# Grow blood-borne tumour cells to test drugs on the cells that actually spread

Source: https://onco.cc/ideas/idea-bio2-ctc-culture-functional-testing/  
OnCo record `idea-bio2-ctc-culture-functional-testing` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Drug tests normally use cells from the original tumour. Growing the rarer cells found in blood would test drugs against the cells that are actually travelling.

## Summary

Cultures and xenografts derived from circulating tumour cells have been established in small-cell lung, breast and prostate cancer, with success rates that rise with CTC burden. They capture the metastasis-competent population and can be sampled repeatedly without a biopsy. Scaling the protocols, publishing failure rates honestly, and linking drug sensitivity to subsequent clinical course would create the first functional assay of metastatic competence.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Ex vivo models can be established from circulating tumour cells in over 40% of patients with high CTC burden, and their drug sensitivity predicts subsequent clinical response better than sequencing of the archival primary.
- Rationale: CTC-derived explant models in small-cell lung cancer reproduce patient chemosensitivity and molecular subtype, and are the field's best worked example. Serial sampling makes resistance trackable in a way tissue biopsy cannot.
- Proposed test: Multi-centre protocol harmonisation study in small-cell lung and prostate cancer, reporting establishment rate, time to model and concordance of ex vivo sensitivity with clinical response in 100 patients.
- Maturity: preclinical-evidence
- Actor: research

## Sources

- Bottleneck evidence (Metastasis is understood least and studied last): Dillekås et al., Are 90% of deaths from cancer caused by metastases? (Cancer Medicine 2019): https://doi.org/10.1002/cam4.2474

## Connected records

- cancers: [Prostate cancer](https://onco.cc/cancers/prostate/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- technologies: [Functional (ex vivo) drug testing](https://onco.cc/technologies/functional-drug-testing/), [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/), [Patient-derived organoids](https://onco.cc/technologies/organoids/), [Patient-derived xenografts](https://onco.cc/technologies/pdx-models/)
- people: [Caroline Dive](https://onco.cc/people/caroline-dive/), [Fiona Blackhall](https://onco.cc/people/fiona-blackhall/)
- bottlenecks: [Lab models that fail to predict what happens in patients](https://onco.cc/bottlenecks/b-preclinical-models/), [Metastasis is understood least and studied last](https://onco.cc/bottlenecks/b-metastasis-biology/)
- key papers: [Are 90% of deaths from cancer caused by metastases?](https://onco.cc/key-papers/paper-dillekas-cancer-med/)

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