ARA-290 (cibinetide)

01 · What it is

ARA-290, also called cibinetide, is an eleven-amino-acid peptide designed from the tertiary structure of erythropoietin — specifically the helix-B domain, a region of the molecule that faces away from the classical erythropoietin receptor binding surface ^2,3. It is not a fragment of convenience. It was engineered to separate two functions that erythropoietin performs together: tissue protection, which is mediated by a heteromeric complex of the erythropoietin receptor and the β-common receptor often called the innate repair receptor, and erythropoiesis, which is mediated by the classical receptor homodimer and is responsible for erythropoietin’s thrombotic and cardiovascular liabilities ^10,15.

That design intent gives ARA-290 something almost nothing else in this family has: a named molecular target, a stated reason for the structural modification, and a testable prediction — that it should produce tissue protection without raising haematocrit.

It also has, by a wide margin, the most randomised human data in Family A. Four clinical studies are indexed, three of them randomised and placebo-controlled, with at least 95 subjects whose enrolment can be confirmed from published reports ^1,8,14 and a fourth trial whose enrolment its abstract does not state ⁴. The largest is a 64-subject phase 2b trial that met its primary endpoint at one dose ⁸.

The constraint on all of it is uniform and severe: Brines and Cerami, who designed the molecule, appear as authors on essentially every study of it, clinical and preclinical alike.

As of September 2026 ARA-290 holds no marketing authorisation from any regulator.

02 · Evidence at a glance

Evidence grade

Early Clinical

Sequence

11 residues, derived from the helix-B domain of erythropoietin ³

Molecular target

Innate repair receptor — an erythropoietin receptor / β-common receptor heteromer ^10,15

Erythropoietic activity

None by design; the compound is non-hematopoietic ^3,17

Indexed clinical studies

4 ^1,4,8,14

Randomised placebo-controlled trials

3 ^1,4,8

Confirmed human subjects

At least 95

Largest trial

64 subjects, phase 2b, 28 days ⁸

Primary endpoint met

Yes, at 4 mg/day; not at 1 mg or 8 mg ⁸

Anti-drug antibodies

Assessed and not detected in the diabetic macular oedema trial ¹⁴

Independent replication

Minimal — the originators appear on nearly all published work

Approval status

None, any jurisdiction

03 · Mechanism of action

The innate repair receptor

Erythropoietin has two distinct receptor interactions. The classical homodimeric erythropoietin receptor drives red cell production. A separate heteromeric complex pairing the erythropoietin receptor with the β-common receptor — the innate repair receptor — mediates the tissue-protective, anti-inflammatory and anti-apoptotic effects observed when erythropoietin is given after injury ^10,15. ARA-290 was designed to engage only the second. Work using cibinetide as a selective probe has been used to attribute effects specifically to the heteromeric complex, including in bone, where it inhibited osteoclastogenesis in vitro and increased bone mineral density in mice ¹⁷. That is a receptor-level mechanism with an experimental handle, which distinguishes this compound sharply from most of Family A.

Innate immune cell modulation

The receptor sits on innate immune cells, and much of the reported activity follows from their behaviour. Cibinetide dampened innate immune cell function and improved the clinical course of experimental colitis in mice, with improved weight gain and survival ⁹. Early administration modulated monocytes and decelerated pathology in a model of Alzheimer-like disease ¹⁸. In islet transplantation, it inhibited macrophage activation and reduced the instant blood-mediated inflammatory reaction that destroys transplanted islets ^6,13,16.

The consistent thread is suppression of an early innate inflammatory response rather than stimulation of growth.

Nociception and TRPV1

A separate line of work reports analgesic activity in pathophysiological pain that involves the TRPV1 channel, positioning the compound at the interface of immune signalling and nociception ⁵, with long-term relief of neuropathic pain in animals accompanied by suppression of the spinal microglial response ². This matters clinically, because the human trials have been in painful neuropathies.

Nerve fibre regeneration

The most distinctive claim is structural rather than symptomatic: that cibinetide increases small nerve fibre abundance. In humans this has been measured by corneal confocal microscopy, quantifying corneal nerve fibre area, alongside regenerating intraepidermal fibres identified by GAP-43 positivity ^8,11. Corneal nerve fibre size has been proposed by the same group as a diagnostic and therapeutic-response measure in small fibre neuropathy ¹¹.

