IFN-Gamma Expression as a Predictor of Response to Immune Checkpoint Inhibitors in First-Line Metastatic Melanoma

Immune checkpoint inhibitors have significantly improved survival in patients with metastatic melanoma. However, treatment response varies considerably, and a substantial proportion of patients do not achieve durable benefit. The identification of predictive biomarkers remains an important unmet clinical need. This prospective, single-arm interventional study evaluates biological markers in patients receiving first-line immune checkpoint inhibitor therapy for metastatic melanoma. The primary objective is to assess whether interferon-gamma (IFN-γ) expression in tumor tissue and peripheral blood is associated with objective response to treatment. Tumor IFN-γ expression is assessed using immunohistochemistry, and peripheral blood IFN-γ concentration is measured using enzyme-linked immunosorbent assay (ELISA). The study also evaluates additional biomarkers, including PD-L1 expression, to explore their potential predictive value. Furthermore, the study investigates the relationship between gut microbiome composition and treatment outcomes. Microbiome diversity and bacterial taxonomic profiles are analyzed from stool samples to determine whether microbial characteristics are associated with response to immunotherapy. The study is conducted at a single tertiary oncology center and includes adult patients with metastatic melanoma receiving standard-of-care first-line immune checkpoint inhibitor therapy. The findings aim to support improved risk stratification and biomarker-guided therapeutic decision-making.