HER2 Amplification by Next-Generation Sequencing in Lung Carcinoma: A Comparison of NGS Amplified and Non-amplified Cases by Immunohistochemistry and In Situ Hybridization

Abstract

Background: Although the role of HER2 amplification and its evaluation methods are well known in breast carcinoma, methods for detection of HER2 amplification in non-small cell lung carcinoma are unclear. Next-generation sequencing is widely used in searching multiple therapeutic targets, and it is possible to evaluate copy number variation of genes by next-generation sequencing. Aims: To re-evaluate the HER2 status of non-small cell lung carcinoma cases detected as HER2 amplified and non-amplified by next-generation sequencing via the most commonly used HER2 investigation methods in routine pathology practice, namely immunohistochemistry and in situ hybridization. Study Design: Retrospective cross-sectional study. Methods: Among the 256 patients whose mutation profiles were examined by next-generation sequencing, HER2 amplified (13 cases) and non-HER2-amplified (13 cases) were determined as study and control groups, respectively, by next-generation sequencing. HER2 next-generation sequencing amplified tumors were investigated for HER2 expression and amplification using immunohistochemistry and silver in situ hybridization. Results: From a group of 256 non-small cell lung carcinoma, 33 tumors (12.8%) showed HER2 amplification with next-generation sequencing. Although we observed more frequent HER2 positivity by immunohistochemistry in next-generation sequencing-amplified cases, when compared to non-amplified cases (50% and 23% respectively), the difference was not significant ( P = .221). Within the HER2 amplified group, inter-method-agreement was very good between next-generation sequencing results amplification and in situ hybridization status. Next-generation sequencing results showed a strong interclass correlation coefficient with HER2/cell ( P = .009, r = 0.777) and HER2/CEP17 ratio ( P = .001, r = 0.805). The median HER2/CEP17 ratio was higher in the next-generation sequencing amplified group ( P = .013); however, three cases were found to be amplified by silver in situ hybridization among the next-generation sequencing non-amplified cases. EGFR and FGFR1 amplification were more frequent in HER2 next-generation sequencing amplified group than next-generation sequencing non-amplified group ( P < .001). Conclusion: Until the effects of HER2 amplification on the HER2 protein are well understood and pulmonary carcinoma algorithms are defined, non-small cell lung carcinomas found to be amplified by next-generation sequencing should be verified by additional methods.

PIK3CA somatic mutations as potential biomarker for immunotherapy in elder or TP53 mutated gastric cancer patients

“…24 Notably, there are several limitations to this study. First, HER2 amplification status was determined using NGS rather than immunohistochemistry, although no significant difference in the ability in detecting HER2 amplification of these two methods, 25 a certain extent error is likely to exist in our results; Second, a small cohort from TCGA database was used to validate the correlations of the new subgroups we found with immunotherapy, so whether or not it is statistically significant in Chinese GC patients is insufficient; third, this was a retrospective study. Prospective multicenter studies with a larger cohort are needed to gain a better understanding of the relationship between these gene mutations and immunotherapy benefits.…”