Patients receive gamma secretase inhibitor PF-03084014 orally (PO) twice daily (BID) on days 1-21. Treatment repeats every 21 days for up to 4 courses in the absence of disease progression or unacceptable toxicity. Patients with PR, CR, or stable disease (SD) at the end of 4 courses may receive an additional 4 courses of gamma secretase inhibitor PF-03084014 in the absence of disease progression or unacceptable toxicity.