The study will be conducted in 2 stages. In Stage 1 of the study, successive groups of 3 to 6 patients will receive progressively higher PTC299 dose levels; in this stage, treatment will be given in repeated 6-week cycles consisting of 4 weeks of oral PTC299 twice per day followed by a 2-week, no-drug period. During Stage 2, study candidates must be women with natural or induced suppression of ovarian function to post-menopausal levels who are receiving or are candidates for hormonal therapy. These subjects will receive continuous administration of PTC299, 100 mg/dose BID, in repeated 6-week cycles in combination with continuous administration of one of 3 hormonal agents. All planned PTC299 dose levels in all stages are expected to achieve circulating blood levels of PTC299 known to be active in animal models of human cancer. Treatment for each patient can continue as long as the therapy appears to be safely offering tumor control to that patient. Up to 36 evaluable patients will be accrued across both stages.