Thymosin Beta 4 (Tβ4) is a synthetic copy of the naturally-occurring 43-amino acid peptide that is found in a variety of tissues. Tβ4 promotes/accelerates wound repair in dermal, ocular, and cardiac animal models. Two recent pre-clinical evaluations have demonstrated that Tβ4 promotes corneal ocular surface defects healing in animal models of dry eye. RGN-259 (formulation of Tβ4 ophthalmic solution) mechanism of action offers potential to be a product that meets a major unmet medical need in patients with dry eye.

Tβ4 promotes wound repair and regeneration in various tissues. In the eye, it promotes corneal epithelial cell migration, decreases inflammation and has anti-apoptotic activities. It up-regulates the gene expression of laminin-5, a major subepithelial adhesion protein, located in the basement membrane region of the cornea, conjunctiva, and important in wound healing. In compassionate-use cases, Tβ4 has demonstrated efficacy in repairing non-healing neurotrophic corneal ulcers and other corneal epithelial wounds. In twenty-four nonclinical toxicology and safety pharmacology studies, the safety of Tβ4 has been demonstrated for its current and planned uses in man. The results of the two recent dry eye murine mouse model studies show that Tβ4 reduced corneal staining more than positive controls and demonstrated statistically significant reduction in staining compared to vehicle control. The results of these studies, in addition to data from compassionate use studies in patients with non-healing corneal surface defects, suggests that Tβ4 has a significant potential to be an important new safe and effective therapeutic in the treatment of dry eye syndrome.