INTRATUMORAL DEPOT INTERLEUKIN-2 THERAPY INHIBITS TUMOR-GROWTH IN DUNNING ADENOCARCINOMA OF THE PROSTATE IMPLANTED SUBCUTANEOUSLY IN RATS

The purpose of this study was to determine the effectiveness and toxic ity of local continuous immuno-therapy of prostatic cancer. A group of 60 young male Copenhagen rats with Dunning adenocarcinoma of the pros tate, implanted subcutaneously into both flanks, after proven tumor gr owth, were treated with either human interleukin-2 (IL-2) depot prepar ations(n = 30) or albumin (placebo) depot preparations (n = 30) implan ted directly into one tumor site. IL-2 depots released IL-2 reliably f or more than 24 days. The rat serum was tested during treatment for hu man IL-2, possibly absorbed from depots, and for rat interferon gamma. IL-2 treatment reduced tumor growth significantly (P < 0.001) compare d with albumin-treated sites or untreated contralateral sites. No toxi city was observed during treatment. Neither human IL-2 nor rat interfe ron gamma was detected in the serum, which indicates an exclusively lo cal IL-2 effect. IL-2 depot preparations reduce tumor growth in Dunnin g adenocarcinoma of the prostate significantly without toxicity.