ARA-290 (Neuropathy Use)

Erythropoietin is strongly tissue-protective, but you cannot use it that way because the same molecule raises haematocrit and drives thrombosis. ARA-290 is the solution: it reproduces only the surface of helix B, which is the face of EPO that engages the innate repair receptor (EPOR paired with the beta common receptor, CD131) expressed on injured tissue, neurons and immune cells. Engaging that receptor suppresses local inflammatory signalling, reduces apoptosis and — the clinically interesting part — promotes regrowth of small unmyelinated nerve fibres. It has no affinity for the EPOR homodimer, so it does not stimulate erythropoiesis at all. In sarcoidosis-associated small fibre neuropathy, 28 days of daily dosing increased corneal nerve fibre abundance and reduced neuropathic pain scores versus placebo. Its plasma half-life is measured in minutes, yet the biological effects persist for days, which fits a receptor-triggered repair cascade rather than continuous occupancy.

Targets: Innate repair receptor (EPOR/CD131 heterodimer), Small unmyelinated C-fibres, Macrophage and glial inflammatory signalling

• · 4 mg daily is the dose that produced corneal nerve fibre regrowth and pain reduction in the phase 2 sarcoidosis trial. This is the one number in the whole ARA-290 space that comes from a real controlled study.
• · The phase 2 programme tested 1 mg, 4 mg and 8 mg daily. 8 mg was not clearly better than 4 mg, and 1 mg underperformed. Grey-market protocols that run 1-2 mg daily are dosing below what worked in trials.

Work out your exact syringe units →

• very commonNo change in haemoglobin, haematocrit or blood pressure— This is the point of the molecule, and trials confirmed it — the absence of erythropoietic effect is the key safety finding, not a side effect.
• commonInjection-site redness or irritation— Usually transient and self-limiting.
• uncommonHeadache
• uncommonTransient fatigue

• Nothing firmly established — the trial safety profile was close to placebo. The honest contraindication is the absence of long-term human data beyond a few 28-day courses.
• Active malignancy is a theoretical concern because the innate repair receptor is anti-apoptotic and tissue-protective, and that is not necessarily desirable in tumour tissue.

• synergybpc-157 — Commonly stacked in nerve-injury protocols; the mechanisms are non-overlapping, though the combination has never been studied.
• synergyss-31 — Both target the mitochondrial and metabolic side of neuropathy; anecdotally paired for diabetic small fibre neuropathy.

• · Neuropathic symptom scores — a validated small fibre instrument such as the SFN-SIQ or a simple 0-10 burning-pain diary makes the difference between knowing and guessing.
• · Haemoglobin and haematocrit once at baseline and once during use, to confirm the absence of erythropoietic effect with whatever material you actually have.
• · Autonomic symptoms: orthostatic tolerance, sweating, GI motility, which often improve before the pain does.

Not approved anywhere. It holds FDA orphan drug designation for sarcoidosis neuropathic pain but was never brought to market; it is sold only as a research chemical.

• Culver et al. 2017, cibinetide improves corneal nerve fibre abundance in sarcoidosis-associated small nerve fibre loss (trial)
• Brines and Cerami, innate repair receptor and non-erythropoietic EPO derivatives (review)
• NCT02039687 — ARA-290 in sarcoidosis, corneal nerve fibre density (trial)

Erythropoietin does two entirely separate jobs through two entirely separate receptor assemblies, and ARA-290 exists to split them. The classical job — making red cells — runs through the EPO receptor homodimer (EPOR)2 on erythroid progenitors, which has very high affinity for EPO and drives JAK2/STAT5 signalling. The tissue-protective job runs through a heterodimer of EPOR with the beta common receptor CD131 (the shared signalling subunit of the IL-3, IL-5 and GM-CSF receptors), which Brines and Cerami named the innate repair receptor. That heterodimer has much lower affinity for EPO, is only expressed on injured or stressed tissue, and signals through JAK2 with downstream Akt activation, NF-kB modulation and suppression of apoptosis. This is why systemic EPO looks tissue-protective in animal models and is unusable clinically: you cannot reach the low-affinity repair receptor without saturating the high-affinity erythropoietic one first, and the haematocrit rise and thrombosis get you before the protection does. ARA-290 reproduces only the outward-facing surface of helix B — the part of EPO that contacts CD131 and not the part that contacts (EPOR)2 — so it engages the repair receptor with no erythropoietic activity at all. The trials confirmed this directly: haemoglobin and haematocrit did not move. What that receptor does downstream in neuropathy is the more interesting question. Engaging it on macrophages and glia suppresses pro-inflammatory signalling; engaging it on Schwann cells and neurons is anti-apoptotic; and the observed outcome in humans is regrowth of small unmyelinated C-fibres measured by corneal confocal microscopy and by skin biopsy nerve fibre density. That regrowth endpoint is what makes ARA-290 unusually well evidenced for a research peptide — corneal confocal microscopy is an objective, blinded, quantitative measurement of nerve fibre abundance, not a symptom questionnaire. There is also a metabolic arm nobody expected: in the type 2 diabetes study, ARA-290 improved HbA1c and lipid parameters alongside the neuropathy endpoints, which does not follow obviously from the neuroprotection story and has never been properly explained.

The commonest error is underdosing. The trial dose that produced measurable nerve regrowth was 4 mg daily; the 1 mg arm underperformed and grey-market protocols routinely run 1-2 mg daily, which is below the dose that worked. If you are going to run this at all, run it at the dose that has evidence behind it. The second error is running it too briefly or judging it too early — the published course is 28 days and pain scores did not separate meaningfully until weeks two to four. The third is identity. Araim Pharmaceuticals wound down, no phase 3 was completed, and there is no legitimate supply chain; everything on the market is research material whose actual content is unverified. An 11-residue peptide with a pyroglutamate cap is not trivially easy to make correctly, and a mis-synthesised or partially degraded product is indistinguishable by eye. The haematocrit check is your one cheap identity assay, and it is a negative control rather than a positive one — it tells you the material is not erythropoietic, not that it is ARA-290. The fourth error is expecting it to work on large-fibre neuropathy. Everything ARA-290 has demonstrated is in small unmyelinated fibres: burning pain, autonomic symptoms, corneal and intraepidermal fibre density. Numbness and weakness from large-fibre or compressive pathology are a different problem and there is no evidence it touches them. Finally, and least dramatically, subcutaneous injection volume is a nuisance — a 4 mg dose from a 16 mg vial reconstituted in 4 mL is a full millilitre, which stings and often needs splitting between two sites.

• Innate repair receptor — EPOR/CD131 (beta common receptor) heterodimer — No published Kd for ARA-290 at the heterodimer. What is established is the selectivity: ARA-290 engages the heterodimer and has no measurable activity at the (EPOR)2 homodimer.

  JAK2-mediated signalling with downstream Akt activation, suppression of apoptosis, and dampening of NF-kB-driven inflammatory transcription in injured tissue. The receptor is only meaningfully expressed on stressed or damaged cells, which is why the drug behaves as though it is targeted despite being given systemically.

• EPO receptor homodimer (EPOR)2 on erythroid progenitors — None. This is a designed-out interaction.

  No erythropoiesis. Trials confirmed haemoglobin, haematocrit and blood pressure did not change. This absence is the whole reason the molecule exists, and it is also the cheapest thing to verify on yourself with a CBC.

• Small unmyelinated C-fibres — corneal sub-basal nerve plexus and intraepidermal nerve fibres — Not a receptor — the measured tissue outcome.

  Increased corneal nerve fibre abundance and increased small nerve fibre density on skin biopsy after 28 days of dosing. This is the objective endpoint that separates ARA-290 from almost everything else sold as a nerve-repair peptide.

• Macrophage and glial inflammatory signalling — Via the same innate repair receptor.

