Stem Cell-Derived, Fully Differentiated Islets for Type 1 Diabetes

  • Reichman, Trevor W. M.D.
  • Markmann, James F. M.D., Ph.D.
  • Odorico, Jon M.D.
  • Witkowski, Piotr M.D., Ph.D.
  • Fung, John J. M.D., Ph.D.
  • Wijkstrom, Martin M.D.
  • Kandeel, Fouad M.D., Ph.D.
  • de Koning, Eelco J.P. M.D., Ph.D.
  • Peters, Anne L. M.D.
  • Mathieu, Chantal M.D., Ph.D.
  • Kean, Leslie S. M.D., Ph.D.
  • Bruinsma, Bote G. M.D., Ph.D.
  • Wang, Chenkun Ph.D.
  • Mascia, Molly M.D.
  • Sanna, Bastiano Ph.D.
  • Marigowda, Gautham M.D., M.P.H.
  • Pagliuca, Felicia Ph.D.
  • Melton, Doug Ph.D.
  • Ricordi, Camillo M.D.
  • Rickels, Michael R. M.D.
New England Journal of Medicine 393(9):p 858-868, September 4, 2025. | DOI: 10.1056/NEJMoa2506549

Abstract

Background

Zimislecel is an allogeneic stem cell-derived islet-cell therapy. Data on the safety and efficacy of zimislecel in persons with type 1 diabetes are needed.

Methods

We conducted a phase 1-2 study of zimislecel in persons with type 1 diabetes. In part A, participants received a half dose of zimislecel (0.4×109 cells) as a single infusion into the portal vein, with an option for a second half dose within 2 years. In parts B and C, participants received a full dose of zimislecel (0.8×109 cells) as a single infusion. All the participants also received glucocorticoid-free immunosuppressive therapy. The primary end point in part A was safety. The primary end point in part C was freedom from severe hypoglycemic events during days 90 through 365, with a glycated hemoglobin level of less than 7% or a decrease of at least 1 percentage point from baseline in the glycated hemoglobin level at one or more time points between days 180 and 365. Secondary end points in part C included safety and insulin independence between days 180 and 365. Assessment of the primary and secondary end points in part C involved the participants who received the full dose of zimislecel as a single infusion in part B or C. Detection of serum C-peptide during a 4-hour mixed-meal tolerance test was used to assess engraftment and islet function. All the analyses were interim and not prespecified.

Results

A total of 14 participants (2 in part A and 12 in parts B and C) completed at least 12 months of follow-up and were included in the analyses. C-peptide was undetectable at baseline in all 14 participants. After zimislecel infusion, all the participants had engraftment and islet function, as evidenced by the detection of C-peptide. Neutropenia was the most common serious adverse event, occurring in 3 participants. Two deaths occurred — one caused by cryptococcal meningitis and one by severe dementia with agitation owing to the progression of preexisting neurocognitive impairment. All 12 participants in parts B and C were free of severe hypoglycemic events and had a glycated hemoglobin level of less than 7%; these participants spent more than 70% of the time in the target glucose range (70 to 180 mg per deciliter). Ten of the 12 participants (83%) had insulin independence and were not using exogenous insulin at day 365.

Conclusions

The results of this small, short-term study involving persons with type 1 diabetes support the hypothesis that zimislecel can restore physiologic islet function, warranting further clinical investigation. (Funded by Vertex Pharmaceuticals; VX-880-101 FORWARD ClinicalTrials.gov number, NCT04786262.)

Stem Cell−Derived Islets for Type 1 Diabetes

Zimislecel is an allogeneic stem cell-derived islet-cell therapy. This phase 1-2 study supports the hypothesis that zimislecel can restore physiologic islet function and thus treat persons with type 1 diabetes.

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