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Phase 1/2RecruitingNCT02846571

Islet transplantation into the anterior chamber of the eye

A two-person safety study putting donor islets into the front chamber of a blind eye — a site chosen because the graft can be watched through a microscope, and because the eye may tolerate a transplant with less drug cover. It is often described as "immunosuppression-free". It is not. Every recipient gets a short course of systemic induction immunosuppression around the transplant, then ongoing maintenance immunosuppression as eye-drops (topical steroids plus ciclosporin or tacrolimus). Recipients who already have a kidney transplant stay on their chronic systemic anti-rejection drugs throughout. What is genuinely being tested is whether *maintenance* immunosuppression can be local rather than systemic — a real question, but a narrower one than "no drugs".

Primary endpoints

  • Absence of ocular complications in the transplanted eye at 24 months
  • Absence of sympathetic ophthalmia (immune damage to the *other*, untreated eye) at 24 months
  • Confirmation of intraocular islet graft survival — C-peptide above 1 ng/ml in the aqueous humour of the transplanted eye, plus imaging of graft integrity

Results so far

No results posted. Note what this trial is and is not designed to show. Target enrolment is 2 participants; it opened in December 2019 and is still recruiting, with primary completion estimated December 2026. All three primary endpoints are about ocular safety and whether the graft survives *in the eye* — none is about insulin independence, HbA1c, or time in range. So even a completely successful result here would be evidence that islets can live in the eye under local drug cover, in a couple of people, with a graft too small and a site too novel to be a treatment. It would not be evidence of a cure, and it would not be evidence of a drug-free transplant. The supporting preclinical work is honest about the ceiling: in mice, releasing rapamycin locally in the anterior chamber *delayed* islet rejection rather than preventing it.

The full picture

What is being tested

Donor islets are infused into the anterior chamber of the eye — the fluid-filled space between the cornea and the iris — instead of the liver, where clinical islet transplants normally go.1 The islets settle on the iris, where they take up a blood supply and can be looked at directly through a slit lamp, month after month, in a living person. That is the main attraction: it is the only transplant site in the body where you can see the graft.1

The second attraction, and the reason this record needed correcting, is immunological. The eye is an immune-privileged site, and the hope is that a graft there can be held with local drug cover rather than the systemic anti-rejection drugs that make conventional islet transplant a bad trade for most people.12

This is not an immunosuppression-free approach

Say it plainly, because the framing in the field drifts:

  • Every participant receives systemic induction immunosuppression — a short course of drugs in the days around the transplant.2
  • Maintenance immunosuppression is not absent; it is topical. It is given as eye-drops — steroids plus a calcineurin inhibitor (ciclosporin or tacrolimus).1 Local is not none. It is a different route, and it carries its own risk of local toxicity and of failing to control an attack that is happening systemically.
  • Participants who already have a kidney transplant stay on chronic systemic immunosuppression for that kidney, on their transplant team's instructions, for as long as the kidney lasts.2 For those participants the eye graft is protected by drugs they were already taking. It is not a demonstration that a drug-free islet graft is possible.
  • Nothing here touches the autoimmunity. The topical drugs are anti-rejection cover for a foreign graft. The immune memory that destroyed the person's own beta cells in the first place is untreated.

The genuine, narrower claim the trial is testing: that for a recipient without another organ transplant, maintenance immunosuppression could be delivered locally to the eye instead of systemically — reducing, not eliminating, lifetime drug exposure.2 That would be worth having. It is not the same claim as "no immunosuppression", and the only human on record with transplanted insulin-producing cells surviving on zero immunosuppressive drugs remains the single Sana UP421 participant.

How far along it is

Very early. It is a Phase 1/2 safety study with a target enrolment of two people, open since December 2019 at the Diabetes Research Institute and the Bascom Palmer Eye Institute in Miami, still recruiting as of July 2026.1 Eligibility requires an eye that is already effectively blind — hand-motion vision down to no light perception — which is the ethical premise of the whole design: you do not put an experimental graft in an eye that still sees.1

The three primary endpoints are ocular safety (no corneal decompensation, raised pressure, uveitis, endophthalmitis), absence of sympathetic ophthalmia in the other eye, and confirmation that the graft is alive — C-peptide above 1 ng/ml in the aqueous humour of the treated eye.1 Note what is missing from that list: HbA1c, time in range, insulin dose, insulin independence. This trial is not designed to make anyone's diabetes better, and its results cannot show that it did.

The realistic ceiling

The preclinical literature supports the site, and is candid about the drug question. Islets survive and function in the anterior chamber in mice and non-human primates, and the site allows imaging nobody can do elsewhere.3 But when researchers tried delivering the immunosuppressant locally in the eye — rapamycin released from microparticles alongside the islets — the grafts survived longer than controls and were still rejected.3 Delay, not prevention, in mice.

So the honest read of this trial: it is a monitoring and site-feasibility study, valuable mainly because it lets us watch a human islet graft live and learn how it is attacked. Treat any framing of it as a step toward a drug-free cure with suspicion.

References

  1. ClinicalTrials.gov. Pancreatic Islet Transplantation Into the Anterior Chamber of the Eye (NCT02846571). Retrieved 15 July 2026. https://clinicaltrials.gov/study/NCT02846571 ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  2. Diabetes Research Institute Foundation. Intraocular Islet Transplant. https://diabetesresearch.org/intraocular-islet-transplant/ ↩ ↩2 ↩3 ↩4

  3. Fan Y, Zheng X, Ali Y, Berggren P-O, Loo SCJ. Local release of rapamycin by microparticles delays islet rejection within the anterior chamber of the eye. Scientific Reports (2019);9:3918. https://doi.org/10.1038/s41598-019-40404-0 ↩ ↩2