  Reduced pro-inflammatory cytokine output. This is the proposed mechanism for the reduction in neuropathic pain and autonomic symptoms that appears before any measurable structural regrowth could plausibly account for it.

• Heij et al. — ARA 290 in sarcoidosis patients with symptoms of small fibre neuropathy Phase 2, randomised, double-blind, placebo-controlled · n=22 · 4 weeks · 2012

  ARA 290 2 mg intravenously three times weekly for four weeks produced a significant improvement in the small fibre neuropathy screening list (SFNSL) score at week 4 versus placebo. Small, but the first controlled human signal, and note that this study used the intravenous route rather than the subcutaneous dosing the later trials and all grey-market protocols use.

• Culver et al. — cibinetide in sarcoidosis-associated small nerve fibre loss and neuropathic pain Phase 2, randomised, double-blind, placebo-controlled, dose-ranging · n=64 · 4 weeks · 2017

  28 days of cibinetide at 1, 4 or 8 mg daily. The 4 mg dose significantly increased small nerve fibre abundance in both cornea (by confocal microscopy) and skin, alongside improvement in neuropathic pain. This is the trial that produced the 4 mg daily figure, and it is the only objective structural regeneration endpoint in the whole compound's evidence base. 8 mg was not better than 4 mg and 1 mg underperformed.

• Brines et al. — ARA 290 in type 2 diabetes with neuropathic symptoms Phase 2, randomised, double-blind, placebo-controlled · 4 weeks · 2015

  ARA 290 4 mg daily for 28 days improved neuropathic symptoms and increased corneal nerve fibre density, and unexpectedly improved HbA1c and lipid parameters. The metabolic findings have never been satisfactorily explained and have not been replicated in a larger study.

Nothing in the first week, usually. The plasma half-life is minutes and the mechanism is a repair cascade, so there is no acute effect to feel. Autonomic symptoms — orthostatic tolerance, sweating abnormalities, GI motility — are often the first thing to shift, sometimes in the second week, and they tend to move before the pain does. Neuropathic pain and burning scores began separating from placebo in the second to fourth week across the trials. Measurable structural regrowth of corneal and skin nerve fibres was demonstrated at day 28, which is the earliest anyone has looked. Effects appear to persist after the course ends, which fits a regeneration mechanism rather than a symptomatic one, but nobody has published a proper durability follow-up so how long the benefit lasts is genuinely unknown. Judge the compound at day 28, not day 10.

ARA-290 is one of the more sensibly stackable compounds in this class because its mechanism overlaps with almost nothing else. The common pairings are with BPC-157 for nerve injury and with SS-31 for diabetic small fibre neuropathy; neither combination has ever been studied, but neither is pharmacologically contradictory, and the mechanisms (innate repair receptor, angiogenic and growth-factor signalling, cardiolipin-targeted mitochondrial protection respectively) do not collide. The pairing with the strongest theoretical rationale is with actual glycaemic control if the neuropathy is diabetic — ARA-290 regrowing fibres while the underlying hyperglycaemia keeps killing them is a treadmill. What you should not stack it with is anything erythropoietic, and this is not theoretical: if you are running ARA-290 alongside EPO or a hypoxia-inducible-factor stabiliser you have lost your ability to interpret the one safety test that matters. The genuine caution is oncological. The innate repair receptor is anti-apoptotic and tissue-protective by design, and those are not properties you want acting on a tumour. Nobody has shown ARA-290 promotes cancer, but nobody has looked hard either, and the theoretical concern is real enough that active malignancy is a sensible exclusion.

