Variability in organ-specific EGFR mutational spectra in tumour epithelium and stroma may be the biological basis for differential responses to tyrosine kinase inhibitors

Role of EGFR and FASN in breast cancer progression

Breast cancer (BC) emerged as one of the life-threatening diseases among females. Despite notable improvements made in cancer detection and treatment worldwide, according to GLOBACAN 2020, BC is the fifth leading cancer, with an estimated 1 in 6 cancer deaths, in a majority of countries. However, the exact cause that leads to BC progression still needs to be determined. Here, we reviewed the role of two novel biomarkers responsible for 50-70% of BC progression. The first one is epidermal growth factor receptor (EGFR) which belongs to the ErbB tyrosine kinases family, signalling pathways associated with it play a significant role in regulating cell proliferation and division. Another one is fatty acid synthase (FASN), a key enzyme responsible for the de novo lipid synthesis required for cancer cell development. This review presents a rationale for the EGFR-mediated pathways, their interaction with FASN, communion of these two biomarkers with BC, and improvements to overcome drug resistance caused by them.

The role of next-generation sequencing in the examination of signaling genes in Brca1/2-negative breast cancer cases

INTRODUCTION

Breast cancer is the most prevalent malignancy in women worldwide. Although pathogenic variants in the BRCA1/2 genes are responsible for the majority of hereditary breast cancer cases, a substantial proportion of patients are negative for pathogenic variations in these genes. In cancers, the signal transduction pathways of the cell are usually affected first. Therefore, this study aimed to detect and classified genetic variations in non-BRCA signaling genes and investigate the underlying genetic causes of susceptibility to breast cancer.

METHODS

Ninety-six patients without pathogenic variants in the BRCA1/2 genes who met the inclusion criteria were enrolled in the study, and 34 genes were analyzed using next-generation sequencing (NGS) for genetic analysis.

RESULTS

Based on the ClinVar database or American College of Medical Genetics criteria, a total of 55 variants of 16 genes were detected in 43 (44.8%) of the 96 patients included in the study. The pathogenic variants were found in the TP53, CHEK2, and RET genes, whereas the likely pathogenic variants were found in the FGFR1, FGFR3, EGFR, and NOTCH1 genes.

CONCLUSION

The examination of signaling genes in patients who met the established criteria for hereditary breast cancer but were negative for BRCA1/2 pathogenic variants provided additional information for approximately 8% of the families. The results of the present study suggest that NGS is a powerful tool for investigating the underlying genetic causes of occurrence and progression of breast cancer.

Structural Insight and Development of EGFR Tyrosine Kinase Inhibitors

Lung cancer has a high prevalence, with a growing number of new cases and mortality every year. Furthermore, the survival rate of patients with non-small-cell lung carcinoma (NSCLC) is still quite low in the majority of cases. Despite the use of conventional therapy such as tyrosine kinase inhibitor for Epidermal Growth Factor Receptor (EGFR), which is highly expressed in most NSCLC cases, there was still no substantial improvement in patient survival. This is due to the drug’s ineffectiveness and high rate of resistance among individuals with mutant EGFR. Therefore, the development of new inhibitors is urgently needed. Understanding the EGFR structure, including its kinase domain and other parts of the protein, and its activation mechanism can accelerate the discovery of novel compounds targeting this protein. This study described the structure of the extracellular, transmembrane, and intracellular domains of EGFR. This was carried out along with identifying the binding pose of commercially available inhibitors in the ATP-binding and allosteric sites, thereby clarifying the research gaps that can be filled. The binding mechanism of inhibitors that have been used clinically was also explained, thereby aiding the structure-based development of new drugs.

Reciprocal priming between receptor tyrosine kinases at recycling endosomes orchestrates cellular signalling outputs

Integration of signalling downstream of individual receptor tyrosine kinases (RTKs) is crucial to fine-tune cellular homeostasis during development and in pathological conditions, including breast cancer. However, how signalling integration is regulated and whether the endocytic fate of single receptors controls such signalling integration remains poorly elucidated. Combining quantitative phosphoproteomics and targeted assays, we generated a detailed picture of recycling-dependent fibroblast growth factor (FGF) signalling in breast cancer cells, with a focus on distinct FGF receptors (FGFRs). We discovered reciprocal priming between FGFRs and epidermal growth factor (EGF) receptor (EGFR) that is coordinated at recycling endosomes. FGFR recycling ligands induce EGFR phosphorylation on threonine 693. This phosphorylation event alters both FGFR and EGFR trafficking and primes FGFR-mediated proliferation but not cell invasion. In turn, FGFR signalling primes EGF-mediated outputs via EGFR threonine 693 phosphorylation. This reciprocal priming between distinct families of RTKs from recycling endosomes exemplifies a novel signalling integration hub where recycling endosomes orchestrate cellular behaviour. Therefore, targeting reciprocal priming over individual receptors may improve personalized therapies in breast and other cancers.

Molecular Targeting Therapy against EGFR Family in Breast Cancer: Progress and Future Potentials

The epidermal growth factor receptor (EGFR) family contains four transmembrane tyrosine kinases (EGFR1/ErbB1, Her2/ErbB2, Her3/ErbB3 and Her4/ErbB4) and 13 secreted polypeptide ligands. EGFRs are overexpressed in many solid tumors, including breast, pancreas, head-and-neck, prostate, ovarian, renal, colon, and non-small-cell lung cancer. Such overexpression produces strong stimulation of downstream signaling pathways, which induce cell growth, cell differentiation, cell cycle progression, angiogenesis, cell motility and blocking of apoptosis.The high expression and/or functional activation of EGFRs correlates with the pathogenesis and progression of several cancers, which make them attractive targets for both diagnosis and therapy. Several approaches have been developed to target these receptors and/or the EGFR modulated effects in cancer cells. Most approaches include the development of anti-EGFRs antibodies and/or small-molecule EGFR inhibitors. This review presents the state-of-the-art and future prospects of targeting EGFRs to treat breast cancer.

Detection of rare and novel EGFR mutations in NSCLC patients: Implications for treatment-decision

OBJECTIVES

Mutations in the gene that encodes epidermal growth factor receptor (EGFR) are biomarkers that predict how non-small cell lung cancer (NSCLC) patients respond to EGFR-targeted therapies collectively known as tyrosine kinase inhibitors (TKIs). Thus, EGFR genotyping provides crucial information for treatment decision. Both Sanger sequencing and real-time PCR methodologies are used for EGFR genotyping. However, methods based on real-time PCR have limitations, as they may not detect rare or novel mutations. The aim of this study was to determine the prevalence of rare mutations in the tyrosine kinase domain (exons 18-21) of the EGFR gene not targeted by the most frequently used real-time PCR approaches, i.e., the cobas® EGFR Mutation Test, and the Idylla™ EGFR Mutation Assay.

