Efficacy and Safety of Pimavanserin as Adjunctive Treatment for the Negative Symptoms of Schizophrenia

Inclusion Criteria: * Male or female, ≥18 and ≤55 years of age at the time of Screening * Has a caregiver or some other identified responsible person (e.g., family member, social worker, caseworker, or nurse) considered reliable by the Investigator in providing support to the subject to help ensure compliance with study treatment, study visits, and protocol procedures, and who is also able to provide input helpful for completing study rating scales * Diagnosis of schizophrenia made ≥1 year prior to Screening * Is being treated must be one of the antipsychotics listed below: * Aripiprazole * Aripiprazole long-acting injectables * Abilify Maintena® * Aristada® * Asenapine * Brexpiprazole * Cariprazine * Lurasidone * Olanzapine * Paliperidone extended release (ER) (≤9 mg) * Paliperidone palmitate * Invega Sustenna® (≤156 mg) * Invega Trinza® (≤546 mg) * Trevicta® (≤350 mg) * Xeplion® (≤100 mg) * Risperidone * Risperidone long-acting injection * Must be medically stable (including no recent hospitalization for exacerbation of psychiatric disorder) and has been medically stable for at least 12 weeks prior to Screening, in the opinion of the Investigator Exclusion Criteria: * Has a current comorbid psychiatric disorder other than schizophrenia or a disorder that would interfere with the ability to complete study assessments * Is at a significant risk of suicide, in the opinion of the Investigator * Has a significant risk of violen…