# Video research-update insert: The Rare, Fixed Cancer Stem Cell Hierarchy

Editorial script and storyboard insert, 5 October 2026. No rendered video. Read alongside the original review; no new grade is announced.

## Narration

Functional hierarchies and relapse-sustaining cell states occur in particular tumours. Permissive transplantation and lineage-resolved state switching challenge a universal rare, fixed and irreplaceable compartment.

In the 1997 study, a prospectively isolated compartment serially generated heterogeneous leukemia. Transplantation sufficiency depends on host and assay; endogenous universal necessity is separate. [P9212098]

In the 2017 study, differentiated cells reverted and contributed to regrowth after LGR5-positive depletion. Organoid/xenograft plasticity is distinct from patient relapse under therapeutic targeting. [P28355176]

In the 2026 study, zFP36L2 regulated stress-adaptive dedifferentiation and lineage plasticity. Loss of canonical stem-state entry can permit alternative malignant states. [P42557330]

The next discriminating question is: How rare is tumour-sustaining capacity in the native tumour? Host permissiveness and sorting may create apparent rarity. Pair transplantation with endogenous lineage tracing; vary recipient immune status, matrix and cell viability while fixing sampling and follow-up.

The timeline shows selected changes in evidence, not inevitable progress or proof of a single cause. The review’s archived grade remains unchanged; the depth of source reading is documented in the update.

## Storyboard and source locks

| Insert | Visual | Narration anchor | Sources |
|---|---|---|---|
| Opening | Claim and bounded update statement | First paragraph | Review claim and source ledger |
| Timeline 1997 | Dated study card with design, result and limit | A prospectively isolated compartment serially generated heterogeneous leukemia. | [P9212098](https://pubmed.ncbi.nlm.nih.gov/9212098/) |
| Timeline 2017 | Dated study card with design, result and limit | Differentiated cells reverted and contributed to regrowth after LGR5-positive depletion. | [P28355176](https://pubmed.ncbi.nlm.nih.gov/28355176/) |
| Timeline 2026 | Dated study card with design, result and limit | ZFP36L2 regulated stress-adaptive dedifferentiation and lineage plasticity. | [P42557330](https://pubmed.ncbi.nlm.nih.gov/42557330/) |
| G1 | Question → competing explanation → discriminating test | How rare is tumour-sustaining capacity in the native tumour? | [P9212098](https://pubmed.ncbi.nlm.nih.gov/9212098/), [P12629218](https://pubmed.ncbi.nlm.nih.gov/12629218/), [P19052619](https://pubmed.ncbi.nlm.nih.gov/19052619/), [P22855427](https://pubmed.ncbi.nlm.nih.gov/22855427/) |
| G2 | Question → competing explanation → discriminating test | Can other states replace the depleted compartment? | [P28358093](https://pubmed.ncbi.nlm.nih.gov/28358093/), [P28355176](https://pubmed.ncbi.nlm.nih.gov/28355176/), [P32169167](https://pubmed.ncbi.nlm.nih.gov/32169167/), [P42557330](https://pubmed.ncbi.nlm.nih.gov/42557330/) |
| G3 | Question → competing explanation → discriminating test | Which cell state maintains post-treatment residual disease? | [P22854781](https://pubmed.ncbi.nlm.nih.gov/22854781/), [P36352230](https://pubmed.ncbi.nlm.nih.gov/36352230/), [P41565826](https://pubmed.ncbi.nlm.nih.gov/41565826/) |
| G4 | Question → competing explanation → discriminating test | Does targeting a state improve human outcomes without bypass? | [P28355176](https://pubmed.ncbi.nlm.nih.gov/28355176/), [P36352230](https://pubmed.ncbi.nlm.nih.gov/36352230/), [P41565826](https://pubmed.ncbi.nlm.nih.gov/41565826/) |

## Editorial constraints

- Use the primary-source links shown above and keep the inference limit on screen with each milestone.
- Do not narrate an abstract check as complete-paper examination, a model result as human proof, or an unresolved inference as absence of all research.
- Preserve trial endpoint hierarchy, cohort reuse, correction notices and online/issue dates.
- Use original graphics made from this ledger. Publisher figure imagery has not been cleared or supplied for video reuse.
- Confirm any change in verdict through a separate documented HSEF review; this insert makes none.