Phase 1 Study of Topical Administration of Novel Phosphodiesterase‐4 Inhibitor PF‐07038124 in Japanese Healthy Participants

The purpose of this study was to evaluate the safety, tolerability, skin irritation potential, and pharmacokinetics of topical administration of a novel phosphodiesterase‐4 inhibitor PF‐07038124 in Japanese healthy adult participants. This randomized, vehicle‐controlled, parallel cohort study consisted of two cohorts to evaluate participants by two administration areas in parallel: PF‐07038124 at 0.01% concentration and vehicle to 2000 cm 2 of skin (Cohort 1) or 4000 cm 2 of skin (Cohort 2). Participants received repeated topical administrations of PF‐07038124 or vehicle, topically applied once daily for 10 consecutive days from Day 1. In total, one mild treatment‐emergent adverse event of alanine aminotransferase increase was reported and was not considered to be treatment‐related. There were no changes in vital signs or in electrocardiographic data in this study. The skin irritation was reported to be score 0 using Draize scoring in all participants. The majority of concentrations on Day 10 were below the lower limit of quantification up to 24 h postdose; PF‐07038124 concentrations were not measurable in 94% and 66% of plasma PK samples for the 2000 cm 2 and 4000 cm 2 treatment groups, respectively. All PF‐07038124 topical doses were generally safe and well‐tolerated both locally and systemically in Japanese healthy participants evaluated in this study. Trial Registration: ClinicalTrials.gov identifier: NCT04863417