METHODS

A total of 1228 NSCLC patients were screened for mutations in exons 18-21 of the EGFR gene using Sanger sequencing.

RESULTS

We observed that 252 patients (∼20%) had at least one mutation in the EGFR gene, and 38 (∼3%) carried uncommon genetic alterations that would not be identified by the cobas® or the Idylla™ tests. We further found six new single mutations and seven previously unreported compound mutations. Clinical information and patient outcome are presented for these cases.

CONCLUSIONS

This study highlights the value of sequencing-based approaches to identify rare mutations. Our results add to the inventory of known EGFR mutations, thus contributing to improved lung cancer precision treatment.

A Single-Center Retrospective Study of Patients with Double Primary Cancers: Breast Cancer and EGFR-Mutant Non-Small Cell Lung Cancer

BACKGROUND

Second primary malignancies (SPM) in the lung are not common in breast cancer (BC) patients. EGFR-mutant lung cancer (LC) is a separate molecular subset, and the co-existence of EGFR-mutant LC and BC has not been explored. We hypothesized that EGFR-mutant LC patients could have higher rates of primary BC than those with EGFR-wild type (WT).

METHODS

We collected data on clinical and molecular characteristics and outcomes of female patients with LC and a previous or simultaneous history of primary BC treated in our hospital from 2008 to 2014.

RESULTS

Data on treatment, follow-up, and EGFR mutation status were available for 356 patients. 17.7% (11/62) of patients with EGFR mutations had BC, compared to 1.02% (3/294) of EGFR-WT patients (p < 0.001). Both tumors were metachronous in 81.8%, with LC diagnosed 9 years after the diagnosis of BC. 5 of the 6 (83.3%) BC patients treated with radiotherapy developed LC in an area within the radiation field. No EGFR mutations were detected in BC tissue and no HER2 expression was detected in LC samples.

CONCLUSION

SPM in the lung and breast occur more frequently among EGFR-mutant compared to EGFR-WT LC patients. Radiotherapy for BC may increase the risk of developing primary LC.

Strontium Sulfite: A New pH-Responsive Inorganic Nanocarrier to Deliver Therapeutic siRNAs to Cancer Cells

Inorganic nanoparticles hold great potential in the area of precision medicine, particularly for treating cancer owing to their unique physicochemical properties, biocompatibility and improved pharmacokinetics properties compared to their organic counterparts. Here we introduce strontium sulfite nanoparticles as new pH-responsive inorganic nanocarriers for efficient transport of siRNAs into breast cancer cells. We employed the simplest nanoprecipitation method to generate the strontium sulfite nanoparticles (SSNs) and demonstrated the dramatic roles of NaCl and d-glucose in particle growth stabilization in order to produce even smaller nanosize particles (Na-Glc-SSN) with high affinity towards negatively charged siRNA, enabling it to efficiently enter the cancer cells. Moreover, the nanoparticles were found to be degraded with a small drop in pH, suggesting their potential capability to undergo rapid dissolution at endosomal pH so as to release the payload. While these particles were found to be nontoxic to the cells, they showed higher potency in facilitating cancer cell death through intracellular delivery and release of oncogene-specific siRNAs targeting ros1 and egfr1 mRNA transcripts, than the strontium sulfite particles prepared in absence of NaCl and d-glucose, as confirmed by growth inhibition assay. The mouse plasma binding analysis by Q-TOF LC-MS/MS demonstrated less protein binding to smaller particles of Na-Glc-SSNs. The biodistribution studies of the particles after 4 h of treatment showed Na-Glc-SSNs had less off-target distribution than SSNs, and after 24 h, all siRNAs were cleared from all major organs except the tumors. ROS1 siRNA with its potential therapeutic role in treating 4T1-induced breast tumor was selected for subsequent in vivo tumor regression study, revealing that ROS1 siRNA-loaded SSNs exerted more significant anti-tumor effects than Na-Glc-SSNs carrying the same siRNA following intravenous administration, without any systemic toxicity. Thus, strontium sulfite emerged as a powerful siRNA delivery tool with potential applications in cancer gene therapy.

Somatic alterations of targetable oncogenes are frequently observed in BRCA1/2 mutation negative male breast cancers

Male breast cancer (MBC) is a rare disease. Due to its rarity, MBC research and clinical approach are mostly based upon data derived from its largely known female counterpart. We aimed at investigating whether MBC cases harbor somatic alterations of genes known as prognostic biomarkers and molecular therapeutic targets in female breast cancer.

We examined 103 MBC cases, all characterized for germ-line BRCA1/2 mutations, for somatic alterations in PIK3CA, EGFR, ESR1 and CCND1 genes.

Pathogenic mutations of PIK3CA were detected in 2% of MBCs. No pathogenic mutations were identified in ESR1 and EGFR. Gene copy number variations (CNVs) analysis showed amplification of PIK3CA in 8.1%, EGFR in 6.8% and CCND1 in 16% of MBCs, whereas deletion of ESR1 was detected in 15% of MBCs. Somatic mutations and gene amplification were found only in BRCA1/2 mutation negative MBCs.

Significant associations emerged between EGFR amplification and large tumor size (T4), ER-negative and HER2-positive status, between CCND1 amplification and HER2-positive and MIB1-positive status, and between ESR1 deletion and ER-negative status.

Our results show that amplification of targetable oncogenes is frequent in BRCA1/2 mutation negative MBCs and may identify MBC subsets characterized by aggressive phenotype that may benefit from potential targeted therapeutic approaches.

Prognostic Evaluation of Epidermal Growth Factor Receptor (EGFR) Genotype and Phenotype Parameters in Triple-negative Breast Cancers

BACKGROUND

Epidermal growth factor receptor (EGFR) aberrations have been implicated in the pathogenesis of triple-negative breast cancer (TNBC) but their impact on prognosis and, therefore, druggability, remain controversial. Herein, we studied EGFR aberrations at different molecular levels and assessed their prognostic impact in patients with operable TNBC treated with adjuvant anthracycline-based chemotherapy.

MATERIALS AND METHODS

We evaluated the prognostic impact of EGFR gene status by fluorescent in situ hybridization (FISH), EGFR coding mutations by Sanger and next-generation sequencing, relative EGFR messenger RNA (mRNA) levels by qPCR (upper quartile) and EGFR and p53 protein expression by immunohistochemistry (IHC), in 352 centrally-assessed tumors from an equal number of TNBC patients.

