Investigation of the effect of adapalene 0.3%/benzoyl peroxide 2.5% gel in Korean patients with acne: a randomized, double-blind clinical trial, with a histopathological and immunohistochemical study

Background: Acne vulgaris poses significant physical and psychological challenges worldwide. Data of adapalene 0.3%/benzoyl peroxide 2.5% gel (A0.3/BPO2.5) for acne treatment in Asian patients is limited. Methods: In this randomized double-blind clinical trial, 49 Korean patients with moderate-to-severe acne and scars were assigned to the A0.3/BPO2.5 (N.=37) or vehicle (N.=12) group. Acne and acne scar severity scores were assessed at baseline and 4, 8, 12, and 24 weeks. The primary outcomes were treatment success rate (reduction of >= 2 Investigator's Global Assessment grade and reaching a grade of 0 or 1) and proportional acne lesion and scar count reduction against the baseline. To assess histological changes, 2-mm punch biopsies were performed at baseline and week 24 on the respective inflammatory lesions or scars. Results: At week 24, the A0.3/BPO2.5 group had a significantly higher treatment success rate than the vehicle group. The total acne count, inflammatory lesion count, and non-inflammatory lesion count percentages (against baselines) with A0.3/BPO2.5 and the vehicle were 12.1% vs. 96.7%, 8.0% vs. 101.2%, and 13.3% vs. 98.9%, respectively (all P<0.001). Scar count percentages (against baselines) with A0.3/BPO2.5 and the vehicle were 27.3% and 96.5%, respectively (P<0.001). Significant elevations in collagen 1 and 3, elastin, CK15, and p63 levels, with increases of 172.7%, 230.6%, 176.5%, 286.2%, and 105.9%, respectively, in comparison to baseline (all P<0.05). No major adverse events leading to discontinuation were observed. Conclusions: A0.3/BPO2.5 was an effective and safe treatment for acne and acne scars in Asian patients supported by robust histopathological and immunohistochemical evidence.