The role of irinotecan in colorectal cancer.

Irinotecan, also known as CPT-11, is a topoisomerase I inhibitor currently approved for use as a second-line agent in the treatment of advanced colorectal cancer. Preliminary reports from randomized studies exploring combinations of CPT-11 plus 5-fluorouracil have shown improved antitumor activity versus 5-fluorouracil-based treatments alone, and suggest a first-line role for these combination regimens. The role of CPT-11/5-fluorouracil regimens in the adjuvant setting is now being actively explored. Studies of single-agent CPT-11 in the first-line treatment of metastatic colorectal cancer have shown activity; however response rates do not appear to be superior to those seen with standard first-line 5-fluorouracil-based regimens. The use of specific molecular markers as prognostic indicators of response or resistance to specific chemotherapies may, however, permit the identification of a selected population of patients with tumor characteristics that would specifically favor consideration of up-front use of single-agent CPT-11.