RESULTS

Approximately 53.5% of the tumors expressed EGFR, 59.3% p53 and 35.9% both EGFR and p53 proteins; 4.1% showed EGFR gene amplification and 4.4% carried EGFR mutations. The latter were located outside the druggable kinase domain region and presented at low frequencies. Amplification and mutations overlapped only in one case of glycogen-rich carcinoma. EGFR and CEN7 copies were higher in tumors from older patients (p=0.002 and p=0.003, respectively). Patients with amplified tumors (n=11) had excellent prognosis (0 relapses and deaths). Upon multivariate analysis, high EGFR copies conferred significantly favorable disease-free survival (HR=0.57, 95% CI 0.36-0.90, Wald's p=0.017) and high CEN7 copies favorable overall survival (HR=0.49, 95% CI=0.29-0.83, Wald's p=0.008). Patients with EGFR-/p53+ and EGFR+/p53- tumors had significantly higher risk for relapse than those with EGFR-/p53- and EGFR+/p53+ tumors (HR=1.73, 95% CI=1.12-2.67, Wald's p=0.013).

CONCLUSION

EGFR gene amplification and mutations are rare in TNBC, the latter of no apparent clinical relevance. Surrogate markers of EGFR-related chromosomal aberrations and combined EGFR/p53 IHC phenotypes appear to be associated with favorable prognosis in patients with operable TNBC receiving conventional adjuvant chemotherapy.

Structure-based virtual screening and molecular docking for the identification of potential multi-targeted inhibitors against breast cancer

Breast cancer is characterized by an uncontrolled growth of cells in breast tissue. Genes that foster cell growth in breast cells are overexpressed, giving rise to breast tumors. The identification of effective inhibitors represents a rational chemopreventive strategy. The current in silico study provides a pharmacoinformatic approach for the identification of active compounds against a co-chaperone HSP90 and the human epidermal growth factor receptors EGFR and HER2/neu receptor. The elevated levels of expression of these target proteins have been documented in breast cancer. The utilization of drug-likeness filters helped to evaluate the pharmacological activity of potential lead compounds. Those fulfilling this criterion were subjected to energy minimization for 1000 steepest descent steps at a root means square gradient of 0.02 with an Amber ff12SB force field. Based on molecular docking results and binding interaction analysis, this study represents five chemical compounds (S-258282355, S-258012947, S-259417539, S-258002927, and S-259411474) that indicate high binding energies that range between -8.7 to -10.3 kcal/mol. With high cytochrome P inhibitory promiscuity activity, these multi-targeted potential hits portray not only good physiochemical interactions but also an excellent profile of absorption, distribution, metabolism, excretion, and toxicity, which hypothesizes that these compounds can be developed as anticancer drugs in the near future.

Detection of IKKε by immunohistochemistry in primary breast cancer: association with EGFR expression and absence of lymph node metastasis

Background

IKKε is an oncogenic kinase that was found amplified and overexpressed in a substantial percentage of human breast cancer cell lines and primary tumors using genomic and gene expression analyses. Molecular studies have provided the rational for a key implication of IKKε in breast cancer cells proliferation and invasiveness through the phosphorylation of several substrates.

Methods

Here, we performed immunohistochemical detection of IKKε expression on tissue microarrays constituted of 154 characterized human breast cancer tumors. We further determined the association with multiple clinicopathological parameters and 5-years overall, disease-free and distant disease free survival.

Results

We observed expression of IKKε in 60.4% of the breast cancer tumors. IKKε expression status showed no association with a panel of markers used for molecular classification of the tumors, including ER/PR/HER2 status, or with the molecular subtypes. However, IKKε expression was inversely associated with lymph node metastasis status (p = 0.0032). Additionally, we identified a novel association between IKKε and EGFR expression (p = 0.0011).

Conclusions

The unexpected observation of an inverse association between IKKε and lymph node metastasis advocates for larger scale immunohistochemical profiling of primary breast tumors to clarify the role of IKKε in metastasis. This study suggests that breast cancer tumors expressing EGFR and IKKε may be potential targets for drugs aiming at inhibiting IKKε activity or expression.

Rational design of non-resistant targeted cancer therapies

Drug resistance is one of the major problems in targeted cancer therapy. A major cause of resistance is changes in the amino acids that form the drug-target binding site. Despite of the numerous efforts made to individually understand and overcome these mutations, there is a lack of comprehensive analysis of the mutational landscape that can prospectively estimate drug-resistance mutations. Here we describe and computationally validate a framework that combines the cancer-specific likelihood with the resistance impact to enable the detection of single point mutations with the highest chance to be responsible of resistance to a particular targeted cancer therapy. Moreover, for these treatment-threatening mutations, the model proposes alternative therapies overcoming the resistance. We exemplified the applicability of the model using EGFR-gefitinib treatment for Lung Adenocarcinoma (LUAD) and Lung Squamous Cell Cancer (LSCC) and the ERK2-VTX11e treatment for melanoma and colorectal cancer. Our model correctly identified the phenotype known resistance mutations, including the classic EGFR-T790M and the ERK2-P58L/S/T mutations. Moreover, the model predicted new previously undescribed mutations as potentially responsible of drug resistance. Finally, we provided a map of the predicted sensitivity of alternative ERK2 and EGFR inhibitors, with a particular highlight of two molecules with a low predicted resistance impact.

Early clinical development of epidermal growth factor receptor targeted therapy in breast cancer

INTRODUCTION

Epidermal growth factor receptor (EGFR) targeted treatment has been evaluated but has not shown a clear clinical benefit for breast cancer. This review article aims to consider the knowledge of the biological background of EGFR pathways in dissecting clinical studies of EGFR targeted treatment in breast cancer. Areas covered: This review focuses on the role of the EGFR pathway and the investigational drugs that target EGFR for breast cancer. Expert opinion: Recent studies have indicated that EGFR targeted therapy for breast cancer has some promising effects for patients with triple-negative breast cancer, basal-like breast cancer, and inflammatory breast cancer. However, predictive and prognostic biomarkers for EGFR targeted therapy have not been identified. The overexpression or amplification of EGFR itself may not be the true factor of induction of the canonical pathway as an oncogenic driver of breast cancer. Instead, downstream, non-canonical pathways related to EGFR may contribute to some aspects of the biological behavior of breast cancer; therefore, the blockade of the receptor could result in sufficient suppression of downstream pathways to inhibit the aggressive behavior of breast cancer. Mechanistic studies to investigate the dynamic interaction between the EGFR pathway and non-canonical pathways are warranted.

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.

