- The effects of GDC-0449 on the developing human fetus at the recommended therapeutic dose are unknown; for this reason and because Hh signal pathway inhibitors are known to be teratogenic, women of child-bearing potential and men must use two forms of contraception (i.e., barrier contraception and one other method of contraception) prior to study entry, for the duration of study participation, and for at least 12 months post-treatment; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately