This is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, fixed-dose study in adult patients with a primary diagnosis of schizophrenia according to criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM-5).

The study will be conducted in the following 5 phases:

• A no-drug Screening Phase up to 7 days in duration during which patient eligibility will be assessed;
• A 6-week, open-label Run-in Phase (RIP) during which all patients will receive oral lumateperone 42 mg/day;
• A 12-week, open-label Stabilization Phase (SP) during which all patients will receive oral lumateperone 42 mg/day;
• A Double-blind Treatment Phase (DBTP) 26 weeks in duration during which patients receive either lumateperone 42 mg or placebo (1:1 ratio);
• A 2-week Safety Follow-up (SFU) Phase.

Inclusion Criteria:

• Male or female, 18 to 60 years of age, inclusive.
• Current diagnosis of schizophrenia according to DSM-5 criteria as determined by the modified Structured Clinical Interview for DSM-5 (modified SCID-5).
• Diagnosis of schizophrenia for a minimum of 1 year before Visit 1.
• Current psychotic episode < 4 weeks duration at Visit 1.
• PANSS total score ≥ 70 and ≤ 120 at Visit 1 and Visit 2.
• Rating of at least 4 (moderate) on at least two of the following four PANSS positive symptoms: delusions (P1), hallucinatory behavior (P3), conceptual disorganization (P2), suspiciousness/persecution (P6) at Visit 1 and Visit 2.
• Patient must identify a caregiver who provides consents to participate in the study.
• In the opinion of the Investigator, the patient has significant risk for suicidal behavior during the course of his/her participation in the study.

Exclusion Criteria:

• Currently meeting DSM-5 criteria for any of the following:

Schizoaffective disorder, schizophreniform disorder, and other psychotic disorders; Bipolar I or Bipolar II Disorder; Intellectual developmental disorder, delirium, dementia, amnestic and other cognitive disorders; Known or suspected borderline or antisocial personality disorder or other DSM 5 personality disorder of sufficient severity to interfere with participation in this study; Substance use disorder (other than nicotine) within the 3 months prior to Visit 1 of this study.

• Patients in their first episode of psychosis.
• Treatment-resistant schizophrenia over the last 2 years, defined as little or no symptomatic response to at least 2 courses of antipsychotic treatment of an adequate duration (at least 6 weeks) and at a therapeutic dose (according to the package insert for the antipsychotic treatment).