A regeneration claim measured by an imaging surrogate developed and validated largely by the same investigators is a strength and a circularity at once.

Vascular repair

Cibinetide enhanced the vasoreparative capacity of endothelial colony-forming cells in the ischaemic retina ¹², and activation of the erythropoietin receptor–β-common complex improved wound healing in genetically diabetic mice ¹⁰.

These support the tissue-protection framing without bearing directly on the neuropathy indications the clinical programme has pursued.

04 · Key research findings

Sarcoidosis small fibre neuropathy — the first randomised trial. Twenty-two patients with sarcoidosis and symptoms of small fibre neuropathy were randomised to intravenous ARA-290 2 mg three times weekly (n = 12) or placebo (n = 10) for four weeks. The treated group showed significant improvement in the Small Fiber Neuropathy Screening List score at week 4 (Δ −11.5 ± 3.04 versus Δ −2.9 ± 3.34) and significant change from baseline in the pain and physical functioning dimensions of the SF-36. Brief Pain Inventory and Fatigue Assessment Scale scores improved significantly but equivalently in both groups, and no change was seen in depressive symptoms ¹.

The headline finding sits alongside an equally important one: the two most direct pain measures improved just as much on placebo.

Sarcoidosis, phase 2b — the largest trial and a non-monotonic result. Sixty-four subjects with sarcoid-associated small nerve fibre loss and neuropathic pain received cibinetide 1, 4 or 8 mg/day or placebo for 28 days, with change in corneal nerve fibre area as the primary endpoint. The placebo-corrected mean change at day 28 was 109 µm² (95% CI −429 to 647) at 1 mg, 697 (159 to 1236; P = 0.012) at 4 mg, and 431 (−130 to 992) at 8 mg. Intraepidermal GAP-43-positive fibres increased in the 4 mg group (P = 0.035), and changes in corneal nerve fibre area correlated with GAP-43 changes and with six-minute walk distance. Pain improved significantly in all groups, and the placebo-corrected pain reduction in moderate-to-severe subjects did not reach significance (P = 0.157) ⁸.

The effect appeared at the middle dose and not at the highest, pain improved on placebo as well, and the positive result is on an imaging surrogate rather than a clinical outcome — three qualifications that belong beside the headline in any honest account.

Type 2 diabetes with painful neuropathy. In a phase 2 study, subjects self-administered ARA-290 4 mg or placebo subcutaneously daily for 28 days and were followed for a further month. The treated group showed improvement in HbA1c and lipid profiles across the 56-day observation period, significant improvement in neuropathic symptoms on the PainDetect questionnaire, and, in the subgroup with corneal nerve fibre density more than one standard deviation below normal, a significant increase in density against no change on placebo ⁴.

A metabolic signal alongside a neuropathy signal is an unusual combination and would be important if reproduced; the abstract does not state the enrolment, and no confirmatory trial has been published.

Diabetic macular oedema — a null trial that was reported anyway. Nine patients were recruited and eight completed twelve weeks of self-administered cibinetide 4 mg/day. There was no improvement in best-corrected visual acuity, central retinal thickness, central retinal sensitivity or tear production. The National Eye Institute Visual Function Questionnaire composite score improved, some participants showed improvements in individual measures, and no serious adverse events or anti-cibinetide antibodies were observed ¹⁴.

Every objective endpoint was null and the patient-reported one was positive — the same pattern seen in the GHK-Cu trial, and a pattern worth recognising across this family.

Preclinical breadth. Beyond neuropathy: experimental colitis ⁹, islet protection and transplant survival in three studies ^6,13,16, diabetic wound healing ¹⁰, ischaemic retina ¹², Alzheimer-like pathology ¹⁸, bone mineral density ¹⁷, and neuropathic pain with spinal microglial suppression ².

Broad, internally consistent, and almost entirely produced by or with the originating group.

Independent assessment. A systematic review of interventions for sarcoidosis-associated fatigue included ARA-290 among six interventions evaluated and found the strongest support for anti-TNF therapies rather than for cibinetide ⁷. A review of drug development for diabetic neuropathy positions it among candidates that have not progressed to confirmatory trials ¹⁵, and a 2026 review of peptides in regenerative medicine and chronic pain reaches a comparable conclusion ¹⁹.

