Clinical Research Directory

Gastrointestinal Microbiome and Response to Immunotherapy in Metastatic Malignant Melanoma

The aim of this prospective clinical study is to evaluate the prognostic and predictive significance of the gastrointestinal microbiome in patients with metastatic malignant melanoma treated with first-line immunotherapy using immune checkpoint inhibitors (PD-1 inhibitors and CTLA-4 inhibitors). Although immunotherapy has significantly improved survival outcomes, treatment response remains unpredictable and a substantial proportion of patients develop immune-related adverse events, pseudoprogression, or hyperprogression. The gastrointestinal microbiome is an important regulator of immune homeostasis and may influence systemic immune response. This study investigates whether specific microbiome composition is associated with objective treatment response assessed according to iRECIST criteria, progression-free survival (PFS), and the occurrence of immune-related adverse events. Patients treated at the Institute of Oncology Ljubljana between March 2022 and March 2024 were enrolled. In addition to standard-of-care immunotherapy, participants underwent protocol-defined collection of stool and peripheral blood samples at predefined time points for microbiome and immune profiling analyses.