 - Men or women of childbearing potential who are unwilling to employ adequate contraception NOTE: breastfeeding should be discontinued if the mother is treated with nivolumab; women of childbearing potential and men must use two forms of contraception hormonal or barrier method of birth control; abstinence prior to study entry and for the duration of study participation; they must adhere to contraception for a period of 31 weeks after the last dose of nivolumab 