# Metastasis prevention as a formal indication with its own trials and regulatory pathway

Source: https://onco.cc/ideas/idea-moon-metastasis-prevention-indication/  
OnCo record `idea-moon-metastasis-prevention-indication` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Metastasis causes most cancer deaths, yet no drug is developed to stop cells spreading. Create a formal approval route for drugs that prevent metastasis, tested in people at high risk of it.

## Summary

Drug development targets established tumours; anti-metastatic mechanisms (blocking dissemination, colonisation or pre-metastatic niche formation) fail in trials designed to shrink measurable disease. The proposal is a recognised metastasis-prevention indication: trials in high-risk localised disease or MRD-positive patients with distant-recurrence-free survival as the endpoint, acceptance of mechanistically anti-metastatic agents without expectation of response in bulk disease, and biomarkers of dissemination (circulating tumour cells, ctDNA) as enrichment tools, developed with regulators.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Under the new pathway, at least two agents with anti-metastatic but not cytoreductive activity demonstrate reduced distant recurrence in randomised adjuvant trials within a decade.
- Rationale: Adjuvant trials already accept recurrence endpoints; what is missing is a route for drugs whose only activity is anti-metastatic, and the biology of metastasis is now detailed enough to target.
- Proposed test: Regulatory guidance issued; first randomised MRD-enriched adjuvant trials of anti-metastatic agents in colorectal and breast cancer with distant recurrence as primary endpoint.
- Maturity: speculative
- Actor: regulator

## 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: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/)
- terms: [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/), [Neoadjuvant / adjuvant / perioperative](https://onco.cc/terms/neoadjuvant-adjuvant/)
- bottlenecks: [Metastasis is understood least and studied last](https://onco.cc/bottlenecks/b-metastasis-biology/), [Trial design, endpoints and cost](https://onco.cc/bottlenecks/b-trial-design/)
- key papers: [Are 90% of deaths from cancer caused by metastases?](https://onco.cc/key-papers/paper-dillekas-cancer-med/)

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