For research and educational purposes only · Not medical advice · Consult a qualified physician before any human use
ARA-290 (cibinetide) is an 11 amino acid synthetic peptide derived from the helix-B surface domain of erythropoietin. It is the only compound in this research series to have demonstrated structural nerve regeneration in a properly controlled human trial: a 23% increase in corneal nerve fiber area (CNFA) in a pre-specified primary endpoint in a double-blind Phase 2b RCT (Culver et al., 2017, IOVS). The original developer, Araim Pharmaceuticals, has closed. No active IND or clinical trial program exists as of May 2026. The Phase 2b evidence is real and unrefuted. The development pathway does not currently exist.
ARA-290 holds a unique position in this research series: it has the most compelling Phase 2 human evidence of any non-approved peptide in the series, and simultaneously has no active development program.
Development status (May 2026): Araim Pharmaceuticals, the company that developed ARA-290 through Phase 2, has closed. No active investigational new drug application (IND) exists. No active clinical trials for ARA-290 or cibinetide are registered on ClinicalTrials.gov as of May 2026. Phase 3 would require a new sponsor to initiate an entirely new development program. That has not happened. The FDA Fast Track and Orphan Drug designations were held by Araim; their status following company closure is uncertain.
The stalling of ARA-290's development is attributable to commercial and organizational factors at Araim, not to a scientific failure of the compound itself. The underlying biology remains scientifically compelling. The development infrastructure to act on it no longer exists.
The Phase 2b primary endpoint was correctly measured: the pre-specified primary endpoint was change in corneal nerve fiber area (CNFA) measured by corneal confocal microscopy, not intraepidermal nerve fiber density (IENFD) by skin punch biopsy. IENFD was a secondary endpoint. GAP-43 positive fiber increase was also a secondary finding. These distinctions matter for interpreting what was proven vs what was observed incidentally.
The 4 mg dose met the primary endpoint. The 1 mg and 8 mg doses did not reach statistical significance for the primary endpoint, indicating a non-linear dose response.
ARA-290 is not available through any commercial, compounding, or clinical trial channel as of May 2026.
ARA-290, also called cibinetide or the helix B surface peptide (HBSP), is a synthetic 11 amino acid peptide derived from the helix-B surface domain of erythropoietin (EPO). Scientists identified that a portion of EPO's molecular structure, the helix-B domain, was responsible for its tissue-protective and anti-inflammatory effects but not its red blood cell-stimulating activity. By isolating and modifying this sequence, Araim Pharmaceuticals created ARA-290, designed to capture the healing and protective properties of EPO while avoiding risks like increased hematocrit, blood viscosity, and clotting associated with EPO use.
The key distinction is the receptor. EPO stimulates red blood cell production by activating a homodimeric EPO receptor (EPOR) complex. The tissue-protective effects of EPO are mediated by a completely different receptor: a heterodimeric complex of EPOR and CD131 (the beta-common cytokine receptor), also known as the innate repair receptor (IRR). ARA-290 selectively activates the IRR without touching the hematopoietic receptor complex, producing tissue protection and nerve repair without any increase in hematocrit, hemoglobin, or clotting risk.
Araim Pharmaceuticals developed ARA-290 through a Phase 2b trial completed in 2017 and conducted subsequent Phase 2 trials through 2020. The company has since closed. No Phase 3 program was initiated.
ARA-290 mediates tissue protection by selectively activating the innate repair receptor (IRR): a heterodimeric receptor complex composed of the EPO receptor (EPOR) and CD131, the beta-common cytokine receptor. This receptor is distinct from the homodimeric EPOR complex responsible for erythropoiesis. Because ARA-290 selectively activates the IRR rather than the hematopoietic EPOR homodimer, it produces tissue-protective effects without stimulating red blood cell production.
The IRR is rapidly upregulated locally following tissue injury. Despite a short plasma half-life (approximately 2 minutes IV, approximately 20 minutes SubQ), ARA-290 triggers sustained biological effects when concentrations exceed the low nanomolar affinity threshold of the receptor. The peptide acts as a trigger rather than a persistent agent, briefly activating the IRR to initiate a cascade of tissue-protective events that outlast the peptide's presence in circulation.
The downstream effects include: reduction in pro-inflammatory cytokines via NF-kB inhibition; protection of mitochondria and cell membranes from oxidative stress; activation of repair pathways in neurons and endothelial cells; and suppression of the NLRP3 inflammasome in Schwann cells during the acute phase of nerve injury.
A second mechanism operates entirely separately from IRR activation: TRPV1 channel antagonism on small nerve fibers. TRPV1 is the receptor involved in mechanical hypersensitivity and neuropathic pain. ARA-290 blocks it directly, addressing pain through a pathway distinct from the repair mechanism.
