Salvage immunotherapy with subcutaneous recombinant interleukin 2 (rIL-2) and alpha-interferon (A-IFN) for stage D3 prostate carcinoma failing second-line hormonal treatment

Immunotherapy with subcutaneous rIL-2 and alpha IFN was administered to stage D3 prostate cancer patients after the failure of secondary treatment with oral estramustine phosphate. Of a total of 15 patients, 2 are in partial response, with estramustine maintained after 44+ and 36+ weeks, respectively. Response to estramustine was observed initially in 7 of 13 patients, with a median duration of 12 weeks (range, 8-20). No response to estramustine was observed in the remaining 6 patients. After the failure of estramustine, 13 patients were treated with immunotherapy. After the first cycle, progression of disease with increasing levels of PSA was observed in 7 of 13 patients (53.8%). No further immunotherapy was given to those patients. A reduction of PSA levels was observed during the first cycle in 2 patients (15.3%); levels subsequently increased during the second cycle of treatment. A partial response was observed in 4 patients (30.7%), with a reduction of PSA levels in 3. The duration of response was 28 and 32 weeks in 2 patients who survived after failure for 18 and 21 weeks, respectively. Two patients are still alive, with continued partial response at 62+ and 42+ weeks. Side effects were represented mainly by a flu-like syndrome, associated with fever and nausea in all the patients. The serum concentration of IL-10 was measured in 8 patients under study and in 11 matched controls. Levels higher than mean + 2 SD of controls before, during, or after immunotherapy were correlated with treatment failure, whereas levels below 6 ng/ml were encountered among the patients who showed a clinical response and a reduction of PSA during treatment. Within the limitations of this pilot study, it appears difficult to distinguish between a spontaneously slowly progressing disease and a true response to therapy.