Aims Human epidermal growth factor receptor 2 (HER2)-targeted agents are an effective approach to treating patients with HER2-positive breast cancer. However, the lack of survival benefit in HER2-negative patients, as well as the toxic effects and high cost of the drugs, highlight the need for accurate and prompt assessment of HER2 status. Our aim was to evaluate the clinical utility of a novel reagent-saving immunohistochemistry method (AC-IHC) that saves HER2 antibody by taking advantage of the non-contact mixing effect in microdroplets subjected to an alternating current electric field.
Methods Ninety-five specimens were used from patients diagnosed with primary breast cancers identified immunohistochemically as HER2 0/1+, 2+ or 3+ using ASCO/CAP guideline-certified standard IHC. The specimens were all tested using the conventional IHC method (1:50 antibody dilution) as well as AC-IHC (1:50 dilution) and reagent-saving AC-IHC (1:100 dilution).
Results The reagent-saving AC-IHC produced stable results with less non-specific staining using smaller amounts of labelled antibody. Moreover, the staining and accuracy of HER2 status evaluated with the reagent-saving AC-IHC method was equal to that achieved with standard IHC.
Conclusions These results suggest reagent-saving AC-IHC could be used as a clinical tool for accurate and stable HER2 IHC, even when reagent concentrations vary.
- breast cancer
- molecular pathology
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Handling editor Runjan Chetty.
Contributors IH conducted the experiments. YS, SF, HS, KT, AW, YS and SM helped to collect the data. KI analysed data and wrote the paper. HN made pathological diagnoses and supported this research. RN and YA contributed to the development of the device enabling application of a high-voltage, low-frequency AC electric field. YM designed and supervised the research. All authors read and approved the final manuscript.
Funding This work was supported in part by a Grant-in-Aid from the Japan Agency for Medical Research and Development.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The institutional review board of Akita University Hospital, Japan (Permit numbers: 1282 and 1408).
Provenance and peer review Not commissioned; externally peer reviewed.