# A regulatory endpoint for drugs that block spread, not tumours

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

## TL;DR

Today a cancer drug is approved for shrinking tumours. A drug that stopped cancer spreading would fail that test, so almost nobody develops one. A new endpoint would fix that.

## Summary

Anti-metastatic agents act on dissemination, seeding and outgrowth, not on the size of existing lesions, so they look inactive by RECIST and are killed in phase 2. A qualified endpoint family (new-lesion-free survival, number of new anatomical sites over time, and site-specific metastasis-free survival) would let sponsors run trials that can succeed. Regulators already accept metastasis-free survival in non-metastatic prostate cancer, which is the precedent to generalise.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: If FDA and EMA qualify a new-lesion-based endpoint family for the adjuvant and oligometastatic settings, at least five mechanistically anti-metastatic programmes that are currently shelved enter registrational trials within five years.
- Rationale: Endpoint availability drives portfolio choices more than biology does: metastasis-free survival in the non-metastatic castration-resistant prostate trials created an entire treatment setting almost overnight. The same instrument applied to any cancer would make anti-seeding mechanisms commercially legible.
- Proposed test: A regulatory workshop plus a retrospective analysis pooling adjuvant trial datasets to show that new-lesion-free survival is estimable, reproducible across readers, and correlated with overall survival; then a formal endpoint qualification submission.
- Maturity: speculative
- Actor: regulator

## Sources

- FDA Oncology Center of Excellence (page moved; nearest live section): https://www.fda.gov/about-fda/

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- terms: [Oligometastatic disease](https://onco.cc/terms/oligometastatic/), [Overall survival (OS)](https://onco.cc/terms/os/), [RECIST](https://onco.cc/terms/recist/)
- 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/)

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