FM Value Audit

Do foundation models actually add value?

A leakage-aware benchmark testing whether single-cell foundation model representations improve a real target-prioritisation decision over cheaper baselines.

v0.5.0a1 · Pre-release View repository

The question

Foundation models produce impressive high-dimensional embeddings of single-cell data. Whether those embeddings help is a separate question, and it is often left unanswered:

  • are the embeddings contextual, or only static token vectors?
  • were test outcomes used indirectly during feature selection or tuning?
  • does the model beat a cheap historical or expression-based baseline?

FM Value Audit tests whether representations from models such as Geneformer and scGPT add measurable value beyond simpler, easier-to-explain alternatives in immuno-oncology target prioritisation.

The design

The project is built to be able to say no.

flowchart TB
    A[Prespecified decision metric] --> B[Historical baseline]
    A --> C[Expression baseline]
    A --> D[Foundation-model representation]
    B --> E[Temporal holdout<br/>unseen future outcomes]
    C --> E
    D --> E
    E --> F{Does FM improve AUPRC?}
    F -->|No| G[Report negative result]
    F -->|Yes| H[Report improvement with CI]

A sophisticated embedding is not treated as useful merely because it looks biologically structured. It has to improve a prespecified decision metric on outcomes that were not available when the features were built.

Current status — read this carefully

v0.5.0a1 is a pre-release containing two clearly separated evidence layers.

1. Final v0.4 result. Static Geneformer token geometry did not improve the prespecified AUPRC contrast over the historical baseline.

Metric Value
Primary conclusion NOT_SUPPORTED
Point delta (AUPRC) −0.00033
95% CI −0.0095 to +0.0014
Temporal holdout rows 79,542
Holdout positives 14

2. Prospective v0.5 protocol. Contextual cell-state embeddings are preregistered, but the GPU runs and future-outcome evaluation are not complete.

This release must therefore not be described as evidence that contextual foundation-model representations improve target prioritisation. It is evidence about static token geometry only.

Why a negative result is the point

Most published comparisons appear when a method wins. That selection pressure makes the literature look more favourable to new methods than the underlying evidence supports.

A benchmark designed in advance, with a declared metric and a leakage-controlled holdout, produces a usable answer either way. Here the answer was no — and reporting it plainly is more useful to anyone deciding whether to invest GPU time than a reframed positive.

The 14 holdout positives are also worth stating openly: with that few events, the confidence interval is wide, and the honest reading is “no detectable improvement,” not “proven equivalence.”

Data

Cohort Cells retained
GSE115978 7,186
GSE120575 16,291
GSE179994 150,849

Verified release

Item Current state
Automated tests 70
Integration audit PASS_WITH_WARNINGS
Engineering evidence Executable GitHub Actions jobs with uploaded JUnit, coverage and audit artefacts
Licence Apache-2.0

Release claims are machine-checked against result JSON rather than hand-written into the README, so the documented numbers cannot silently drift from the executed ones.

Honest limitations

  • The completed result concerns static token geometry, not contextual embeddings.
  • 14 holdout positives is a small number of events; the interval is correspondingly wide.
  • A negative result in this specific decision task does not generalise to all uses of foundation models in biology.
  • Research software only: it evaluates methods for preclinical target prioritisation and does not recommend a medicine, diagnose a patient, or make a clinical decision.