Liquid biopsy kinetics and detection of ERBB2 amplification/HER2-positivity in refractory hepatocellular carcinoma
The Journal of Liquid Biopsy. 2023;2:100009. DOI 10.1016/j.jlb.2023.100009. PMID 40028484. PMCID PMC11863877.
How to cite
AMA
Geddam AS, Lutfi A, Afghan MK, Currie BM, Rosenblatt R, Ramirez AB, et al. Liquid biopsy kinetics and detection of ERBB2 amplification/HER2-positivity in refractory hepatocellular carcinoma. J Liq Biopsy. 2023;2:100009. doi:10.1016/j.jlb.2023.100009APA
Geddam, A. S., Lutfi, A., Afghan, M. K., Currie, B. M., Rosenblatt, R., Ramirez, A. B., et al. (2023). Liquid biopsy kinetics and detection of ERBB2 amplification/HER2-positivity in refractory hepatocellular carcinoma. The Journal of Liquid Biopsy, 2, 100009. https://doi.org/10.1016/j.jlb.2023.100009BibTeX
@article{geddam2023liquid,
title = {Liquid biopsy kinetics and detection of ERBB2 amplification/HER2-positivity in refractory hepatocellular carcinoma},
author = {Geddam, Aaditya Srivant and Lutfi, Areeb and Afghan, Maaz Khan and Currie, Brian M. and Rosenblatt, Russell and Ramirez, Arturo B. and others},
journal = {The Journal of Liquid Biopsy},
volume = {2},
pages = {100009},
year = {2023},
doi = {10.1016/j.jlb.2023.100009},
pmid = {40028484}
}Hepatocellular carcinoma is usually treated without a specific molecular target, and when imaging looks classic the diagnosis can be made without a biopsy at all, so an actionable mutation may never be looked for.
This report follows one patient with metastatic disease whose routine circulating-tumor-DNA test unexpectedly showed a very high ERBB2, or HER2, amplification. The team confirmed it with HER2 immunohistochemistry and tissue sequencing, then treated with dual HER2 blockade.
To watch the response in real time they read two blood signals in parallel: the tumor DNA in plasma and the HER2-positive circulating tumor cells themselves. Over the first ten days of therapy the circulating-tumor-cell count fell steadily, and about a third of those cells were HER2-negative, a direct cell-level look at the tumor's heterogeneity.
Key findings
- A routine ctDNA liquid biopsy revealed a very high ERBB2 amplification. Plasma copy number reached 77.5 against a high-call threshold of 6 to 8, and tissue sequencing on the biopsy confirmed a focal ERBB2 amplification of 183 copies with 3+ membranous HER2 staining.
- HER2-positive circulating tumor cells fell as the targeted therapy took hold. Counts dropped from 8 per 7.5 mL at baseline to 4 by day 3 and 1 by day 10 of trastuzumab and pertuzumab, while the plasma alpha-fetoprotein later declined from over 200,000 ng/mL to under 1,000.
- The circulating tumor cell assay exposed HER2 heterogeneity that DNA alone would miss. About one-third of the circulating tumor cells were HER2-negative, and the HER2-positive fraction declined across the day 0, day 3 and day 10 timepoints.
CyteFinder in the methods
“For CTCs here, blood samples were processed with the AccuCyte® blood separation technology (RareCyte®, Seattle, WA). Briefly, 7.5 ml of whole blood is processed using a tube and float system to separate the buffy coat from the red blood cells and plasma. The buffy coat is retrieved and spread as a cell monolayer onto 8 microscope slides. The slides are then stained via immunofluorescence on automated stainers for markers that differentiate CTCs from surrounding white blood cells. Slides are automatically scanned on a CyteFinder® instrument (RareCyte) and image files are analyzed by automated software to identify candidate CTCs for confirmation by a trained reviewer.”
— Geddam et al., The Journal of Liquid Biopsy (2023), Methods, “With respect to methodology for liquid biopsy testing and turnaround times”
Disclosure: RareCyte is listed as an author affiliation on the publication cited above.
Disclosure: RareCyte is named in the competing-interests statement of the publication cited above.
Why it matters for CyteFinder users
If you are weighing CyteFinder for rare-cell work, look at the step it carried in this case. The cellular readout depended on finding HER2-positive tumor cells among the blood cells around them, counting them reliably enough to trust a change of one or two cells per 7.5 mL, and reading the HER2 protein on each cell. After the blood was separated and the nucleated cells were spread and immunostained across eight slides, CyteFinder scanned those slides and its software flagged candidate tumor cells for a trained reviewer to confirm. That scan is what turned a monolayer of cells into a HER2-positive circulating-tumor-cell count the team could follow day by day. Two things follow for your own workflow. Because every candidate cell stays in view on the slide, you can quantify a marker like HER2 cell by cell rather than in bulk, which is how this study saw that about a third of the cells were HER2-negative. And because the scan hands candidates to a reviewer rather than replacing one, a rare-cell call you will act on clinically still ends with a human eye.
