Contact Sensitization and Phototoxic and Photoallergic Potential of Tirbanibulin 1% Ointment in Healthy Volunteers

Tirbanibulin 1% ointment is approved for the topical treatment of actinic keratosis, applied once daily for 5 days. Three phase 1 randomized, single-center, controlled, within-subject comparison studies were conducted to evaluate the sensitization (KX01-AK-006), phototoxic (KX01-AK-008), and photoallergic (KX01-AK-009) potential of tirbanibulin 1% ointment in healthy adults. In KX01-AK-006 and KX01-AK-009, subjects received repeated applications of tirbanibulin or vehicle for induction (followed by irradiation in KX01-AK-009) and an additional application for the challenge on naïve sites. In KX01-AK-008, subjects received single applications, followed by irradiation. Sensitization was defined as a reaction scoring 3 at naïve sites, recurring at rechallenge. Photoallergy was assessed based on the dermal response of erythema + edema at naïve sites. Phototoxicity was assessed based on the average dermal response score (days 3‒4). Adverse events were collected. In KX01-AK-006, none of the 229 subjects scored 3 at naïve sites. In KX01-AK-008, none of the 31 subjects developed edema, not meeting the criteria for phototoxicity. In KX01-AK-009, none of the 59 subjects showed reactions compatible with photoallergy. Mild-to-moderate contact irritations were reported. The evidence provided by these phase 1 studies showed that tirbanibulin 1% ointment lacks sensitization and phototoxic or photoallergic potential, and supports the safety of its topical application.