Worldwide variations in EGFR somatic mutations: a challenge for personalized medicine

Somatic mutational landscape across Indian breast cancer cases by whole exome sequencing

Breast cancer (BC) has emerged as the most common malignancy among females. The genomic profile of BC is diverse in nature and complex due to heterogeneity among various geographically different ethnic groups. The primary objective of this study was to carry out a comprehensive mutational analysis of Indian BC cases by performing whole exome sequencing. The cohort included patients with a median age of 48 years. TTN, TP53, MUC16, SYNE1, and OBSCN were the frequently altered genes found in our cohort. The PIK3CA and KLC3 genes are driver genes implicated in various cellular functions and cargo transportation through microtubules, respectively. Except for CCDC168 and PIK3CA, several gene pairings were found to be significantly linked with co-occurrence. Irrespective of their hormonal receptor status, RTK/RAS was observed with frequently altered signaling pathways. Further analysis of the mutational signature revealed that SBS13, SBS6, and SBS29 were mainly observed in our cohort. This study supplements the discovery of diagnostic biomarkers and provides new therapeutic options for the improved management of BC.

Mutations of the Epidermal Growth Factor Receptor Gene in Triple-Negative Breast Cancer

Purpose

Epidermal growth factor receptor (EGFR) is considered a potential therapeutic target for anti-EGFR therapy in triple-negative breast cancer (TNBC). However, the frequency of EGFR gene mutation in TNBC is low and varies with ethnicity. This study aimed to investigate the incidence of EGFR gene mutation in TNBC.

Methods

EGFR protein expression was evaluated by immunohistochemistry in tissue microarrays of 493 TNBC cases using four different primary antibodies, which included mutation-specific antibodies. For cases with an immunoreactivity level ≥1+, we performed pyrosequencing analysis for EGFR gene mutation. A case was considered mutation-positive when its mutation frequency minus its limit of detection (LOD) was >10%. Cases with mutation frequency higher than LOD were assessed for EGFR gene mutation status using the Cobas assay and by peptide nucleic acid-mediated polymerase chain reaction (PNA-clamping).

Results

Among 493 TNBCs, 148 (30.0%) exhibited staining ≥1+ for EGFR, including 78 with 1+, 49 with 2+, and 21 with 3+. Positive EGFR expression (≥2+) was significantly associated with lymphovascular invasion (p=0.010), but not with overall survival (p=0.444) or disease-free survival (p=0.388). None of the 493 TNBCs harbored an EGFR gene mutation. Among 148 cases with an EGFR staining result ≥1+, five (3.4%) showed mutation frequencies (4.4%–10.9%) higher than LOD (2.6%–4.3%) in exons 19 (L747_P753>Q) or 21 (L858R and L861Q) as determined by pyrosequencing. However, Cobas and PNA-clamping failed to detect the presence of EGFR gene mutation in these five cases.

Conclusion

No activating mutation of EGFR gene of clinical significance was observed in 148 TNBC cases using three commercially available methods. Thus, EGFR gene mutation appears to be an extremely rare event in patients with TNBC.

Immunohistochemical Localization of Wild-type EGFR, E746-A750 Frame Deletion in Exon 19, and L858R Point Mutation in Exon 21 in Triple-negative Breast Cancer

AIM

This study evaluated wild-type EGFR, E746-A750 frame deletion in exon 19, and L858R point mutation in exon 21 by immunohistochemistry in patients with triple-negative breast cancer (TNBC).

METHODS

A retrospective study included 99 untreated early-stage and advanced-stage TNBC patients. Immunohistochemical localization of wild-type EGFR, EGFR E746-A750 deletion in exon 19, and EGFR L858R mutation in exon 21 was performed on formalin-fixed paraffin-embedded tissue blocks using mutation-specific primary antibodies.

