Inclusion Criteria:

• Patient has given signed informed consent.
• Patient has documented histologically confirmed malignant melanoma or renal cell carcinoma which is metastatic.
• Patient is eligible for high dose IV IL-2 therapy.
• Tumor dimension of at least one lesion is measurable in two dimensions.
• Patient is at least 18 years of age.
• Patient is ambulatory with good performance status (ECOG PS 0,1; Karnofsky 100-70%).
• If the patient is a woman of child bearing potential, patient is not lactating and ahs a negative pregnancy test (beta-HCG test obtained within 72 hours of enrollment) and agrees to use an adequate method of contraception for the duration of the study.

• Patient has adequate organ function as defined by:

  • WBC count >3,500 per cubic millimeter; platelet count> 100,000 per cubic millimeter;
  • Bilirubin within institutional normal range; creatinine less than or equal to 2.0 mg/dl or creatinine clearance > 50 ml/min;
  • No evidence of congestive heart failure, symptoms of coronary artery disease, serious cardiac arrhythmias or evidence of prior myocardial infarction. A pretreatment cardiac stress test must be performed within 42 days of IL-2 treatment. Patients with documented ischemia on the pretreatment cardiac stress test will be excluded from the study;
  • Adequate pulmonary reserve. Pulmonary function tests (PFTs) must be performed within 42 days of IL-2 treatment and an FEV1 > 2.0 liters or 75% of predicted for height and age is the minimum acceptable criteria for patient entry. PAtients unable to perform PFTs will be excluded from the study.
• Patient has recovered from all toxic effects of prior therapy.
• Patient has a life expectancy, in the opinion of the investigator, of at least 4 months.

Exclusion Criteria:

• Patient has an organ allograft.
• Patient has brain metastases. A Brain CT or MRI scan should be performed within 42 days of IL-2 treatment.
• Patient is know to be HIV antibody positive. HIV testing is not required for enrollment into this study.
• Patient has evidence of active infection which requires antibiotic therapy.
• Patient has received systemic corticosteroids in the four weeks prior to the first dose of study drug, or requires or is anticipated to require corticosteroids for intercurrent disease.
• Patient has received radiotherapy, chemotherapy, or immunotherapy in the four weeks prior to the first dose of study drug, or is scheduled to receive concurrent radiotherapy, chemotherapy, or immunotherapy.
• Patient has contraindication to treatment with pressor agents.
• Patient currently receives chronic medication for asthma.
• Patient has a history of another malignancy other than basal cell skin cancer within 5 years prior to the first dose of study drug.
• Patient has any significant medical disease other than the malignancy which, in the opinion of the investigator, may interfere with completion of the study.
• Patient has previously received any IL-2 therapy.
• Patient has received another investigational medication within 4 weeks prior to M40403 administration or is scheduled to receive an investigational drug other than M40403 during the course of the study.