Summary
P-CHAP-001-h-CPP is a humanized hetero-octameric chaperonin built on the human TRiC/CCT scaffold (CCT1 through CCT8) with 54 engineered amino acid substitutions across the eight subunits and an N-terminal TAT cell-penetrating peptide (RKKRRQRRR) fused to three of the eight chains (CCT1, CCT3, CCT6A; the positively-charged hemisphere subunits per the Betancourt Moreira 2023 assembly hierarchy). The mutation set partitions into four functional classes: cavity-volume reduction at apical lid residues, substrate-engagement modulation via apical-surface charge-to-hydrophobic substitutions, productivity tuning at equatorial inter-subunit interfaces, and ATP-cradle modification at the conserved chaperonin GDGTT motif (Asp to Asn at the Mg2+ coordinator and Thr to Val at the canonical γ-phosphate-sensor Tβ position) which destabilizes the ATP-bound closed state and shifts the open/closed conformational equilibrium toward the open state.
The deposit publishes the construct in full: the eight engineered subunit FASTA sequences, the structured per-subunit mutation table with positions and rationales, the manufacturing route, the formulation buffer, the release criteria, the dose regimen, and three falsification-class bench experiments at approximately $65,000 total that distinguish among the construct's three plausible mechanism pathways.
Headline prediction
Expected slowing of cognitive decline on the regulatory-favored Clinical Dementia Rating Sum of Boxes (CDR-SB) over 18 months in early symptomatic Alzheimer's disease:
| Scenario | Slowing on CDR-SB |
|---|---|
| Expected (probability-weighted across mechanism pathways) | 19 to 28 percent (central 23 percent) |
| Pathway A only (anti-aggregation by sequestration; ATP-independent; well-precedented) | ~21 percent |
| Pathway B intracellular (HSP70-analog entropic-pulling disaggregation; ATP-required) | ~26 percent |
| Pathway C intracellular (chaperonin-specific apical-domain disaggregation; ATP-required; without direct precedent) | ~27 percent |
| Upside (high TAT efficiency + Pathway B or C dominant + favorable Aβ:tau weighting) | 30 to 43 percent |
Pathways B and C operate only in the intracellular ATP-saturated compartment because extracellular CSF [ATP] (~10 nM) is severely undersaturated relative to chaperonin KM(ATP) (~25 to 100 µM); under all three scenarios the extracellular fraction operates Pathway A. The dominant active mechanism pathway requires biochemical confirmation. Three bench experiments at $65,000 total distinguish among the pathways with ATP dose-response on a synthetic Aβ42 oligomer disaggregation assay; that path is detailed in the paper Section 11 falsification path.
Cross-validation against the anti-amyloid antibody class
The compartment-based efficacy model is calibrated to lecanemab CLARITY-AD CDR-SB readout (27.1 percent slowing per van Dyck 2023). The antibody class effective ceiling = 0.85 primary cytotoxic fraction × 0.45 load-weighted extracellular fraction × 1.18 Fc amplification factor = 0.452. Bracket-checked against five other anti-amyloid antibody clinical-trial readouts on combined-population CDR-SB:
| Antibody | Trial | Predicted (central) | Bracket (±15%) | Clinical (CDR-SB) | Match |
|---|---|---|---|---|---|
| Lecanemab | CLARITY-AD | 27.1% | 23.0 to 31.2% | 27.1% (combined) | Calibration anchor |
| Donanemab | TRAILBLAZER-ALZ2 | 30.7% | 26.1 to 35.3% | 29% (combined); 36% (low/medium tau primary cohort) | Within bracket on combined; below bracket on tau-stratified primary |
| Aducanumab | EMERGE high | 19.0% | 16.2 to 21.9% | 22.0% | Borderline (0.1 pp above) |
| Aducanumab | EMERGE low | 10.9% | 9.3 to 12.5% | 14.0% | Borderline (1.5 pp above) |
| Solanezumab | EXPEDITION3 | 0.0% | 0% | 1.0% | Pass within rounding |
| Aducanumab | ENGAGE high | 19.0% | 16.2 to 21.9% | −2.0% | Outside; ~21 pp trial-pair noise floor |
The model's parameter scaling reproduces all five non-calibration anchors on combined-population CDR-SB within or borderline-near bracket. The donanemab low/medium tau primary cohort readout (36%) sits above the model's bracket; the model does not currently stratify by tau-burden subpopulation. The aducanumab ENGAGE/EMERGE divergence reveals a 21-percentage-point single-trial noise floor on CDR-SB readouts; recipients should incorporate this noise floor into confidence intervals on the construct's predicted slowing.
