Clinical and biological effects of interleukin-2 with or without a concomitant administration of granulocyte-macrophage colony-stimulating factor in metastatic cancer patients

GM-CSF has been shown to modulate the anticancer activity of IL-2 with, however, controversial results depending on the great variety of biological effects induced by GM-CSF itself. The activation of dendritic cells and the generation of suppressive cells would constitute the main favourable and unfavourable biological effects of GM-CSF, respectively. The present study was performed in an attempt to evaluate the clinical and biological effects of a concomitant GM-CSF administration of the immunotherapy of metastatic renal cell carcinoma with IL-2. The study included 25 patients, who were randomized to be treated with IL-2 alone or IL-2 plus GM-CSF. IL-2 was injected subcutaneously at 6 MIU/day for 6 days/week for 4 consecutive weeks, coressponding to one complete cycle. GM-CSF was injected subcutaneously at 0.3 micrograms/kg b.w. for 3 consecutive days for the first 3 days of each week of IL-2 administration. Two immunotherapeutic cycles at 21-day intervals were planned. No significant difference was observed in the percent of non-progressive disease between the two groups of patients. The increase in leukocyte mean number was significantly higher in patients concomitantly treated with GM-CSF, whereas no difference was observed in that of lymphocytes. This preliminary study suggests that the concomitant administration of GM-CSF does not enhance the therapeutic efficacy of IL-2 immunotherapy of metastatic renal cell cancer.