 - Women of child-bearing potential WOCBP must agree to use adequate contraception hormonal or barrier method of birth control; abstinence prior to study entry and for the duration of study participation; WOCBP should use an adequate method to avoid pregnancy for 31 weeks after the last dose of investigational drug; women of childbearing potential must have a negative serum or urine pregnancy test minimum sensitivity 25 IUL or equivalent units of human chorionic gonadotropin HCG within 24 hours prior to the start of nivolumab; women must not be breastfeeding; women who are not of childbearing potential i.e., who are postmenopausal or surgically sterile do not require contraception 