The purpose of this non-interventional extension study is to continue to collect long-term safety and other clinical data for an additional 42 months in participants who completed the PROTECT study.

This study is the long-term extension of the PRV-031-001 (PROTECT) study. PROTECT is a Phase 3, randomized, double-blind, placebo-controlled, multinational, multi-center study to evaluate the efficacy and safety of teplizumab, a humanized, anti-CD3 monoclonal antibody, in children and adolescents ages 8 through 17 recently diagnosed with type 1 diabetes (within 6 weeks of diagnosis) in which approximately 300 participants were randomized at a ratio of 2:1 to the teplizumab or placebo and received two courses of treatment administered 6 or 12 months apart with final follow-up at approximately 18 months (78 weeks) after the first dose.

Participants who complete the PROTECT study are invited to enroll in this observational, extension study to collect long-term safety and other clinical data. The decision to participate can be made within 12 months of completing the PROTECT study.

No study drug will be administered during this extension study. Participants will continue to receive standard care for type 1 diabetes from their primary physicians.

Participants will return to the study sites for assessments once every 6 months through Month 42. Therefore, the combined duration of the PROTECT and PROTECT Extension studies will be 60 months.

Inclusion Criteria:

1. Completion of the PRV-031-001 (PROTECT) study by completing the Week 78 visit in that study, regardless of how many doses of study drug were administered.
2. Provide written informed consent within 12 months of the Week 78 in the PRV-031-001 study. Written assent will be obtained for participants under 18 years of age at the time of enrollment, according to applicable regulations. If possible, written informed consent and/or assent for the current PROTECT Extension study (PRV-031-003) should be obtained at the final (Week 78) visit in the PROTECT study.

Exclusion Criteria:

1. Premature discontinuation from the PRV-031-001 (PROTECT) study for any reason.

Participants who completed the PROTECT (PRV-031-001) study

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org