 open-label lead-in treatment of ridaforolimus. After this 8 week period patients will be re-assessed for disease status. Patients who are stable after 8 weeks are randomized in a double-blind fashion to continue treatment with ridaforolimus or to a placebo until disease progression. Those patients who have stable disease but are randomized to placebo may cross-over to open-label ridaforolimus at the time of disease progression. 