The useful comparison between islet therapies is not a single insulin-free percentage. The studies differ in cell source, immune protection, treatment exposure, patient selection and outcome timing. A percentage stripped of those fields can make different questions look like a controlled comparison.
The table below separates selected approaches rather than ranking them for treatment.
Compare the architecture before comparing the number
| Approach | Cell source | Immune strategy in the cited evidence | Main evidence boundary |
|---|---|---|---|
| Lantidra | Donor-derived islets | Immunosuppression required | Approved for a restricted U.S. adult population; some study participants received repeated infusions |
| Zimislecel | Stem-cell-derived differentiated islets | Immunosuppression in the published study | Early clinical results in a defined cohort; investigational development |
| UP421 | Modified donor-derived islets | Early study without immunosuppression | Low-dose proof of concept not intended to establish insulin independence |
| SC451 | A separate stem-cell-derived candidate | Intended hypoimmune strategy | Development plans are not UP421 patient outcomes |
| VX-264 | Cells combined with a device approach | Device-based protection strategy | Program discontinued after missed efficacy endpoint |
The rows are supported by FDA labeling, a clinical paper and developer statements with different evidentiary roles. They should not be read as if all products were studied together. 1 2 3 4 5
Why donor-derived and stem-cell-derived are different
A donor-cell product and a manufactured differentiated-cell product can seek a similar clinical function without being the same intervention. A result from one does not validate the identity, consistency or performance of the other.
That is not a claim that one source is inherently superior. It explains why the source belongs in the evidence record. The Lantidra report and zimislecel report give each product its own regulatory or clinical basis.
Why avoiding immunosuppression is not the same as avoiding insulin
A study can show that transplanted cells remain functional without immune-suppressing drugs while not testing whether their insulin output is enough to replace external insulin. Sana explicitly describes that limitation for the low-dose UP421 proof of concept. 3
The two outcomes are independently valuable. One addresses protection of the cells; the other addresses the amount and quality of metabolic function they provide. Combining them into “no drugs needed” adds a conclusion neither outcome alone supplies.
The UP421/SC451 report keeps the current result and intended future product separate.
Why the follow-up clock changes the comparison
An outcome reached at any point during observation differs from an outcome required at a fixed visit. A result after one infusion differs from a pathway permitting additional infusions. A full-dose analysis group differs from everyone initially included in development.
These are methodological differences, not reasons to ignore outcomes. They determine what a result means. The correct response is to state each denominator and time point, not calculate a “winner” from percentages that answer different questions.
For this edition, the named product reports hold the actual denominators. The comparison page deliberately avoids a pooled success-rate column.
Benefits and burdens belong together
NIDDK's transplant explanation describes why immune-suppressing medication can be required and why the associated risks matter. 6
A benefit comparison should therefore not stop at whether insulin injections continued. It should also retain the accompanying treatment burden and relevant harms. Insulin independence with other continuing medication is not the same proposition as a medication-free cure.
This is particularly important when comparing a selected high-risk transplant population against a broader group of people with type 1 diabetes. Different starting risks can lead to different benefit-risk questions.
What can a reader conclude now?
The evidence supports a field with several distinct strategies and uneven maturity: an approved donor-cell option for a restricted population, investigational differentiated-cell therapy, early immune-evasion evidence and a documented discontinued program. 7 8 3 5
It does not establish that any one approach is appropriate for every person, or that the newest candidate has already inherited all the strongest outcomes from the others.
Use this comparison to understand program identity and endpoint differences. It is not a substitute for individualized transplant assessment or a reason to change prescribed care. The research hub connects the dated reports and the outcome guide explains the measures in detail.