- Pregnant women are excluded from this study because the risks with B-701 are unknown and pembrolizumab is a PD-1 inhibitor with the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with B-701 and pembrolizumab, breastfeeding should be discontinued. Women of child-bearing potential must agree to use adequate birth control throughout the study duration.