Real-World Effectiveness, Safety, and Adverse Event Kinetics of Pembrolizumab in Advanced Melanoma within the Brazilian Public Health System

IntroductionMelanoma, though relatively rare, is the most aggressive form of skin cancer due to its high metastatic potential and mortality rate. Immunotherapy, such as pembrolizumab, has improved outcomes for patients. However, access to these therapies remains limited in low- and middle-income countries, including Brazil, where real-world evidence is scarce and population genetics may influence treatment response and adverse drug reactions (ADRs).ObjectiveThis study aimed to analyze the effectiveness and safety of first-line treatment for advanced melanoma with pembrolizumab, with a focus on the kinetics of ADRs.MethodsThis retrospective study included patients from the Brazilian Public Health System, with a follow-up period of 1 year (CAAE: 95157018.9.0000.5274).ResultsThe study analyzed 40 patients (57.5% male, median age 65.5 years). The most frequent primary site of melanoma was the lower limbs (47.5%), and the main histological types were acral (30%) and nodular melanoma (30%). ADRs were identified in 87.5% of the patients, with pruritus (40%) and vitiligo (37.5%) being the most common. Cutaneous reactions were observed in the early cycles and persisted until the end of treatment. The cohort exhibited a different ADR profile and fewer severe events (10.5%) compared to clinical trials. The median progression-free survival was 7.7 months, and the overall survival rate was 60%.ConclusionPembrolizumab was effective and safe as a first-line treatment for advanced melanoma patients in a real-world Brazilian public health setting. Additionally, we characterized the kinetics of ADRs, offering practical insights for healthcare teams in managing these events throughout the treatment course.