A Clinical Study to Evaluate the Long-term Safety and Tolerability of an Investigational Drug in People With Schizophrenia

This is a clinical trial to determine the long-term safety and tolerability of an investigational drug in people with schizophrenia. Participants in the study will receive the drug being studied. This study is accepting male and female participants between 13 and 65 years old who have been diagnosed with schizophrenia and have completed Study SEP361-301 (NCT04072354) or Study SEP361-302 (NCT04092686). This study will be conducted in approximately 80 study centers worldwide. The treatment duration for this study is one (1) year.

An open-label extension study to assess the safety and tolerability of SEP-363856 in participants with schizophrenia This is an open-label extension study to evaluate long-term safety and tolerability of SEP-363856. This is a 52-week, outpatient, multicenter, flexible-dose, open-label extension study designed to evaluate the long-term safety and tolerability of SEP-363856 (25 to 100 mg/day) for the treatment of participants with schizophrenia who have completed the Treatment Period of one of the two following double-blind studies: Study SEP361-301 (NCT04072354) or Study SEP361-302 (NCT04092686).

Sumitomo Pharma America Inc. was the former Sponsor and conducted this study. Sumitomo was responsible for analysis and clinical study report (CSR) completion. Otsuka took over study after IND was transferred and is concluding activities with registry postings.

Eligibility Criteria:
Inclusion Criteria:

1. Participant (or participants parent/legal guardian for adolescents) must give written informed consent and privacy authorization prior to participation in the study; adolescents must also provide informed assent.
2. Participant has completed the Treatment Period of Study SEP361-301 or Study SEP361-302.
3. Participant has not taken any medication other than the study drug and protocol-allowed medications for the purpose of controlling schizophrenia symptoms during Study SEP361-301 or SEP361-302.
4. Female participant must have a negative urine pregnancy test at the End of Treatment (EOT) Visit of Study SEP361-301 or Study SEP361-302.
5. Female participants of childbearing potential must agree to use highly effective and reliable contraception throughout the study and for at least 30 days after the last dose of study drug has been taken.
6. Male participants must agree to avoid fathering a child and use highly effective methods of birth control from screening in Study SEP361-301 or Study SEP361-302, until at least 30 days after the last study drug administration in the present study (SEP361-303).

Exclusion Criteria

1. Participant answered "yes" to "suicidal ideation" Item 4 (active suicidal ideation with some intent to act, without specific plan) or Item 5 (active suicidal ideation with specific plan and intent) on the Columbia Suicide Severity Rating Scale (C-SSRS) assessment at the End of treatment (EO) Visit of Study SEP361-301 or SEP361-302.
2. Participant has a clinically significant abnormality including physical examination, vital signs, ECG, or laboratory test at the EOT Visit of Study SEP361-301 or SEP361-302 that the investigator in consultation with the medical monitor considers to be inappropriate to allow participation in the study.
3. Participant has a positive urine drug screen (UDS) at the EOT Visit of Study SEP361-301 or SEP361-302. However, a positive UDS test may not result in exclusion of participants if the Investigator determines that the positive test is as a result of prescription medicine(s). participants may enter this study before the urine drug screen results are received from the central laboratory. However, after receipt and review of the results any participant meeting this exclusion criterion must be discontinued from the study. Retesting of the UDS is allowed once with prior approval from the Medical Monitor with the retest used to determine eligibility
4. Female participant is pregnant or lactating.