Insulin Cells Survived 14 Months Without Immunosuppression
What Sana’s New NEJM Data Actually Means — and What It Doesn’t (Yet)
Cells that make insulin, living in a person’s forearm for over a year, hiding from the immune system without a single anti-rejection drug. That’s the headline. Here’s the careful version.
On July 13, 2026, Sana Biotechnology announced that The New England Journal of Medicine published a peer-reviewed letter from clinicians at Uppsala University Hospital reporting 14-month follow-up data from a first-in-human study of insulin-producing cells engineered to hide from the immune system. The person who received them still isn’t taking any drugs to prevent rejection, and the cells are still making insulin.
Three things to get straight before we go further.
The findings are not new. Sana reported these same 14-month results on March 13, 2026, and presented them at the ATTD conference that day. What happened on July 13 is that NEJM published them — a peer-reviewed letter, not a new result. Peer review is a real credential and worth something. It is not the same thing as new evidence, and a lot of this week’s coverage is quietly treating it as though it were.
We put the two releases side by side. These are the findings in each:
Not similar findings. The same findings, in largely the same sentences. The bottom row is what actually changed this week.
It is also a follow-on. NEJM published the original findings from this study back in 2025. This new letter reports that the result has held up over a longer stretch of time.
And this is Sana’s own press release — a publicly traded company describing its own data, with the forward-looking language that comes with that. The letter itself cleared peer review. The framing around it belongs to the company. All of that can be true without anything being wrong.
Now. If you live with type 1, or you love someone who does, this is worth sitting with. Two of the hardest problems in curing type 1 have always been stacked on top of each other. First, the immune system destroys insulin-producing cells — that’s what type 1 is. Second, if you transplant new cells in, the body attacks those too, both as foreign tissue and as the same old target. The standard answer has been lifelong Drugs that deliberately weaken the immune system so it won’t reject a transplant. They work — but suppressing the immune system long-term carries its own real risks, which is a large part of why islet transplantation has never become a mainstream option for type 1. Removing the need for these drugs is precisely what this study set out to test.immunosuppression
This study tests a different idea: what if you could edit the cells so the immune system simply doesn’t see them?
What was actually reported
The data comes from an investigator-sponsored study run by clinicians at Uppsala University Hospital in Sweden, supported by a grant from the Helmsley Charitable Trust. The therapy is UP421 — donor human Clusters of cells in the pancreas that include the beta cells — the ones that make insulin. In type 1, the immune system destroys them. Transplanting new islets is a decades-old idea; keeping them alive has always been the hard part. Sana calls it HIP — hypoimmune. The cells are engineered so the immune system doesn’t flag them, either as foreign tissue or as the autoimmune target it already went after once. The goal is cells that survive without anti-rejection drugs. This study is the first test of whether that holds up in a human body over time.islet cells
hypoimmune
Sana says the study met its primary endpoint — safety — and its secondary endpoints: immune evasion, cell survival, and C-peptide production. That last one is how they know it worked.
They measured A byproduct your body releases in equal amounts to the insulin it makes on its own. Injected or pumped insulin does not produce it. So C-peptide is how researchers can tell that the transplanted cells are making insulin, rather than the person’s own pump or pen doing the work.C-peptide
At month 14, C-peptide — both fasting and meal-stimulated — was comparable to the levels seen in the first six months of the study, and higher than the levels measured at months 9 and 12. Between months 12 and 14 the patient achieved tighter glycemic control, and Sana says the improved insulin secretion at month 14 underscores the importance of glucose control in optimizing beta-cell function. A 52-week PET-MRI scan still showed islet cells at the transplant site. No safety issues were identified.
Is that person off insulin?
No. And the reason why is the most clarifying number in this entire story.
The dose this patient received was, according to reporting from FirstWord Pharma when the data was first presented, equivalent to roughly 2–7% of the islet cells that would typically be needed to achieve insulin independence. Sana’s own release says the same thing in words rather than numbers: the study used a deliberately low dose and was never intended to demonstrate better glucose control or a reduction in injected insulin.
Read that again, because it reframes everything. This was never a near-miss at a cure. Researchers deliberately gave a person a small fraction of the cells it would take to get them off insulin, because they were asking a different question entirely: do these cells survive without anti-rejection drugs? The answer, so far, is yes. The person is still taking insulin, exactly as the study intended.
Sana’s own people said as much back in March, in their own words. Carlsson described the cells as transplanted in “a single low dose” and looked ahead to SC451 as a more scalable approach at higher doses. Sana’s president and CEO, Steve Harr, MD, said that improvement in glycemic control is anticipated with higher doses of hypoimmune islets. Both men are telling you, plainly, that this dose was not expected to move anyone’s blood sugar. That is not a criticism of the study. It is the study working precisely as designed.
