OUTLINE: This is a dose-escalation study of PI3K inhibitor BKM120. Patients receive PI3K inhibitor BKM120 orally (PO) once daily (QD) on days 1-28 (if enrolled in Phase IA or Cohort C) or on a 5 days on/2 days off schedule (if enrolled in Phase IB). All patients will receive fulvestrant intramuscularly (IM) on days 1 and 15 of Cycle 1 and day 1 of all subsequent cycles. Cycles repeat ever 28 days in the absence of disease progression or unacceptable toxicity.