Urinary neopterin concentrations during combination therapy with cetuximab in previously treated patients with metastatic colorectal carcinoma

Increased concentrations of neopterin, a biomarker of systemic immune response, have been reported after administration of cytokines, cytotoxic chemotherapy or external-beam radiation, but little is known about the effects of targeted-agents on neopterin. Urinary neopterin was studied in pre-treated patients with metastatic colorectal carcinoma during therapy with cetuximab, administered mostly in combination with irinotecan, 5-fluorouracil and leucovorin. Urinary neopterin was determined by high-performance liquid chromatography. High initial urinary neopterin concentrations predicted poor prognosis. A significant correlation was observed between urinary neopterin and peripheral blood leukocyte count, hemoglobin and carcinoembryonic antigen concentrations. Urinary neopterin concentrations significantly increased during therapy only in patients with initially low neopterin concentrations. Urinary neopterin concentrations predict prognosis in patients with metastatic colorectal carcinoma treated with cetuximab. Rising neopterin concentrations indicate an activation of systemic immune response that could be responsible for the antitumor activity of cetuximab.