Toll-like receptor (TLR) agonists can fuel the immune system in the fight against cancer. For peritoneal cancer of colorectal origin (CRC), however, immune therapy is still in its infancy. We will characterize the peritoneal immune microenvironment in patients with CRC, develop a TLR-agonist therapy for local peritoneal administration and investigate the effect of TLR activation on cancer- associated fibroblasts and epithelial-to-mesenchymal transition in cancer cells.