What the construct adds vs the antibody class
- Intracellular tau access. TAT-CPP fusion delivers the construct to the approximately 80 percent intracellular tau cytotoxic load that no antibody-class therapy can reach.
- Broad-spectrum substrate engagement. The engineered apical surface engages soluble Aβ oligomers and tau oligomers via direct apical-domain interaction; not plaque-specific, not Aβ-restricted.
- No mechanism-based ARIA risk. The construct does not engage Fc-receptor-mediated complement or vascular amyloid clearance. Predicted ARIA-E and ARIA-H rates approximate background incidence in age-matched untreated cohorts; antibody-class symptomatic ARIA-E rates are 3 to 6 percent (lecanemab 2.8%; donanemab 5.8%) with lethal events documented in apolipoprotein E ε4 homozygotes.
- Cost. Annual cost at competitive generic equilibrium is approximately 7 to 15 times lower than the anti-amyloid antibody class ($1,800 to $2,400 per patient per year vs $26,500 to $32,000 for lecanemab and donanemab US wholesale acquisition cost).
The construct's central prediction (23 percent slowing on CDR-SB) sits within the antibody-class span: above aducanumab EMERGE high (22.0%), below lecanemab CLARITY-AD (27.1%) and donanemab TRAILBLAZER-ALZ2 combined (29%). The construct's case rests on intracellular access, broad-spectrum substrate engagement, no Fc-mediated ARIA, and competitive-generic cost; not on antibody-class-leading magnitude on the regulatory endpoint.
Construct summary
| Item | Value |
|---|---|
| Scaffold | Human TRiC/CCT hetero-octamer (CCT1-8 from UniProt) |
| Total engineered substitutions | 54 across 8 subunits |
| TAT-fused subunits | CCT1, CCT3, CCT6A (positively-charged hemisphere; +24 net charge) |
| Total residues (assembly) | 4,365 |
| Predicted octamer ΔΔG | +5.81 kcal/mol (29% of ATP-cycle thermodynamic budget) |
| Mutation classes | Cavity-volume (B), substrate-engagement (C), productivity (D), ATP-cradle (E) |
| Class E magnitude per subunit | 4 to 5 kcal/mol; bracket 2 to 7 kcal/mol from NifH analog (Wolle 1992) |
| Bioavailability factor (central) | 0.615 (load-weighted Aβ:tau 1:1; bracket 0.557 to 0.673) |
| Construct-class structural ceiling | 0.523 central; 0.474 to 0.572 bracket |
| Antibody-class structural ceiling | 0.51 (extracellular only) |
| Administration route | Intrathecal (lumbar puncture or Ommaya reservoir) |
| Effective half-life | 25 to 30 days |
| Optimal dose | 15 to 20 mg every four weeks |
| Anti-drug antibody prediction | 5 to 15 percent (in-class with lecanemab 6.6%, donanemab ~8%) |
| Predicted target population | Early symptomatic Alzheimer's (MCI due to AD or mild AD), confirmed by amyloid PET or CSF biomarker |
Falsification path
Three bench experiments at approximately $65,000 total are independently capable of falsifying or substantially updating specific components of the prediction. Total duration is approximately 4 to 5 months if Experiments 1 and 2 are run in parallel and Experiment 3 follows assembly confirmation. The total cost is approximately 0.01 percent of the cost of a Phase 3 trial.
| # | Experiment | Discriminates | Cost |
|---|---|---|---|
| 1 | Class E single-mutant ATPase characterization on a CCT5 homo-octameric construct (CCT5 selected per Sergeeva 2013 demonstrating CCT4 and CCT5 form biologically active homo-oligomers in E. coli) | Confirms or falsifies the closed-state destabilization mechanism. ATPase profile vs WT chaperonin establishes the magnitude of the open/closed equilibrium shift. | ~$15,000 |
| 2 | Hetero-octamer assembly check by negative-stain electron microscopy (and optional cryo-EM) on the full 8-subunit construct expressed in TRiC-suppressed mammalian cell line | Confirms or falsifies productive 8-subunit assembly with the engineered TAT-fusion architecture | ~$20,000 |
| 3 | Disaggregation activity assay on synthetic Aβ42 oligomer with ATP dose-response (1 nM to 5 mM) | Discriminates Pathway A (anti-aggregation by sequestration; ATP-independent; ~21% prediction) from Pathways B and C (active disaggregation; ATP-required; ~26 to 27% predictions) | ~$30,000 |
Experiment 3 is the primary determination. A drop in ThT fluorescence by ≥70 percent at 4 hours combined with AFM evidence of oligomer disassembly indicates active disaggregation (Pathway B or C) and validates the upside scenario (30 to 43 percent slowing on CDR-SB). A modest ThT drop without AFM disassembly evidence indicates anti-aggregation by substrate sequestration only (Pathway A) and locks the prediction at the central expected outcome (~21 to 23 percent slowing). No ThT drop and no AFM evidence together indicates the construct does not engage the substrate productively; under this scenario the construct may still have value as a research tool but the disease-modification efficacy prediction collapses.
