasting relative to the peptide’s short circulating presence.
• Spinal microglial response in a neuropathic-pain model — Swartjes and colleagues (2014, Mol Pain, PMID 24529189) reported relief of neuropathic pain behaviour in rodents coupled with suppression of the spinal microglia response, linking the behavioural readout to a cellular one in the same animals.
• Small nerve fibre density as a structural endpoint — across the clinical work below, corneal confocal microscopy is used to count small nerve fibres, giving an imaging measure alongside symptom questionnaires.

Each bullet names a pathway or endpoint examined in a defined system, not an effect a reader would obtain. The receptor account in particular is a hypothesis that the founding group advanced and defended; it is reported here as their framework, which is what it is.

Research areas in the literature

Sarcoidosis-associated small nerve fibre loss

This is the indication ARA-290 is best known for. Dahan and colleagues (2013, Mol Med, PMID 24136731) ran a blinded, placebo-controlled trial in patients with documented small nerve fibre loss and damage associated with sarcoidosis. They reported improvement in neuropathic symptom scores, an increase in corneal small nerve fibre density, changes in cutaneous temperature sensitivity, and an increase in six-minute walk distance. van Velzen and colleagues (2014, Expert Opin Investig Drugs, PMID 24555851) reviewed the development case for the indication. Culver and colleagues (2017, Invest Ophthalmol Vis Sci, PMID 28475703) followed with a study focused on corneal nerve fibre abundance in the same population.

Type 2 diabetes and painful neuropathy

Brines and colleagues (2015, Mol Med, PMID 25387363) reported a phase 2 study in subjects with type 2 diabetes and painful neuropathy, in which the published outcomes included changes in haemoglobin A1c and lipid profile alongside neuropathic symptom measures, with no safety issues identified by the investigators. The framing of that paper — metabolic and neuropathic endpoints in one trial — reflects the breadth the sponsors were testing.

Ophthalmic and preclinical work

Lois and colleagues (2020, J Clin Med, PMID 32674280) reported a phase 2 clinical trial of cibinetide in diabetic macular oedema. On the preclinical side the record is broader than the clinical one: ischaemic stroke and renal ischaemia–reperfusion models in the founding paper, rodent neuropathic-pain models (Swartjes 2014), and a range of transplantation, colitis and organ-injury models by independent groups. Collino and colleagues (2015) is the review that collects the preclinical breadth in one place.

Research models and evidence status

ARA-290 occupies a genuinely unusual position: it has more real human trial data than almost anything else in this catalogue, and it is still nowhere near an established therapy. Both halves of that sentence matter.

What the human record actually consists of

Four small, mostly phase 2, placebo-controlled studies in three different indications, run largely by overlapping investigator groups with sponsor involvement, published between 2013 and 2020. The largest reported outcomes are symptom scores and imaging-derived nerve fibre counts rather than hard clinical endpoints. There is no phase 3 programme in the published record, no regulatory approval anywhere, and no independent replication of the sarcoidosis result at scale. The pattern — promising small trials, no confirmatory programme — is common in drug development and is not evidence of anything either way; it simply means the question is open.

What is not established

The innate-repair-receptor account itself, while well argued and widely cited, remains a model rather than a settled fact of receptor biology; the EPOR/CD131 heterocomplex is not as structurally characterised as the erythropoietin receptor homodimer. No outcome in any of these trials has been confirmed by an independent phase 3. And nothing in this literature says anything about the supplied research material in a person: the studies above used clinical-grade drug product under trial protocols, which is a different thing from a lyophilized research reagent. This page makes no efficacy, therapeutic, analgesic, neuroprotective, anti-inflammatory or other use claim of any kind, and the material is supplied for laboratory research use only — not for human or veterinary use.

The one claim that is well supported

ARA-290 is non-erythropoietic. That was the design goal, it was reported as a measured result in the founding 2008 paper, and it has not been contradicted in the subsequent literature. It is also the single most important thing to know about the molecule, because it is what separates it from the excluded compound it descends from.

How to verify this compound yourself

ARA-290 is short, which makes synthesis comparatively tractable, but it has two features that put specific demands on the certificate of analysis:

• Mass-spec identity against the pyroglutamate — the N-terminal pyroglutamate is a cyclised glutamate, and incomplete cyclisation yields a species differing by the mass of a water molecule. Mass spectrometry is what distinguishes the intended molecule from that near neighbour; the expected mass to check against is ≈ 1257.3 Da.
• HPLC purity — an eleven-residue sequence with three acidic residues and a serine-serine C-terminus generates a characteristic impurity profile. Reversed-phase chromatography is what separates full-length product from deletion sequences, and the percentage figure on the certificate is the summary of that separation.
• Counter-ion documentation — synthetic peptides are usually isolated as a salt, commonly trifluoroacetate. This affects net peptide content per unit mass and is a documentation question rather than a purity question, but it should appear somewhere on the paperwork.
• Endotoxin — relevant for any compound studied in immune-cell assays, since endotoxin contamination confounds exactly the readouts this molecule is used to investigate. Reported in EU/mL where tested, and independent of chemical purity.

See how to read a COA for what each certificate line means, and how to verify peptide purity for how the methods fit together. The exact batch received can be checked on the self-serve verify tool.

Research-grade sourcing and verification

ARA-290 is not held in stock. It is listed on our sourcing catalogue as available to order — our supplier lists it, we have not bought it, and material of this kind typically takes about two to three weeks to reach us. For laboratory research use only, it is supplied with a per-batch Certificate of Analysis reporting HPLC purity (%) and mass-spec identity confirmation, verifiable at the lot level. For a neighbouring innate-immunity peptide with an entirely different chemistry and literature, see LL-37 research; for the immune-signalling tripeptide studied against NF-κB-linked pathways, see KPV research. This is sourcing and quality-assurance framing only.

Frequently asked questions

Literature cited

1. Brines M, Patel NS, Villa P, et al. “Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin.” Proc Natl Acad Sci U S A. 2008;105(31):10925–10930. PMID 18676614. pubmed.ncbi.nlm.nih.gov/18676614.
2. Brines M, Cerami A. “The receptor that tames the innate immune response.” Mol Med. 2012;18(1):486–496. PMID 22183892. pubmed.ncbi.nlm.nih.gov/22183892.
3. Dahan A, Dunne A, Swartjes M, et al. “ARA 290 improves symptoms in patients with sarcoidosis-associated small nerve fiber loss and increases corneal nerve fiber density.” Mol Med. 2013;19(1):334–345. PMID 24136731. pubmed.ncbi.nlm.nih.gov/24136731.
4. Swartjes M, van Velzen M, Niesters M, et al. “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.” Mol Pain. 2014;10:13. PMID 24529189. pubmed.ncbi.nlm.nih.gov/24529189.
5. van Velzen M, Heij L, Niesters M, et al. “ARA 290 for treatment of small fiber neuropathy in sarcoidosis.” Expert Opin Investig Drugs. 2014;23(4):541–550. PMID 24555851. pubmed.ncbi.nlm.nih.gov/24555851.
6. Brines M, Dunne AN, van Velzen M, et al. “ARA 290, a nonerythropoietic peptide engineered from erythropoietin, improves metabolic control and neuropathic symptoms in patients with type 2 diabetes.” Mol Med. 2015;20(1):658–666. PMID 25387363. pubmed.ncbi.nlm.nih.gov/25387363.
7. Collino M, Thiemermann C, Cerami A, Brines M. “Flipping the molecular switch for innate protection and repair of tissues: Long-lasting effects of a non-erythropoietic small peptide engineered from erythropoietin.” Pharmacol Ther. 2015;151:32–40. PMID 25728128. pubmed.ncbi.nlm.nih.gov/25728128.
8. Culver DA, Dahan A, Bajorunas D, et al. “Cibinetide Improves Corneal Nerve Fiber Abundance in Patients With Sarcoidosis-Associated Small Nerve Fiber Loss and Neuropathic Pain.” Invest Ophthalmol Vis Sci. 2017;58(6):BIO52–BIO60. PMID 28475703. pubmed.ncbi.nlm.nih.gov/28475703.
9. Lois N, Gardner E, McFarland M, et al. “A Phase 2 Clinical Trial on the Use of Cibinetide for the Treatment of Diabetic Macular Edema.” J Clin Med. 2020;9(7):2225. PMID 32674280. pubmed.ncbi.nlm.nih.gov/32674280.
10. National Center for Biotechnology Information. “PubChem Compound Summary for CID 91810664, Cibinetide.” pubchem.ncbi.nlm.nih.gov/compound/91810664 (sequence, formula, mass, CAS 1208243-50-8).