Quantitative Assays for TROP2 Measurement in Breast Cancer and Comparison to H-Score
Applied Immunohistochemistry & Molecular Morphology. 2026;34(3):143-154. DOI 10.1097/pai.0000000000001311. PMID 41709478. PMCID PMC13143368.
How to cite
AMA
He M, Chan NNN, Liu M, Robbins CJ, Bates K, Benanto J, et al. Quantitative Assays for TROP2 Measurement in Breast Cancer and Comparison to H-Score. Appl Immunohistochem Mol Morphol. 2026;34(3):143-154. doi:10.1097/pai.0000000000001311APA
He, M., Chan, N. N. N., Liu, M., Robbins, C. J., Bates, K., Benanto, J., et al. (2026). Quantitative Assays for TROP2 Measurement in Breast Cancer and Comparison to H-Score. Applied Immunohistochemistry & Molecular Morphology, 34(3), 143-154. https://doi.org/10.1097/pai.0000000000001311BibTeX
@article{he2026quantitative,
title = {Quantitative Assays for TROP2 Measurement in Breast Cancer and Comparison to H-Score},
author = {He, M. and Chan, N. N. N. and Liu, M. and Robbins, C. J. and Bates, K. and Benanto, J. and others},
journal = {Applied Immunohistochemistry & Molecular Morphology},
volume = {34},
number = {3},
pages = {143--154},
year = {2026},
doi = {10.1097/pai.0000000000001311},
pmid = {41709478}
}TROP2 is a protein found on most breast tumors, and a new class of antibody-drug conjugate therapies is aimed squarely at it. Yet only about a third of patients respond, even though roughly nine in ten breast cancers carry TROP2 — so a reliable way to measure how much is present could help decide who will benefit.
This study built two assays that report TROP2 as an actual concentration rather than a subjective score. One reads a fluorescent signal and the other a brown-stain signal, and both are calibrated against known amounts of protein using mass spectrometry.
Tested across hundreds of breast cancer samples and checked against the readings of five pathologists, the assays matched expert scoring while resolving finer differences, particularly in tumors carrying high levels of TROP2.
Key findings
- Two mass-spectrometry-calibrated TROP2 assays reached defined analytical limits. The quantitative immunofluorescence (QIF) and quantitative hematoxylin-DAB (QH-DAB) assays convert imaging signal to absolute TROP2 concentration (amol/mm2) using cell-line standards, giving limits of detection of 90 and 667 amol/mm2 and limits of quantification of 272 and 2021 amol/mm2, with standard-curve R2 of 0.99.
- A broad TROP2 dynamic range emerged across two Yale breast-cancer cohorts. Applied to a 264-case serial breast cancer cohort and a 100-case triple-negative breast cancer cohort from Yale New Haven Hospital, the assays resolved a wide range of TROP2 expression, with the QIF assay reading up to roughly 10,000 amol/mm2 before saturation.
- Quantitative measurement agreed with pathologist H-scores while adding sensitivity. Across 68 breast cancer biopsies read by 5 certified pathologists, the QIF and QH-DAB values tracked the manual H-scores, but the quantitative assays showed higher sensitivity and less subjectivity, with H-scores saturating in TROP2-high cases.
CyteFinder II HT in the methods
“Fluorescent slides were scanned using the Rarecyte Cytefinder II HT (Rarecyte, Seattle, WA), an automated widefield fluorescence slide scanner at 20× magnification with fixed exposure times for each channel.”
— He et al., Applied Immunohistochemistry & Molecular Morphology (2026), Methods, “Image Acquisition, Quantification, and H-Score Evaluation”
Why it matters for CyteFinder II HT users
If you are weighing the CyteFinder II HT for a quantitative tissue assay, look at what the imaging step was asked to carry here. The claim the authors needed to support is numerical: not whether TROP2 is present, but how much, in absolute units per unit area. That kind of measurement only holds if the imaging is reproducible enough to sit under a calibration curve, which is why the assay depended on scanning every slide at a fixed magnification with fixed exposure times for each channel. Here the CyteFinder II HT scanned the fluorescence slides at 20×, and the resulting images fed an open QuPath-based analysis tool rather than a closed one. Two points carry over to your own workflow. Consistent per-channel exposures are what let a raw signal be converted to a protein concentration across hundreds of samples. And because the scanner writes standard image files, the downstream quantification stays a choice you make, not one the instrument makes for you.
