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Phase 3RecruitingNCT04786262

FORWARD: zimislecel (VX-880) and VX-017 stem-cell islets

What this study tests

Vertex’s open-label stem-cell-islet study now includes VX-017 alongside zimislecel (VX-880). In the published VX-880 cohort, 10 of 12 full-dose recipients were insulin-independent at one year, with chronic immunosuppression. The September registry adds VX-017 safety follow-up; it reports no VX-017 outcomes.

Editorial review: .

Registry checked: 2026-09-17. Registry’s own update: 2026-09-01.

Most recent recorded citation date: 2026-08-03. Only explicit date metadata is included; an undated citation may be newer. This does not mean every claim was reviewed on that date.

Trial status, labels and access can change between reviews. How we review the evidence · How to read the evidence

Full sources ↓Full discussion ↓Report an issue →

Evidence at a glance

Who can enter the study?
Adults aged 18–65 with at least five years of insulin dependence, at least two documented severe hypoglycemic episodes in the prior 12 months, stable treatment and consistent CGM use for at least three months. Prior islet, organ or cell transplants are excluded; further protocol criteria apply. Registered eligibility ↗Enrollment criteria describe who may enter. They do not establish who was analyzed or the denominator for a reported result.
Reported benefit and results
In the published interim Phase 1/2 analysis, all 14 followed participants (who had no detectable C-peptide at baseline) showed engraftment and restored insulin production after infusion. Among the 12 who received a full single dose, all 12 were free of severe hypoglycemic events during days 90–365 with HbA1c under 7% and spent more than 70% of time in the target glucose range; 10 of 12 (83%) were completely off injected insulin at day 365. The analyses were interim and not prespecified. The most common serious adverse event was neutropenia (3 participants). Two deaths occurred, from cryptococcal meningitis and progression of pre-existing neurocognitive impairment. The investigator attributed the cryptococcal meningitis to immunosuppressive medication; the patient also received prolonged high-dose glucocorticoids prohibited by the protocol and sustained a skull-base injury during sinus surgery. Serious acute kidney injury occurred in two participants. These are risks of the combined regimen, even though no serious adverse event was attributed to the cells. No VX-017 results are posted in the registry.Read the result sources and their limitations →
Important harms
Read the reported results, safety discussion and original sources. A separate harms summary is not available; this does not establish safety.
Research access and approval
Study regions: United States, United Kingdom, European Union, Canada, Other regions. A trial listing does not establish product approval or current recruitment at a particular site. Check the study’s current entry requirements.
What remains uncertain?
Read the full discussion and original sources for study limitations. Planned endpoints and completion dates are not results.

Research status alone does not establish approval, clinical benefit or local availability. This record cites company or conference reports. Those sources may describe interim findings; their source type is shown in the source list.

Primary endpoints

  • Part A (VX-880): adverse events from infusion through at least five years of follow-up.
  • Parts B/C (VX-880): insulin independence without severe hypoglycemic events, one year after achieving insulin independence.
  • Part D (VX-017): adverse events from infusion through at least five years of follow-up.

The full picture

What changed in September

The registry update posted 1 September 2026 makes NCT04786262 a study of VX-880 and VX-017, with estimated total enrollment of 57. It lists primary completion on 31 December 2027 and final completion on 31 December 2031. These estimates replace the earlier 52-participant and June 2027/2030 entries.1

VX-017 is included as a separate safety part. A registry entry is not evidence that a participant has been dosed, that immune suppression is unnecessary, or that the new product has achieved the results of VX-880. No VX-017 human outcomes were available in the checked record.1

Published zimislecel findings

The 2025 paper reports 14 recipients with at least one year of follow-up. All developed detectable C-peptide after starting with none detectable. Of the 12 full-dose recipients, ten were insulin-independent at day 365; all twelve were free from severe hypoglycemic events during days 90–365, had HbA1c below 7%, and spent more than 70% of time in 70–180 mg/dL (3.9–10.0 mmol/L).2

This was a small, open-label study. The published interim analyses were not prespecified. Neutropenia was the most common serious adverse event (three people); two deaths occurred, from cryptococcal meningitis and progression of pre-existing neurocognitive impairment. All participants received immunosuppression. Investigators attributed the cryptococcal meningitis to immunosuppressive medication; that patient also received prolonged high-dose glucocorticoids prohibited by the protocol and sustained a skull-base injury during sinus surgery. Serious acute kidney injury occurred in two participants. No serious adverse event was attributed to zimislecel itself, but the risks of the complete regimen remain clinically relevant.2

What to watch next

The current registry separates the long-term safety outcomes for VX-880 and VX-017 from the VX-880 insulin-independence endpoint. The endpoint in the published interim paper and the current registry endpoint are not identical; readers should keep their analysis dates and populations in view.21

Vertex’s August 2026 update said FORWARD continued to enroll and dose, with revised zimislecel timelines expected later in 2026. It did not repeat the former 2026 regulatory-filing forecast. Registry completion dates are not filing or approval dates.3

Sources

  1. [1]
    FORWARD: VX-880 and VX-017 (NCT04786262) · Trial registry — Updated 1 September 2026; checked 16 September.

    ClinicalTrials.gov. FORWARD, NCT04786262. Update posted 1 September 2026, checked 16 September 2026.

  2. [2]
    Stem Cell-Derived, Fully Differentiated Islets for Type 1 Diabetes · Peer-reviewed study

    Reichman TW et al. Stem Cell-Derived, Fully Differentiated Islets for Type 1 Diabetes. NEJM (2025).

  3. [3]
    Vertex second-quarter 2026 financial results · Manufacturer · 2026-08-03

    Vertex Pharmaceuticals. Second-quarter 2026 financial results, 3 August 2026.