First-in-Human Study to Evaluate AMG 579 in Healthy Subjects and Patients With Stable Schizophrenia

Inclusion Criteria: * Diagnosis of schizophrenia (chronic, all types) or schizoaffective disorder according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition Text Revision (DSM-IV-TR) criteria and by Mini International Neuropsychiatric Interview (M.I.N.I.) 6.0 for Schizophrenia and Psychotic Disorders Studies * Body weight greater or equal to 50 kg and body mass index (BMI) between 18 and 38.0 kg/m2, inclusive, at screening * Patient is judged by the Investigator to be likely to tolerate being off of antipsychotic medications for the duration of the trial (for patients withdrawing from or currently not taking antipsychotic medications) * Clinically stable, as judged by the investigator, and in a non-acute phase for at least 12 weeks within enrollment. If patient is on antipsychotic medications, they must be on second generation oral antipsychotic therapy (eg, ziprasidone, quetiapine, olanzapine, etc) for at least 8 weeks within enrollment and at least one month within enrollment on a stable dose Exclusion Criteria: * Hospitalized for psychiatric symptoms in the 3 months within enrollment * Patients with evidence of mental retardation by history or clinical examination or known premorbid IQ ≤ 70 * Current risk of self-harm or violence as determined by the investigator, or current risk of suicide or history of suicidal behavior within 12 months of enrollment, and/or ongoing suicidal ideation as assessed using Columbia-Suicidal Severity Rating Scale (C-SSRS) at screening (eg, any response of "yes" to the Suicidal Ideation questions on the C-SSRS in the past 12 months). Additional critera apply. Eligibility criteria for healthy subjects (Part A) not outlined above.