ideasIdea
Re-test the metastasis, not the old primary, before every change of treatment
Treatment is often chosen from a biopsy taken years earlier from the original tumour. The spread disease may now look different. Test it again before switching drugs.
Receptor and biomarker discordance between primary and metastasis is well documented (oestrogen receptor, HER2, PD-L1, and actionable alterations). Yet most line changes rely on archival tissue. The proposal is a payer-backed policy that a contemporaneous biopsy or validated liquid biopsy is offered before each line change in metastatic disease, with a registry to quantify how often the result changes therapy.
Hypothesis
Contemporaneous re-testing changes the selected therapy in at least 15 percent of line changes and is cost-neutral or cost-saving through avoided ineffective treatment.
Rationale
Discordance rates of 10 to 30 percent for key biomarkers are consistently reported; the rate of unnecessary or missed targeted therapy is a direct cost to payers.
What would test it
Coverage-with-evidence pilot in one health system: fund re-testing for 1,000 line changes, record decision changes and downstream costs over 18 months.
Maturity
early clinical
Who has to act
payer
Cost to try
Medium ($1M to $50M)
Years to first evidence
2
Bottlenecks it attacks
- Tumour heterogeneity and clonal evolution · A tumour is many tumours. Treatments that kill most cells leave the rest to grow back, changed.
- Acquired resistance to every therapy · Nearly every targeted therapy stops working within months to a few years as the tumour adapts.