ideasIdea
Watch the immune system's response in the blood three weeks in
When immunotherapy works, specific immune cell families multiply in the blood within weeks. Tracking that could tell patients early whether to continue.
Peripheral T-cell receptor repertoire dynamics — clonal expansion, clonal replacement and the appearance of tumour-matched clones — have been associated with response in melanoma, lung and bladder cancer, but the analyses are retrospective, use different metrics and different platforms, and have never been locked as a prospective decision rule. Sequencing cost is now low enough for serial monitoring.
Hypothesis
A locked repertoire dynamics metric measured at baseline and three weeks identifies non-responders with negative predictive value above 85%, allowing early switch decisions before radiographic progression.
Rationale
Repertoire change is mechanistically upstream of tumour shrinkage, and blood is easy to sample serially. The same logic works clinically in leukaemia through clonality tracking, and the assays are already commercially available.
What would test it
Prospective locked-metric validation in an existing checkpoint inhibitor trial with serial blood samples, pre-registering the metric, threshold and analysis plan before unblinding.
Maturity
early clinical
Who has to act
data
Cost to try
Medium ($1M to $50M)
Years to first evidence
4
Bottlenecks it attacks
- No one can predict who responds to immunotherapy · Checkpoint drugs cure some patients and do nothing for most. We still cannot tell the two apart before treating.
- Biomarkers are not validated or standardised · Tests that decide who gets a drug are often not validated prospectively and are measured differently in every lab.