Mechanism of Action of High-Dose IL-2 (Aldesleukin) in Metastatic Melanoma and Kidney Cancer

Background: -Although IL-2 can shrink tumors in about 20 percent of patients with metastatic kidney cancer and in 15 percent of patients with metastatic melanoma, it is not fully known how the drug works. Objectives: -To better understand how IL-2 causes tumors to shrink. Eligibility: -Patients 18 years of age or older with metastatic kidney cancer or metastatic melanoma Design: * 135 patients with melanoma and 110 patients with kidney cancer may be enrolled. * Patients are hospitalized for about 7 days for each treatment. They receive IL-2 intravenously (through a vein) over 15 minutes every 8 hours for up to 4 days or 12 doses. This constitutes one treatment cycle. * Research blood samples are collected daily during the first treatment cycle and for one or two days following the last dose. * Patients may be asked to undergo leukapheresis, a procedure for collecting large quantities of white blood cells. This involves collecting blood through a needle in an arm vein. The blood is directed through a cell separator where the white cells are extracted. The rest of the blood (red cells, platelets, and plasma) is returned to the patient through the same needle or through a needle in the other arm. * About 7-10 days after discharge from the hospital, patients return for a second treatment cycle but without research blood sampling. * 2 months after therapy, patients are evaluated with scans, and x-rays, and blood tests to evaluate the tumor and the effects of the treatment on immune cells. * Patients whose tumors shrink or remain stable may continue treatment (without repeating the full set of research blood samples) as long as they benefit from the treatment and do not develop unacceptable side effects. Patients who continue treatment are evaluated every 2 months for 3 to 4 times and then every 3 to 6 months.