When investigators outside the programme have assessed it, the verdict has been “not yet.”

05 · Evidence overview

06 · Safety profile

Animal data. The preclinical literature spans colitis, islet transplantation, retinal ischaemia, neurodegeneration, bone and wound models without reports of dose-limiting toxicity ^{2,6,9,10,12,17,18}. The compound’s defining safety property is designed rather than observed: by engaging the heteromeric receptor rather than the classical erythropoietin receptor, it is intended to avoid the increases in haematocrit and thrombotic risk that constrain erythropoietin itself ^3,15.

Human data. No safety concerns were raised by clinical or laboratory assessment in the 22-subject sarcoidosis trial ¹. No potential safety issues were identified in the phase 2 diabetic neuropathy study over 28 days of dosing and 56 days of observation ⁴. The twelve-week diabetic macular oedema study reported no serious adverse events or reactions and no anti-cibinetide antibodies ¹⁴. Across the programme, exposure at 1 to 8 mg/day for up to twelve weeks has been reported as well tolerated ^8,14.

What is genuinely unknown. Exposure beyond twelve weeks in any human study. Whether the non-hematopoietic design holds under chronic dosing — the trials are short, and erythropoietic effects would be expected to accumulate slowly if the receptor selectivity were imperfect. No published human pharmacokinetics in the trials cited here, so exposure–response cannot be modelled, which is a specific problem given the non-monotonic dose result ⁸. No reproductive or developmental data. No carcinogenicity programme. And a mechanistic question that follows from the target: the innate repair receptor sits on immune cells and the compound suppresses innate immune responses ^9,18, so the consequences of sustained suppression — infection risk, tumour surveillance — have not been examined in any published study.

07 · US regulatory status

Current as of 6 September 2026. ARA-290 (cibinetide) is not approved as a drug in the United States or any other jurisdiction, and is not a controlled substance. It has been studied under investigational applications in sarcoidosis-associated small fibre neuropathy, type 2 diabetic neuropathy and diabetic macular oedema, and has not progressed to a confirmatory phase 3 programme in any indication ^1,4,8,14,15.

ARA-290 does not appear in FDA’s category 2 bulk drug substances tables and was not among the seven substances reviewed by FDA’s Pharmacy Compounding Advisory Committee on 23–24 July 2026, which covered BPC-157, KPV, TB-500, MOTS-c, emideltide, Semax and Epitalon ²⁰. No agency evidence review exists for this compound.

Under the World Anti-Doping Code, substances not approved by any governmental regulatory health authority for human therapeutic use fall within category S0 and are prohibited at all times.

08 · Limitations of the evidence

1. Research concentration is the defining limitation. The molecule’s designers appear as authors on essentially every published study of it, preclinical and clinical. That is normal in early development and it means something specific here: not one finding in this compound’s literature has been generated by a group with no stake in the answer.

1. The largest trial’s dose response is non-monotonic. The primary endpoint was met at 4 mg/day and not at 8 mg/day, with the 1 mg group flat ⁸. A dose–response that rises and then falls can reflect real receptor biology, or it can reflect chance in a trial with roughly sixteen subjects per arm. Without human pharmacokinetics the two cannot be distinguished.

1. The positive endpoints are surrogates. Corneal nerve fibre area and intraepidermal GAP-43 positivity are imaging and histological measures of nerve fibre abundance, not clinical outcomes ^8,11. They were substantially developed and validated by the same investigators who used them as endpoints, which is efficient and circular in equal measure.

1. Pain improved on placebo in both sarcoidosis trials. In the first, Brief Pain Inventory and fatigue scores improved equivalently in both arms ¹; in the phase 2b, pain improved in all groups and the placebo-corrected reduction did not reach significance ⁸. Neuropathic pain is notoriously placebo-responsive, and the compound’s symptomatic case is weaker than its structural one.

1. The one trial with fully objective endpoints was null. In diabetic macular oedema, visual acuity, retinal thickness, retinal sensitivity and tear production all failed to improve; only the patient questionnaire did ¹⁴. Nine patients cannot exclude an effect, but the direction of the result is what it is.

