Cibinetide (ARA-290): experimental nerve-pain drug derived from the EPO hormone
A synthetic peptide based on erythropoietin (the hormone that makes red blood cells) that protects nerves and eases pain without affecting blood cells; tested in small trials for nerve damage from sarcoidosis and diabetes, experimental and not yet an approved drug.
- Class
- EPO-derived tissue-protective peptide (innate repair receptor agonist)
- Status
- Investigational — orphan drug designation (US); no approved indication identified in any jurisdiction
- Best-supported effect
- Improved neuropathic symptom scores and corneal nerve fiber density in sarcoidosis-associated small fiber neuropathy (Phase 2 human trials; n=22–48; Phase 3 not conducted)
- Main caveat
- Phase 3 trials have not been conducted; all human evidence is from small Phase 2 studies (n=22–48 patients); no regulatory approval in any indication
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A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
ARA-290 (also called cibinetide, or "helix B surface peptide" / HBSP) is a short synthetic peptide derived from a specific region of erythropoietin (EPO) — the hormone that tells the body to make red blood cells. The peptide was engineered to keep EPO's tissue-protective and anti-inflammatory effects while stripping out its red-blood-cell-stimulating activity, which is what makes recombinant EPO risky cardiovascularly. ARA-290 is 11 amino acids long and is given as an injection; it has been tested in small Phase 2 clinical trials, mainly in patients with nerve pain from sarcoidosis and from type 2 diabetes. The peptide is investigational — it has US FDA orphan drug designation and US Fast Track designation for sarcoidosis-associated small fiber neuropathy, but no regulatory approval anywhere. The active drug is the pyroglutamate-stabilized 11-mer pQ-EQLERALNSS; the N-terminal glutamine is cyclized to pyroglutamate to block aminopeptidase cleavage, and that cyclized N-terminus is part of what the molecule actually is even though it isn't visible from the bare letter sequence (Brines and colleagues, PNAS 2008).
History
ARA-290 came out of work by Michael Brines and Anthony Cerami, who in 2004 showed that EPO's tissue-protective effects run through a different receptor from its red-blood-cell effects — a heterodimer of the EPO receptor (EPOR) and the β-common receptor (βcR, also called CD131) that they later named the innate repair receptor (Brines and colleagues, PNAS 2004). That separation made it possible to ask whether a fragment of EPO could be designed to hit the protective receptor only. In 2008 the same group reported that short peptides modeled on the aqueous face of helix B of EPO retained tissue protection without erythropoiesis (Brines and colleagues, PNAS 2008) — the work that produced ARA-290. The peptide was developed clinically by Araim Pharmaceuticals. Early human work in sarcoidosis-associated small fiber neuropathy was published by Heij and colleagues (Molecular Medicine 2012), followed by a corneal-nerve-fiber regeneration study by Dahan and colleagues (Investigative Ophthalmology & Visual Science 2017, the DOSARA trial) and a Phase 2 trial in type 2 diabetes with neuropathic symptoms by Brines and colleagues (Molecular Medicine 2014). The US FDA granted orphan drug designation for sarcoidosis in 2016 and Fast Track designation for sarcoidosis-associated small fiber neuropathy.
What it does
ARA-290 selectively activates the innate repair receptor (IRR), which is only present on cells that are injured or actively inflamed — healthy tissue doesn't express it. That means the peptide's anti-inflammatory and pro-repair signal lands at injury sites rather than across the whole body, which is a different pharmacological logic from broad immunosuppression. The downstream effects documented in preclinical work include suppression of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), reduced apoptosis, support for nerve fiber regeneration, and reduced oxidative stress (Brines and colleagues, PNAS 2008). Because ARA-290 does not engage the homodimeric EPO receptor on red-cell precursors, it does not raise hemoglobin or hematocrit — confirmed in the Phase 2 human trials, where hematologic parameters did not change (Heij and colleagues, Molecular Medicine 2012).
