Teplizumab (Tzield)

Screening: finding T1D before it strikes

Teplizumab only matters if you can identify the right people before they get sick — and that depends on screening. Type 1 diabetes develops along a defined three-stage path. Stage 1 is two or more islet autoantibodies (against insulin, GAD, IA-2, or ZnT8) with normal blood glucose and no symptoms; stage 2 adds abnormal glucose (dysglycemia) but still no symptoms; stage 3 is clinical disease, when insulin is needed.¹ The autoantibodies are powerful predictors: in a pooled multi-cohort analysis, children who developed two or more had a ~70% risk of clinical diabetes within 10 years, with the majority progressing over the following 15 years — approaching certainty over a lifetime.²

Screening can be offered to relatives of people with T1D, but roughly 90% of new cases have no family history — so finding most at-risk people requires general-population testing using autoantibody (and sometimes genetic-risk) panels.³ Early detection is valuable even without treatment: people identified through screening are monitored, so when they reach stage 3 they are far less likely to arrive in diabetic ketoacidosis (DKA), a dangerous and sometimes fatal emergency.¹ Detection now uses capillary or home-collected samples, lowering the burden and cost that long blocked wide screening.³

Therapy: bending the timeline

Teplizumab is an Fc-receptor-nonbinding anti-CD3 monoclonal antibody. It binds CD3 on T cells, blunting the autoreactive T-cell attack on the body's own insulin-producing cells and expanding "exhausted," less-destructive T-cell populations — buying the pancreas time.⁴

The pivotal evidence is the TN-10 trial (NCT01030861): 76 autoantibody-positive stage-2 relatives got a single 14-day infusion course of teplizumab or placebo. Median time to clinical (stage 3) diagnosis was 48.4 months with teplizumab versus 24.4 months with placebo — a roughly 24-month delay — with a hazard ratio of 0.41.⁴ On extended follow-up (median ~923 days), the gap widened to 59.6 vs 27.1 months, and 50% of treated participants remained diabetes-free versus 22% on placebo; treatment also improved and stabilised insulin-producing (C-peptide) function.⁵ The effect is a delay, not a cure — most participants still progressed eventually, and there is no established re-dosing schedule.

In newly diagnosed stage-3 patients, the phase-3 PROTECT trial (NCT03875729, 328 children/adolescents) showed two 12-day courses preserved C-peptide at 78 weeks, with ~95% of treated patients keeping a clinically meaningful level versus ~79% on placebo — though it did not significantly change insulin dose or HbA1c.⁶

Safety: the common effects are transient lymphopenia, rash, headache, and mild cytokine-release symptoms, generally self-limited — but they are not trivial when treating someone who currently feels healthy.⁴

On the strength of TN-10, the FDA approved Tzield in November 2022 — the first disease-modifying therapy for T1D — to delay stage-3 onset in stage-2 patients aged 8 and older.⁷ The current 2026 label extends that stage-2 delay indication to adults and children aged 1 year and older.⁸ It is given as a once-daily IV infusion for 14 consecutive days and carries a very high list price per course, a major access barrier alongside its US-only availability and dependence on prior screening.⁹

What's coming

Two 2026 label changes sharpened the case for screening and early treatment. In April 2026 the FDA extended the stage-2 delay indication down to age 1, after the PETITE-T1D study in young children — the years when T1D is hardest to manage.⁸ In June 2026 the FDA granted accelerated approval for newly diagnosed stage-3 disease in children aged 8-17, supported by PROTECT, with a confirmatory BETA-PRESERVE trial enrolling.¹⁰ Trials in additional populations (including Japan) are also running, pointing toward broader global access over time.

References

1. Sims EK, et al. Screening for Type 1 Diabetes in the General Population: A Status Report and Perspective. Diabetes (2022). https://doi.org/10.2337/dbi20-0054 ↩ ↩²

2. Ziegler AG, et al. Seroconversion to multiple islet autoantibodies and risk of progression to diabetes in children. JAMA (2013). https://doi.org/10.1001/jama.2013.6285 ↩

3. Sims EK, et al. Screening for Type 1 Diabetes in the General Population: A Status Report and Perspective. Diabetes (2022). https://doi.org/10.2337/dbi20-0054 ↩ ↩²

4. Herold KC, et al. An Anti-CD3 Antibody, Teplizumab, in Relatives at Risk for Type 1 Diabetes. N Engl J Med (2019). https://doi.org/10.1056/NEJMoa1902226 ↩ ↩² ↩³

5. Sims EK, et al. Teplizumab improves and stabilizes beta cell function in antibody-positive high-risk individuals. Sci Transl Med (2021). https://doi.org/10.1126/scitranslmed.abc8980 ↩

6. Ramos EL, et al. Teplizumab and β-Cell Function in Newly Diagnosed Type 1 Diabetes (PROTECT). N Engl J Med (2023). https://doi.org/10.1056/NEJMoa2308743 ↩

7. Keam SJ. Teplizumab: First Approval. Drugs (2023). https://doi.org/10.1007/s40265-023-01847-y ↩

8. U.S. Food and Drug Administration. TZIELD (teplizumab-mzwv) prescribing information (2026 label; stage-2 delay indication in adults and pediatric patients 1 year and older). https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/761183s013lbl.pdf ↩ ↩²

9. Provention prices type 1 diabetes drug Tzield at $194,000. pharmaphorum (2022). https://pharmaphorum.com/news/provention-prices-type-1-diabetes-drug-tzield-at-194000 ↩

10. U.S. Food and Drug Administration. FDA Approves Drug for Pediatric Stage 3 Type I Diabetes (accelerated approval, content current June 12, 2026). https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-drug-pediatric-stage-3-type-i-diabetes ↩