Reactivation of a normal endogenous secretion of interleukin-2 in metastatic cancer patients by a chronic subcutaneous injection of interleukin-2.

It is known that advanced cancer patients may show abnormally low levels of IL-2. The immunotherapy with IL-2 can induce objective tumor regressions, but at present there are no data about the influence of a chronic exogenous IL-2 administration on endogenous secretion of IL-2. This preliminary study was performed to evaluate whether a prolonged IL-2 injection may be able to correct an eventual IL-2 endogenous deficiency in cancer patients. The study included 10 metastatic renal cancer patients, who underwent an immunotherapeutic cycle consisting of IL-2 at 6 million IU/day subcutaneously for 6 days/week for 4 weeks. Serum levels of IL-2 evaluated on venous blood samples collected before and 21 days after the end of IL-2 injection. Before the onset of treatment, abonormally low levels of IL-2 were seen in 6/10 patients. In patients with response or stable disease, mean levels of IL-2 observed 21 days after IL-2 cycle were significantly higher than those seen before therapy, whereas no difference occurred in those who progressed. This preliminary study would suggest that a prolonged subcutaneous injection of low-dose IL-2 may correct an eventual IL-2 endogenous deficiency in advanced cancer patients.