1. The programme has stalled. Publication output falls away sharply after 2018, no phase 3 trial has been reported in any indication, and independent reviews place the compound among candidates that have not advanced ^7,15. An eight-year gap after promising phase 2 data is itself information, even though the literature does not explain it.

1. Chronic exposure and immune consequences are untested. Twelve weeks is the longest reported dosing ¹⁴. The mechanism is suppression of innate immune activation ^9,18, and no study has examined what sustained suppression does to infection risk or immune surveillance.

09 · References

1. Heij L, Niesters M, Swartjes M, et al. Safety and efficacy of ARA 290 in sarcoidosis patients with symptoms of small fiber neuropathy: a randomized, double-blind pilot study. Mol Med. 2012;18(1):1430–1436.

   PMID 23168581 ↗

2. 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 ↗

3. 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 ↗

4. 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 ↗

5. Zhang W, Yu G, Zhang M. ARA 290 relieves pathophysiological pain by targeting TRPV1 channel: integration between immune system and nociception. Peptides. 2016;76:73–79.

   PMID 26774587 ↗

6. Watanabe M, Lundgren T, Saito Y, et al. A nonhematopoietic erythropoietin analogue, ARA 290, inhibits macrophage activation and prevents damage to transplanted islets. Transplantation. 2016;100(3):554–562.

   PMID 26683514 ↗

7. Atkins C, Wilson AM. Managing fatigue in sarcoidosis — a systematic review of the evidence. Chron Respir Dis. 2017;14(2):161–173.

   PMID 27507833 ↗

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 ↗

9. Nairz M, Haschka D, Dichtl S, et al. Cibinetide dampens innate immune cell functions thus ameliorating the course of experimental colitis. Sci Rep. 2017;7(1):13012.

   PMID 29026145 ↗

10. Bitto A, Irrera N, Pizzino G, et al. Activation of the EPOR-beta common receptor complex by cibinetide ameliorates impaired wound healing in mice with genetic diabetes. Biochim Biophys Acta Mol Basis Dis. 2018;1864(2):632–639.

    PMID 29223734 ↗

11. Brines M, Culver DA, Ferdousi M, et al. Corneal nerve fiber size adds utility to the diagnosis and assessment of therapeutic response in patients with small fiber neuropathy. Sci Rep. 2018;8(1):4734.

    PMID 29549285 ↗

12. O’Leary OE, Canning P, Reid E, et al. The vasoreparative potential of endothelial colony-forming cells in the ischemic retina is enhanced by cibinetide, a non-hematopoietic erythropoietin mimetic. Exp Eye Res. 2019;182:144–155.

    PMID 30876881 ↗

13. Yao M, Watanabe M, Sun S, et al. Improvement of islet allograft function using cibinetide, an innate repair receptor ligand. Transplantation. 2020;104(10):2048–2058.

    PMID 32345869 ↗

14. 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 ↗

15. Rendell MS. The time to develop treatments for diabetic neuropathy. Expert Opin Investig Drugs. 2021;30(2):119–130.

    PMID 33423557 ↗

16. Yao M, Domogatskaya A, Ågren N, et al. Cibinetide protects isolated human islets in a stressful environment and improves engraftment in the perspective of intra portal islet transplantation. Cell Transplant. 2021;30:9636897211039739.

    PMID 34498509 ↗

17. Awida Z, Bachar A, Saed H, et al. The non-erythropoietic EPO analogue cibinetide inhibits osteoclastogenesis in vitro and increases bone mineral density in mice. Int J Mol Sci. 2021;23(1):55.

    PMID 35008482 ↗

18. Al-Onaizi MA, Thériault P, Lecordier S, Prefontaine P, Rivest S, ElAli A. Early monocyte modulation by the non-erythropoietic peptide ARA 290 decelerates AD-like pathology progression. Brain Behav Immun. 2022;99:363–382.

    PMID 34343617 ↗

19. Luansritisakul C, Chiang MC, Burns SL, Fonseca ACG. Peptides in regenerative medicine: a comprehensive review of clinical applications in tissue repair and chronic pain management. Curr Pain Headache Rep. 2026;30(1):109.

    PMID 42635865 ↗

20. US Food and Drug Administration. July 23–24, 2026: Meeting of the Pharmacy Compounding Advisory Committee. Docket FDA-2025-N-6895. Regulatory document; no PMID.

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