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H02 — Engineered LBP Thesis (Stub)

Evidence status: stub. Assumptions, pre-committed thresholds, kill switches, and failure-mode coverage remain incomplete; see engineered-lbp-chassis.md.

The pre-registration note on H01 (H01-ward-dual-cassette.md §Pre-registration) does not apply until this stub is upgraded to a full card. When the upgrade happens, the upgraded version is what gets pre-registered; the stub is informational scaffolding only.

Claim (provisional, stub-level)

An engineered Faecalibacterium prausnitzii strain producing colonic butyrate is a testable peer-track chassis. Its supported primary mechanism is PPARγ-mediated induction of wild-type ABCG2; genotype-agnostic coverage is not established:

  • Wild-type ABCG2: butyrate → PPARγ → upregulated ABCG2 transcription → increased gut-lumen urate efflux
  • Q141K variant ABCG2 (~10% of gout patients): butyrate's class-I HDAC inhibitor activity is proposed to rescue the broken Q141K trafficking phenotype (restoring functional surface expression) — unvalidated: Basseville 2012 demonstrated pharmacological/HDACi Q141K rescue with vorinostat, not butyrate; direct butyrate rescue is assumption 6, gated on validation §1.14

The "viable peer-track" claim has multiple sub-components that the full card will decompose: 1. F. prausnitzii engineering toolkit is mature enough to produce therapeutic-grade butyrate-augmenting strains (vs. WT colonization establishing the colonic baseline) 2. Lyophilized oxygen-protected capsule formulations achieve sufficient post-ingestion viability to colonize at therapeutic densities 3. FDA LBP regulatory path is traversable within the track's capital constraints 4. WT-ABCG2 induction translates to functional human urate flux at achievable colonic butyrate concentrations

Assumption Stack (placeholder — to be populated in Phase 2 P2-5)

The full assumption stack will be populated after fresh engineering, commercial, and regulatory scans plus an exact-strain genetic-entry test. Retired COMP-008 supplies no feasibility result. Anticipated load-bearing assumptions, to be confirmed:

  1. An exact Faecalibacterium strain can be transformed reproducibly and maintain reporter expression without unacceptable fitness loss.
  2. A qualified oral F. prausnitzii preparation can deliver a prespecified viable-cell exposure to the intended colonic compartment; neither the achieved exposure nor a therapeutic threshold is established here.
  3. Engineered butyrate overproduction does not destabilize F. prausnitzii viability or trigger PFOR-pathway feedback that quenches the augmentation
  4. Colonic butyrate concentration thresholds for clinically-meaningful PPARγ activation (WT) and HDAC inhibition (Q141K) are achievable from a single delivered LBP strain rather than requiring a designed consortium
  5. The applicable FDA LBP pathway, containment expectations, and evidence package are compatible with the exact engineered strain and intended use; timeline and precedent require a current regulatory assessment.
  6. Proposed butyrate-mediated Q141K trafficking rescue—not directly shown by Basseville 2012—translates to native human gut epithelium at exposures achievable from the engineered LBP

Killshot Menu (placeholder — to be populated in Phase 2 P2-5)

The full killshot menu will follow the H01 template: ranked by score = (kill_pr × info_weight) / (cost × time_penalty), with each killshot tagged to specific assumptions and failure modes per linter-design.md §4–5.

Anticipated highest-priority killshots:

  • Lit scan + commercial scan first. Cheapest possible upstream move — answers whether NextBiotix, Synlogic-adjacent, or other published programs have already killed (or already validated) major sub-claims of this hypothesis. (Phase 2 P2-1 + P2-2 do this.)
  • Exact-strain genetic-entry gate. Demonstrate stable transformation and reporter expression before evaluating a native-pathway intervention or heterologous payload.
  • In vivo butyrate concentration measurement after engineered-strain colonization (animal model). Tests assumption 4 directly.
  • Q141K trafficking rescue dose-response in primary human enterocytes. Tests assumption 6 directly.
  • GMP anaerobic manufacturing feasibility. Obtain configuration-specific process, release, storage, and dose-cost estimates, then compare them with a prespecified program budget before commercial routing.

Pre-Committed Thresholds (placeholder — to be populated in Phase 2 P2-5)

To be defined when the killshot menu is populated. Anticipated structure follows H01: declared Alive / Killed / Pending thresholds for each load-bearing claim, plus kill switches independent of the scientific thresholds (regulatory-precedent collapse, manufacturing-cost ceiling, etc.).

Failure Modes Probed (placeholder — to be populated in Phase 2 P2-5)

To be populated. Anticipated relevant failure modes from linter-design.md §5: published-literature-gap, species-gap-translation (mouse colonic butyrate vs. human), expression / localization mismatch, kinetics / concentration, dose-translation scaling, regulatory-precedent gap (a category not in H01).

Status

Stub. No killshot executed. No assumption stack pre-registered. Full hypothesis card is queued as Phase 2 P2-5 — see engineered-lbp-chassis.md § Open Follow-Ups.

Survival count: 0.

Survival score: 0.0 (undefined until full card and first survived killshot).

Cross-References