ALI 3D Tumor Fragment Models for ADC Penetration & Efficacy
ProNAMs provides antibody-drug conjugate (ADC) evaluation services using air-liquid interface (ALI) 3D tumor fragment models that retain stroma and endogenous immune cells from the source tissue. The platform supports quantification of ADC penetration depth, free payload release, cytotoxic potency, and bystander activity in a human tissue context.
The Challenge: ADC Preclinical Evaluation Bottlenecks
ADCs pair a target-directed monoclonal antibody with a cytotoxic payload via a chemical linker. The intended mechanism (such as antigen binding, internalization, linker processing, and intracellular payload release) depends on the molecule reaching its target within intact tissue. Several development questions are difficult to address in models that lack that tissue context:
- Penetration into Solid Tumors: ADCs are large molecules moving through dense stroma and extracellular matrix. Penetration is influenced by molecular properties including drug-antibody ratio (DAR) and payload hydrophobicity, and by tissue properties including matrix density and interstitial pressure. Models without representative matrix do not report on this.
- Bystander Activity: Where a cleavable linker releases a membrane-permeable payload, that payload can act on neighboring cells. This produces two distinct effects that require separate measurement: killing of antigen-negative tumor cells, which is often the intended benefit, and cytotoxicity toward stromal and immune cells in the same region, which is not.
- TME Interactions: Effects on endogenous fibroblasts and immune populations sit outside the reach of tumor-cell-only models.
- Immune Consequences of Payloads: Certain payload classes are reported to have immunomodulatory effects beyond direct cytotoxicity. Assessing these requires a system in which immune cells are present.
Limitations of Standard 3D Models
| Limitation | Consequence for ADC work |
|---|---|
| Epithelial-only composition | No stroma or CD45⁺ immune cell populations; TME-mediated effects cannot be observed |
| Reconstituted matrix | Matrix composition and density differ from the source tissue, which affects diffusion and penetration measurements |
| Phenotypic drift over extended culture | Target antigen expression can shift away from the source tissue over successive passages, affecting binding and internalization data |
The ALI 3D Tumor Fragment Platform
We provide the system using a biphasic culture configuration. Minced tumor tissue is combined with a collagen matrix and applied to a permeable membrane support. Culture medium in the lower compartment reaches the tissue by diffusion through the membrane, while the upper surface remains exposed to the gas phase. This reduces the oxygen and nutrient gradients that develop toward the interior of fully submerged 3D cultures, and allows tissue fragments to be maintained with their original cellular composition rather than reconstituted from purified components.
Penetration Measurement in Intact Tissue
Because the spatial arrangement of tumor cells, stroma and matrix is retained from the source tissue, ADC distribution can be mapped across the fragment rather than inferred from a homogeneous cell suspension.
Separate Measurement of Bystander Killing and Off-Target Toxicity
Endogenous immune populations and stroma are present alongside tumor cells, so payload effects on antigen-negative tumor cells and payload effects on non-tumor cells in the same tissue can be assessed as distinct endpoints.
Immune Context Retained
CD8⁺ T cells, regulatory T cells, macrophages and other CD45⁺ populations from the source tissue are present at assay start, supporting assessment of ADC effects on the local immune compartment and of ADC–checkpoint inhibitor combinations.
Short Culture Window Limits Drift
The platform is used within a defined assay window measured in days rather than through extended passaging. This limits the phenotypic drift in target antigen expression that accumulates in long-term culture. Antigen expression is characterized at assay start rather than assumed to match the source tissue.
Standard 3D Models vs. ALI 3D Tumor Fragment Models
| Feature | Standard 3D Models | ALI 3D Tumor Fragment Models | Relevance to ADC Evaluation |
|---|---|---|---|
| Cellular composition | Predominantly epithelial | Tumor cells with retained stroma and endogenous immune populations | Supports assessment of TME-mediated effects and off-target toxicity |
| Matrix context | Reconstituted matrix, uniform density | Native matrix carried over with the tissue fragment | Penetration is measured against tissue-derived rather than reconstituted resistance |
| Antigen expression | May shift over extended passaging | Assessed at assay start within a short culture window | Binding and internalization data are anchored to a characterized expression profile |
| Immune context | Absent, or reconstituted by co-culture | CD45⁺ populations retained from source tissue | Allows evaluation of ADC effects on the local immune compartment |
| Throughput | Higher: plate-based screening feasible | Lower: technically demanding | Suited to focused mechanistic and comparative studies rather than large screening campaigns |
| Material requirement | Established models or cryopreserved stocks | Fresh resected tissue within a defined collection window | Study scheduling depends on tissue availability |
ADC-Specific Assay Menu
Our ADC endpoints are organized by stage of the mechanism, from target antigen characterization through to effects on the immune compartment. Target expression is characterized at assay start by IHC and immunofluorescence to establish the baseline against which efficacy data is interpreted, followed by assessment of ADC binding and internalization using fluorescently labelled material. Tissue penetration is addressed through three orthogonal approaches including confocal imaging of labelled ADC, mass spectrometry imaging of unlabeled payload, and IHC on sectioned fragments. Free payload release is quantified by LC-MS/MS in both tissue and culture medium across the time course, with method performance established in matched matrix during feasibility.
