4. Not pregnant and not nursing, because this study involves an agent that has known genotoxic, mutagenic and teratogenic effects. A female of childbearing potent is a sexually mature female who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 12 consecutive months (ie, has had menses at any time in the preceding 12 consecutive months). For women of childbearing potential only, a negative pregnancy test done ≤ 5 days prior to registration is required.