-  INCLUSION CRITERIA:

        In order to be eligible to participate in this study, an individual must meet all of the
        following criteria:

          -  Adult patients (18 years and older)

          -  Confirmed biochemical diagnosis of Cushing s disease (primary or recurrent) as
             evidenced by increased 24-hour urine free cortisol (UFC), normal or increased morning
             plasma Adrenocorticotropic Hormone (ACTH), and pituitary origin of excess ACTH.

          -  Surgical candidate for resection of ACTH producing pituitary adenoma

          -  Enrolled in 03-N-0164, Evaluation of Neurosurgical Disorders.

          -  Able to provide written informed consent at the time of study enrollment.

          -  Participants who are physically able to become pregnant must use an effective form of
             birth control from 14 days prior to enrollment through 6 months following the last
             dose of vorinostat. Participants who are able to father a child must use an effective
             form of birth control from Day 0 through 3 months following the last dose of
             vorinostat.

        EXCLUSION CRITERIA:

          -  Patients who have been previously treated with vorinostat.

          -  Patients who have received sellar radiation.

          -  Significant medical illnesses that in the investigator s opinion cannot be adequately
             controlled or would compromise the patient s ability to tolerate this vorinostat.

          -  Any history of cancer, unless in complete remission and off of all therapy for that
             disease for a minimum of 3 years.

          -  History of thromboembolic disorder or deep vein thrombosis

          -  Presence of abnormal hematological and biochemical parameters, (such as anemia or
             thrombocytopenia) as defined as:

               -  Neutrophil count < 1.5 K//micro L

               -  Hemoglobin < 8.0 g/dL.

               -  Hematocrit < 0.75x LLN (lower limit of normal)

               -  RBC count < 0.75x LLN

               -  Platelet count < 100 x 10^3 cells/micro L.

               -  Prothrombin time-international normalized ratio (PT-INR) > 1.5x ULN or Activated
                  partial thromboplastin time (aPTT) > 1.5x ULN, with the exception of patients on
                  prophylactic anticoagulation therapy

               -  Serum bilirubin level > 1.5x ULN.

          -  Active infection being currently treated with systemic antibiotics.

          -  Serious concurrent medical illness including renal failure (creatinine >3.0x - 6.0x
             ULN) liver failure (ALT/AST >5.0x - 20.0x ULN) or severe cardio-respiratory disease.

          -  Pregnancy or lactation.

          -  Presence of any disease that will obscure toxicity or dangerously alter drug
             metabolism (such as uncontrolled diabetes or bleeding disorders)

          -  Currently receiving other investigational agents.

          -  History of allergic reactions attributed to compounds of similar chemical or biologic
             composition to vorinostat, such as valproate.

          -  Currently taking another HDACi, such as valproate.

          -  Currently taking coumadin or its derivative anticoagulants.

          -  Currently taking any other medication to reduce cortisol or ACTH levels