What is a patient-derived xenograft (PDX) model?
A PDX model is made by implanting tumor tissue from a patient into immunodeficient mice and passaging it. A widely cited review by Hidalgo and colleagues (Cancer Discovery, 2014) describes PDX models as a platform for translational cancer research and sets out their strengths and limits. Because each model comes from a different patient, a set of PDX models can represent some of the variety between patients that a single cell line cannot.
To describe models consistently, the PDX-MI standard (Meehan et al., 2017) groups the information into modules: the patient and tumor, how the model was created, model quality assurance, and the model study itself. It is a useful checklist when choosing models from a supplier's collection.
How many models, and how many mice per model?
This is the central design choice, and it trades depth for breadth. Gao and colleagues (Nature Medicine, 2015) screened 62 treatments across about 1,000 PDX models using a 1 x 1 x 1 design, one mouse per model per treatment, to read out responses at the population level. Weiss and colleagues (Cancer Informatics, 2022) showed that such designs can detect large effects, but in the scenarios they modelled about 5 mice per group were needed for a medium effect and about 21 for a small effect to reach 80% power.
The right answer depends on whether you want to know if a drug works in a particular model or how often it works across a population, so settle it with a statistician. The planner records your numbers and shows the arithmetic; it does not recommend a design.
What should PDX model selection be based on?
Write down the criteria before looking at a catalogue: indication, biomarker or mutation status, prior treatment of the donor patient, growth rate, passage number and the characterization data available (histology, genomic profile). Ask how long each model needs to expand to the number of mice you need, because expansion often sets the study start date.
Endpoints, tissue and analysis
Agree how response is classified per model, so results compare across models, and how tumor volume, body weight and time to endpoint are recorded. Decide in advance what tissue is collected at the end, when, and how it is preserved (for example formalin-fixed paraffin-embedded or snap frozen), because the choice limits which biomarker and pathology analyses are possible later. The OBSERVE guidelines (2024) cover clinical signs and humane endpoints for PDX and other rodent cancer models.
Frequently asked questions
How many mice per arm in a PDX study?
It depends on the effect size you need to detect and whether you analyze models one by one or as a population. Published analyses range from one mouse per model per treatment for population screens (Gao et al., 2015) to about 5 or more per group for model-level comparisons (Weiss et al., 2022). Decide with a statistician; the planner does not recommend a number.
What is a mouse clinical trial (1 x 1 x 1 design)?
A design that tests a treatment in many PDX models with one mouse per model per treatment, then reads out response rates across the population, much as a clinical trial does across patients. Gao et al. (2015) used it across about 1,000 models.
CDX vs PDX: what is the difference?
A CDX model grows an established cancer cell line; a PDX model grows tumor tissue taken from a patient. PDX models keep more of the patient tumor's characteristics but take longer to expand and vary more between models.
Can PDX models be used for immunotherapy studies?
Standard PDX hosts are immunodeficient, so they lack the immune system most immunotherapies act on. Humanized mice, engrafted with human immune cells, are one approach; syngeneic mouse models are another. Record the host strain as an explicit decision in the plan.
What information should a PDX supplier provide for each model?
Clinical and tumor information, how the model was created, quality assurance data such as histology and identity checks, and any prior study data. The PDX-MI standard groups these into modules and is a good checklist.
Is anything I type stored or shared?
No. The planner runs entirely in your browser. Nothing you enter is saved, sent to BioBridgeX, put in the page address or passed to analytics or AI services. Closing or refreshing the page clears it, so copy or print the plan before you leave.
Is the generated plan a protocol?
No. It organizes the requirements you entered into a structured outline and lists what is still undecided. It is not a validated protocol, it does not recommend sample sizes, and it does not establish GLP, GMP or regulatory compliance. Have the plan reviewed by qualified scientific, statistical, ethical and regulatory experts.
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Sources
- Hidalgo M et al. Patient-derived xenograft models: an emerging platform for translational cancer research. Cancer Discovery 2014;4(9):998-1013
- Gao H et al. High-throughput screening using patient-derived tumor xenografts to predict clinical trial drug response. Nature Medicine 2015;21(11):1318-1325
- Weiss J et al. Optimizing drug response study design in patient-derived tumor xenografts. Cancer Informatics 2022;21:11769351221136056
- Meehan TF et al. PDX-MI: minimal information for patient-derived tumor xenograft models. Cancer Research 2017;77(21):e62-e66
- De Vleeschauwer SI et al. OBSERVE: guidelines for the refinement of rodent cancer models. Nature Protocols 2024;19(9):2571-2596
- Percie du Sert N et al. The ARRIVE guidelines 2.0. PLoS Biology 2020;18(7):e3000410
This planner organizes requirements. It is not a validated protocol, does not recommend sample sizes, and does not establish GLP, GMP or regulatory compliance. Review every plan with qualified scientific, statistical, ethical and regulatory experts. Facts on this page last checked 27 October 2026.
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