What cell lines are typically used in your ADC screening panels?

We use a combination of client-provided cell lines and our own validated bank, including target-positive and target-negative pairs, isogenic models, and normal primary cells. The exact panel is defined during project scoping based on your target, payload, and desired toxicity coverage.

Can you evaluate bystander killing with my ADC?

Yes. Bystander effect can be assessed using co-culture experiments (target-positive and target-negative cells mixed at defined ratios) or conditioned-medium transfer assays. The design is scoped per project to match the intended tumor microenvironment and payload diffusibility.

How do you distinguish on-target from off-target toxicity?

By running matched target-positive and target-negative cell lines under identical conditions, we separate antigen-specific killing from non-specific cytotoxicity. Off-target toxicity on normal cells is further evaluated using a panel of tissue-relevant cell types, and the contribution of free payload, linker stability, and Fc-mediated effects can be deconvoluted.

What endpoints are included in a standard evaluation?

Our standard package includes cell viability (dose-response IC50), internalization kinetics, and apoptosis detection (caspase 3/7, Annexin V). Additional endpoints such as oxidative stress, inflammation markers, or cell-cycle analysis can be added as scoped.

Can you test ADCs with different payloads and linkers?

Yes. Our platform is payload-agnostic and can accommodate various linker-payload combinations, including MMAE, DM1, calicheamicin, PBD dimers, and others. The assay conditions are adjusted to account for payload stability and release kinetics.

How long does a typical study take?

Project duration depends on the scope of cell panel, number of ADC candidates, and endpoints selected. Timelines are confirmed during the scoping phase and communicated in the study plan. Please contact us to discuss your specific schedule requirements.

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ADC In Vitro Toxicity Screening & Mechanism Evaluation

In Vitro Toxicology

Identify antibody-drug conjugate off-target liabilities and cytotoxic mechanisms early with our integrated in vitro screening platform.

Target-positive vs. target-negative cancer cell pair screening
Internalization kinetics and payload release profiling
Apoptosis detection (caspase activation, Annexin V)
Off-target toxicity assessment across normal cell panels
Bystander killing and resistance mechanism evaluation

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Why Validate ADC Safety Early?

Off-target toxicity is a leading cause of ADC clinical-stage attrition and dose-limiting adverse events. Proactive in vitro profiling lets you compare candidates head-to-head for cytotoxicity, selectivity, and mechanism before advancing to expensive in vivo studies.

Identify on-target, off-tumor toxicity risks
Differentiate payload-linked versus antibody-driven effects
Characterize bystander killing and resistance pathways
Generate data to support candidate ranking and IND-enabling packages

Mechanistic

Actionable

Effective

Our Approach

Systematic In Vitro ADC Toxicology Assessment

We combine comprehensive cell panel screening with mechanistic endpoint analysis to provide a clear picture of ADC safety and efficacy.

Target-Specific Cytotoxicity & Internalization

ADC candidates are dosed on paired target-positive and target-negative cancer cell lines to establish selective killing curves and confirm receptor-mediated internalization and payload release.

Dose-response viability assays (CellTiter-Glo, MTT, WST-1)
Live-cell internalization monitoring (IncuCyte imaging or flow cytometry)
Time-course analysis for payload release kinetics

Off-Target & Bystander Profiling

Using expanded cell panels and co-culture models we identify off-target effects on normal cell types and quantify bystander killing of antigen-negative cells in mixed tumor environments.

Normal cell panel (hepatocytes, endothelial cells, bone marrow progenitors)
Co-culture or conditioned medium transfer bystander assay
Apoptosis and necrosis discrimination (caspase 3/7, Annexin V/PI)

Comprehensive Cell Panels

Cell lines are selected to match your target indications and include isogenic pairs, patient-derived lines, and normal tissue types to cover on-target and off-target toxicity scenarios.

Multiparametric Readouts

We integrate multiple endpoints—viability, apoptosis, internalization, and inflammation markers—from the same experiment to provide a rich mechanistic picture.

Translational Insights

Data are reported with IC50 values, AUC comparisons, and toxicity matrices to directly support candidate ranking and guide in vivo study design.

Deliverables

What You Receive

A complete dataset and interpretation package designed for rapid decision-making.

Data Deliverables

Dose-response curves and IC50 values for each cell line
Internalization kinetics report (percentage internalized over time)
Apoptosis activation profiles (caspase 3/7, Annexin V)
Off-target toxicity matrix across normal cell panel
Bystander killing quantification (where scoped)

Reporting & Support

Comprehensive final study report with methods and interpretation
Raw data files (Excel or CSV) for internal meta-analysis
Statistical analysis including curve fitting and significance testing
Project scientist review call to discuss results and next steps

Service Scope

Tailored to Your Program Needs

Every project is scoped collaboratively; the table below illustrates typical parameters we can incorporate.