Lack of mutations in protein tyrosine kinase domain coding exons 19 and 21 of the EGFR gene in oral squamous cell carcinomas

BACKGROUND

The epidermal growth factor receptor (EGFR) plays a vital role in the activation and inactivation of receptor tyrosine kinases. Mutations in exons 19 and 21 of EGFR are commonly found to be associated with non small cell lung carcinoma and triple negative breast cancer, enhancing sensitivity to EGFR targeting chemotherapeutic agents. Since amplification and prolonged activation of EGFR molecules have been identified in oral squamous cell carcinomas (OSCC), we investigated whether OSCCs carried mutations in exons 19 and 21 of EGFR to their incidence.

MATERIALS AND METHODS

Tumor chromosomal DNA isolated from forty surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking exons 19 and 21 of the EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status.

RESULTS

Data analysis of the EGFR exon 19 and 21 coding sequences did not show any mutations in the forty OSCC samples that were analyzed.

CONCLUSIONS

To the best of our knowledge, this is the first study to have investigated the genetic status of exons 19 and 21 of EGFR in Indian OSCCs and identified that mutation in EGFR exon 19 and 21 may not contribute towards their genesis. The absence of mutations also indicates that oral cancerous lesions may not be as sensitive as other cancers to chemotherapeutic agents targeting EGFR.

HER family kinase domain mutations promote tumor progression and can predict response to treatment in human breast cancer

Resistance to HER2-targeted therapies remains a major obstacle in the treatment of HER2-overexpressing breast cancer. Understanding the molecular pathways that contribute to the development of drug resistance is needed to improve the clinical utility of novel agents, and to predict the success of targeted personalized therapy based on tumor-specific mutations. Little is known about the clinical significance of HER family mutations in breast cancer. Because mutations within HER1/EGFR are predictive of response to tyrosine kinase inhibitors (TKI) in lung cancer, we investigated whether mutations in HER family kinase domains are predictive of response to targeted therapy in HER2-overexpressing breast cancer. We sequenced the HER family kinase domains from 76 HER2-overexpressing invasive carcinomas and identified 12 missense variants. Patients whose tumors carried any of these mutations did not respond to HER2 directed therapy in the metastatic setting. We developed mutant cell lines and used structural analyses to determine whether changes in protein conformation could explain the lack of response to therapy. We also functionally studied all HER2 mutants and showed that they conferred an aggressive phenotype and altered effects of the TKI lapatinib. Our data demonstrate that mutations in the finely tuned HER kinase domains play a critical function in breast cancer progression and may serve as prognostic and predictive markers.

Eprobe mediated real-time PCR monitoring and melting curve analysis

Real-time monitoring of PCR is one of the most important methods for DNA and RNA detection widely used in research and medical diagnostics. Here we describe a new approach for combined real-time PCR monitoring and melting curve analysis using a 3′ end-blocked Exciton-Controlled Hybridization-sensitive fluorescent Oligonucleotide (ECHO) called Eprobe. Eprobes contain two dye moieties attached to the same nucleotide and their fluorescent signal is strongly suppressed as single-stranded oligonucleotides by an excitonic interaction between the dyes. Upon hybridization to a complementary DNA strand, the dyes are separated and intercalate into the double-strand leading to strong fluorescence signals. Intercalation of dyes can further stabilize the DNA/DNA hybrid and increase the melting temperature compared to standard DNA oligonucleotides. Eprobes allow for specific real-time monitoring of amplification reactions by hybridizing to the amplicon in a sequence-dependent manner. Similarly, Eprobes allow for analysis of reaction products by melting curve analysis. The function of different Eprobes was studied using the L858R mutation in the human epidermal growth factor receptor (EGFR) gene, and multiplex detection was demonstrated for the human EGFR and KRAS genes using Eprobes with two different dyes. Combining amplification and melting curve analysis in a single-tube reaction provides powerful means for new mutation detection assays. Functioning as “sequence-specific dyes”, Eprobes hold great promises for future applications not only in PCR but also as hybridization probes in other applications.

Role of epidermal growth factor receptor in breast cancer

Decades of research in molecular oncology have brought about promising new therapies which are designed to target specific molecules which promote tumor growth and survival. The epidermal growth factor receptor (EGFR) is one of the first identified important targets of these novel antitumor agents. Approximately half of cases of triple-negative breast cancer (TNBC) and inflammatory breast cancer (IBC) overexpress EGFR. Thus, EGFR inhibitors for treatment of breast cancer have been evaluated in several studies. However, results so far have been disappointing. One of the reasons for these unexpected results is the lack of biomarkers for predicting which patients are most likely to respond to EGFR inhibitors. Recent studies have shown that EGFR and its downstream pathway regulate epithelial-mesenchymal transition, migration, and tumor invasion and that high EGFR expression is an independent predictor of poor prognosis in IBC. Further, recent studies have shown that targeting EGFR enhances the chemosensitivity of TNBC cells by rewiring apoptotic signaling networks in TNBC. These studies indicate that EGFR-targeted therapy might have a promising role in TNBC and IBC. Further studies of the role of EGFR in TNBC and IBC are needed to better understand the best way to use EGFR-targeted therapy-e.g., as a chemosensitizer or to prevent metastases-to treat these aggressive diseases.

Tumor microenvironment and breast cancer progression: a complex scenario

It is now widely accepted that the development and progression of a tumor toward the malignant phenotype is highly dependent on interactions between tumor cells and the tumor microenvironment. Different components of the tumor microenvironment may have stimulatory or inhibitory effects on tumor progression by regulating the gene expression repertoire in tumor cells and stromal cells. This review analyzes novel research findings on breast cancer progression, discussing acquisition of the metastatic phenotype in breast disease in relation to different aspects of cross-talk among components of the tumor microenvironment. Knowledge of the interaction of all of these factors would contribute to elucidating the mechanisms that disrupt regulatory/signaling cascades and downstream effects in breast cancer.

EGFR protein overexpression correlates with chromosome 7 polysomy and poor prognostic parameters in clear cell renal cell carcinoma

Background

The role of epidermal growth factor (EGF) and its receptor (EGFR) in the pathogenesis and progression of various malignant tumors has long been known, but there is still disagreement concerning prognostic significance of EGFR expression in clear cell renal cell carcinoma (CCRCC). The present study was designed to analyze more objectively the protein EGFR expression in CCRCC and to compare its value with EGFR gene copy number changes and clinicopathologic characteristics including patient survival.

Methods

The protein EGFR expression was analyzed immunohistochemically on 94 CCRCC, and gene copy number alterations of EGFR by FISH analysis on 41 CCRCC selected according to distinct membrane EGFR staining.

Results

Membrane EGFR expression in tumor cells was heterogeneous with respect to the proportion of positive cells and staining intensity. FISH analysis did not reveal EGFR gene amplification, while polysomy of chromosome 7 found in 41% was associated with higher EGFR membrane expression. Moreover, EGFR overexpression was associated with a higher nuclear grade, larger tumor size and shorter patient's survival, while there was no connection with pathological stage.

