(Toronto, June 20, 2025) — University Health Network (UHN) is the first centre in Canada to deliver a new investigational therapy for Type 1 diabetes as part of a landmark international clinical trial sponsored by Vertex Pharmaceuticals. The study is evaluating the therapy in people with long-standing, hard-to-manage Type 1 diabetes.
The results from Phase 1/2 of the study are published today in The New England Journal of Medicine. The clinical trial is investigating a therapy called zimislecel, which uses lab-grown insulin-producing islet cells derived from pluripotent stem cells. These are special cells that can become any type of cell in the body — in this case, the insulin-producing cells normally found in the pancreas. The cells are infused into a blood vessel that supplies the liver, where they settle and may begin to produce insulin.
This phase of the trial included 14 participants in total. The first two received a half dose of zimislecel as part of a planned safety phase. The remaining 12 received the full dose and were followed for at least one year.
To prevent rejection of the transplanted cells, all participants received immunosuppressive therapy.
Key outcomes in participants who received the full dose:
- Ten of 12 participants (83 per cent) were insulin-independent at the one-year follow-up, though long-term outcomes remain under investigation.
- All avoided severe low blood sugar episodes — dangerous events that can lead to confusion, seizures, or hospitalization.
- All achieved improved blood sugar control, with HbA1c levels (a key long-term glucose marker) below seven per cent.
- All spent significantly more time with blood sugar in a healthy range, with fewer extreme highs or lows.
- Blood sugar variability decreased across the group, reducing the risk of diabetes-related complications.
"These early results mark a promising step toward a potential breakthrough in diabetes care," said Dr. Trevor Reichman, Director of the Pancreas and Islet Transplant Program at UHN's Ajmera Transplant Centre and first author of the study. "Ten out of 12 patients achieved insulin independence, meaning they are no longer managing their disease every hour of every day. In many cases, they are free from insulin for the first time since diagnosis."
"As Canada's leading transplant centre, UHN is proud to help bring first-in-world therapies to patients," said Dr. Deepali Kumar, Medical Director of UHN's Ajmera Transplant Centre. "This trial underscores the groundbreaking innovations happening at our transplant centre in transforming chronic disease care."
The majority of adverse events (AEs) were mild or moderate, and there were no serious AEs related to zimislecel treatment. As previously reported, two participants in the study died. Both deaths were determined to be unrelated to the therapy. The overall safety profile was consistent with expectations for the immunosuppressive regimen, infusion procedure, and complications associated with long-standing diabetes.
As previously announced, the study is now in Phase 3, which will take the total participant number to 50. Vertex anticipates completing enrollment and dosing in the coming months, and expects to submit the therapy for regulatory approval in 2026. Vertex is also researching additional approaches that could reduce or eliminate the need for immunosuppression, including alternative immunosuppressive regimens, gene-edited hypoimmune stem-cell derived islet cell therapies, and novel devices to encapsulate islet cells.
About Type 1 Diabetes
More than eight million people worldwide live with Type 1 diabetes (T1D). It is an autoimmune disease in which the body's immune system destroys insulin-producing cells in the pancreas. People with T1D require daily insulin therapy and constant glucose monitoring to survive. Even with the best tools, the disease is difficult to manage and can lead to serious long-term health complications.
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Credit: University Health Network
Credit: Vertex Pharmaceuticals
About University Health Network (UHN)
UHN is Canada's hospital. With 10 sites and more than 44,000 TeamUHN members, UHN consists of Toronto General Hospital, Toronto Western Hospital, Princess Margaret Cancer Centre, Toronto Rehabilitation Institute, The Michener Institute of Education and West Park Healthcare Centre. As Canada's top research hospital, the scope of biomedical research and complexity of cases at UHN have made it a national and international source for discovery, education and patient care. UHN has the largest hospital-based research program in Canada, with major research in neurosciences, cardiology, transplantation, oncology, surgical innovation, infectious diseases, genomic medicine and rehabilitation medicine. UHN is a research hospital affiliated with the University of Toronto. For more information, visit:
www.uhn.ca
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