. For females of childbearing potential, use effective contraception from time of screening though days post last dose of TAB. Since the teratogenic potential of this combination is currently unknown, females who are pregnant or lactating are excluded. Males and females should perform abstinence or use barrier to prevent pregnancy. Females of childbearing potential not using a medically acceptable means of contraception. Female subjects of childbearing potential must not be pregnant at screening; females of childbearing potential are defined as premenopausal females capable of becoming pregnant (i.e., females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression or other reasons Females of childbearing potential (FCBP) must: Females of childbearing potential who: Pregnant or breastfeeding; males and females of childbearing potential who are unwilling or unable to use a highly effective method of contraception as outlined in this protocol for the duration of the study and for at least days after last dose of investigational product Females of childbearing potential must agree and meet the following conditions below: to Females of childbearing potential who: Female subjects of childbearing potential must not be pregnant at screening; females of\r\nchildbearing potential are defined as premenopausal females capable of becoming pregnant (i.e., females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy or bilateral oophorectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression or other reasons All males and females of childbearing potential must agree to use adequate contraception during the study; adequate contraception is defined as any medically recommended method (or combination of methods) as per standard of care; females of non-childbearing potential are those who are postmenopausal greater than year or who have had a bilateral tubal ligation or hysterectomy or bilateral oophorectomy Subjects of childbearing potential who are unwilling to take appropriate precautions (throughout the study from screening including days after discontinuation of the study drug) to avoid becoming pregnant or fathering a child; A) females of non-childbearing potential are defined as women who (a) are equal to or greater than years of age with history of amenorrhea for year, OR (b) are surgically sterile for at least months; B) for females of childbearing potential, or for males, appropriate precautions are those that are at least % effective in preventing the occurrence of pregnancy; these methods should be communicated to the subjects and their understanding confirmed: a) double barrier methods; b) condom with spermicide in conjunction with use of an intrauterine device (IUD); c) condom with spermicide in conjunction with use of a diaphragm; d) oral, injectable, or implanted contraceptives; e) tubal ligation or vasectomy (surgical sterilization) Females must be of non-childbearing potential, surgically sterile, postmenopausal, or practice adequate methods of contraception during the study and for days after the last dose of study drug or Das Females must be of non-childbearing potential, surgically sterile, postmenopausal, or practice adequate methods of contraception during the study and for days after the last dose of study drug or LDAC Female subjects of childbearing potential must not be pregnant at screening; females of childbearing potential are defined as premenopausal females capable of becoming pregnant (ie, females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression or other reasons Females are either postmenopausal for at least year, are surgically sterile for at least months, or must agree to take appropriate precautions to avoid pregnancy (with at least % certainty) from screening through months after the last dose of rituximab if of childbearing potential; (Note: permitted methods that are at least % effective in preventing pregnancy should be communicated to the participants and their understanding confirmed) Participants of childbearing potential must have a negative pregnancy test at screening and enrollment; participants of childbearing potential are defined as premenopausal females capable of becoming pregnant, i.e. females who have had any evidence of menses in the past months with the exception of those who had prior hysterectomy (oophorectomy or surgical sterilization); however, women who have been amenorrheic for >= months are still considered to be of childbearing potential if the amenorrhea is possibly due to any other cause including prior chemotherapy, antiestrogens, or ovarian suppression Subjects of childbearing potential who are unwilling to take appropriate precautions (from screening through follow-up) to avoid becoming pregnant or fathering a child; females of non-childbearing potential are defined as women who a) are years of age with history of amenorrhea for year OR b) are surgically sterile for at least months; for females of childbearing potential, or for males, pregnancy must be avoided by taking appropriate precautions; these precautions and the methods of contraception should be communicated to the subjects and their understanding confirmed Pregnancy or breastfeeding; (females of childbearing potential must have a negative serum or urine beta human chorionic gonadotropin [beta-hCG] pregnancy test result within days prior to the first dose of brentuximab vedotin; females with false positive results and documented verification that the patient is not pregnant are eligible for participation; females of non-childbearing potential are those who are postmenopausal greater than year or who have had a bilateral tubal ligation or hysterectomy; females of childbearing potential and males who have partners of childbearing potential must agree to use effective contraceptive methods during the study and for months following the last dose of brentuximab vedotin or months following the last dose of nivolumab, whichever is later) Pregnancy or lactation; females of childbearing potential and males who are admitted to the study will be advised that the study procedures and study drugs may be teratogenic, and they will be required to take adequate measures to prevent conception for the duration of the study Females of childbearing potential must have a negative pregnancy test result before