Safety and Tolerability Trial of Lumateperone in Pediatric Patients With Schizophrenia, Bipolar Disorder or Autism Spectrum Disorder

The study will enroll pediatric patients as follows: De Novo Patients: * Patients with schizophrenia, including patients who have previously participated in the lumateperone open-label pediatric pharmacokinetic (PK) study (Study ITI-007-020) * Patients with bipolar disorder who have previously participated in the lumateperone open-label pediatric PK study (Study ITI-007-030) * Patients with irritability associated with autism spectrum disorder who have previously participated in the lumateperone open-label pediatric PK study (Study ITI-007-035) Rollover Patients: * Patients with bipolar disorder who are enrolling directly from a lead-in efficacy study. * Patients with irritability associated with autism spectrum disorder who are enrolling directly from a lead-in efficacy study. This study will be conducted as follows: * A Screening Period of up to 2 weeks during which patient eligibility will be assessed. * A 26-week Open-label Treatment Period (OLTP) during which all patients will receive open-label lumateperone once daily. * A 2-week Safety Follow-up (SFU) Period: All patients should return to the clinic for the SFU visit approximately 2 weeks after the last dose of open-label lumateperone.