Immunotherapy with low-dose interleukin-2 in association with melatonin as salvage therapy for metastatic soft tissue sarcomas

Polychemotherapy represents the only standard medical therapy of metastatic soft tissue sarcomas (STS), whereas the recent biotherapies with cytokines, such as interleukin-2 (IL-2), seem not to have a relevant therapeutic role. The pineal hormone melatonin (MLT), whose immunomodulating activity is well known, would seem to exert a direct cytostatic action on STS cell proliferation. Moreover, MLT has been proven to amplify IL-2 efficacy. On this basis, a pilot phase II study with low-dose IL-2 plus MLT has been performed in untreatable metastatic STS patients. The study included 13 evaluable metastatic STS patients with poor PS, who progressed on at least one previous polychemotherapeutic line. IL-2 was injected subcutaneously at 3 million IU/day for 6 days/week for 4 weeks and MLT was given orally at 40 mg/day in the evening. A partial response was achieved in one patient with leiomyosarcoma. Eight other patients had a stable disease (SD) whereas the remaining 4 patients progressed. A survival longer than 1 year was achieved in 6/13 patients and the percent of 1-year survival was significantly higher in patients with response or SD than in the progressed ones (6/9 vs 0/4). Mean increases in lymphocyte and eosinophil numbers were significantly higher in patients with response or SD than in the progressed ones. These preliminary results would suggest that immunotherapy with low-dose IL-2 plus MLT may have some impact at least on the survival time of untreatable metastatic STS patients with poor clinical conditions.