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Target-Gated Cargo QSP

Mechanistic QSP model for an intravenously dosed biologic designed to remain closed systemically and open after engaging a tumor-enriched gate. It connects three-compartment disposition, reversible cargo accessibility, tumor retention, and central-versus-tumor receptor occupancy using transparent UBI-authored equations and synthetic exploratory assumptions.

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Gating

First-order opening rate when construct is not bound to tumor gate target.

1/h

Suggested: 0.002–0.006. You can explore beyond this range.

0.004 → —
Gate target

Total accessible binding capacity of the generic tumor-enriched gate target.

nmol

Suggested: 0.075–0.225. You can explore beyond this range.

0.15 → —

Dissociation rate of gate-bound open construct.

1/h

Suggested: 0.015–0.045. You can explore beyond this range.

0.03 → —
Cargo receptor

Association rate shared by free-open and gate-retained open construct.

1/(nM*h)

Suggested: 0.2–0.6. You can explore beyond this range.

0.4 → —
Distribution

Symmetric concentration-driven exchange clearance between central plasma and accessible tumor space.

L/h

Suggested: 1.00e-5–3.00e-5. You can explore beyond this range.

0.00002 → —
Simulation time
hour
hour
336 → 168

Time between reported samples.

hour
6 → 1

2 changes · Variation 1

Biology

Explores how systemic closure, tumor-gate abundance and affinity, gate-assisted opening, tumor retention, cargo-receptor affinity, and dose combine to create a local-versus-systemic receptor-occupancy window.

An 11-state, three-compartment model follows closed and open construct in central plasma, peripheral tissue, and tumor. Central open construct can bind a finite cargo-receptor capacity. In tumor, free closed or open construct can bind a finite gate capacity; gate-bound construct switches between closed and open states, and open free or gate-retained construct can engage tumor cargo receptor. The main outputs are central and tumor construct concentrations, receptor occupancy, and tumor gate occupancy.

Assumptions & evidence

Assumptions & limitations

  • No paper-specific numerical comparator is distributed or executed.
  • No external or UBI experimental dataset has calibrated the nominal parameters.
  • Directional similarity to a restricted paper is mechanism-consistency evidence, not reproduction.
  • The 30 nmol amount is a neutral exploratory perturbation, not a clinical dose.
  • All values are synthetic and uncalibrated.
  • Directional similarity to another model is not paper reproduction.
  • The zero-gate control is a mechanism-isolation experiment, not a target-negative patient prediction.
  • This is an assumed engineering perturbation, not an experimentally achieved molecule.
  • This is an assumed mechanism stress test, not a measured construct.
  • A receptor-association change may also alter pharmacology not represented by occupancy alone.

Parameter origins

  • UBI synthetic exploratory assumption; target identity is intentionally unspecified
  • UBI synthetic exploratory assumption; intended for replacement by construct PK data
  • UBI synthetic exploratory assumption; intended for replacement by biodistribution data
  • UBI synthetic exploratory assumption
  • UBI synthetic exploratory assumption; collapses any microscopic gate-coupling steps into one effective rate
  • UBI synthetic exploratory assumption; not copied from an IL-12 receptor table
  • UBI synthetic exploratory assumption; not estimated from Kahn et al. 2026

Validation & references

Internal invariants, mass-balance checks, directional controls, and governed scenario and parameter-scan qualification passed. No external calibration dataset has yet been attached.

No reference paper is attached to this model.

Model details

21 parameters · 11 states · 11 equations · 19 derived outputs

Classification & API access
Therapeutic
generic target-gated cargo
Modality
Other biologic or therapeutic modality
Target
configurable tumor gate target, configurable cargo receptor
Disease / scope
Solid tumors with an accessible tumor-enriched gate target
ParameterDefaultUnitDescription
Accessible tumor gate target capacitygate_capacity_tumor_nmol0.15nmolTotal accessible binding capacity of the generic tumor-enriched gate target.
Central peripheral exchange clearanceintercompartmental_clearance_peripheral_L_h0.012L/hSymmetric concentration-driven exchange clearance between central and peripheral spaces.
Central tumor exchange clearanceintercompartmental_clearance_tumor_L_h0.00002L/hSymmetric concentration-driven exchange clearance between central plasma and accessible tumor space.
Background closing ratek_close_background_h0.251/hFirst-order closing rate when construct is not bound to tumor gate target.
Gate bound closing ratek_close_gate_bound_h0.031/hEffective closing rate while construct remains gate-bound.
Cargo receptor complex internalizationk_internalize_receptor_complex_h0.061/hEffective loss rate for receptor-engaged construct; receptor capacity is assumed homeostatically replenished.
Gate bound construct lossk_loss_gate_bound_h0.0021/hSlow effective loss of gate-bound construct; gate-target capacity is assumed replenished.
Background opening ratek_open_background_h0.0041/hFirst-order opening rate when construct is not bound to tumor gate target.
Gate assisted opening ratek_open_gate_bound_h0.31/hEffective opening rate after construct binds the tumor gate target.
Cargo receptor dissociationkoff_cargo_receptor_h0.251/hDissociation rate shared by central and tumor cargo-receptor complexes.
Closed construct gate dissociationkoff_gate_closed_h0.251/hDissociation rate of gate-bound closed construct.
Open construct gate dissociationkoff_gate_open_h0.031/hDissociation rate of gate-bound open construct.
Cargo receptor associationkon_cargo_receptor_per_nM_h0.41/(nM*h)Association rate shared by free-open and gate-retained open construct.
Closed construct gate associationkon_gate_closed_per_nM_h0.081/(nM*h)Association rate between closed construct and free tumor gate target.
Open construct gate associationkon_gate_open_per_nM_h0.121/(nM*h)Association rate between open construct and free tumor gate target.
Central cargo receptor capacityreceptor_capacity_central_nmol0.015nmolHomeostatically maintained central capacity available for cargo engagement.
Tumor cargo receptor capacityreceptor_capacity_tumor_nmol0.0015nmolHomeostatically maintained tumor capacity available for cargo engagement.
Central construct clearancesystemic_clearance_L_h0.005L/hLinear clearance applied to free closed and open central construct.
Central plasma volumevolume_central_L3.5LNominal adult central volume used for exploratory concentration conversion.
Peripheral accessible volumevolume_peripheral_L10.5LNominal accessible peripheral volume.
Tumor extracellular accessible volumevolume_tumor_L0.004LNominal accessible tumor extracellular volume.

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