TROP2 PET to choose and sequence TROP2 ADCs

The proposal is to use a whole-body TROP2 PET scan, rather than a single tissue stain, to decide which patients receive a TROP2 ADC, which agent they get and when to switch. Baseline uptake and heterogeneity would predict benefit, and a fall in uptake at progression would signal antigen loss that should prompt a move to a non-TROP2 ADC rather than a second TROP2 agent. IHC on archival tissue failed to predict sacituzumab govitecan benefit, whereas PSMA PET already plays this role for Pluvicto and 89Zr-antibody and 68Ga-nanobody tracers image human tumours. The test is an imaging sub-study inside a first-line TNBC ADC trial, then a randomised PET-guided versus standard sequencing trial. At early-clinical maturity, it bears on the bottleneck Biomarkers are not validated or standardised.