An Interim Report of a Phase 3, Long-Term, Open-Label Study to Evaluate Efficacy and Safety of Difamilast Ointment in Japanese Infants with Atopic Dermatitis.

Introduction: Difamilast is the first selective phosphodiesterase 4 inhibitor approved for atopic dermatitis (AD) in Japan. A phase 3, 52-week, open-label study is ongoing to establish efficacy and safety of difamilast ointments in infants with AD aged 3 to < 24 months because a clinical study has not been conducted in this population.
Methods: This study consisted of a 4-week primary evaluation period in which difamilast 0.3% ointment was applied twice daily to Japanese infants aged 3 to < 24 months (n = 41) and an ongoing 48-week long-term extension period in which difamilast 0.3% or 1% ointment was applied based on existing symptoms. The data on efficacy and safety of difamilast were obtained as of an interim report in the study period.
Results: The response rate in Investigator's Global Assessment score was 45.0% at week 1, which was maintained at 56.1% at week 4 and 63.4% at the interim report. Infants achieved the response rate in Eczema Area and Severity Index 75 (improvement of ≥ 75%) of 47.5% at week 1, which further improved to 82.9% at week 4 and 78.1% at the interim report. Adverse events (AEs) were reported in 22 (53.7%) infants in the primary evaluation period: of those the most frequent AE was nasopharyngitis (19.5%) followed by dermatitis contact (7.3%). As of the interim report, 36 (87.8%) infants experienced AEs: of those, nasopharyngitis (70.7%) and gastroenteritis (22.0%) were most frequently observed. The total AEs were mostly mild or moderate in severity. No investigational medicinal product-related AEs and no AEs leading to discontinuation were reported.
Conclusion: Difamilast ointments applied twice daily to Japanese infants with AD aged 3 to < 24 months is effective and well tolerated as of the interim report in the study period. The final results will be reported in the near future.
Clinical Trial Registration: Clinical Trials. gov identifier: NCT05372653.
(© 2024. The Author(s).)