12 People With Type 1 Diabetes, 12 Off Insulin: The Tegoprubart Trial and a Gentler Path for Islet Transplants

Sometimes the biggest news in diabetes isn't a brand-new idea — it's an old idea finally made livable.

Islet cell transplantation has been able to free people with type 1 diabetes from insulin for years. The problem was never the transplant. It was the anti-rejection drugs patients had to take afterward — powerful immunosuppressants like tacrolimus that can damage kidneys, raise blood pressure, and injure nerves. For many people, the cure felt nearly as punishing as the disease.

A small trial is now testing a different bargain: what if the anti-rejection drug itself were gentler?

The drug: tegoprubart

Tegoprubart is an experimental monoclonal antibody developed by Eledon Pharmaceuticals (Nasdaq: ELDN), a clinical-stage biotech based in Irvine, California. It targets something called CD40 ligand (CD40L) — a signaling pathway immune cells use to coordinate an attack.

In plain language: standard transplant drugs like tacrolimus work like a hammer, broadly shutting down large parts of the immune system. Tegoprubart works more like a scalpel — it blocks the specific lines of communication immune cells use to mount a rejection, while leaving most of the immune system functioning. It has also been shown to boost regulatory T cells, the immune system's own peacekeepers.

The trial: 12 patients, 12 off insulin

The study is an investigator-initiated trial — meaning it was designed and run by academic researchers, not the drug company — at the University of Chicago Medicine Transplant Institute, led by Dr. Piotr Witkowski, in collaboration with the Diabetes Research Institute at the University of Miami.

Twelve adults with type 1 diabetes received donor islet cell transplants, with tegoprubart standing in for tacrolimus in their anti-rejection regimen. The results, presented at the American Diabetes Association's Scientific Sessions in June 2026, were striking:

• All 12 patients (100%) achieved insulin independence — producing their own insulin, no longer needing injected insulin.
• All 12 reached an HbA1c below 6.5%, with an average of about 5.4% — well within the non-diabetic range, and roughly a 2.6-point improvement from where they started.
• Zero severe hypoglycemic episodes after transplant — remarkable, since every enrolled patient had a history of recurrent severe lows before the procedure.
• No rejection episodes. No new donor-specific antibodies (a marker of immune attack). And critically: none of the kidney damage, high blood pressure, or nerve toxicity that tacrolimus-based regimens commonly cause.
• Follow-up so far: a median of 8 months, with the longest-treated patient out to 22 months.

One trial participant, a 40-year-old woman living with type 1 diabetes for 13 years, was recently profiled by NBC News (October 2026) as the trial gains national attention.

Why this matters — and what it doesn't mean

This is genuinely exciting, and the "100%" number deserves a moment. But this community deserves the full picture too:

• It's 12 people. Small trials can mislead. Larger studies are needed before anyone knows how reliably this works.
• It's still a transplant. Patients still take immunosuppressive drugs — just a gentler combination (tegoprubart plus mycophenolic acid). This is better-tolerated immunosuppression, not no immunosuppression.
• Donor islets are scarce. Like all donor-islet approaches, this one is limited by organ supply. It can't scale to millions of patients without a manufactured cell source.
• Follow-up is short. A median of 8 months is encouraging, not conclusive. The key question is durability over years.
• It's not approved. Tegoprubart is investigational. This was an academic pilot study, not the large company-run trial the FDA would require for approval.

Where it fits in the bigger picture

The field is attacking the same problem — keeping transplanted insulin-producing cells alive — from three directions at once: Vertex's zimislecel (stem-cell islets, furthest along, but requires standard immunosuppression), Sana's UP421 (gene-edited "invisible" cells aiming for no immunosuppression, but very early with a single patient), and now tegoprubart (keeping standard donor islets but replacing the harshest anti-rejection drug with a targeted one — with actual insulin-independence results in 12 people).

Each approach has a different trade-off. Tegoprubart's is arguably the most practical near-term: it doesn't require inventing new cells, just improving the drug regimen around a transplant procedure doctors already know how to do.

What to watch

The next milestones: longer follow-up on these 12 patients, larger trials, and whether Eledon advances tegoprubart toward the kind of pivotal study that could support FDA approval. If the durability holds, this could reopen the door to islet transplantation for far more people than the procedure has ever been able to help.

Cautious hope, both hands — that's how this community holds progress. This one is worth watching.

This article is for informational purposes only and is not medical advice. Tegoprubart is an investigational therapy and is not an available treatment. Always talk to your own healthcare team about your care.