Characterization of skin adverse events associated with cetuximab: real-world insights from the two global pharmacovigilance databases of FAERS and VigiAccess

Background: Cetuximab, an IgG1 monoclonal antibody targeting the epidermal growth factor receptor (EGFR), is widely used in metastatic colorectal cancer and other solid tumors. Cutaneous adverse events (AEs) are among its most frequent toxicities, but real-world evidence on their spectrum and risk profile remains limited. Methods: We conducted a pharmacovigilance study using spontaneous reports from the FDA Adverse Event Reporting System (FAERS) and the World Health Organization VigiAccess database, from database inception to 2025. Reports in which cetuximab was recorded as the primary suspected drug were retrieved. After deduplication, AEs were coded using MedDRA preferred terms (PTs) and system organ classes. Descriptive analyses were performed, and disproportionality was evaluated using reporting odds ratio (ROR), proportional reporting ratio (PRR), empirical Bayes geometric mean (EBGM), and information component (IC). Subgroup analyses by age and sex were conducted using FAERS data. Results: A total of 69,588 reports were identified, including 20,862 from FAERS and 48,726 from VigiAccess. Most reports involved male patients and those aged 45-64 or ≥65 years. Skin and subcutaneous tissue disorders showed significant disproportionality signals for cetuximab (FAERS: ROR 2.58, 95% CI 2.52-2.65; VigiAccess: ROR 2.73, 95% CI 2.69-2.77). The most frequently reported skin-related PTs were rash, dermatitis acneiform, and erythema in FAERS, and rash, acne, and dermatitis acneiform in VigiAccess. The strongest signals were observed for dermatitis acneiform, nail bed inflammation, and rash follicular in FAERS, and for dermatitis acneiform, nail cuticle fissure, and nail fold inflammation in VigiAccess. Subgroup analyses indicated that skin AEs were more commonly reported in patients older than 45 years and in males. Conclusions: Real-world pharmacovigilance data from two independent international databases demonstrate consistent and strong disproportionality signals for cetuximab-associated cutaneous AEs. Common events such as rash and dermatitis acneiform, as well as several less frequently described reactions, warrant heightened clinical vigilance, especially in older and male patients. Prospective and mechanistic studies are needed to confirm these associations and to refine strategies for preventing and managing cetuximab-induced skin toxicity.