ARA-290
Cibinetide, Araim ARA 290
An erythropoietin fragment stripped of the blood-building activity, with phase 2 data showing it regrows small nerve fibres in sarcoidosis. Among the better evidenced peptides here.
Human trials
Not approved. Completed phase 2 trials in sarcoidosis-associated small fibre neuropathy with orphan drug designation, and development has not progressed to approval.
What it is
Erythropoietin does two separate things. It stimulates red blood cell production, which is what it is known for, and it protects and repairs tissue through a different receptor complex made of the EPO receptor paired with the beta common receptor.
ARA-290 is an eleven amino acid peptide derived from a region of EPO that engages only the second of those. It carries the tissue-protective signalling and none of the haematopoietic activity, which means it does not raise haemoglobin, does not thicken blood, and does not carry the thrombotic risk that limits EPO itself.
That is an elegant piece of drug design, and unusually for this site, it was tested properly.
What the evidence shows
A randomised, double-blind placebo-controlled pilot in 22 sarcoidosis patients with small fibre neuropathy gave ARA 290 intravenously three times weekly for four weeks. The treated group improved significantly on the small fibre neuropathy screening list, with changes in pain and physical functioning measures.
The phase 2b was more convincing. Sixty-four patients with painful sarcoid neuropathy received daily subcutaneous cibinetide at 1, 4 or 8 mg or placebo for 28 days. It met its primary endpoint: corneal nerve fibre area increased significantly at the 4 mg dose, roughly 23% from baseline, measured by corneal confocal microscopy. Intraepidermal nerve fibre length in skin also increased, and improvements in patient function correlated with the nerve fibre changes.
Measured structural nerve regrowth, correlated with symptom improvement, in a randomised placebo-controlled trial. That is a genuinely strong result for a peptide in this space.
What it does not establish
Everything outside sarcoidosis-associated small fibre neuropathy.
The trials studied one condition with a specific, measurable pathology. ARA-290 is now marketed for diabetic neuropathy, general nerve pain, inflammation and recovery, none of which it has been shown to treat. The mechanism is plausible across those settings, and plausible is where most of this site's compounds already live.
Development also stopped. A compound with a positive phase 2b that has not progressed toward approval in the years since usually has a reason, whether commercial or clinical, and the absence of a phase 3 is itself information.
Practical notes
- The dose response was not linear. 4 mg met the endpoint and 8 mg did not do better. Assuming more is better here contradicts the only dose-finding data that exists.
- Trials ran four weeks. Nothing establishes what daily use over months does, which is how it is used in practice.
- Diagnosis first. Small fibre neuropathy has many causes, several of them treatable and several of them serious. A peptide that regrows nerve fibres does not address why they were lost.
Side effects and warning signs
Commonly reported
- Injection-site reactions
- Generally well tolerated in trials, with adverse events comparable to placebo
- No effect on haemoglobin or haematocrit, which is the design goal rather than a side effect
Stop and get medical help
- Absence of a long-term safety dataset. The trials ran four weeks, and reported practice runs much longer
- Any use as a substitute for investigating unexplained neuropathy, which needs a diagnosis before it needs a peptide
Sources
From the community
Discussion for this compound concentrates in r/Peptides.
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