On the efficacy side, cytotoxicity is assessed both as overall tumor cell killing and as a spatial pattern relative to penetration depth, which addresses whether killing tracks with where the ADC actually reached. Bystander activity is deliberately reported as two separate endpoints rather than one: killing of antigen-negative tumor cells adjacent to target-positive regions, and cytotoxicity toward stromal and CD45⁺ populations in the same tissue. A payload can show desirable bystander killing and substantial immune toxicity at the same concentration, and a composite readout would obscure that. Finally, because endogenous immune populations are retained in the fragment, effects on immune composition, activation and exhaustion phenotype, and cytokine response can be measured directly, including in parallel arms combining the ADC with checkpoint-targeting antibodies.
Service Workflow
| Stage | Activity | Client Input | Indicative Duration |
|---|---|---|---|
| 1. Scoping | Consultation to define the ADC construct, tumor indication, endpoints, and analytical approach | Molecule information, target antigen, indication, research question | 3–5 business days |
| 2. Design & Quotation | Written protocol covering concentration series, controls, assay window, penetration method selection, and analytical plan | Protocol review and sign-off | 5–10 business days |
| 3. Tissue Sourcing & Scheduling | Coordination with tissue supply for the specified indication; scheduling against collection availability | Test article shipment; documentation | Variable by indication; commonly 4–12 weeks |
| 4. Feasibility | Establishment of fragments from a first tissue sample; confirmation of achievable assay window, target antigen expression, and LC-MS/MS method performance in matched matrix | - | 3–4 weeks |
| 5. Study Execution | Fragment establishment, dosing, time-course sampling, imaging and analytical acquisition | - | 3–5 weeks, depending on assay window and number of arms |
| 6. Analysis & Reporting | Image analysis, LC-MS/MS data processing, statistical evaluation, draft report, client review, final report | Comments on draft report | 15–20 business days |
Runs are evaluated against pre-defined criteria before results are reported. These typically cover fragment viability in the vehicle control at readout, target antigen expression within the range established at feasibility, response of the positive control, LC-MS/MS system suitability, and inter-fragment variation within a defined range.
Browse Deliverables & Timelines
NOTE: All timelines, replicate numbers and deliverables described on this page are indicative.
Frequently Asked Questions
Dosing and readout are commonly conducted over 7–14 days from establishment, with longer observation achievable for some tumor origins. The published method this format derives from reports maintenance of endogenous stromal and immune cells over considerably longer periods under supplemented conditions, but the same reports note gradual loss of some immune subsets over time. For ADC studies, the assay window is set so that the populations relevant to the endpoint are present throughout, rather than to the maximum achievable duration. The achievable window for a given tissue type is confirmed during feasibility.
It depends on what needs to be distinguished. Fluorescently labelled ADC with confocal imaging gives direct spatial visualization of the antibody component but reports on the label rather than the payload, and labelling can alter molecular properties. MSI reports payload distribution without labelling, which matters for cleavable-linker molecules where antibody and payload distributions diverge. IHC correlates antibody localization with antigen expression and stromal architecture on the same section. Studies frequently combine two approaches; the selection is made at Stage 2 based on the molecule and the question.
Yes. Free payload is quantified by LC-MS/MS in tissue and in culture medium across the time course. This requires a reference standard for the payload and, for best quantification performance, a stable-isotope-labelled internal standard. Method performance including limits of detection and quantification is established during feasibility in matched matrix and reported with the results.
They are treated as two endpoints with different readouts. Bystander killing of antigen-negative tumor cells is assessed by dual staining for target antigen and an apoptosis marker with spatial correlation analysis. Off-target toxicity is assessed by co-staining lineage markers for stromal and CD45⁺ populations with the same apoptosis marker, and by flow phenotyping of dissociated fragments where the design calls for it. Reporting these separately is deliberate: a payload can show desirable bystander killing and substantial immune toxicity at the same concentration, and a composite readout would obscure that.
No. The format is low-throughput and constrained by fresh tissue availability. It is applied where tissue context is material to the question - penetration behavior, bystander profile, or effects on non-tumor compartments - typically for a small number of candidates or construct variants. For ranking larger numbers of candidates, plate-based 3D models are the appropriate tool, and we can discuss a staged approach across both formats.
The number of conditions a single resection can support depends on tumor size, viable tumor content, and the endpoints selected - sectioning-based endpoints consume fragments that imaging endpoints can share. This is assessed at Stage 2 and confirmed at feasibility. Where a design exceeds what a single sample supports, the study is run across multiple donors, and donor identity is tracked in the analysis.
Yes, provided both molecules are supplied or can be sourced. Comparative studies are run on matched fragments from the same source tissue so that tissue variability does not confound the comparison. Where multiple donors are used, the design is structured so that each donor contributes to both arms.
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