supported

Is the hypoxic-core / wound-rim niche real in PFA tumors?

ModeledSpeculative

Question

PFA tumors are theorized to have a stereotyped hypoxic core surrounded by a wound-healing rim. If true, that coupled niche could be a drug target. Does the pattern show up in bulk transcriptomics?

What we found

Yes — strongly. Hypoxia and wound-healing pathway scores correlate at r = 0.88 within PFA samples vs r = 0.72 in non-PFA EPN. The Δ of +0.16 passes our gate. The biology is consistent with the published story.

Caveat

Bulk correlation cannot prove SPATIAL coupling — only that the two signals are co-elevated in the same tumors. The decisive test is Visium spatial transcriptomics. Also: Cabozantinib (the named drug in the original hypothesis) ranks 68/92 for PFA — the niche may be real but Cabozantinib may not be the right drug.

Next step

Ingest Donson 2022 Visium. Parser is already written + unit-tested. Spatial autocorrelation (bivariate Moran's I) at the spot level confirms or refutes the coupling. If confirmed, design a PFA PDX experiment with a CNS-penetrant multi-RTK alternative.

Scroll for the data, methods, and per-sample detail.

PFA1 hypoxia-wound niche → Cabozantinib

Do PFA samples (n=124) show coupled hypoxia × EMT signal that non-PFA EPN doesn't? Niche-based test — independent of the falsification framework verdict.

✗Developmental framework: refuted · (not gating)

For a clinician with a PFA patient

PFA tumors show a real hypoxic-core / wound-healing-rim coupling at bulk-RNA resolution — hypoxia and wound-healing signals move together with correlation 0.88 within PFA samples, versus 0.72 in non-PFA ependymoma. This is the same niche the field has been trying to target since bevacizumab, which blocks only VEGF, failed in trials.

The therapeutic hypothesis is that a multi-target receptor kinase inhibitor that simultaneously blocks VEGF, MET, and AXL could collapse this coupled niche where a single-target antibody could not. Cabozantinib is the leading candidate-class drug, though it ranks poorly in KIRhub's drug-ranking engine — the niche biology appears real, but Cabozantinib itself may not be the right drug for it.

The caveat: bulk-RNA correlation does not prove the two signals are spatially coupled within the same regions of tissue — only Visium spatial transcriptomics can confirm or refute that. No drug currently targeting this niche is approved in pediatric ependymoma, and no trial is presently open.

Research Use Only — not validated for clinical decisions.

✓ Bulk niche coupling supported

ModeledSpeculative

PFA samples show hypoxia × EMT bulk-correlation above gate AND meaningfully higher than non-PFA EPN. Justifies Donson 2022 Visium ingestion to confirm at spatial resolution.

PFA correlation

0.883

n=124

Non-PFA EPN correlation

0.720

n=246

Delta (PFA − non-PFA)

0.163

gate: ≥ 0.15

Cabozantinib median rank (PFA)

68/92

top-half = ≤ 46

Hypoxia × EMT bulk coupling

MeasuredDerivedReference

Why bevacizumab failed in PFA — one-axis blockade vs a braided secretome

Bevacizumab is a monoclonal antibody against VEGF-A. In PFA, that's a single thread of a coupled niche: the hypoxic core simultaneously secretes HGF (→ MET), GAS6 (→ AXL), PDGF (→ PDGFRβ on stromal/pericyte cells), and FGFs (→ FGFR2). Knock out VEGF and the wound-rim signalling continues through the other RTK axes — the tumor adapts within weeks. That's the published clinical-failure pattern, and it's the geometric reason a CNS-penetrant multi-RTK like Cabozantinib is a more biology-faithful candidate: it covers VEGFR2, MET, and AXL at once.

Plain-English version: Bevacizumab pulled one rope; the niche has five ropes tying it together. Cabozantinib pulls three of them at the same time — still not all five, but enough that the bypass routes the tumor uses for bevacizumab escape (HGF/MET and GAS6/AXL specifically) get blocked too.

RTK target coverage across KIRhub's multi-RTK panel

MeasuredDerived

Each row is a drug; each column is one of the five RTK axes the PFA niche signals through. Filled portion = inhibition (%) at 1 µM (i.e. 100 − residual activity). The visual story: Cabozantinib, Crizotinib, and Tepotinib collapse the MET + AXL axes the niche relies on for bevacizumab-escape; Pazopanib and Lenvatinib pick up FGFR2/PDGFRβ that the others miss — there is no single drug in our panel that covers all five axes.

Filled bar = % inhibition at 1.0 µM (lower residual activity = more filled). "*" indicates we fell back to the best-inhibited variant measurement because no wild-type kinase measurement was available for that drug × target pair.

How this test runs (caveats)

PRD §EPN-2 prefers a bespoke wound signature (POSTN/COL1A1/HGF/TGFB1/PDGFB) from raw RNA + Visium spatial autocorrelation. Bulk pathway correlation is a weaker proxy — strong here only refutes the spatial coupling cheaply if it fails, justifies Donson 2022 Visium ingestion if it holds.

A high bulk correlation is necessary but not sufficient for the spatial coupling the hypothesis predicts: bulk averaging can show correlation if both signals are co-elevated in the same samples even when they're spatially separate within the tissue. Visium is the decisive test.

# Platform
Saifudeen, A., et al. (2026). KIRhub: a falsification-first research workbench for translational oncology. Nature Biotechnology. https://doi.org/10.1038/s41587-026-03090-8

# Data source
McFerrin, L. G., et al. (2018). Oncoscape: a tool for interactive cancer genomics data analysis. Nature Genetics.
Arora, S., et al. (2026). A pan-pediatric brain tumor reference map: medulloblastoma and ependymoma in shared UMAP space. Neuro-Oncology.

# Datasets used in this insight
Oncoscape pediatric brain tumor compendium (n=1,358)

# Provenance
insight_id: pfa1-niche

Is the hypoxic-core / wound-rim niche real in PFA tumors?i

✓ Bulk niche coupling supportedi