ESMO Congress 2023 | OncologyPRO

Abstract 110P

Background

The human epidermal growth factor receptor 2 (HER2/neu), a member of epidermal growth factor receptor protein family, play a role as predictive and prognostic biomarkers in various tumor types, particularly biliary tract cancers (BTCs), a heterogeneous group of poor-prognosis solid tumors with limited treatment options. Accurate evaluating of HER2 overexpression is essential for selection and determination of eligible patients for HER2-directed therapy. Herein, we report the results of an immunohistochemistry (IHC) concordance study comparing the AmoyDx® HER-2(29D8) assay and the well-established Ventana PATHWAY anti-HER-2/neu (4B5) assay using a BTC cohort of 432 samples.

Methods

Performance of the AmoyDx® HER-2 (29D8) assay was compared against the Ventana PATHWAY anti-HER-2/neu (4B5) assay using 432 pre-selected BTC samples. Further ISH testing was successfully performed in 134 of the samples to identify HER2-positive and HER2-negative samples according to standard criteria.

Results

There was a high concordance between results from the AmoyDx 29D8 and PATHWAY 4B5 assays for HER2-negative (IHC 0, 1 +) and HER2-positive (IHC 2 + , 3 +) BTCs (98.38%, 425/432). When combined with the ISH results, the aggrement was even increased to 99.29% (422/425) (Table). In addition, the low concordance (34.63%, 9/26) between the two assays for IHC 1+ samples, indicating that the detecton criteria for HER2 IHC 0 and 1+ still need further clarification, which reminds researchers to carefully select appropriate assays if they focus on BTC with HER2-low expression types. Table: 110P

Comparison of HER2 scorings derived from the indicated assays

	Ventana PATHWAY anti-HER-2/neu (4B5)
		+	-	Total
AmoyDx® HER-2 (29D8)	+	19	2	21
-	1	403	404
Total	20	405	425
Positive percent agreement	95.00% (95%CI: 75.13%, 99.87%)
Negative percent agreement	99.51% (95%CI: 98.23%, 99.94%)
Overall percent agreement	99.29% (95%CI: 97.95%, 99.85%)

Conclusions

Our data demonstrate that AmoyDx 29D8 exhibited high concordance with PATHWAY 4B5, and could provide critical information for the selection of HER2-targeted therapy for BTC patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

W. Su, H. Lu, Z. Liu, Z. Tang, Z. Huang: Financial Interests, Personal, Full or part-time Employment: Amoy Diagnostics. L. Ruan, C. Zhu: Financial Interests, Personal, Advisory Board: Amoy Diagnostics. All other authors have declared no conflicts of interest.