- Patients must not be pregnant or nursing because STI-571 at the recommended therapeutic dose may be harmful to the developing fetus or newborn; for this reason women of child-bearing potential and men must agree to use an effective contraceptive method; women of reproductive potential must have a negative pregnancy test within 7 days prior to registration; since interactions with oral contraceptives cannot be excluded at present, male and female patients of reproductive potential must agree to employ an effective barrier method of birth control throughout the study and for up to 3 months following discontinuation of study drug