Insulin-making cells still working at six months, no anti-rejection drugs
Sana reported its gene-engineered donor islet cells were still making insulin at six months in a person with type 1, with no immune-suppressing drugs.
On 23 June 2025 Sana reported that the gene-engineered donor islet cells it had put into a person with type 1 diabetes were still making insulin at six months, with no anti-rejection drugs. Back in January the same cells had lasted four weeks; now they had held for half a year. That is the whole point of this update: it is early evidence that hidden-from-the-immune-system cells can last, not just appear briefly. It is still one person, and still years from being a treatment.
- Islet cells are the clusters in the pancreas that make insulin; type 1 destroys your own, so replacing them with working cells is one cure route.
- These cells were engineered to be hypoimmune, hidden from the immune system, so the person needed no immunosuppression, the lifelong anti-rejection drugs that usually come with a transplant.
- At six months, Sana reported the cells were safe, still hidden, and still producing insulin in the patient.
- Durability is why this matters: a result that lasts six months is stronger evidence than one that lasts four weeks.
- It remains a single patient and early-stage work, so it changes nothing about type 1 care today and is not something you can be referred for.
From four weeks to six months
In January 2025 Sana reported a first: a person with type 1 received donor islet cells that were engineered to evade the immune system, and they survived and made insulin for four weeks without any anti-rejection drugs. The obvious next question was whether that would last, because a cell transplant that works for a month and then fails would not help anyone. This June update is the answer so far, and it is a good one: at six months the cells were still there, still undetected by the immune system, and still making insulin.
They confirmed this the same way, by measuring markers that show the transplanted cells are alive and working. The headline from Sana was that the cells remained safe and well-tolerated, kept evading the immune system, and continued to produce insulin in the patient, all without immune-suppressing medication.
Lasting is the hard part, and the important part
The reason durability is such a big deal is that anti-rejection drugs are the main thing holding cell-based cures back. Islet transplants already exist on the NHS, but they are limited to people with the most dangerous hypos, precisely because the immunosuppression they require carries serious risks. A cell that the immune system simply ignores could, in principle, remove that barrier. For that to be believable, though, the cells have to keep working over time, not just survive the first few weeks.
Six months in one person is real progress towards that, and it is fair to be encouraged. It is also worth keeping the frame steady: this is still a single case, the follow-up is still short in transplant terms, and the path to a proven, approved, widely available treatment runs through much larger and longer trials. The right response is interest in the direction, not an expectation of a cure around the corner.