The mechanism is immunomodulatory rather than immunosuppressive: it calms excessive inflammation without shutting down immune defense. The absence of anti-drug antibodies across multiple trials is an important safety feature.
Phase 2b RCT (Culver et al., 2017, IOVS, n=64, double-blind, placebo-controlled, 28 days): patients with sarcoidosis-associated small fiber neuropathy self-administered cibinetide at 1 mg, 4 mg, or 8 mg daily subcutaneously.
Primary endpoint: change in corneal nerve fiber area (CNFA) measured by corneal confocal microscopy. At 28 days, the 4 mg dose produced a placebo-corrected mean increase in CNFA of 697 square micrometers (95% CI: 159 to 1,236; p=0.012): approximately 23% increase from baseline. The primary endpoint was met at the 4 mg dose. The 1 mg and 8 mg doses did not reach statistical significance for the primary endpoint, indicating a non-linear dose response.
Secondary endpoints: GAP-43-positive intraepidermal nerve fibers (a marker of newly generating axonal growth cones) increased significantly in the 4 mg group (p=0.035). CNFA changes correlated significantly with improvements on the 6-minute walk test (rho=0.645, p=0.009). Pain improvement was observed in patients with moderate to severe baseline pain at 4 mg.
CNFA is a structural biological endpoint: actual measurable nerve fiber area, not a pain score or patient-reported outcome. This is the only compound in this research series to have demonstrated structural nerve regeneration in a properly controlled human trial.
The strongest and most rigorously demonstrated area of ARA-290's evidence base. A pre-specified primary endpoint was met in a double-blind RCT, demonstrating not just symptomatic relief but actual measurable nerve fiber regeneration: a structural and biological endpoint rather than purely subjective pain reporting. This stands as the only compound in this entire research series that has demonstrated structural nerve regeneration in a properly controlled human trial. The critical limitation is development status: Araim Pharmaceuticals has closed and no active program exists to build on this evidence.
Phase 2 (Brines et al., 2015, Molecular Medicine, n=49, 28 days): 4 mg cibinetide subcutaneously daily. Significant improvements in HbA1c (p=0.002), PainDetect neuropathic symptom score (p=0.03), cholesterol-to-HDL ratio (p=0.039), and triglycerides (p=0.043), alongside an increase in corneal nerve fiber density.
The mechanistic rationale is coherent: the same inflammatory pathways ARA-290 targets via the IRR are the pathways driving diabetic nerve damage. The compound appears to address the pathology rather than mask symptoms.
Phase 2 evidence with statistically significant improvements across multiple metabolic and neuropathic endpoints in a relevant patient population. The 28-day treatment duration limits interpretation of long-term durability. No Phase 3 program exists given Araim's closure.
Watanabe et al. (2016) showed ARA-290 inhibits macrophage activation and prevents damage to transplanted islets in preclinical models.
Yao et al. (2020) reported cibinetide improves islet allograft function: in an allogeneic mouse model, cibinetide-treated animals showed allograft survival of 19.3 days versus 1.4 days in controls (p less than 0.01). The mechanism involves anti-apoptotic protection of transplanted islet cells via caspase 3/7 suppression during cytokine exposure.
EU Orphan Medicinal Product designation was granted for prevention of graft loss in pancreatic islet transplantation, reflecting the regulatory recognition of this evidence.
Primarily preclinical with the EU Orphan designation reflecting scientific merit. The allograft survival finding (19.3 vs 1.4 days) is a striking preclinical result. No human islet transplantation trial has been conducted. Without an active development program, this indication remains preclinical.
A 15-month formal randomized controlled trial in aged Fischer 344 x Brown Norway rats (n=48 longitudinal, n=144 cross-sectional) demonstrated that chronic ARA-290 administration counteracted age-related cardiovascular and inflammatory changes: preserving cardiac function, reducing cardiac inflammation, mitigating hypertrophic remodeling, and attenuating frailty. This is one of the few preclinical aging studies that used a formal RCT design with adequate sample sizes and a 15-month treatment window: design rigor rarely seen in the longevity peptide literature.
The 15-month RCT design is unusually rigorous for preclinical longevity research. The mechanistic grounding in inflammaging biology is strong. This is entirely preclinical: the cardiac aging application has not been tested in humans. Without an active development program, this remains a compelling but unvalidated research finding.
Nine patients received 4 mg cibinetide subcutaneously daily for 12 weeks. Primary visual endpoints were not met: no improvement in mean change from baseline in best corrected visual acuity, central retinal thickness, central retinal sensitivity, or tear production.
