Interleukin 2 treatment in colorectal cancer: current results and future prospects

Recent interest in the treatment of advanced colorectal cancer with immunotherapy has focused on the use of recombinant interleukin 2 (rIL2). These studies have shown that rIL2 used alone, in combination with lymphokine-activated killer (LAK) cells or tumour-infiltrating lymphocytes (TILs), has little anti-tumour activity, with low, short-lived clinical responses being documented. However, phase I and II studies evaluating rIL2 in combination with 5-fluorouracil (5FU) or 5FU and leucovorin (LV) have been more encouraging, with response rates of up to 46% being reported. Only one randomized, controlled study, however, has compared rIL2 combined with 5FU/LV vs 5FU/LV alone. Although there was no difference in tumour response rates between the two groups, there was a doubling in the median survival of those patients in the poor performance status group (ECOG 1). Also, studies have evaluated the effects of rIL2, given in the peri-operative period, on reversing the immunosuppression that occurs following 'curative' resection for colorectal cancer. These studies have shown an abrogation of immune suppression induced by surgery and an enhancement of host anti-tumour defence mechanisms in the peri-operative period, a time when active tumour dissemination has been shown to occur. These results may have important implications for the management of those patients with malignant disease who are undergoing major curative surgery.