RESULTS

EGFR protein expression was noted in 27% (27/99) of patients with 2+ or 3+ staining intensity in 7% (7/99) of patients. Significant correlation of EGFR protein expression with subgroups of clinicopathologic parameters was not found. In univariate and multivariate survival analysis, high EGFR expression (2+ or 3+) emerged as a significant prognostic factor for disease-free survival. With respect to mutation status, exon 19 deletion was observed in 3% (3/99) of patients. One patient with exon 19 deletion having high EGFR protein (2+) expression developed lung metastasis, whereas the other 2 patients with exon 19 deletion had low EGFR protein (1+) expression and remained disease free during the study period.

CONCLUSIONS

EGFR protein overexpression was observed in one fourth of TNBCs with very low incidence of EGFR-activating mutations in patients of western India.

Whole-Exome Sequencing Identifies Novel Somatic Mutations in Chinese Breast Cancer Patients

Most breast cancer genomes harbor complex mutational landscapes. Somatic alterations have been predominantly discovered in breast cancer patients of European ancestry; however, little is known about somatic aberration in patients of other ethnic groups including Asians. In the present study, whole-exome sequencing (WES) was conducted in DNA extracted from tumor and matched adjacent normal tissue samples from eleven early onset breast cancer patients who were included in the Shanghai Breast Cancer Study. We discovered 159 somatic missense and ten nonsense mutations distributed among 167 genes. The most frequent 50 somatic mutations identified by WES were selected for validation using Sequenom MassARRAY system in the eleven breast cancer patients and an additional 433 tumor and 921 normal tissue/blood samples from the Shanghai Breast Cancer Study. Among these 50 mutations selected for validation, 32 were technically validated. Within the validated mutations, somatic mutations in the TRPM6, HYDIN, ENTHD1, and NDUFB10 genes were found in two or more tumor samples in the replication stage. Mutations in the ADRA1B, CBFB, KIAA2022, and RBM25 genes were observed once in the replication stage. To summarize, this study identified some novel somatic mutations for breast cancer. Future studies will need to be conducted to determine the function of these mutations/genes in the breast carcinogenesis.

The epidermal growth factor receptor (EGFR / HER-1) gatekeeper mutation T790M is present in European patients with early breast cancer

The epidermal growth factor receptor (EGFR) is one of the major oncogenes identified in a variety of human malignancies including breast cancer (BC). EGFR-mutations have been studied in lung cancer for some years and are established as important markers in guiding therapy with tyrosine kinase inhibitors (TKIs). In contrast, EGFR-mutations have been reported to be rare if not absent in human BC, although recent evidence has suggested a significant worldwide variation in somatic EGFR-mutations. Therefore, we investigated the presence of EGFR-mutations in 131 norwegian patients diagnosed with early breast cancer using real-time PCR methods. In the present study we identified three patients with an EGFR-T790M-mutation. The PCR-findings were confirmed by direct Sanger sequencing. Two patients had triple-negative BC (TNBC) while the third was classified as luminal-A subtype. The difference in incidence of T790M mutations comparing the TNBC subgroup with the other BC subgroups was statistical significant (P = 0.023). No other EGFR mutations were identified in the entire cohort. Interestingly, none of the patients had received any previous cancer treatment. To our best knowledge, the EGFR-T790M-TKI-resistance mutation has not been previously detected in breast cancer patients. Our findings contrast with the observations made in lung cancer patients where the EGFR-T790M-mutation is classified as a typical „second mutation”causing resistance to TKI-therapy during ongoing anticancer therapy. In conclusion, we have demonstrated for the first time that the EGFR-T790M-mutation occurs in primary human breast cancer patients. In the present study the EGFR-T790M mutation was not accompanied by any simultaneous EGFR-activating mutation.

