RESUMEN
INTRODUCTION: SHR0302 is a highly selective JAK1 inhibitor. This study aimed to investigate the safety, tolerability, and pharmacokinetics of single and multiple-dose topical skin application of SHR0302 base ointment in healthy adult subjects. METHODS: This phase I clinical trial (registration number: CTR20192188) consisted of two parts. Part 1 was a single-dose ascending study with four dose levels in 32 healthy Australian adults (8 subjects in each dose group). All Australian subjects were randomized 3:1 to a single-dose topical skin application of SHR0302 base ointment or placebo. The dose escalated from 1% SHR0302 base ointment on 3% of body surface area (BSA) to 2% SHR0302 base ointment on 20% of BSA. Part 2 combined single and multiple-dose ascension studies with two dose levels in 20 healthy Chinese adults (10 subjects in each dose group). All Chinese subjects were randomized 4:1 to a combination of single and multiple doses for consecutive 10 days of topical application of 1% SHR0302 base ointment on 20% BSA or 2% SHR0302 base ointment on 20% BSA. The safety and pharmacokinetics of the SHR0302 base ointment were evaluated. RESULTS: The incidence of treatment-emergent adverse events (TEAEs) in both parts was comparable between the SHR0302 base ointment group and the vehicle group (part 1: 33.3% vs. 37.5%; part 2: 56.3% vs. 75.0%). All TEAEs were transient, recovered, and equally well-tolerated in the two racial groups. The overall absorption of the SHR0302 base ointment was slow after topical application, with Tmax>10 h. After a single dose of the SHR0302 base ointment, drug exposure in healthy Australian and Chinese subjects increased nonlinearly with the increase in the administration area and drug content. Drug exposure increased in a less-than-dose-proportional manner within the dose range tested. Due to differences in the clinical practice of topical application, the Tmax of the drug in Australian subjects was earlier than in Chinese subjects, but the overall extent of absorption seemed comparable in Australian and Chinese subjects (with comparable AUC0-t). CONCLUSION: The SHR0302 base ointment (either single or multiple doses) was well tolerated and safe, with no racial disparity. KEY MESSAGE: The SHR0302 base ointment (either single or multiples doses) was well tolerated and safe.