Which Breast Cancer Model Should You Use?
From Organoid Screening to PDX Validation

For HER2 or TROP2 ADCs, targeted therapies and immuno-oncology programs, the key question is not simply whether a compound works in a breast cancer cell line. A stronger strategy begins by matching the preclinical model and biomarker profile to the therapeutic mechanism.

Breast Cancer Is Not One Disease

Breast tumors differ in ER, PR and HER2 status as well as mutations, RNA expression, copy-number alterations and expression of therapeutic targets.

A response observed in one cell line therefore may not represent the biological diversity encountered across patient populations.

Biomarker-driven model selection can help connect preclinical efficacy with the molecular characteristics most likely to influence therapeutic response.

1. Organoids — Scalable Screening Across Tumor Diversity

Patient-derived organoids provide three-dimensional tumor models that can retain clinically relevant characteristics of the original tumor.

Panels of organoid models can support scalable screening across molecular subtypes and enable comparison of responder and non-responder populations.

For ADC and targeted therapy programs, this creates an opportunity to investigate relationships between target expression and drug response.

2. PDX — Translating Selected Responses In Vivo

Patient-derived xenograft models preserve patient tumor material through propagation in immunodeficient mice and can support in vivo efficacy studies.

Following organoid or in vitro screening, selected PDX models can be used to evaluate tumor growth inhibition, dose response and treatment schedules.

When PDX selection is informed by molecular and biomarker data, the study can extend beyond efficacy into a more translational investigation of response and resistance.

3. Syngeneic Models — When the Immune System Matters

Conventional human PDX models require immunodeficient hosts and therefore have limitations when intact tumor-immune interactions are central to the study.

For checkpoint inhibitors and immune-mediated combinations, immunocompetent syngeneic models may provide a more appropriate experimental system.

The most sophisticated model is not automatically the best model. The best model is the one that answers the biological question.

ADC Development Makes Biomarker Selection Critical

Because ADCs depend on recognition of tumor-associated surface antigens, target expression can be a major consideration in model selection.

Start With the Biomarker, Not Just the Model

For a TROP2-directed ADC, for example, selecting models across a range of TROP2 expression may be more informative than selecting breast cancer models without considering target biology.

Connecting response with target expression can help investigate why one tumor responds while another does not.

Mutation, RNA expression, copy number, fusion, HLA and IHC datasets can further support biomarker-driven model selection and translational hypothesis generation.

A Translational Preclinical Workflow

STEP 1 — Biomarker-Defined Organoid Screening
Screen candidates across molecularly diverse tumor models.

STEP 2 — Responder / Non-Responder Analysis
Connect therapeutic response with target expression and molecular profiles.

STEP 3 — PDX In Vivo Validation
Evaluate efficacy and dose response in selected models.

STEP 4 — Translational Biomarker Analysis
Investigate biomarkers associated with sensitivity or resistance.

STEP 5 — Combination Strategy
Extend promising programs into targeted or immuno-oncology combinations where appropriate.

Breast Cancer Model Selection Checklist

✓ What is the ER / PR / HER2 subtype?

✓ For an ADC, has target antigen expression been characterized?

✓ Is scalable high-throughput screening required?

✓ Is a patient-derived model important?

✓ Is in vivo efficacy evaluation required?

✓ Is an intact immune system essential to the study?

✓ Will responders and non-responders be compared?

✓ Are genomic, RNA or IHC biomarker datasets required?

Planning a Breast Cancer or ADC Preclinical Study?

Dana Bioscience can help identify CRO solutions for organoid screening, PDX/CDX efficacy studies, biomarker analysis and ADC preclinical development.

Share your drug modality, target, biomarker strategy, development stage and study endpoints, and we can help evaluate appropriate model and study options.