We have retrospectively analyzed pretreatment parameters of gastrointestinal permeability and urinary neopterin in 21 consecutive patients with metastatic colorectal carcinoma treated with the ombination of cetuximab, irinotecan, leucovorin and 5-fluorouracil. Present data demonstrate that gastrointestinal permeability is associated with systmic immune activation and may be of prognostic significance in patients with metastatic colorectal carcinoma.