- The effects of pembrolizumab on the developing human fetus are unknown. For this reason and because the chemotherapy and radiation also used in this trial are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) or be surgically sterile prior to study entry and for the duration of study participation. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for > 1 year. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately.