This is an open label study of KW2871 plus high dose IFN-α2b (HDI) in patients with measurable metastatic melanoma. All eligible patients will receive KW2871 IV every two weeks (Wednesday) starting on week 1. HDI will also be given at a dose of 20 MU/m2 IV for five consecutive days (Monday thru Friday) per week for four weeks, and then 10 MU/m2 sc three times a week (Monday, Wednesday, Friday). Patients will be treated with KW2871-HDI combination therapy until disease progression requiring treatment intervention that would interfere with the interpretation of the study results.