11. Pregnancy or breast feeding. Female subjects must be surgically sterile or postmenopausal, or must agree to use effective contraception during the period of therapy. All female subjects with reproductive potential must have a negative pregnancy test (serum) prior to enrolment. Male subjects must be surgically sterile or must agree to use effective contraception during the period of therapy. The definition of effective contraception will be based on the judgment of the principal investigator or a designated associate