Mechanism
Erythropoietin signals through two distinct receptor configurations. The classical homodimeric EPOR2 on erythroid precursors drives red blood cell production. A separate heteromeric complex of EPOR plus the β-common receptor (βcR / CD131) — the innate repair receptor — mediates EPO's tissue-protective effects (Brines and colleagues, PNAS 2004). ARA-290 corresponds to the aqueous-facing surface of helix B of EPO; this surface engages the IRR but not the erythropoietic homodimer, which is why the peptide selectively activates the IRR without raising red-cell mass (Brines and colleagues, PNAS 2008). IRR engagement triggers JAK2/STAT3, PI3K/Akt, and MAPK signaling, leading to anti-apoptotic and anti-inflammatory programs in the affected tissue. In peripheral neuropathy models and in the human corneal-nerve-fiber regeneration data, IRR signaling is proposed to support regrowth of unmyelinated C-fibers and epidermal/corneal nerve endings (Dahan and colleagues, IOVS 2017).
The molecule's biology is shaped by two chemistry features that the raw letter sequence does not show: the N-terminal pyroglutamate cap (a cyclized glutamine that blocks aminopeptidase cleavage and provides storage stability) and the very short 11-residue length, which limits exposure half-life and is why clinical studies have used daily or three-times-weekly dosing schedules rather than long-interval injections (Brines and colleagues, PNAS 2008).
Evidence
- Human: Three published Phase 2 trials. Heij and colleagues (Molecular Medicine 2012) ran a randomized, double-blind, placebo-controlled pilot in 22 sarcoidosis patients with small fiber neuropathy: 2 mg IV three times weekly for 4 weeks improved the Small Fiber Neuropathy Screening List score and SF-36 pain and physical-functioning subscales versus placebo, with hemoglobin unchanged. Dahan and colleagues (IOVS 2017, the DOSARA Phase 2b trial) randomized 64 sarcoidosis patients with painful small nerve fiber loss to daily subcutaneous cibinetide (1, 4, or 8 mg) or placebo for 28 days and reported a 23% increase in corneal nerve fiber area at the 4 mg dose by in vivo confocal microscopy — an objective regenerative endpoint, paired with neuropathic-symptom improvement. Brines and colleagues (Molecular Medicine 2014) tested cibinetide against placebo in 48 patients with type 2 diabetes and reported improvement in HbA1c, lipid profile, and neuropathic symptom scores, with effects on glycemic control persisting through a post-treatment follow-up. No Phase 3 trial has been conducted.
- Animal: Extensive preclinical work using ARA-290 / pHBSP across diabetic neuropathy, ischemia-reperfusion injury, traumatic brain injury, myocardial infarction, and wound healing models — including cardioprotection against ischemic myocardial damage (Ahmet and colleagues, Molecular Medicine 2011) and a series of EPO-helix-B-peptide cytoprotection papers building on the founding PNAS 2008 design study.
- In vitro / mechanism: Receptor-level selectivity for the EPOR/βcR heterodimer versus the homodimeric EPOR2 demonstrated at the molecular level (Brines and colleagues, PNAS 2004; Brines and colleagues, PNAS 2008). Downstream JAK2/STAT3, PI3K/Akt, and MAPK activation documented across cell-based assays in the same lines of work.
Known effects
- Sarcoidosis-associated small fiber neuropathy (neuropathic symptoms) — Phase 2 RCT (Heij and colleagues, 2012)
- Sarcoidosis-associated small nerve fiber loss (corneal nerve fiber regeneration) — Phase 2b (Dahan and colleagues, 2017)
- Type 2 diabetes — neuropathic symptoms and metabolic control — Phase 2 RCT (Brines and colleagues, 2014)
- Tissue repair across injury models (cardiac, brain, kidney, skin) — Preclinical only
- Broader chronic pain and neuroinflammation — Mechanistic / preliminary signal only
Safety signals
Across the Phase 2 human trials, ARA-290 was generally well tolerated. Mild injection-site reactions were the most common finding; no serious adverse events attributable to the peptide were described in the published reports (Heij and colleagues, 2012; Dahan and colleagues, 2017; Brines and colleagues, 2014). Hematologic parameters (hemoglobin, hematocrit) did not change — consistent with the molecule's design and with the IRR-versus-EPOR2 selectivity argument. Long-term safety beyond the dosing windows used in these trials (4 weeks in each case) has not been established. Durability of nerve-fiber regrowth and symptom improvement after discontinuation is an open question explicitly flagged in the published literature.
