CP-675,206 is a fully human monoclonal antibody (mAb). It binds to the CTLA4 molecule, which is expressed on the surface of activated T lymphocytes. CP-675,206 is thought to stimulate patients' immune systems to attack their tumors. CP-675,206 is not expected to have a direct effect on tumor cells. CP-675,206 been shown to induce durable tumor responses in patients with metastatic melanoma in Phase 1 and Phase 2 clinical studies.

Inclusion Criteria:

• Surgically incurable Stage III or IV melanoma
• One prior systemic treatment for metastatic melanoma
• Measurable disease
• Eastern Cooperative Oncology Group (ECOG) PS = 0 or 1

Exclusion Criteria:

• Melanoma of ocular origin
• Received prior vaccine
• Received prior CTLA4-inhibiting agent
• History of, or significant risk for, chronic inflammatory or autoimmune disease
• Potential requirement for systemic corticosteroids