IL-2 phase II trial in metastatic melanoma: analysis of clinical and immunological parameters

Twenty-four patients with histologically proven metastatic malignant melanoma were included in a phase II trial of recombinant IL-2 (rIL-2, RU 49637). Twenty million international units (IU)/m2/day were given by continuous intravenous infusion on days 1 to 5, 15 to 18, and 29 to 31, and then monthly for 5 days until disease progression or major intolerance developed. All patients were evaluable for response and toxicity. Toxicity was consistent with one case of myocardial ischemia, 13 cases of grade III and IV hypotension, and 15 cases of proven sepsis. There were 8 objective responses: 4 of them were of short duration as they were observed on day 31 only. An activation of the immune system was detected in all patients. It was demonstrated by an increase in lymphocyte populations, especially in activated NK cells. A tendency for higher numbers of cytotoxic cells was found in patients with objective tumor responses. These results indicate a role for rIL-2 RU 49637 in treating patients with metastatic malignant melanoma. However, further trials are required to determine its optimal dosage and schedule of administration.