Conclusion

In conclusion, the protein expression of EGFR had an impact on prognosis in patients with CCRCC, while an increased copy number of chromosome 7 could be the possible reason for EGFR protein overexpression in the absence of gene amplification.

Personalized medicine: caught between hope, hype and the real world

Genomic and personalized medicine have become buzz phrases that pervade all fields of medicine. Rapid advances in "-omics" fields of research (chief of which are genomics, proteinomics, and epigenomics) over the last few years have allowed us to dissect the molecular signatures and functional pathways that underlie disease initiation and progression and to identify molecular profiles that help the classification of tumor subtypes and determine their natural course, prognosis, and responsiveness to therapies. Genomic medicine implements the use of traditional genetic information, as well as modern pangenomic information, with the aim of individualizing risk assessment, prevention, diagnosis, and treatment of cancers and other diseases. It is of note that personalizing medical treatment based on genetic information is not the revolution of the 21st century. Indeed, the use of genetic information, such as human leukocyte antigen-matching for solid organ transplantation or blood transfusion based on ABO blood group antigens, has been standard of care for several decades. However, in recent years rapid technical advances have allowed us to perform high-throughput, high-density molecular analyses to depict the genomic, proteinomic, and epigenomic make-up of an individual at a reasonable cost. Hence, the so-called genomic revolution is more or less the logical evolution from years of bench-based research and bench-to-bedside translational medicine.

Lack of EGFR-activating mutations in European patients with triple-negative breast cancer could emphasise geographic and ethnic variations in breast cancer mutation profiles

INTRODUCTION

Triple-negative breast cancers (TNBCs) are characterised by lack of expression of hormone receptors and epidermal growth factor receptor 2 (HER-2). As they frequently express epidermal growth factor receptors (EGFRs), anti-EGFR therapies are currently assessed for this breast cancer subtype as an alternative to treatments that target HER-2 or hormone receptors. Recently, EGFR-activating mutations have been reported in TNBC specimens in an East Asian population. Because variations in the frequency of EGFR-activating mutations in East Asians and other patients with lung cancer have been described, we evaluated the EGFR mutational profile in tumour samples from European patients with TNBC.

METHODS

We selected from a DNA tumour bank 229 DNA samples isolated from frozen, histologically proven and macrodissected invasive TNBC specimens from European patients. PCR and high-resolution melting (HRM) analyses were used to detect mutations in exons 19 and 21 of EGFR. The results were then confirmed by bidirectional sequencing of all samples.

RESULTS

HRM analysis allowed the detection of three EGFR exon 21 mutations, but no exon 19 mutations. There was 100% concordance between the HRM and sequencing results. The three patients with EGFR exon 21 abnormal HRM profiles harboured the rare R836R SNP, but no EGFR-activating mutation was identified.

CONCLUSIONS

This study highlights variations in the prevalence of EGFR mutations in TNBC. These variations have crucial implications for the design of clinical trials involving anti-EGFR treatments in TNBC and for identifying the potential target population.

Mutations in the epidermal growth factor receptor (EGFR) gene in triple negative breast cancer: possible implications for targeted therapy

Introduction

Triple negative breast cancer is associated with poorer prognosis and unresponsiveness to endocrine and anti-HER2 directed agents. Despite emerging data supporting the use of polyADP-ribose polymerase (PARP) inhibitors, complete and durable responses are rare and exploration of additional targeted therapies is needed. Epidermal growth factor receptor (EGFR) is expressed in triple negative breast cancer and several clinical trials are testing the role of anti-EGFR directed therapy. However, the rate of EGFR mutations is poorly defined. We, therefore, sought to characterize EGFR mutations in triple negative breast cancers.

Methods

Seventy samples were randomly chosen from a cohort of 653 triple negative breast tumours for EGFR mutation analysis. These samples were immunostained for EGFR protein expression and consisted of negatively stained and positively stained cases. DNA was extracted from paraffin blocks and polymerase chain reaction was performed to amplify exon regions 18 to 21 of the EGFR gene. Direct sequencing of the purified PCR products was performed.

Results

EGFR mutations were found in 8 of 70 samples (11.4%). Mutations were predominantly exon 19 deletions (4 of 70 samples, 5.7%), which clustered in the region spanning codons 746 to 759 within the kinase domain of EGFR. Two types of exon 19 deletions were seen: a 15 nucleotide deletion (del E746-A750) (2 of 70 samples) and a 24 nucleotide deletion (del S752 - I759) (2 of 70 samples). Other exon 19 mutations observed were the inversion of the complementary strand (1 of 70 samples). Exon 21 mutations included missense substitution, L858R (1 of 70 samples) and T847I (2 of 70 samples). Mutations observed were independent of EGFR protein expression determined by immunohistochemical staining.

Conclusions

This study is among the first to document the presence and estimate the prevalence of EGFR mutations in triple negative breast cancer. These findings have potential implications for the design of clinical trials involving anti-EGFR directed therapy which currently do not select for patients based on presence of activating EGFR mutations, which may hence be underpowered to detect significant benefit in unselected populations. More complete sampling of EGFR mutation status in triple negative breast cancer is needed to determine the true mutation rate.

The contribution of breast cancer pathology to statistical models to predict mutation risk in BRCA carriers

BRCA1 and BRCA2 associated breast cancer comprises a small but important group of hereditary breast cancer. Testing for BRCA1 and BRCA2 has significant clinical and personal implications for the patients in terms of therapy and follow-up of individual family members. The sequencing of the genes is expensive and since the information derived may have a profound effect on the individual and family members, it is important that testing is done only when the risk of carrying a mutation is thought to be high. Over the last decade, researchers have developed a number of statistical models for predicting risk for harboring mutations in these genes and the risk of subsequently developing breast and ovarian cancer. These models usually take into account the type of tumor and age at occurrence as well as family history. Data from pathological analysis show that although breast tumours are heterogeneous, there are histological characteristics that are seen more frequently in carriers of BRCA1 germ line mutations compared to BRCA2 and sporadic breast cancers. A number of authors have suggested that the addition of pathological data to risk algorithms may improve the predictive power of these models and provide a more accurate way of identifying individuals who may benefit from testing. Here we review the pathology of familial breast cancer and assess the evidence to justify the use of pathology in refining risk assessment models.

