Efficacy and safety of adapalene gel as a reactive treatment for cetuximab-induced skin toxicity in recurrent or metastatic squamous cell carcinoma of the head and neck: A historical cohort comparison study.

INTRODUCTION: Despite the common occurrence of cetuximab (Cmab)-induced skin toxicity, management strategies are not well established. The traditional mainstay method consists of topical steroids, which, if used excessively, may give rise to other concerns. Alternatively, adapalene can activate epidermal growth factor receptor pathways to potentially alleviate these toxicities. METHODS: We prospectively studied 31 patients with recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) who were eligible to use adapalene gel as a reactive treatment for topical steroid-refractory skin toxicity. For comparison, we retrospectively reviewed 99 patients with R/M SCCHN (historical control cohort) whose skin toxicity was mainly treated with topical steroids. We compared the frequency and severity of Cmab-induced skin toxicity, Cmab therapy status (e.g., dose modification), side effects caused by topical steroids and adapalene gel itself, and other medical interventions. RESULTS: Adapalene gel was used by eight patients (25.8%) in the prospective cohort. Patients in the historical control cohort more frequently required escalation of topical steroid potency (34.3% vs. 12.9%, p = 0.022). Although there was no statistically significant difference in the frequency of grade ≥3 facial skin rash and paronychia between the two cohorts, the prospective cohort showed a significantly shorter time to complete recovery from grade 2/3 paronychia (16 vs. 47 days, p = 0.017). Further, while no skin infections were observed in the prospective cohort, 13 patients in the historical control cohort developed skin infections, especially periungual infection (0% vs. 13.1%, p = 0.024). In addition, no patients in the prospective cohort received a dose reduction of Cmab due to skin toxicities, compared to 20 patients in the historical control cohort (0% vs. 20.2%, p = 0.003). No apparent adapalene gel-related side effects were observed. CONCLUSIONS: Adapalene gel may be an effective management option for topical steroid-refractory Cmab-induced skin toxicities and could improve compliance with Cmab therapy.