Secondary findings: some participants showed improvement in National Eye Institute Visual Function Questionnaire composite scores. All four patients with abnormal albumin-creatinine ratios at baseline showed improved indices at week 12, suggesting a potential glomerular-protective signal. No serious adverse events or anti-cibinetide antibodies were observed.
Mixed Phase 2 results: all primary visual endpoints missed. The albuminuria finding is an exploratory secondary observation from n=9 and cannot be treated as confirmatory evidence of renal protection. The signal is hypothesis-generating only. No further development is planned given Araim's closure.
ARA-290 ameliorated chronic stress-induced depression-like behavior and inflammatory markers in mice in the Xu et al. (2022) study. The Cerit et al. (2015) pilot study in healthy human volunteers examined neural and cognitive processing following ARA-290 administration, finding preliminary signals in emotional processing.
The mechanistic rationale involves the beta-common receptor's presence in the CNS and ARA-290's anti-inflammatory and neuroprotective properties potentially extending to brain circuitry involved in mood regulation.
Primarily preclinical. The Cerit 2015 study is a small human pilot, not a therapeutic trial. No clinical program has been initiated for neuropsychiatric indications. Blood-brain barrier penetration by ARA-290 has not been formally characterized in humans, which limits conclusions about CNS applications despite the mechanistic rationale.
ARA-290 is not available outside clinical trials. No active clinical trial program exists as of May 2026 following Araim Pharmaceuticals' closure. There is no prescription pathway, no compounding authorization, and no research peptide supply through legitimate channels. The SubQ route is validated by the Niesters 2013 PK study which was the pharmacokinetic basis for the Phase 2b trial's dosing protocol.
ARA-290 vs TB4 (neuroprotection comparison): both have demonstrated nerve-related effects in human trials. TB4's ophthalmic program (RGN-259) focuses on corneal nerve healing via actin cytoskeleton mechanisms; ARA-290's sarcoidosis program demonstrates peripheral small fiber regeneration via IRR activation. Mechanistically distinct and non-competing. TB4's program is more active (SEER-2 ongoing in US) but ARA-290's primary endpoint finding in peripheral neuropathy is more directly relevant to systemic neuropathy applications.
ARA-290 vs BPC-157 (tissue repair comparison): BPC-157 has more extensive preclinical data but less rigorous human evidence (Croatian Phase II IBD exposure vs ARA-290's double-blind primary endpoint met). ARA-290 has the stronger human evidence quality; BPC-157 has broader preclinical application scope.
Clinical studies across multiple Phase 2 trials suggest ARA-290 is well tolerated. Mild headache, dizziness, and transient nausea have occasionally been reported. No increase in hematocrit or hemoglobin. No serious adverse events were reported in the Phase 2b sarcoidosis trial (n=64), the Phase 2 diabetic neuropathy trial (n=49), or the Phase 2 DME trial (n=9).
Notably, no anti-cibinetide antibodies were detected across multiple trials: an important safety feature, as antibody development is one of the most common failure modes for therapeutic peptides in long-term use.
No absolute contraindications have been established from the clinical trial program. Standard precautionary avoidance recommended in pregnancy given absence of formal data. The compound's selective receptor profile (IRR only, no hematopoietic EPOR activation) is the primary structural safety advantage over EPO.
Important limitation: the safety database is small (fewer than 200 total human subjects across all trials) and trial durations were short (28 to 84 days). Long-term safety has not been characterized.
ARA-290 presents the most paradoxical profile in this research series: the strongest Phase 2 human evidence of any non-approved peptide in the series, and simultaneously no active development program.
The Phase 2b sarcoidosis neuropathy finding is genuine and has not been refuted: measurable structural nerve regeneration in a double-blind RCT is a scientifically meaningful result. The FDA Fast Track and Orphan Drug designations reflected regulatory recognition of that evidence quality. The successful end-of-Phase 2 FDA meeting was completed.
Araim Pharmaceuticals has since closed. No active IND exists. No Phase 3 program is registered. The stalling of ARA-290's development is attributable to commercial and organizational factors at Araim, not to a scientific failure of the compound. As a naturally occurring peptide-derived compound, broad patent protection was difficult, reducing commercial incentive for the large investment needed to run Phase 3 trials.
The sarcoidosis small fiber neuropathy population, a group with no approved disease-modifying therapy, continues to lack an option that Phase 2 data suggests could help them. If a new sponsor initiates a Phase 3 program, the regulatory pathway is established and the Phase 2b data clearly supports it. If no new sponsor emerges, this remains an unresolved gap in neuropathy therapeutics.
For research and educational purposes only · Not medical advice · Consult a qualified physician before any human use