Genetic changes in tumour microenvironments

Numerous in vitro and in vivo studies have established that carcinoma-associated fibroblasts differ phenotypically from fibroblasts associated with normal tissue but the mechanisms underlying these differences are unclear. Since carcinoma-associated fibroblasts can be propagated in vitro for extended periods and still maintain their cancer-promoting phenotype, some investigators have proposed that they might have acquired somatic genetic alterations analogous to those observed in malignant epithelium. Early molecular genetic studies appeared to validate this hypothesis by demonstrating remarkably high frequencies of clonal somatic genetic alterations in carcinoma-associated fibroblasts, including loss of heterozygosity, gene amplification, and point mutations in tumour suppressor genes such as TP53 and PTEN. The initial excitement of these paradigm-changing studies overshadowed concerns that there may have been a more mundane explanation for these observations. In addition to the fact that the data would necessarily invoke an unlikely scenario of the simultaneous generation of two symbiotic malignancies, subsequent molecular genetic studies found no evidence of frequent genomic aberrations. One striking common trait of those studies reporting frequent clonal somatic alterations in carcinoma-associated fibroblasts is the use of tissues and techniques which are well known to be highly prone to generating artefacts such as limiting and poor quality DNA followed by highly multiplexed PCR-based analyses. It is now clear that clonal somatic mutations are not the biological basis of the cancer-promoting attributes of carcinoma-associated fibroblasts.

Epidermal growth factor receptor in triple-negative and basal-like breast cancer: promising clinical target or only a marker?

Triple-negative breast cancers represent a subset of breast cancers with a particularly aggressive phenotype and poor clinical outcomes. Recent molecular profiling of these tumors has revealed a high frequency of epidermal growth factor receptor (EGFR) dysregulation, among other abnormalities. EGFR status correlates negatively with survival in patients with triple-negative breast cancers, and thus focus has turned on this receptor as a potential clinical target. Two classes of EGFR inhibitors are currently in clinical use: the monoclonal antibodies and the small molecule tyrosine kinase inhibitors. Trials of these drugs in breast cancer, however, have been largely disappointing. It remains to be seen whether advances in our understanding of the mechanisms of EGFR dysregulation and effects of multiple compensatory pathways in breast cancer, coupled with improved targeting to appropriate patient populations, will yield meaningful improvements in clinical outcomes.

Limited copy number-high resolution melting (LCN-HRM) enables the detection and identification by sequencing of low level mutations in cancer biopsies

Background

Mutation detection in clinical tumour samples is challenging when the proportion of tumour cells, and thus mutant alleles, is low. The limited sensitivity of conventional sequencing necessitates the adoption of more sensitive approaches. High resolution melting (HRM) is more sensitive than sequencing but identification of the mutation is desirable, particularly when it is important to discriminate false positives due to PCR errors or template degradation from true mutations.

We thus developed limited copy number - high resolution melting (LCN-HRM) which applies limiting dilution to HRM. Multiple replicate reactions with a limited number of target sequences per reaction allow low level mutations to be detected. The dilutions used (based on Ct values) are chosen such that mutations, if present, can be detected by the direct sequencing of amplicons with aberrant melting patterns.

Results

Using cell lines heterozygous for mutations, we found that the mutations were not readily detected when they comprised 10% of total alleles (20% tumour cells) by sequencing, whereas they were readily detectable at 5% total alleles by standard HRM. LCN-HRM allowed these mutations to be identified by direct sequencing of those positive reactions.

LCN-HRM was then used to review formalin-fixed paraffin-embedded (FFPE) clinical samples showing discordant findings between sequencing and HRM for KRAS exon 2 and EGFR exons 19 and 21. Both true mutations present at low levels and sequence changes due to artefacts were detected by LCN-HRM. The use of high fidelity polymerases showed that the majority of the artefacts were derived from the damaged template rather than replication errors during amplification.

Conclusion

LCN-HRM bridges the sensitivity gap between HRM and sequencing and is effective in distinguishing between artefacts and true mutations.

Clonal mutations in the cancer-associated fibroblasts: the case against genetic coevolution

It is well established that carcinoma-associated fibroblasts (CAFs) differ phenotypically from fibroblasts associated with normal tissue, but the mechanisms underlying these differences remain controversial. Because CAFs can be propagated in vitro for extended periods and still maintain their cancer promoting phenotype, it has been proposed that they might have acquired somatic genetic alterations analogous to those observed in malignant epithelium. Whereas some investigators have reported frequent and profound genomic alterations in CAFs, other groups have found no such evidence. One striking common trait of those studies reporting frequent clonal somatic alterations in CAFs is the use of tissues and techniques which are well known to be highly prone to generating artefacts, such as limiting and poor quality DNA followed by highly multiplexed PCR-based analysis. We conclude that reported frequent clonal somatic mutations in CAFs are likely to be artefacts and are not the biological basis of the cancer promoting attributes of CAFs. [corrected]

Co-evolution of tumor cells and their microenvironment

Increasing evidence indicates that tumor-stromal cell interactions have a crucial role in tumor initiation and progression. These interactions modify cellular compartments, leading to the co-evolution of tumor cells and their microenvironment. Although the importance of microenvironmental alterations in tumor development is recognized, the molecular mechanisms underlying these changes are only now beginning to be understood. Epigenetic and gene expression changes have consistently been reported in cancer-associated stromal cells and the influence of the host genotype on tumorigenesis is also well documented. However, the presence of clonally selected somatic genetic alterations within the tumor microenvironment has been controversial. A thorough understanding of the co-evolution of these two cellular compartments will require carefully executed molecular studies combined with mathematical modeling.

Molecular characterisation of the tumour microenvironment in breast cancer

The tumour microenvironment plays important roles in cancer initiation, growth, progression, invasion and metastasis, yet the molecular basis underlying these tumour-promoting effects is not fully delineated. Recent advances in gene expression, genetic and epigenetic profiling of stromal cells have improved our understanding of how mesenchymal-epithelial cell interactions may create a permissive microenvironment for malignancy and identified potential targets for cancer prevention and treatment including chemokine and cytokine networks. However, translating these findings into clinical practice may be difficult due to the complexity and redundancy of the interactions and the inherent ability of tumour epithelial cells to evolve and thrive in diverse environmental conditions.

Stimulation of lung carcinoma cell growth by fibronectin-integrin signalling

Throughout many countries, lung cancer will kill more people this year than malignancies related to breast, prostate, colon, liver, kidney and melanoma combined. Despite recent advances in understanding the molecular biology of lung carcinoma and the introduction of multiple new chemotherapeutic agents for its treatment, its dismal five-year survival rate (<15%) has not changed substantially. The lack of advancement in this area reflects the limited knowledge available concerning the factors that promote oncogenic transformation and proliferation of carcinoma cells in the lung. Malignant transformation plays a key role in tumor growth and invasion; however, other factors such as the surrounding stroma, local growth factors, vascularity, and systemic hormones are important contributors as well. We believe that the composition of the lung extracellular matrix is also important due to its ability to affect malignant cell behavior in vitro. The matrix glycoprotein fibronectin, for example, is highly expressed in chronic lung disorders where most lung carcinomas are identified. This document reviews information that implicates fibronectin in the stimulation of lung carcinoma cell growth. Data available to date indicate that by binding to specific integrin receptors expressed on the surface of tumor cells, fibronectin stimulates intracellular signals implicated in the pathobiology of lung carcinogenesis and lung tumor chemoresistance including mitogen-activated protein kinases, GTPases, and the PI3-kinase/Akt/mTOR pathway. Thus, integrin-mediated signals triggered by fibronectin in tumor cells represent promising targets for the development of novel anti-cancer strategies.

