- The effects of rebeccamycin analog on the developing human fetus at the recommended therapeutic dose are unknown; for this reason, women of child-bearing potential must agree to use adequate contraception prior to study entry and for the duration of study participation; women should not become pregnant or nurse, nor expect to become pregnant or nurse, during the study; women in whom there is a suspicion of possible pregnancy must have a documented negative serum pregnancy test prior to beginning therapy; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately