Interleukin-2 in neoadjuvant therapy potentiates inhibitory activity of 5-fluorouracil and interferon in experimental...

Our previous studies showed that interferon (IFN) used in combination with 5-fluorouracil (5-FU) was effective in inhibiting colorectal tumor cell metastases to the liver in nude mice. Furthermore, IFN was also effective in neoadjuvant therapy and allowed the combination treatment (5-FU + IFN) to be delayed for 2-3 weeks following i.s. injections of tumor cells. In this study, we have examined the potential of interleukin-2 (IL-2) to substitute for IFN in neoadjuvant therapy. IL-2 was found to be equally effective, if not superior, to IFN as a neoadjuvant in inhibiting liver and lung metastases with 5-FU + IFN. Moreover, the effect of IL-2 was demonstrable even after 1 week, whereas IFN did not have an effect until 2 weeks of neoadjuvant dosing. These studies demonstrate IL-2 to be more effective than IFN as an immunomodulatory agent in combination with 5-FU + IFN for the inhibition of liver metastases in nude mice.