Per-Ola Carlsson, MD, the study’s principal investigator at Uppsala, said that after a century of relying on insulin, people living with type 1 diabetes “deserve more than incremental improvements” — and that on the strength of this 14-month data, he believes a functional cure for type 1 without immunosuppression is possible. Gary Meininger, MD, Sana’s EVP and chief medical officer, described the results as pointing beyond lifelong disease management and toward restoring natural glucose control, with a stated goal of a one-time functional cure requiring no immunosuppression.
Those are their words about their own work. Which brings us to the part that matters most.
Read the headline. Then read the fine print.
Below are four things you are likely to see written about this study. Each one is accurate. Each one also has a second half. Tap to see it. (These are our summaries of how the news is being framed — not quotations from anyone.)
What you’ll hear
A functional cure for type 1 without immunosuppression is possible.
Tap for the fine print ↓
That is the principal investigator’s stated belief, after seeing his own 14-month data. A belief is not a finding, and it is not a timeline. Nothing in this publication says a cure exists, is approved, or is close. “Possible” is the beginning of the work, not the end of it.
What you’ll hear
The cells survived 14 months with no immunosuppression.
Tap for the fine print ↓
True — and it is the genuinely important thing here. But it happened in one person, in a first-in-human study whose primary purpose was safety. One result, however good, is a starting line. The only answer to a sample size of one is more patients and more time.
What you’ll hear
The transplanted cells are producing insulin.
Tap for the fine print ↓
They are, measurably. But the patient received a dose reported to be 2–7% of the cells needed for insulin independence, and Sana states plainly that the study is not intended to show improvement in blood sugar or a reduction in injected insulin. It was built to answer one question: can these cells survive and function without anti-rejection drugs? That person is still taking insulin — by design.
What you’ll hear
Sana is advancing a one-time treatment for type 1 diabetes.
Tap for the fine print ↓
UP421 uses donor islet cells, which are far too scarce to treat millions of people. The version designed to scale, SC451, is grown from stem cells — and it has not entered human trials. Sana says it expects to file an IND and begin a Phase 1/2 trial as early as this year. The company itself notes that FDA acceptance of an IND is at the agency’s discretion, and is not predictive of how a trial will turn out.
Where this sits on the road
Every cell therapy has to travel roughly the same road. Tap a stage to see what it is, and whether this one has gotten there.
The idea behind Sana’s hypoimmune (HIP) platform: modify the cells so the body does not flag them, either as foreign tissue or as the autoimmune target it already destroyed once.
Every cell therapy must clear laboratory and animal testing before regulators will allow it into a person. This is the standard path; the Sana release does not detail this stage.
One patient. Donor islet cells (UP421), a deliberately low dose — reported at 2–7% of what insulin independence would require — transplanted into a forearm muscle with no immunosuppression. At 14 months: cells alive on imaging, C-peptide measurable while fasting and after a meal, no safety issues. Sana says the study met its safety and secondary endpoints. It was never designed to improve blood sugar or reduce injected insulin, and the patient still takes insulin.
Donor islets are far too scarce to treat millions of people. SC451 — grown from stem cells — is the version that could. It has not entered human trials. Sana says it expects to file an IND and begin a Phase 1/2 trial as early as this year.
Surviving is not the same as sufficient. A therapy has to deliver enough working cells to meaningfully change glucose control or reduce insulin needs. That has not been shown with this approach.
Does the immune evasion hold? Do the cells last years, not months? Does it work in people beyond the first, carefully selected patient? These are the questions large trials exist to answer.
Then it must be approved, manufactured at scale, paid for, and delivered. This is the stage breakthrough headlines rarely mention, and it is measured in years.
This is the general path any cell therapy follows, shown here for context. Only the stage marked “where this is” describes findings reported in Sana’s release.
How to hold this
You’re allowed to be excited. You’re also allowed to keep your guard up, because this community has been handed “five years away” more times than anyone can count, and the disappointment is its own kind of tax.
Both can be true. Something real happened: engineered cells stayed alive and kept making insulin for more than a year inside a human body that was never given a drug to stop it from rejecting them. That is the wall the field has been stuck behind. And the finish line did not suddenly appear — this was a few percent of a dose, in one person, and the scalable version hasn’t been given to a single human being yet.
In the meantime, the thing that actually changes your life with type 1 today hasn’t changed at all. It’s still timing and amount. The right amount of insulin at the right time. That’s what makes today better while the researchers keep working on tomorrow.
We’ll keep watching this one. If SC451 reaches a trial and starts producing data in actual patients, it’ll be worth a much longer conversation.
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