Immune Therapy to Prevent Type 1 Diabetes: Teplizumab and Beyond

A Turning Point in Type 1 Diabetes Prevention

For decades, the medical community could only watch as the immune system mistakenly destroyed the insulin-producing beta cells in the pancreas of people at risk for Type 1 diabetes (T1D). That changed in November 2022 when the FDA approved teplizumab (Tzield), manufactured by Provention Bio (now acquired by Sanofi), making it the first drug ever approved to delay the onset of clinical Type 1 diabetes. This is not a cure — but it is a genuine scientific milestone, and it opens the door to a new era of immune-based prevention strategies.

How Teplizumab Works

Teplizumab is a monoclonal antibody that targets CD3, a protein on the surface of T-cells — the immune cells responsible for attacking beta cells in T1D. By binding to CD3, teplizumab partially dampens the autoimmune assault without completely suppressing the immune system. Think of it as turning down the volume on a misdirected immune attack rather than silencing it entirely.

The drug is given as a 14-day intravenous infusion course and is indicated for people who are in Stage 2 Type 1 diabetes — meaning they have two or more islet autoantibodies and abnormal glucose tolerance, but no symptoms yet. This staging system, developed by the American Diabetes Association, recognizes that T1D begins long before a person ever needs insulin.

The TrialNet TN-10 Study: The Evidence Behind Approval

The FDA approval was primarily based on the landmark TrialNet TN-10 clinical trial, a randomized, placebo-controlled study conducted through the NIH-funded TrialNet network. The trial enrolled 76 relatives of people with T1D who were in Stage 2 — at high risk but not yet symptomatic.

Results were striking: teplizumab delayed clinical T1D diagnosis by a median of approximately 2 years compared to placebo. Among participants who received teplizumab, 50% had not progressed to Stage 3 (clinical) T1D at the time of analysis, compared to 22% in the placebo group. A longer-term follow-up published in The New England Journal of Medicine in 2023 confirmed these benefits extended to at least 5 years for some participants.

Importantly, teplizumab preserved more residual beta cell function — measured by C-peptide levels — suggesting it may slow, not just delay, the underlying disease process.

Who Qualifies for Teplizumab Today?

Teplizumab (Tzield) is currently approved for individuals aged 8 years and older who are in Stage 2 T1D. Identifying these individuals requires screening for islet autoantibodies — proteins the immune system produces when it begins attacking beta cells. First-degree relatives of people with T1D have roughly a 15-fold higher risk and are the primary candidates for screening.

The TrialNet Pathway to Prevention program offers free autoantibody screening to relatives of T1D patients across the United States and internationally. Patients can visit trialnet.org or search ClinicalTrials.gov to find enrollment opportunities near them.

What's Coming Next: Beyond Teplizumab

Teplizumab is just the beginning. Several promising immune therapies are in active development:

• Anti-CD20 therapies (Rituximab, Obinutuzumab): The TrialNet Anti-CD20 study using rituximab demonstrated preservation of beta cell function in newly diagnosed T1D patients. Obinutuzumab, a newer anti-CD20 agent, is being evaluated in the TOPPLE T1D trial to determine if earlier intervention is more effective.
• CTLA-4-Ig (Abatacept/Orencia): Sanofi's abatacept has shown promise in slowing T1D progression. The TrialNet CTLA4-Ig (Abatacept) trial demonstrated that abatacept slowed the loss of beta cell function in newly diagnosed patients, and studies are ongoing to evaluate it in Stage 2 populations.
• IL-2 and Regulatory T-cell Therapies: Low-dose interleukin-2 aims to boost regulatory T-cells that suppress the autoimmune attack. Companies including Innodia and researchers at Cambridge University are pursuing this approach with multiple trials active as of 2025.
• Antigen-Specific Therapies: Rather than broadly suppressing the immune system, antigen-specific approaches aim to re-train the immune system to tolerate insulin-producing cells specifically. This includes peptide vaccines and tolerogenic dendritic cell approaches — still largely in early-phase trials.
• Combination Immunotherapy: Researchers increasingly believe combining agents — for example, teplizumab with abatacept or with regulatory T-cell therapies — may produce stronger, longer-lasting protection. Several combination trials are in planning or early phases as of 2025.

Current Status (2025)

As of 2025, teplizumab is commercially available in the United States under the brand name Tzield, distributed by Sanofi. Access remains limited by the need for specialized infusion centers and the challenge of identifying Stage 2 patients through screening. Insurance coverage varies, and patient assistance programs exist through Sanofi.

Internationally, regulatory review is ongoing in the EU and other markets. Broad population-based screening programs — like the Fr1da study in Bavaria and the ELSA screening program in the UK — are demonstrating how to systematically identify at-risk individuals before symptoms appear, setting the stage for prevention at a population level.

No immunotherapy has yet been proven to prevent T1D entirely — only delay or slow it. The goal of true prevention or durable remission remains an active research frontier.

What This Means for Patients

If you or your child has a parent or sibling with Type 1 diabetes, autoantibody screening is now a meaningful and actionable step. A positive result for two or more autoantibodies — even without any symptoms — places someone in a risk category where FDA-approved prevention therapy may be applicable.

For those already living with T1D and managing daily life with insulin pumps, CGMs, and supplies available through resources like mdsdiabetes.com, these advances represent hope for future generations — and potentially for slowing progression in newly diagnosed individuals today.

Talk to your endocrinologist about whether autoantibody screening is appropriate for your family. You can also visit ClinicalTrials.gov and search "Type 1 diabetes prevention" to find active trials enrolling near you.

Timeline: When Will These Therapies Be Widely Available?

• Now (2025): Teplizumab available in the US for Stage 2 T1D, ages 8+
• 2025–2027: Results expected from ongoing combination therapy trials and obinutuzumab studies
• 2027–2030: Potential additional FDA approvals if combination or earlier-stage therapies prove effective
• Beyond 2030: Population-wide screening and antigen-specific vaccines remain longer-horizon goals

The science is moving faster than at any point in T1D history — but honest timelines matter. Teplizumab delays T1D by roughly two years on average. That is meaningful. A permanent cure or complete prevention is not yet here.