Targeting EGFR activity in blood vessels is sufficient to inhibit tumor growth and is accompanied by an increase in VEGFR-2 dependence in tumor endothelial cells

Epidermal growth factor receptor (EGFR) targeting agents such as kinase inhibitors reduce tumor growth and progression. We have previously reported that EGFR is not only expressed by the tumor cells but by the tumor endothelial cells (EC) as well (Amin, D. N., Hida, K., Bielenberg, D. R., Klagsbrun, M., 2006. Tumor endothelial cells express epidermal growth factor receptor (EGFR) but not ErbB3 and are responsive to EGF and to EGFR kinase inhibitors. Cancer Res. 66, 2173-80). Thus, targeting tumor blood vessel EGFR may be a viable strategy for tumor growth inhibition. We describe here a melanoma xenograft model where the tumor cells express very little or no EGFR but the tumor blood vessels express activated EGFR. The EGFR kinase inhibitor, gefitinib (Iressa), retarded tumor growth with a size decrease of 38% compared to control mice, ostensibly due to targeting of the blood vessels. EC were isolated from tumors of gefitinib-treated mice. These EC were unable to proliferate in response to EGF and displayed relatively weaker activation of MAPK and AKT signaling in response to EGF compared to tumor EC isolated from vehicle-treated mice. In contrast, the tumor EC from gefitinib-treated mice expressed higher levels of VEGFR-2 both at the mRNA and protein level. In addition, these cells were less sensitive to EGFR kinase inhibitors in vitro but more sensitive to a VEGFR-2 kinase inhibitor. These results suggest that in tumor EC from gefitinib-treated mice there is a switch from dependence on EGFR activity to signaling via VEGFR-2. Our data provide a molecular rationale for combination therapies targeting both EGF and VEGF signaling on the tumor vasculature.

Pharmacogenomics and gemcitabine

Approximately half of lung cancer patients present with metastases, and a large proportion will develop recurrent disease, with median survival to cisplatin-based chemotherapy of 11 months. No predictive factor of response to cisplatin-based chemotherapy is yet available in clinical practice. The nucleotide excision repair system plays a major role in repairing a variety of distorting lesions, notably platinum-induced DNA adducts. ERCC1 is a leading gene in repairing cisplatin DNA damage. We carried out three different studies examining individually the role of ERCC1, RRM1, and then both, mRNA expression in paraffin-embedded pretreatment bronchial biopsies from gemcitabine/cisplatin-treated advanced non-small-cell lung cancer (NSCLC) patients. Median survival was significantly prolonged in patients with low levels of ERCC1 or RRM1. BRCA1 is involved in homologous recombination repair, and we observed that low levels of BRCA1 mRNA significantly increased survival in gemcitabine/cisplatin-treated patients. Our observations lead us to recommend that tumors be regularly assessed for ERCC1 and BRCA1 mRNA expression in order to customize gemcitabine/cisplatin treatment.

Microenvironmental regulation of cancer development

Numerous studies have demonstrated that the tumor microenvironment not only responds to and supports carcinogenesis, but also actively contributes to tumor initiation, progression, and metastasis. During tumor progression all cells composing the tumor undergo phenotypic and epigenetic changes. Paracrine signaling between epithelial and stromal cells is important for the regulation of the proliferation, invasive, angiogenic, and metastatic behavior of cancer cells. Better understanding the molecular mechanisms by which stromal cells exert these effects may open up new venues for cancer therapeutic and preventative interventions.

Breast cancer: origins and evolution

Breast cancer is not a single disease, but rather is composed of distinct subtypes associated with different clinical outcomes. Understanding this heterogeneity is key for the development of targeted cancer-preventative and -therapeutic interventions. Current models explaining inter- and intratumoral diversity are the cancer stem cell and the clonal evolution hypotheses. Although tumor initiation and progression are predominantly driven by acquired genetic alterations, recent data implicate a role for microenvironmental and epigenetic changes as well. Comprehensive unbiased studies of tumors and patient populations have significantly advanced our molecular understanding of breast cancer, but translating these findings into clinical practice remains a challenge.

Pathology and gene expression of hereditary breast tumors associated with BRCA1, BRCA2 and CHEK2 gene mutations

Tumors arising in BRCA1 and BRCA2 mutation carriers appear to have specific pathological and gene expression profiles, which show a high level of concordance. BRCA1 tumors are high-grade, negative for hormone receptors, have a high proliferation rate, and are positive for some cell cycle promoter genes. BRCA2 tumors present a phenotype opposite to BRCA1 tumors but very similar to sporadic tumors, except that BRCA2 overexpress some DNA repair markers such as CHEK2, show high cytoplasmic expression of RAD51, and are negative for HER-2 amplification and expression. Some of these characteristics have also been found in cDNA expression studies, although more analysis are necessary in order to obtain new markers that can be associated with a germ line mutation in BRCA1 or BRCA2. In this way, some studies in normal tissues of BRCA1/2 carriers suggest that differences exist in the level of expression of some genes when compared with noncarriers. Finally, IHC studies in tumors carrying a mutation in CHEK2 are rare and show contradictory results, probably due to the low number of these cases. However, they represent an example showing how different mutations of the same gene may be associated with specific histological subtypes of cancer.

Epidermal growth factor receptor biology in head and neck cancer

Epidermal growth factor receptor (EGFR) is overexpressed in several epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC), which exhibits EGFR overexpression in up to 90% of tumors. EGFR ligands such as transforming growth factor alpha are also overexpressed in HNSCC. EGFR plays a critical role in HNSCC growth, invasion, metastasis and angiogenesis. However, EGFR inhibitors as monotherapy have yielded only modest clinical outcomes. Potential mechanisms for lack of response to EGFR inhibition in HNSCC include constitutive activation of signaling pathways independent of EGFR, as well as genetic aberrations causing dysregulation of the cell cycle. EGFR-directed therapy may be optimized by identifying and selecting those HNSCC patients most likely to benefit from EGFR inhibition. Resistance to EGFR inhibition may be circumvented by combination therapy employing EGFR inhibitors together with other treatment modalities.

