Copper chelation reprograms the tumour microenvironment to enhance immune checkpoint blockade therapy in preclinical mesothelioma
Immune checkpoint blockade provides durable benefit to only a minority of patients with pleural mesothelioma. Here we investigated whether targeting copper homeostasis could enhance anti-tumour immunity and improve responses to immune checkpoint blockade. Copper homeostasis genes were upregulated in human mesothelioma, localised to malignant and stromal cells but downregulated in lymphocytes. In murine mesothelioma, these genes were dynamically regulated during anti-CTLA-4 and anti-PD-1 therapy. Treatment with copper chelator triethylenetetramine reduced intratumoural copper, increased cytotoxic lymphocytes, and enriched inflammatory genes in tumour-infiltrating myeloid and lymphoid compartments. Furthermore, copper chelation enhanced anti-CTLA-4 and anti-PD-1 therapy in immunocompetent mesothelioma mouse models, leading to durable tumour control. Our findings identify copper homeostasis as a therapeutic vulnerability in mesothelioma and support clinical evaluation of copper depletion with first-line immune checkpoint blockade.