Female patients are either postmenopausal for at least 1 year, are surgically sterile for at least 6 weeks, or must agree to take appropriate precautions to avoid pregnancy from screening through follow-up if of childbearing potential Males must agree to take appropriate precautions to avoid fathering a child from screening through follow-up Willing to avoid pregnancy or fathering children. Male and female subjects of reproductive non childbearing potential or willing to take appropriate precautions to avoid pregnancy or fathering a child for the duration of study participation Willingness to avoid pregnancy or fathering children Female patients are either postmenopausal for at least 1 year, are surgically sterile for at least 6 weeks, or must agree to take appropriate precautions to avoid pregnancy from screening through follow-up if of child-bearing potential Any woman of childbearing potential, unless she: Agrees to take appropriate precautions to avoid becoming pregnant (with at least 99% certainty) during the study and has a negative serum pregnancy test within 7 days prior to starting treatment. A willingness to avoid pregnancy or fathering children in male and female subjects respectively:\r\n* A woman of childbearing potential must have a negative serum pregnancy test (beta-human chorionic gonadotropin [beta-hCG]) at screening and must be willing to avoid pregnancy during the treatment period and for a specified duration (1 year post hematopoietic cell transplant [HCT]) after the end of treatment\r\n* Women of childbearing potential who have a negative serum pregnancy test at screening must practice a highly effective method of birth control (with at least 99% certainty) from screening through safety follow-up; permitted methods that are at least 99% effective in preventing pregnancy should be communicated to the subject and their understanding confirmed\r\n* Men who are enrolled must agree to take appropriate precautions to avoid fathering children (with at least 99% certainty) from screening through safety follow-up; permitted methods that are at least 99% effective in preventing pregnancy should be communicated to the subject and their understanding confirmed Females are either postmenopausal for at least 1 year, are surgically sterile for at least 3 months, or must agree to take appropriate precautions to avoid pregnancy (with at least 99% certainty) from screening through 12 months after the last dose of rituximab if of childbearing potential; (Note: permitted methods that are at least 99% effective in preventing pregnancy should be communicated to the participants and their understanding confirmed) Males must agree to take appropriate precautions to avoid fathering a child (with at least 99% certainty) from screening through 12 months after the last dose of rituximab; (Note: permitted methods that are at least 99% effective in preventing pregnancy should be communicated to the participants and their understanding confirmed) 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 55 years of age with history of amenorrhea for 1 year OR b) are surgically sterile for at least 3 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 Are instructed to avoid pregnancy through 30 days after the last dose of study medication. Willingness to avoid pregnancy or fathering children. Willingness to avoid pregnancy or fathering children as per protocol-defined criteria. Females of child-bearing potential must have a negative pregnancy test at screening and agree to take appropriate precautions to avoid pregnancy (double barrier method of birth control or abstinence) from screening through 3 months after the last dose of treatment Female participants must have a negative pregnancy test within 7 days of entering into the study; both men and women of child bearing potential must agree to use adequate methods of contraception for the duration of the treatment; women must avoid pregnancy, and men must avoid fathering children while in the study and for 6 months following the last study drug treatment Willingness to avoid pregnancy or fathering children Males who cannot comply with birth control use to avoid fathering a child Females will be either postmenopausal for at least 1 year or surgically sterile for at least 3 months; OR females of child-bearing potential must have a negative pregnancy test at screening and agree to take appropriate precautions to avoid pregnancy from screening until 3 months after their last dose of study medication Males must agree to take appropriate precautions to avoid fathering a child from screening until 3 months after their last dose of study medication Females will be either postmenopausal for at least 1 year or surgically sterile for at least 3 months OR females of child-bearing potential must have a negative pregnancy test at screening and agree to take appropriate precautions to avoid pregnancy (double barrier method of birth control or abstinence) from screening through 3 months after the last dose of treatment Females of childbearing potential must agree to take appropriate precautions to avoid pregnancy (with at least 99% certainty) from screening through end of study; permitted methods for preventing pregnancy must be communicated to study subjects and their understanding confirmed Males must agree to take appropriate precautions to avoid fathering a child (with at least 99% certainty) from screening through follow-up; permitted methods for preventing pregnancy should be communicated to the subjects and their understanding confirmed Avoid pregnancy Women or men of childbearing potential unwilling to take adequate precautions to avoid pregnancy from the start of protocol treatment through 28 days after the last treatment Be willing to avoid pregnancy or fathering children.