Treatment Extension Phase: Participants in this study will be eligible to enroll in an open-label treatment extension phase if they: a) were originally randomized to the vorinostat arm and have not experienced disease progression; b) were randomized to the placebo arm and meet the "Extension Phase Inclusion Criteria for Participants in the Placebo Arm" below; or c) were originally randomized to the vorinostat arm and discontinued study therapy for reasons other than progression and the investigator believes that it is in the participant's best interest to resume vorinostat treatment.