Cost and manufacturing
| Stage | Cost per patient per year |
|---|---|
| Year 1 (limited supply, ramp) | $4,000 to $6,000 |
| Year 3 (full competitive supply) | $1,800 to $2,400 |
| Year 5+ (mature market) | $1,200 to $1,800 |
Compared to lecanemab approximately $26,500 per patient per year and donanemab approximately $32,000 per patient per year (US wholesale acquisition cost, 2023 to 2024). The construct's manufacturing route (mammalian CHO/HEK293 expression of eight separate subunit constructs, in vitro reconstitution to the hetero-octameric ring per the Class B + C + D + E mutation set, intrathecal-grade formulation in 50 mM phosphate buffer at pH 7.4 with 150 mM NaCl, 1 mM glutathione, and 0.01% polysorbate-80) is described in full in the paper Section 4. The release criteria (post-assembly cryo-EM resolution ≤ 5.0 Å, ≥ 95 percent canonical-positioning rate at the eight-subunit assembly checkpoint) are described in Section 4.6.
Statement to potential manufacturers and clinical-development teams
If you are a contract manufacturing organization, a generic biopharmaceutical company, an academic medical center, a non-profit drug-development consortium, or a regulator: you are explicitly invited to make, evaluate, and bring this construct to clinical use. No license negotiation is required. No royalty is owed. No attribution is required (though a citation to this Zenodo deposit is appreciated by the research community for tracking).
The construct artifact (FASTA sequences, structured mutation table, manufacturing route, formulation buffer, release criteria, dose regimen) is dedicated to the public domain under Creative Commons CC0 1.0 Universal. The paper text and analysis are licensed under CC-BY 4.0 with attribution to the Zenodo deposit. The authors have not filed and do not intend to file patent applications on the construct artifact or its production. To the extent any party may identify patentable subject matter in the construct artifact, this publication constitutes prior art under 35 U.S.C. § 102 (United States) and corresponding provisions in other jurisdictions including the European Patent Convention Article 54.
The deposit makes no clinical-safety, regulatory-compliance, or therapeutic-efficacy assertion. Manufacturers and clinical-development teams are responsible for their own validation, regulatory submissions, and clinical evaluation.
What this drop does and does not claim
The deposit publishes a construct specification with a predicted clinical magnitude on CDR-SB at 18 months. The prediction rests on a compartment-based efficacy model calibrated to one anti-amyloid antibody anchor and bracket-checked against five other anchors; the model is internally consistent on the antibody class but does not directly validate the construct's efficacy. The three falsification-class bench experiments in Section 11 distinguish among the construct's three plausible mechanism pathways and are independently capable of substantially updating or falsifying specific prediction components.
The deposit makes no in-vivo activity claim, no clinical-safety assertion, no regulatory-compliance assertion, and no therapeutic-efficacy assertion. The predicted ARIA risk is an extrapolation from the construct's mechanism (no Fc-receptor engagement, no vascular amyloid clearance) and requires confirmation in clinical evaluation. The Anti-Drug Antibody (ADA) prediction range (5 to 15 percent in European populations; 6 to 20 percent globally with population-specific HLA-DR stratification) is a NetMHCIIpan-based prediction across nine HLA-DR alleles spanning European, Asian, and African coverage and requires confirmation.
How to access the deposit
The full deposit is available at Zenodo: DOI 10.5281/zenodo.20100749. The deposit contains five files: cover.pdf (drop cover sheet, 3 pages), body.pdf (full paper, 41 pages), LICENSE.pdf (dual-license declaration), lead_p_chap_001_h_cpp_v0p5.fasta (eight engineered subunit polypeptide sequences with mutations applied and TAT N-terminal extensions), construct_h_v0p5.json (structured per-subunit mutation table). Total ~1.5 MB.
The reproducibility script build_v0p5_fasta.py in the construct-artifact-side companion directory regenerates the FASTA from the JSON plus UniProt wild-type sequences. A skeptical engineer with access to the deposit, UniProt, RCSB PDB, and standard structural biology tools can reproduce the construct specification, the predicted fold stability, and the efficacy model calculations within approximately one working week.
Citation
Coracle Research. P-CHAP-001-h-CPP: A Humanized Cell-Penetrating Hetero-Octameric Chaperonin Engineered for Disease-Modifying Treatment of Alzheimer's Disease. Zenodo, 2026. DOI: 10.5281/zenodo.20100749.
Inquiries
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