Double-Blind, Multicenter, Sham Surgery Controlled Study of CERE-120 in Subjects With Idiopathic Parkinson's Disease

Inclusion Criteria:

   - Diagnosis of bilateral, idiopathic Parkinson's Disease (PD) based on UK Brain Bank
   criteria with motor complications despite adequate oral antiparkinsonian therapy.

   - At least 5 years disease duration, relative to the anticipated date of surgery, since
   diagnosis of PD.

   - Males or nonpregnant females 35-75 years of age, inclusive.

   - A UPDRS motor scale score of 30 or greater in the practically defined off condition
   during the 30-day eligibility evaluation period.

   - Stable doses of antiparkinsonian medications and parkinsonian features for the 60-day
   period preceding the surgical procedure.

   - No conditions that would render the subject unsuitable for surgery, or that would
   interfere with any of the assessments of efficacy or safety in this trial.

   - Subject's informed consent prior to the performance of any study-specific procedures.

Exclusion Criteria:

   - Subjects with atypical or secondary parkinsonism.

   - Any subject, in the judgment of the investigator, for whom participation in the study
   would pose a safety risk including, but not limited to, a history of any clinically
   significant medical, psychiatric, or laboratory abnormality.

   - History of treatment of PD by any procedure involving intracranial surgery or
   implantation of a device.

   - MRI of the brain within 12 months before the surgical procedure that indicates the
   presence of an abnormality that may interfere with the assessments of safety or
   efficacy or would, in the judgment of the investigator, represent a surgical risk to
   the subject.

   - Any disorder that precludes a surgical procedure (e.g., signs of sepsis or
   inadequately treated infection) or alters wound healing.

   - Receipt of antiplatelet agents for at least 10 days prior to the surgical procedure.

   - A score of less than or equal to 27 on the Folstein Mini-Mental examination performed
   during the eligibility evaluation period or clinical evidence of cognitive impairment
   that would affect the subject's ability to sign the informed consent or perform any of
   the protocol required assessments.

   - Chemotherapy, cytotoxic therapy, or immunotherapy within 6 weeks prior to the surgical
   procedure.

   - Vaccinations within 30 days prior to the surgical procedure.

   - History, within 2 years before the surgical procedure, of drug or alcohol abuse.

   - Treatment with neuroleptics within 1 year before the surgical procedure.

   - Any medical disability (e.g., severe degenerative arthritis, compromised nutritional
   state, peripheral neuropathy) that would interfere with the assessment of efficacy and
   safety in this trial or would compromise the ability of the subject to undergo study
   procedures (e.g., MRI, PET), or give informed consent.

   - History of prior gene transfer therapy.

   - Treatment with an investigational agent within 60 days before the surgical procedure.