A Study to Assess the Safety and Efficacy of ASP4345 as Add-on Treatment for Cognitive Impairment in Subjects With Schizophrenia on Stable Doses of Antipsychotic Medication

Subject has a known or suspected hypersensitivity to ASP4345 or any components of the formulation

Subject has had previous exposure with ASP4345

Subject has a history of suicide attempt or suicidal behavior within 1 year prior to screening or has any suicidal ideation that meets criteria at a level of 4 or 5 by using the Columbia Suicide Severity Rating Scale (C-SSRS) or who is at significant risk to commit suicide

Subject has any clinically significant liver chemistry test result (aspartate aminotransferase \[AST\], alanine aminotransferase \[ALT\], total bilirubin \[TBL\]) or a result \> 1.5 times above the upper limit of normal (ULN) at screening or repeated within

1 week prior to potential randomization (day 1). In such a case, the assessment may be repeated once

Subject has any history or evidence of any clinically significant allergic, cardiovascular, gastrointestinal, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, history of seizure disorder, renal and/or other major disease or malignancy

Subject has any clinically significant abnormality of the physical examination, electrocardiogram (ECG) and clinical laboratory tests at screening or at admission to the study (day 1)

Subject has known kidney disease and a glomerular filtration rate (GFR) \< 60 mL/min per meter squared at screening and subjects will be discontinued from treatment only for decreases in the GFR that are clinically relevant

Subject has a resting systolic blood pressure \> 180 mmHg or \< 90 mmHg, and a resting diastolic blood pressure \> 100 mmHg at screening. These assessments may be repeated once, after a reasonable time period, at the investigator's discretion (but within the screening period)

Subject has a mean corrected QTcF \> 450 msec (for male subjects) and \> 470 msec (for female subjects) at screening or at randomization. If the mean QTcF exceeds the limits above, one additional triplicate ECG can be taken on day 1

Subject has a history in the 6 months prior to screening of consuming more than 14 units of alcoholic beverages per week for males and more than 7 units of alcoholic beverages per week for females. (Note 1 unit = 12 ounces of beer, 4 ounces of wine, or 1 ounce of spirits)

Subject is currently using prohibited medications and is unable to washout, including over-the-counter products and agrees not to consume grapefruit and/or grapefruit juice

Subject is currently using clozapine for treatment of schizophrenia

Subject has a positive test for hepatitis B surface antigen (HBsAg), hepatitis A virus antibodies (immunoglobulin M) (anti-HAV \[IgM\]) or hepatitis C virus antibodies (anti- HCV) at Screening or has history of a positive test for human immunodeficiency virus type 1(HIV-1) and/or type 2 (HIV-2)

Subject who has had electroconvulsive therapy within the 6 months prior to screening.

Subject has a history of head injury with clinically significant sequelae, including loss of consciousness for 1 hour or greater

Subject has received investigational study drug within 28 days or 5 half-lives, whichever is longer, prior to screening

What this study is about