High EGFR gene copy number predicts poor outcome in triple-negative breast cancer

Epidermal growth factor receptor (EGFR) is frequently overexpressed in triple-negative breast cancer and is emerging as a therapeutic target. EGFR gene copy number alteration and mutation are highly variable and scientists have been challenged to define their prognostic significance in triple-negative breast cancer. We examined EGFR protein expression, EGFR gene copy number alteration and mutation of exon 18 to 21 in 151 cases of triple-negative breast cancer and correlated these findings with clinical outcomes. In addition, intratumoral agreement of EGFR protein overexpression and gene copy number alteration was evaluated. EGFR overexpression was found in 97 of 151 cases (64%) and high EGFR gene copy number was detected in 50 cases (33%), including 3 gene amplification (2%) and 47 high polysomy (31%). Five EGFR mutations were detected in 4 of 151 cases (3%) and included G719A in exon 18 (n=1), V786M in exon 20 (n=1), and L858R in exon 21 (n=3). One case had two mutations (G719A and L858R). High EGFR copy number, but not EGFR mutation, correlated with EGFR protein overexpression. Intratumoral heterogeneity of EGFR protein overexpression and EGFR copy number alteration was not significant. In survival analyses, high EGFR copy number was found to be an independent prognostic factor for poor disease-free survival in patients with triple-negative breast cancer. Our findings showed that EGFR mutation was a rare event, but high EGFR copy number was relatively frequent and correlated with EGFR overexpression in triple-negative breast cancer. Moreover, high EGFR copy number was associated with poor clinical outcome in triple-negative breast cancer, suggesting that evaluation of EGFR copy number may be useful for predicting outcomes in patients with triple-negative breast cancer and for selecting patients for anti-EGFR-targeted therapy.

Cytotoxic enhancement of hexapeptide-conjugated micelles in EGFR high-expressed cancer cells

OBJECTIVES

The aim of this study was to develop the hexapeptide-conjugated active targeting micelles for delivery of doxorubicin (DOX) and paclitaxel (PTX) to EGFR high-expressed cancer cells.

METHODS

A hexapeptide, which mimicked the EGFR, was applied as a targeting ligand. The active targeting micelles were prepared using the synthesized poly(D,L-lactide-co-glycolide)-PEG copolymer conjugated with the hexapeptide. The micelles were used for encapsulating DOX and/or PTX, and the cellular uptake, in vitro drug release and cellular viability of drug-loaded peptide-conjugated and peptide-free micelles were investigated.

RESULTS

The particle size of drug-loaded peptide-conjugated and peptide-free micelles was < 150 nm with narrow size distribution. The uptake of peptide-conjugated micelles was more efficient in EGFR high-expressed MDA-MB-468 and SKOV3 cells than in EGFR low-expressed HepG2 cells. The in vitro release of DOX and PTX was faster in pH 4.0 (500 U lipase) than in pH 7.4 release medium. The cytotoxicity in terms of IC50 of DOX/PTX-loaded peptide-conjugated micelles was 4.8-folds lower than that of peptide-free micelles and 18.2-folds lower than DOX/PTX drug solution in SOKV3 cells.

CONCLUSION

The peptide-conjugated micelles acted as a nanocarrier to increase intracellular accumulation of anticancer drugs in EGFR high-expressed SKOV3 cancer cells to enhance cell cytotoxicity.

[Characterization of principal predictive biomarkers of targeted therapies in thoracic cancer]

Among non-small cell lung carcinomas, adenocarcinomas are historically the first histological sub-group for which necessary and sufficient mutations driving to cancer can be targeted by tyrosine kinase inhibitors in patients with locally advanced or metastatic forms. In 2013, targeted therapies with a marketing authorization in thoracic oncology are indicated in patients whose tumor has an EGFR-positive or ALK-positive status. Biomarkers KRAS, BRAF, HER2, PI3K, and MET can account for resistance mechanisms to these treatments and are themselves subject to development of new therapeutic inhibitors. Because the systematic detection (or in the process of being) of these biomarkers has become in the last three years an essential task for pathologists and biologists working in hospital platforms of molecular genetics of cancer supported by INCa, this article aims to describe the physiological and pathophysiological role of the main predictive biomarkers of response to targeted therapies indicated in lung adenocarcinomas.

