This trial is conducted in Oceania. A phase 2a study to assess the effect on tumor size. At least 14 to a maximum of 40 patients, who have not previously received treatment for their stage IV disease, will be treated for 6 weeks. IL-21 will be administered intravenously.

Inclusion Criteria:

• Histologically confirmed surgically incurable metastatic melanoma
• Patients must have measurable disease
• ECOG performance status of 0 or 1
• Expected life expectancy at least 4 months

Exclusion Criteria:

• History of and signs/symptoms of uncontrolled brain metastases or edema.
• Previous treatment with chemotherapy or any biological anti-cancer drug (prior adjuvant therapy with interferon-alpha is permitted as long as treatment was completed at least six months prior to study entry.)
• Radiotherapy: Radiation therapy within 4 weeks prior to entering the study.
• Receipt of any investigational drug for treatment of metastatic melanoma prior to this trial.