In the winter of 2025, Vertex Pharmaceuticals presented the results of the first large-scale study (phase I/II) of zimislecel (formerly VX-880), a stem cell-based drug. This experimental treatment aims to restore the cells of the islets of Langerhans in the liver of patients.
The trial involved 14 patients with severe type 1 diabetes and hypoglycemia detection disorders. All participants received a single infusion of zimislecel into the hepatic vein and initial immunosuppressive therapy without glucocorticoids. According to data from one year, 10 out of 12 completely stopped insulin injections, becoming insulin-independent, while the remaining two patients reduced their insulin dose by 92% on average. All participants normalized their HbA1c levels (<7%) and spent more than 70% of their time in the glycemic range of 70-180 mg/dL.
Side effects:
• Neutropenia was observed in 3 patients;
• Two fatalities were recorded: one from cryptococcal meningitis (off-protocol), the other from severe cognitive pathology unrelated to treatment.
The discontinuation of insulin therapy in 83% of participants is a very significant achievement, indicating the possibility of restoring endogenous insulin secretion. The American Diabetes Association (ADA) called the data “unprecedented” after three stages of presentation at the ADA-2025 conference in Chicago.
However, it should be noted that the study was small (12–14 participants) and short (12 months); large-scale control experience is needed. Data on long-term efficacy, safety, and commercial affordability are not yet known.
Phase III has now begun, with approximately 50 patients expected to participate. The next results are expected at the end of the year, after which the FDA application process will begin.
The drug is positioned as a breakthrough “functional remission” for a group of patients with severe diabetes and a tendency to hypoglycemic events. If its effectiveness is fully confirmed, it will be a global revolution in the treatment of type 1 diabetes.
