ARA-290 How Fast Is It

A 2-minute half-life, with longer-lasting signals

ARA 290 is also called cibinetide or pyroglutamate helix B surface peptide (pHBSP). It is an 11-amino-acid peptide modeled on the helix B region of erythropoietin (EPO). A 2015 review of pharmacokinetic and pharmacodynamic data puts its plasma half-life at about 2 minutes. The authors argue that the peptide activates a 'molecular switch' at the innate repair receptor, a complex of the EPO receptor and the beta common receptor. In their account, this switch drives effects in animal models and clinical trials that last long after the peptide has cleared.Review · PMID 25728128

Later researchers see the short half-life as a limitation. A 2024 review says it restricts how ARA 290 can be studied. The review also describes CHBP, a thioether-cyclized variant built to last longer. So the molecule itself circulates very briefly. When measurable changes show up depends on the endpoint and on whether the study used people, animals or cells.Review · PMID 38943972

What human trials measured at the 4-week mark

In a double-blind randomized pilot trial, 22 people with sarcoidosis and small fiber neuropathy symptoms were split into two groups: 12 got ARA 290 and 10 got placebo. After 4 weeks, small fiber neuropathy screening list scores had fallen 11.5 points in the ARA 290 group and 2.9 points in the placebo group. In the ARA 290 group, SF-36 scores also changed from baseline by 23.4 points for pain and 14.6 points for physical functioning. Brief Pain Inventory and fatigue scores fell by similar amounts in both groups.Human RCT · PMID 23168581

A second blinded, placebo-controlled sarcoidosis trial lasted 28 days. Compared with placebo, the ARA 290 group reported lower neuropathic symptom scores. Investigators also measured higher corneal small nerve fiber density, changes in skin temperature sensitivity and a longer 6-minute walk distance. The abstract does not give a participant count.Human RCT · PMID 24136731

A phase 2b randomized trial of 64 adults with sarcoidosis compared three ARA 290 arms with placebo over 28 days. Compared with placebo, corneal nerve fiber area rose by 109, 697 and 431 square micrometers in the lowest, middle and highest-exposure groups. Only the middle group reached statistical significance (P = 0.012). In that group, a skin biopsy marker of nerve fiber growth also rose. Changes in nerve fiber area tracked changes in 6-minute walk distance (rho 0.645). Pain scores fell in every group, including placebo.Human RCT · PMID 28475703

In a phase 2 study of people with type 2 diabetes and painful neuropathy, participants got ARA 290 or placebo for 28 days and were then followed for another month. In the ARA 290 group, HbA1c and lipid profiles changed across the full 56-day observation period, and PainDetect neuropathy scores fell. Among participants who started with the lowest corneal nerve fiber density, density rose, while the placebo group showed no change.Human trial · PMID 25387363

The earliest and latest human timepoints

The earliest human timepoint in this research is one week. In a double-blind randomized trial, 36 healthy volunteers got ARA 290 or placebo and were tested one week later. The ARA 290 group showed lower fusiform gyrus responses to happy faces, faster sorting of positive versus negative words and more attention to positive pictures. Mood and affective symptoms did not differ from placebo. The authors said these results did not clearly point to an antidepressant-like profile.Human RCT · PMID 26431906

The longest human exposure was 12 weeks, in a phase 2 study of diabetic macular edema. Nine participants enrolled and eight finished. On average, visual acuity changed by -2.9 letters, central retinal thickness by +10 microns and retinal sensitivity by -0.53 dB, so none of these structural or visual endpoints moved meaningfully. The NEI VFQ-25 questionnaire composite score rose 2.7 points.Human trial · PMID 32674280

A 2014 review of the two phase 2 sarcoidosis trials called the changes in pain-related and other symptoms long-lasting. Still, the longest human follow-up in this research is 56 days. No trial here establishes how long measured changes last beyond about two months.Review · PMID 24555851Human trial · PMID 25387363

Animal timelines: from 15 minutes to 20 weeks

In 8 pigs with one kidney deprived of blood flow, ARA 290 or saline was given within the first 6 hours after blood flow resumed. MCP-1 and IL-6 expression tended to be lower 15 minutes after reperfusion, which is the fastest signal in this research. Glomerular filtration rate was higher than in controls over 7 days, and interstitial fibrosis was lower at day 7.Animal study · PMID 23302512

In rats with a nerve injury, ARA 290 was given only during the first 10 days. Mechanical and cold allodynia stayed lower than in vehicle controls for up to 20 weeks. At 2 weeks, spinal microglia reactivity had not risen in the ARA 290 groups. At 20 weeks, it was still not elevated only in the higher-exposure group.Animal study · PMID 24529189

Other rodent studies covered a range of timescales. In mice, one month of exposure raised cortical bone mineral density by about 5.8% and trabecular density by about 5.2%. In a rat model of preeclampsia that covered days 14 to 20 of pregnancy, the highest-exposure group showed 31.2% lower systolic blood pressure, 32.8% lower diastolic blood pressure and 76.1% lower proteinuria. In rats with autoimmune encephalomyelitis, exposure starting on day 7 or 9 shortened the course of clinical scores and lowered their severity.Animal study · PMID 35008482Animal study · PMID 32942669Animal study · PMID 24518674

The longest animal study ran for 15 months in aging rats. In that randomized study, cardiac inflammation-related marker levels measured below those of saline controls, and the age-related rise in blood pressure was smaller. Left ventricular ejection fraction held steady compared with saline controls. These results come from animals and do not show what happens in people.Animal study · PMID 36741836

Why the human evidence is still thin

Every human trial here is small, with 9 to 64 participants, and short, lasting 1 to 12 weeks. A 2017 systematic review of fatigue in sarcoidosis included ARA 290 as one of six interventions. It concluded that the trial evidence was limited because the studies were small and short.Meta-analysis · PMID 27507833

Speed is also hard to judge because nerve disease progresses slowly. A 2021 systematic review of diabetic neuropathy noted that many candidate drugs failed in trials and that proving lasting change takes long studies. A 2026 review lists cibinetide among agents still under research, citing changes in neuropathy scores. That makes a 4-week change in nerve fiber measures an early signal, not a long-term finding. A compound's research value depends on what is actually in the vial, which is why batch testing matters.Meta-analysis · PMID 33423557Review · PMID 42693836

The studies at a glance

ARA 290 studies by timepoint: what was measured and when

Frequently asked questions