Melanoma constitutes ∼8% of malignancies diagnosed among adolescents and young adults (AYA). Although immunotherapy with checkpoint inhibitor (ICI) has become a standard treatment for melanoma, available data on immune-related adverse events (irAE) among AYA population are still limited. Some early reports suggested that irAE may be more frequent among AYA than other age groups. We performed a retrospective cohort study of melanoma patients who were previously ICI naive and received ICI at our institution during 2007-2019, comparing the incidences of irAE between AYA and elderly patients. AYA cohort was defined as age 15-39 years and elderly cohort was defined as age >65 years at ICI initiation. Analyses included 153 patients: 48 AYA and 105 elderly. The median age was 31.2 and 72.0 years, respectively. The AYA cohort had better performance status and fewer comorbidities than the elderly cohort. A combined ICI regimen, ipilimumab plus nivolumab, was used more frequently among the AYA than the elderly cohort: 25.0% versus 3.8%, < 0.001. In univariable analyses, AYA experienced more increased liver enzymes, more hospitalization, but less skin rash. After adjusting for baseline characteristics and treatment regimen in multivariable analyses, AYA was independently associated with a lower incidence of skin rash: odds ratio 0.36 (95% confidence interval: 0.14-0.75), = 0.006. In this large cohort of melanoma patients undergoing first-line immunotherapy, skin rash was less frequent among AYA than the elderly. Although some toxicities may appear more prevalent among AYA, this was attributable to the higher use of combined ICI regimen.