Regulatory status
- US (FDA): Not approved. Orphan drug designation granted to Araim Pharmaceuticals for sarcoidosis in 2016. Fast Track designation for sarcoidosis-associated small fiber neuropathy granted earlier in the development program. Orphan drug designation is not approval — it is a development incentive for rare-disease indications.
- EU: No EMA marketing authorization identified.
- WADA: Status not addressed in the published literature reviewed here.
- Access: Investigational — restricted to clinical-research settings per the published trial reports.
Open questions
- Phase 3 confirmation. All human evidence is from small Phase 2 studies (n = 22–64). Whether the sarcoidosis-SFN signal replicates at the scale of a powered Phase 3 trial is the central unresolved question for the molecule.
- Durability after discontinuation. Whether the corneal-nerve-fiber and symptom gains persist once treatment stops is explicitly open in the published literature (Dahan and colleagues, 2017).
- Other neuropathy etiologies. Human evidence outside sarcoidosis-SFN is limited to a single Phase 2 RCT in type 2 diabetes. Idiopathic and other peripheral neuropathies are not yet characterized.
- Route equivalence. The 2012 pilot used intravenous dosing; later trials used subcutaneous. Direct head-to-head efficacy comparison between routes has not been reported.
- Translation of preclinical breadth. Preclinical work spans cardiac, brain, renal, and wound-healing models; human trials so far are confined to neuropathy. Whether the broader tissue-protection signal translates to humans is unknown.
Related peptides
- Erythropoietin (EPO) — the parent hormone. ARA-290 is engineered from helix B of EPO and is the prototypical "non-erythropoietic EPO derivative" designed to keep tissue protection while losing red-cell stimulation.
- Pyroglutamate helix B surface peptide (pHBSP) — the explicit pyroglutamate-stabilized name used for the same molecule in much of the preclinical cardioprotection and neuroprotection literature.
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Does the chemical modification at the start of cibinetide specifically direct it toward the tissue-protective receptor complex and away from the blood-making one?
If true, it would explain cibinetide's safety advantage over EPO and would guide design of future neuroprotective drugs that definitively cannot stimulate blood-cell overproduction, removing a key safety concern that has held back EPO-derived therapies.
Could cibinetide, applied as eye drops, restore corneal nerve fibers destroyed by Sjogren's syndrome and relieve the associated chronic pain?
If true, it would offer the first regenerative treatment for a painful, vision-threatening complication of Sjogren's syndrome affecting millions of people worldwide, using a drug already shown to be safe in human neuropathy trials.
Does cibinetide repair nerve damage by triggering the growth of new small nerve fibers rather than simply reducing inflammation?
If true, it would mean cibinetide could reverse established nerve damage rather than just slowing decline, offering genuine recovery to patients with painful neuropathy from sarcoidosis or diabetes who currently have no regenerative option.
Does cibinetide's constrained ring structure prevent it from activating immune receptors (IL-3, IL-5) that share the same surface protein it binds on?
If true, it would confirm that the cyclic structure is pharmacologically essential, not just a stability trick, and would guide the design of safer EPO-derived drugs by ensuring the ring constraint is preserved in all future analogs.
Could cibinetide reduce life-threatening organ damage in sepsis by dampening the immune overreaction that destroys tissue?
If true, it could provide the first targeted anti-inflammatory organ-protector for sepsis, one of the leading causes of hospital death, using a peptide already shown to be safe in humans, which would substantially shorten the path to clinical use.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.667307436466217 | openfold3-mlx |
| ranking score | 0.8849060535430908 | openfold3-mlx |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.830 | global PDE — lower = better |
| disorder | 0.513 | ! high disorder |
| chain pair ipTM (A, B) | 0.667 | interface quality |
▸3-letter notation
▸recipeopenfold3-mlx 0.3.1
| parameter | value |
|---|---|
| model | openfold3-mlx 0.3.1 |
| weights | — |
| hardware | — |
| mlx version | — |
| python | — |
| random seed | — |
| msa strategy | — |
| diffusion samples | 1 |
| runtime | 480s |
| predicted by | mlx@peptide |
| predicted at | 2026-05-03 |
▸citationbibtex
@peptide{pep10908,
sequence = {CAQCIKSEQPY},
target = {epor},
author = {peptidemodel},
year = {2026},
status = {computed}
}