Abstract
AIMS/HYPOTHESIS: This is the first real-world prospective observational study of teplizumab use following approval by the United States Food and Drug Administration in individuals with stage 2 type 1 diabetes. We examined whether glycaemic responses observed in controlled trials were reproduced in real-world practice and explored immunological biomarkers associated with treatment. METHODS: Children and adults with stage 2 type 1 diabetes were prospectively followed in the Early Type 1 Diabetes Clinic at the Barbara Davis Center. Individuals who received teplizumab between April 2023 and February 2025 (n=30) were compared with an untreated group (n=10). Key assessments included OGTTs, HbA(1c) measurements and continuous glucose monitoring (CGM) data, collected before and after treatment. Longitudinal metabolic data were available for up to 22 treated participants, with follow-up assessments occurring between 2 and 13 months after treatment. Changes in Epstein-Barr virus (EBV) and islet antigen-targeting T cell receptor (TCR) β chains were measured longitudinally from genomic DNA via a PCR-based targeted TCR sequencing assay. RESULTS: Among treated individuals followed up between 2 and 6 months after treatment, OGTT 2 h glucose improved (10.7 ± 2.1 to 8.8 ± 2.8 mmol/l, p=0.007), as did HbA(1c) (40 ± 4 to 39 ± 6 mmol/mol [5.8 ± 0.4% to 5.7 ± 0.5%], p=0.044). In addition, 67% had a stable or reduced CGM time ≥7.8 mmol/l. CD4 preproinsulin-specific TCRs declined after treatment, with no change in the untreated group. These reductions correlated with higher C-peptide AUC (r=-0.656, p=0.013). EBV TCR sequences were similar before and after teplizumab treatment. CONCLUSIONS/INTERPRETATION: Teplizumab can be safely and effectively administered in clinical practice. Early glycaemic improvements and reductions in CD4 preproinsulin-specific TCRs suggest that post-treatment immunological changes may serve as biomarkers to guide early-stage intervention.