VX-880 clinical trial of lab-grown islet cells with immunosuppressants

What is the VX-880 clinical trial?

In the trial, researchers give people with T1D a dose of islets (clusters of pancreatic cells which contain insulin-producing beta cells) via a plastic tube into a vein that goes to the liver. The participants also need to take immunosuppressant drugs to avoid the immune system destroying the new islet cells. After receiving VX-880, the participants are monitored for up to five years.

Because it is the first time these cells have been given to humans, the clinical trial began slowly, with people treated one by one to ensure the treatment was safe. As more data becomes available, the trial continues to expand to enrol more participants.

Participants free from taking insulin

Vertex presented the latest data from the VX-880 clinical trial at the American Diabetes Association’s 2025 conference. They reported that ten of 12 people with type 1 are no longer taking external insulin from an injection or pump. They also announced that the drug’s name is zimislecel.

Dr Piotr Witkowski, one of the researchers on the study, said: “The data we’ve seen to-date in this study are extremely exciting. Stem cell-derived islets regulate blood glucose control as well as natural human islets. The marked improvements seen…have the potential to fundamentally change the treatment landscape for T1D and alleviate the significant burden this disease carries for patients.”

In this study, 12 out of 12 patients were free of severe low blood sugar (hypoglycaemia) and spent 70% of the time within their glucose target range. Ten out of 12 participants were not injecting any insulin after 365 days.

One of two doses of the cellular therapy were given in this trial (either one half dose or one full dose) and their success was measured using a biomarker called C-peptide. The presence of C-peptide levels in the blood directly relate to insulin activity. All 12 participants in the full-dose cohort had detectable C-peptide levels before and after meals, showing that the implanted cells were successfully producing insulin.

What are the next steps?

These new results are promising for cell-therapies in T1D. Further investigations are required with larger, more diverse populations to increase the evidence that lab grown beta cells can be given to patients to successfully treat T1D and help millions of people.

Is the zimislecel islet cell treatment safe?

One of the aims of this clinical trial is to assess how safe zimislecel is. This is why so few participants are involved and why they are being so closely monitored. So far, the trial has not led to serious adverse effects. The most common symptoms people had include dehydration, diarrhoea, low magnesium levels and rashes.

Immunosuppressant drugs have the potential to cause anaemia, reduced kidney function and increased risk of cancer and infections. This is because immunosuppressants suppress the beneficial parts of the immune system as well as the part that attacks beta cells in type 1. International scientists are developing other ways to keep the lab-grown islets safe from the immune system to remove the need for immunosuppressants.

An option for a less harmful immunosuppression is currently being researched in the Eledon trial. The drug is called tegoprubart, you can read about this on our website.

Who can take part in this clinical trial?

The participants in this clinical trial are all people with type 1 who experience severe hypos and hypoglycaemia unawareness. This is because the risks and lifestyle adjustments involved in taking immunosuppressants outweigh the benefits of the exploratory therapy for healthier people with type 1.

The people taking part also need to be either blood type A or AB. As the treatment develops, the researchers hope to grow islet cells that are suitable for people of all blood types.

The current total of participants needed is 37 people, but this may increase as more results come in. Find out if you’re eligible to take part in the clinical trial.

Where is the VX-880 clinical trial taking place?

There are currently many trial sites, including the United Kingdom. The other countries included are the US, Canada, Norway, Switzerland and the Netherlands.