Correlation between pretreatment serum levels of neopterin and response to interleukin-2 immunotherapy in cancer patients.

IL-6 levels have been proven to correlate with resistance to IL-2 immunotherapy. Since IL-6 may be produced by both macrophages and TH2 lymphocytes, it is not possible to establish whether the negative prognostic significance of IL-6 levels may primarily depend on an enhanced macrophage or TH2 activation. Macrophage activation may be documented by the increase in its specific marker neopterin. In an attempt to establish whether the negative significance of IL-6 high levels prior to IL-2 immunotherapy may reflect an enhanced macrophage activation, we have investigated the relation existing between pretreatment concentrations of neopterin and response to IL-2 immunotherapy in cancer patients. The study included 20 metastatic renal cell cancer patients, who were treated with IL-2 subcutaneously at 6 million IU/day for 5 days/week for 6 weeks. Before the onset of IL-2 therapy, abnormally high serum levels of neopterin were seen in 11/20 patients. Moreover, neopterin concentrations were significantly correlated with those of IL-6. Tumor regression rate was significantly higher in patients with normal than in those with elevated levels of neopterin prior to therapy (5/9 vs 1/11, P < 0.05), as well as the percent of the survival at 1 year (9/9 vs 4/11, P < 0.01). This preliminary study would suggest that pretreatment values of the macrophage marker neopterin correlate with resistance to IL-2 cancer immunotherapy.