ARA-290 has better human evidence than almost anything else sold as a research peptide, and it is important to be precise about what 'better' means. Three randomised, double-blind, placebo-controlled phase 2 trials, with an objective imaging endpoint (corneal confocal microscopy) rather than a symptom questionnaire, is a completely different tier of evidence from BPC-157's rodent studies or from the endogenous opioid peptides in this class, which have no human dosing at all. It is also a completely different tier from ziconotide, difelikefalin or the CGRP antibodies, which have phase 3 programmes and regulatory approval. ARA-290 sits in the gap: real controlled human data, in small studies, that was never confirmed at scale because the company ran out of runway rather than because the drug failed. Against the standard of care for small fibre neuropathy — which is gabapentinoids, duloxetine and tricyclics, all purely symptomatic and none of which regrow anything — the mechanistic proposition is genuinely more interesting. Against the honest question of whether you should run it, the answer depends almost entirely on whether the material you can buy is what it claims to be, and that is an unanswerable question rather than a pharmacological one.

$400–$900/month. Estimated, not verified in this session — treat as an order-of-magnitude figure only. The arithmetic is what matters: 4 mg daily is 120 mg per month, which is seven to eight 16 mg vials. At typical research-peptide vendor pricing for a 16 mg vial that lands somewhere in the high hundreds per month. This is one of the more expensive research peptides to run at the dose that actually has evidence behind it, which is a large part of why grey-market protocols drift down to 1-2 mg daily.

• ?No human pharmacokinetic study has been published: tmax, volume of distribution, protein binding and a numerical half-life are all genuinely unknown, not merely omitted here.
• ?Blood-brain barrier penetration is unknown. ARA-290's demonstrated effects are on peripheral small fibres and there is no human CNS penetration data.
• ?Participant count for the Brines 2015 type 2 diabetes trial is left null; I confirmed the publication but did not resolve the enrolment figure.
• ?Whether the nerve fibre regrowth persists after the 28-day course ends has never been published. Repeat-course protocols circulating online are extrapolation, not evidence.
• ?The HbA1c and lipid improvements in the diabetes trial are unexplained by the proposed mechanism and have not been independently replicated.
• ?No Kd for ARA-290 at the EPOR/CD131 heterodimer has been published, so the affinity field is descriptive rather than numerical.
• ?The cost estimate is inferred from typical research-peptide vial pricing and was not price-checked in this session.
• ?The Core record lists the route as subcutaneous only; the first controlled trial (Heij 2012) used intravenous dosing at a different schedule, so the relationship between the IV and SC regimens is not established.

• Cibinetide Improves Corneal Nerve Fiber Abundance in Patients With Sarcoidosis-Associated Small Nerve Fiber Loss and Neuropathic Pain Culver DA, Dahan A, Bajorunas D, et al., Investigative Ophthalmology & Visual Science, 2017 · PMID 28475703

  The central paper. 64 patients, 28 days, 1 / 4 / 8 mg daily, with corneal confocal microscopy and skin biopsy endpoints. The source of the 4 mg daily dose and of the claim that ARA-290 regrows nerve fibres in humans.

• Safety and efficacy of ARA 290 in sarcoidosis patients with symptoms of small fiber neuropathy: a randomized, double-blind pilot study Heij L, Niesters M, Swartjes M, et al., Molecular Medicine, 2012 · PMID 23168581

  The first controlled human study. 22 patients, 2 mg intravenously three times weekly for four weeks. Worth reading specifically because the route and schedule differ from every protocol circulating online.

• ARA 290, a nonerythropoietic peptide engineered from erythropoietin, improves metabolic control and neuropathic symptoms in patients with type 2 diabetes Brines M, Dunne AN, van Velzen M, et al., Molecular Medicine, 2015 · PMID 25387363

  The diabetic neuropathy trial, and the source of the unexplained HbA1c and lipid findings. Also the clearest published confirmation that haemoglobin and haematocrit do not move on this compound.

• Corneal nerve fiber size adds utility to the diagnosis and assessment of therapeutic response in patients with small fiber neuropathy Brines M, Culver DA, Ferdousi M, et al., Scientific Reports, 2018 · PMID 29549285

  The methodological paper behind the corneal confocal endpoint. Useful if you want to judge how solid the nerve-regrowth claim actually is, because the credibility of the whole ARA-290 case rests on this measurement being real.