Crisaborole and atopic dermatitis skin biomarkers: An intrapatient randomized trial

Background: Crisaborole ointment 2% is a nonsteroidal phosphodiesterase 4 inhibitor for the treatment of mild-to-moderate atopic dermatitis (AD). The mechanism of action of crisaborole and its effects on lesional measures of disease severity are not yet well defined. Objective: This phase 2a, single-center, vehicle-controlled, intrapatient study was designed to further characterize the mechanism of action of crisaborole through evaluation of clinical efficacy and changes in skin biomarkers in adults (n = 40) with mild-to-moderate AD. Methods: Two target lesions were randomized in an intrapatient (1:1) manner to double-blind crisaborole/vehicle applied twice daily for 14 days. Patients then applied crisaborole (open-label) to all affected areas for 28 days. Punch biopsy specimens were collected for biomarker analysis at baseline, day 8 (optional), and day 15. Results: Crisaborole treatment resulted in early improvement in lesional signs/symptoms versus vehicle, with improvement in pruritus (pruritus numeric rating scale) observed as early as 24 hours after the first application. Crisaborole-treated lesions showed significant percentage improvement from baseline in lesional transcriptomic profile compared with vehicle at day 8 (91.15% vs 36.02%, P < 10⁻¹⁵) that was sustained until day 15 (92.90% vs 49.59%, P < 10⁻¹⁵). Crisaborole significantly modulated key AD biomarkers versus vehicle, including T_H2 and T_H17/T_H22 pathways and epidermal hyperplasia/proliferation. Molecular profiles and epidermal pathology normalized toward nonlesional skin and correlated with clinical changes in lesion severity and barrier function. Conclusion: Crisaborole reversed biomarker profiles of skin inflammation and barrier function, with associated improvements in clinical efficacy measures, highlighting the therapeutic utility of targeting phosphodiesterase 4 in patients with AD.