enrollment. Males and females of childbearing potential must agree to use a highly effective method of birth control during the study for at least days after enrollment in the study. Females who are of childbearing potential must practice effective contraception and meet the following criteria: RENAL & BLADDER: Female subjects of childbearing potential must not be pregnant at screening; females of childbearing potential are defined as premenopausal females capable of becoming pregnant (ie, females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression or other reasons Female subjects of childbearing potential must not be pregnant at screening; females of childbearing potential are defined as premenopausal females capable of becoming pregnant (ie, females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression or other reasons Female subjects of childbearing potential must have a negative pregnancy test at screening; females of childbearing potential are defined as premenopausal females capable of becoming pregnant (ie, females who have had any evidence of menses in the past months, with the exception of those who had prior hysterectomy); however, women who have been amenorrheic for or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, or ovarian suppression or other reasons Females of childbearing potential who: Females of childbearing potential (FCBP) must: Females of childbearing potential (FCBP) may participate, providing the subject meets the following conditions: Both females of childbearing potential and males who have partners of childbearing potential must agree to use an effective contraceptive method during the study and for days following the last dose of study drug Males and females of childbearing potential must agree to use protocol-specified method(s) of contraception Both females of childbearing potential and males who have partners of childbearing potential must agree to use an effective contraceptive method during the study and for days following the last dose of study drug Males and females of childbearing potential must agree to use protocol-specified method(s) of contraception Females of childbearing potential must agree to take appropriate precautions to avoid pregnancy (with at least % certainty) from screening through end of study; permitted methods for preventing pregnancy must be communicated to study subjects and their understanding confirmed All males and females of childbearing potential must agree to use adequate contraception during the study; adequate contraception is defined as any medically recommended method (or combination of methods) as per standard of care; females of non-childbearing potential are those who are postmenopausal greater than year or who have had a bilateral tubal ligation or hysterectomy Females of childbearing potential, and males who have partners of childbearing potential must agree to use an effective contraceptive method during the study and for months following the last dose of brentuximab vedotin; effective contraception is defined as any medically recommended method (or combination of methods) as per standard of care, including abstinence; females of non-childbearing potential are those who are postmenopausal greater than year or who have had a bilateral tubal ligation or hysterectomy Females of childbearing potential (FCBP) must: Males and females of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of contraception Females of childbearing potential and males who have partners of childbearing potential must agree to use an effective contraceptive method during the study and for months following the last dose of brentuximab vedotin or months following the last dose of rituximab, whichever is later. Willing to practice methods of birth control (both males who have partners of childbearing potential and females of childbearing potential) from screening through months after taking the final dose of RTA ; Females of childbearing potential (FCBP) must not become pregnant for days prior to initiation of study drug, during the study, and for days after discontinuation Females of childbearing potential not using adequate contraception precautions for the duration of the study treatment and for months after the last administration of investigational product. Females of childbearing potential who: Subjects of childbearing potential who are unwilling to take appropriate precautions (throughout the study from screening, including days after discontinuation of the study drug) to avoid becoming pregnant or fathering a child\r\n* Females of non-childbearing potential are defined as women who (a) are equal to or greater than years of age with history of amenorrhea for year, or (b) are surgically sterile for at least months\r\n* For females of childbearing potential, or for males, appropriate precautions are those that are at least % effective in preventing the occurrence of pregnancy; these methods should be communicated to the subjects and their understanding confirmed:\r\n** Complete abstinence from sexual intercourse \r\n** Double barrier methods\r\n** Condom with spermicide in conjunction with use of an intrauterine device (IUD) \r\n** Condom with spermicide in conjunction with use of a diaphragm \r\n** Oral, injectable, or implanted contraceptives\r\n** Tubal ligation or vasectomy (surgical sterilization) For females of childbearing potential who are sexually active and males who have sexual contact with a female of childbearing potential: willingness to use of reliable methods of contraception (oral contraceptives, intrauterine device, hormone implants, contraceptive injection or abstinence) during study participation Females subjects of childbearing potential (FCBP) may participate, providing they meet the following conditions: Pregnant females; breastfeeding females; males and females of childbearing potential; males and females of childbearing potential not using highly effective contraception or not agreeing to continue highly effective contraception for at least days after last dose of investigational product; males and females of childbearing potential not using two () methods of highly effective contraception or not agreeing to continue two () methods of highly effective contraception for at least days after last dose of investigational product.