Comparing Intravenous or Intradermal Administration of Anti-CTLA-4 in Combination With Anti-PD1 Treatment in Patients With Melanoma

This study investigates whether a single intradermal (i.d.) injection of low-dose anti-CTLA-4 (ipilimumab), given at the tumour site, can enhance immune activation when combined with standard intravenous (i.v.) anti-PD-1 therapy in patients with advanced melanoma. While combined checkpoint inhibition is effective, it is associated with high toxicity, creating a need for strategies that maintain efficacy with fewer side effects. Preclinical and early clinical data suggest that local (intradermal) CTLA-4 blockade can stimulate systemic anti-tumour immune responses with reduced toxicity, potentially by reactivating suppressed T cells in tumour-draining lymph nodes. This study compares systemic immune effects of intradermal versus standard intravenous CTLA-4 administration, both combined with nivolumab. The primary objective is to assess systemic immune activation by measuring changes in CD4+ and CD8+ T-cell frequencies and ICOS expression in peripheral blood. Additional immune monitoring includes blood sampling, tumour biopsies, and advanced imaging using FDG-PET/CT and a novel CD8-targeted PET tracer. The study is a prospective, open-label pilot trial in patients with metastatic melanoma, with follow-up for clinical outcomes and immune response over approximately 13 weeks.