Crisaborole Topical Ointment, 2% in Patients Ages 2 to 17 Years with Atopic Dermatitis: A Phase 1b, Open-Label, Maximal-Use Systemic Exposure Study

Background: Phosphodiesterase-4 (PDE4) is a promising target in atopic dermatitis (AD) treatment. The pharmacokinetics (PK), safety, and efficacy of crisaborole topical ointment, 2% (formerly AN2728) (Anacor Pharmaceuticals, Palo Alto, CA), a boron-based benzoxaborole PDE4 inhibitor, were evaluated in children with mild to moderate AD. Methods: This phase 1b, open-label, maximal-use study of crisaborole topical ointment, 2% applied twice daily (dose 3 mg/cm(2)) for 28 days enrolled patients ages 2 to 17 years with extensive AD involving 25% or more or 35% or more treatable body surface area, depending on age. Primary PK and safety assessments included systemic exposure to crisaborole and its metabolites after 7 days of treatment and the incidence of treatment-emergent adverse events (TEAEs). Secondary efficacy assessments included change from baseline in Investigator Static Global Assessment (ISGA), treatment success (ISGA score <= 1 with a two-grade or greater improvement from baseline), and improvement in five AD signs and symptoms. Results: Of 34 patients enrolled, 31 completed the study. Crisaborole was rapidly absorbed, with limited systemic exposure between days 1 and 8. Twenty-three of 34 patients reported one or more TEAEs; 95% were mild or moderate and one patient discontinued because of a TEAE. Mean ISGA scores declined from 2.65 at baseline to 1.15 at day 29, 47.1% of patients achieved treatment success, and 64.7% of patients achieved ISGA scores of clear (0) or almost clear (1). Mean severity scores for AD signs and symptoms declined throughout the study. Conclusions: This open-label study provides evidence that crisaborole topical ointment, 2% was well tolerated, with limited systemic exposure under maximaluse conditions in patients ages 2 years and older.