METHODS	We randomly assigned 502 patients with previously untreated metastatic melanoma , in a 1:1 ratio , to ipilimumab ( 10 mg per kilogram ) plus dacarbazine ( 850 mg per square meter of body-surface area ) or dacarbazine ( 850 mg per square meter ) plus placebo , given at weeks 1 , 4 , 7 , and 10 , followed by dacarbazine alone every 3 weeks through week 22 .\