Tufted angioma (Angioblastoma) of eyelid in adults-report of two cases

Abstract

Tufted angioma, first recognized in Japanese literature as “Angioblastoma of Nagakawa”, is a rare benign vascular tumour with a variable clinical presentation. It commonly manifests as a macule, papule or nodule in infancy or childhood in the region of the upper trunk and neck. Here in we report two cases of this rare progressive angioma as lesions of the eyelid in adults. Tufted angioma has a classical “cannon ball” like appearance of vascular tufts on histopathology. Immunohistochemical staining with actin highlights the spindly stromal cells surrounding the capillaries. Complete physical examination and haematological work up is recommended in patients with tufted angioma to exclude rare association of port wine stain and Kasabach-Merritt syndrome with this rare entity. To the best of our knowledge, our cases illustrate the first case report of tufted angioma presenting as an eyelid lesion.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1230909536950947.

Immunohistochemical detection of mutations in the epidermal growth factor receptor gene in lung adenocarcinomas using mutation-specific antibodies

BACKGROUND

The recent development of antibodies specific for the major hotspot mutations in the epidermal growth factor receptor (EGFR), L858R and E746_A750del, may provide an opportunity to use immunohistochemistry (IHC) as a screening test for EGFR gene mutations. This study was designed to optimize the IHC protocol and the criteria for interpretation of the results using DNA sequencing as the gold-standard.

METHODS

Tumor sections from fifty lung adenocarcinoma specimens from Chinese patients were immunostained using L858R and E746_A750del-specific antibodies using three different antigen retrieval solutions, and the results were evaluated using three different sets of criteria. The same specimens were used for DNA purification and analysis of EGFR gene mutations.

RESULTS

In this study the optimal buffer for antigen retrieval was EDTA (pH 8.0), and the optimal scoring method was to call positive results when there was moderate to strong staining of membrane and/or cytoplasm in >10% of the tumor cells. Using the optimized protocol, L858R-specific IHC showed a sensitivity of 81% and a specificity of 97%, and E746_A750del-specific IHC showed a sensitivity of 59% and a specificity of 100%, both compared with direct DNA analysis. Additionally, the mutant proteins as assessed by IHC showed a more homogeneous than heterogeneous pattern of expression.

CONCLUSIONS

Our data demonstrate that mutation-specific IHC, using optimized procedures, is a reliable prescreening test for detecting EGFR mutations in lung adenocarcinoma.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2059012601872392.

The genomic landscape of TP53 and p53 annotated high grade ovarian serous carcinomas from a defined founder population associated with patient outcome

High-grade ovarian serous carcinomas (HGSC) are characterized by TP53 mutations and non-random patterns of chromosomal anomalies, where the nature of the TP53 mutation may correlate with clinical outcome. However, the frequency of common somatic genomic events occurring in HGSCs from demographically defined populations has not been explored. Whole genome SNP array, and TP53 mutation, gene and protein expression analyses were assessed in 87 confirmed HGSC samples with clinical correlates from French Canadians, a population exhibiting strong founder effects, and results were compared with independent reports describing similar analyses from unselected populations. TP53 mutations were identified in 91% of HGSCs. Anomalies observed in more than 50% of TP53 mutation-positive HGSCs involved gains of 3q, 8q and 20q, and losses of 4q, 5q, 6q, 8p, 13q, 16q, 17p, 17q, 22q and Xp. Nearly 400 regions of non-overlapping amplification or deletion were identified, where 178 amplifications and 98 deletions involved known genes. The subgroup expressing mutant p53 protein exhibited significantly prolonged overall and disease-free survival as compared with the p53 protein null subgroup. Interestingly, a comparative analysis of genomic landscapes revealed a significant enrichment of gains involving 1q, 8q, and 12p intervals in the subgroup expressing mutant p53 protein as compared with the p53 protein null subgroup. Although the findings show that the frequency of TP53 mutations and the genomic landscapes observed in French Canadian samples were similar to those reported for samples from unselected populations, there were differences in the magnitude of global gains/losses of specific chromosomal arms and in the spectrum of amplifications and deletions involving focal regions in individual samples. The findings from our comparative genomic analyses also support the notion that there may be biological differences between HGSCs that could be related to the nature of the TP53 mutation.