Parameter	Typical Project Scope
Cell line selection	Target-positive and target-negative cell pairs are selected from our validated bank or provided by the client; isogenic lines and patient-derived models are also available as scoped.
ADC concentrations and time points	Multi-point dose-response (e.g., 8-point, 3–4 replicates) over 24–96 hours as scoped per project
Viability assay method	CellTiter-Glo, MTT, or WST-1 luminescent/colorimetric readout
Internalization assay	IncuCyte live-cell imaging or flow cytometry-based internalization; time points scoped per antibody internalization kinetics
Apoptosis detection	Caspase 3/7 activation assay and Annexin V/propidium iodide staining by flow cytometry
Off-target normal cell panel	The normal cell panel includes hepatocytes, endothelial cells, renal epithelial cells, and bone marrow progenitors where suitable for the candidate's predicted toxicity profile.
Bystander effect evaluation	Co-culture of target-positive and target-negative cells or conditioned medium transfer; readout is cytotoxicity in antigen-negative cells
Mechanism of resistance studies	Assess target expression modulation, efflux pump involvement, and point mutation impact; design scoped per candidate
Data analysis	IC50 calculation, AUC, pairwise comparisons, and dose-response curve fitting (GraphPad Prism or equivalent)
Report format	Electronic study report with methods, results, and interpretation; raw data provided on request

How It Works

Workflow from Consultation to Report

A streamlined process that integrates your ADC candidates and study goals to deliver actionable safety data.

Project Scoping

We review your ADC constructs, target biology, and desired endpoints to define cell line panels, assay formats, and timelines. A detailed study plan is confirmed before work begins.

Cell Line Preparation

Target-positive and target-negative cell lines are cultured and validated for antigen expression. Normal cell panels are expanded as needed from validated sources.

ADC Treatment & Internalization Monitoring

Cells are treated with ADC at multiple concentrations. Internalization is tracked via IncuCyte live-cell imaging or flow cytometry at selected time points to confirm uptake kinetics.

Viability, Apoptosis & Off-Target Profiling

At assay endpoints, viability (CellTiter-Glo), apoptosis (caspase activation, Annexin V), and off-target effects on normal cell panels are measured in parallel.

Data Analysis & Reporting

Raw data are analyzed to generate dose-response curves, IC50 values, and toxicity matrices. A comprehensive study report with interpretation and raw data files is delivered.

Applications

Supporting Key ADC Development Decisions

Our in vitro platform addresses critical questions across the ADC pipeline.

Confirm Target Specificity and Internalization

Determine whether candidate ADCs selectively kill target-positive cells and undergo receptor-mediated internalization. Essential for lead selection and target validation.

Compare ADC activity on paired isogenic cell lines
Quantify internalization rates and payload release
Rule out non-specific cytotoxicity from free payload

Assess Killing of Antigen-Negative Tumor Cells

Bystander effect can broaden efficacy in heterogeneous tumors but also increase normal tissue toxicity. Our co-culture assays measure the true bystander potential of your ADC.

Co-culture of target-positive and target-negative cells
Conditioned medium transfer to evaluate diffusible payload
Determine contributor (payload stability, linker design)

Early Identification of Resistance Pathways

Understanding how cancer cells may evade ADC killing guides combination strategies and next-generation payload design. We can test antigen downregulation, efflux, and apoptosis defects.

Target expression modulation after chronic exposure
ABC transporter activity and inhibition studies
Apoptosis pathway dependency (Bcl-2, caspase profiles)

Frequently Asked Questions

Common Questions About ADC In Vitro Toxicity Screening

Answers to key concerns regarding project scope, methodology, and data interpretation.

We use a combination of client-provided cell lines and our own validated bank, including target-positive and target-negative pairs, isogenic models, and normal primary cells. The exact panel is defined during project scoping based on your target, payload, and desired toxicity coverage.
Yes. Bystander effect can be assessed using co-culture experiments (target-positive and target-negative cells mixed at defined ratios) or conditioned-medium transfer assays. The design is scoped per project to match the intended tumor microenvironment and payload diffusibility.
By running matched target-positive and target-negative cell lines under identical conditions, we separate antigen-specific killing from non-specific cytotoxicity. Off-target toxicity on normal cells is further evaluated using a panel of tissue-relevant cell types, and the contribution of free payload, linker stability, and Fc-mediated effects can be deconvoluted.
Our standard package includes cell viability (dose-response IC50), internalization kinetics, and apoptosis detection (caspase 3/7, Annexin V). Additional endpoints such as oxidative stress, inflammation markers, or cell-cycle analysis can be added as scoped.
Yes. Our platform is payload-agnostic and can accommodate various linker-payload combinations, including MMAE, DM1, calicheamicin, PBD dimers, and others. The assay conditions are adjusted to account for payload stability and release kinetics.
Project duration depends on the scope of cell panel, number of ADC candidates, and endpoints selected. Timelines are confirmed during the scoping phase and communicated in the study plan. Please contact us to discuss your specific schedule requirements.

Scientific Literature

References

Song D, Han J, Dong C, et al. Identification and Preclinical Evaluation of a Novel GD2 Antibody-Drug Conjugate for Solid Tumors in Children and Adults. Molecular cancer therapeutics. 2026;25(7):1037-1048. View on PubMed
Wang LM, Yang C, Chen S, et al. Development of SDP0505: a first-in-class HER3 × c-Met bispecific ADC, demonstrates potent antitumor activity in EGFR TKI-resistant NSCLC, CRC, and beyond. Antibody therapeutics. 2026;9(2):201-213. View on PubMed
Hoffmann RM, Mele S, Cheung A, et al. Rapid conjugation of antibodies to toxins to select candidates for the development of anticancer Antibody-Drug Conjugates (ADCs). Scientific reports. 2020;10(1):8869. View on PubMed

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