A rapid and sensitive enzymatic method for epidermal growth factor receptor mutation screening

PURPOSE

Mutations in the epidermal growth factor receptor (EGFR) are associated with clinical and radiographic responses to EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Currently available methods of EGFR mutation detection rely on direct DNA sequencing, which requires isolation of DNA from a relatively pure population of tumor cells, cannot be done on small diagnostic specimens, and lack sensitivity. Here we describe the use of a sensitive screening method that overcomes many of these limitations.

EXPERIMENTAL DESIGN

We screened 178 non-small cell lung cancer specimens for mutations in exons 18 to 21 of EGFR using a DNA endonuclease, SURVEYOR, which cleaves mismatched heteroduplexed DNA. Samples were analyzed by high-performance liquid chromatography on the Transgenomic WAVE HS system. Selected specimens that produced digestion products using SURVEYOR were subsequently reanalyzed by size separation or under partially denaturing conditions, followed by fractionation and sequencing. The specimens included DNA isolated from frozen tumor specimens, dissected formalin-fixed, paraffin-embedded tumor specimens undergoing clinical sequencing, and undissected formalin-fixed, paraffin-embedded specimens. One hundred sixty specimens were independently analyzed using direct DNA sequencing in a blinded fashion.

RESULTS

EGFR mutations were detected in 16 of 61 fresh frozen tumor specimens, 24 of 91 dissected formalin-fixed, paraffin-embedded tumor specimens, and 11 of 26 undissected formalin-fixed, paraffin-embedded tumor specimens. Compared with sequencing, the sensitivity and specificity of the present method were 100% and 87%. The positive and negative predictive values were 74% and 100%, respectively. SURVEYOR analysis detected 7 (4%) mutations that were not previously detected by direct sequencing.

CONCLUSIONS

SURVEYOR analysis provides a rapid method for EGFR mutation screening with 100% sensitivity and negative predictive value. This unbiased scanning technique is superior to direct sequencing when used with undissected formalin-fixed, paraffin-embedded specimens.

Total-genome analysis of BRCA1/2-related invasive carcinomas of the breast identifies tumor stroma as potential landscaper for neoplastic initiation

We have shown that the tumor microenvironment of sporadic breast cancer is diverse in genetic alterations and contributes to the cancer phenotype. The dynamic morphology of the mammary gland might be of special interest in hereditary breast/ovarian cancer syndrome (HBOC). We hypothesized that hotspots of loss of heterozygosity or allelic imbalance (LOH/AI) within the tumor stroma of BRCA1/2-related breast cancers provide an impaired mammary stroma that could facilitate later malignant transformation of the breast epithelium. We conducted a total genome LOH/AI scan of DNA derived from the epithelium and stroma of 51 BRCA1/2-related breast cancers, using 372 microsatellite markers. We compared these data with those from a set of 134 sporadic breast cancers. HBOC-related breast cancers accumulated significantly more genetic alterations than did sporadic breast cancers. BRCA1/2-related breast cancer stroma showed LOH/AI at 59.7% of all loci analyzed, similar to the average frequency of LOH/AI observed in the epithelium (66.2%). This is remarkably different from sporadic breast cancers, for which the average epithelial LOH/AI frequency (36.7%) far exceeds the average stromal LOH/AI frequency (28.4%) (P=.03). We identified 11 hotspot loci of LOH/AI in the BRCA1/2 stroma, encompassing genes such as POLD1, which functions in DNA replication, and SDHB. In a subset of samples, enriched for BRCA1 cases, we found 45.0% overall LOH/AI in the stroma, which was significantly higher than the 41.8% LOH/AI observed in corresponding epithelium (P=.04). Together, our data indicate that, in HBOC-related breast cancers, the accumulation of genomic instability in the cancer stroma coincides with that in the neoplastic epithelium, and we postulate that such a genetically unstable stroma might facilitate a microenvironment that functions as a landscaper that promotes genomic instability in the epithelium and, subsequently, neoplastic transformation.

Mutations in the tyrosine kinase domain of the EGFR gene are rare in synovial sarcoma

The prognosis of patients with synovial sarcomas is poor. New therapeutic strategies, such as target inhibition of the tyrosine kinase activity of the epidermal growth factor receptor (EGFR) with erlotinib and gefinitib, could be effective, because most synovial sarcomas overexpress this protein. In lung cancer, the responsiveness to gefinitib is strongly related to the presence of mutations in the tyrosine kinase domain of the EGFR gene, while erlotinib sensitivity seems to be partly linked to chromosome 7 polysomy or gene amplification. To clarify the role of EGFR in synovial sarcoma and to explore the potential for a targeted therapy approach, we have examined 13 of these soft tissue tumors. We have analyzed the EGFR expression by immunohistochemistry, searched for polysomy and gene amplification with fluorescence in situ hybridization (FISH) and screened for EGFR mutations in exons 18-21 using PCR and direct sequencing. All 13 tumors showed strong diffuse or focal EGFR expression. No amplifications of the EGFR gene were found. In contrast, several point mutations were identified in exons 18-21 of two synovial sarcomas. Whereas one of these tumors carried only a synonymous mutation, two missense mutations in exons 19 and 21 of the EGFR gene (P733S and A840 T, respectively) could be demonstrated in the second sample. In conclusion, strong EGFR expression in synovial sarcomas is not related to gene amplification. The existence of mutations in the tyrosine kinase domain of the EGFR gene in a small subset of synovial sarcomas suggests that only few patients may profit from the tyrosine kinase inhibitor therapy.

Future directions in the second-line treatment of non-small cell lung cancer

Single-agent chemotherapy has shown limited activity as second-line treatment in metastatic non-small cell lung cancer (NSCLC), with short-lived responses and modest survival benefit over best supportive care or placebo. There are multiple ways to improve the poor outcome of patients whose disease progresses after first-line chemotherapy. First, individualizing second-line chemotherapy could optimize its effect; the discovery of dramatic responses and significant improvement in survival in patients with epidermal growth factor receptor (EGFR) gene mutations who are treated with EGFR tyrosine kinase inhibitors may lead to the application of other novel therapeutic approaches. Cancer vaccines, using autologous tumor cells genetically modified with granulocyte-macrophage colony-stimulating factor, constitute a new therapeutic option for patients with chemoresistant advanced NSCLC. Vaccines based on lymphocyte-defined tumor antigens, such as melanoma-associated antigen-3, toll-like receptor 9, and mucin 1, are also in the first stages of testing and have shown promising preliminary results. New approaches in gene therapy, including a p53-based method, are currently being investigated. The ultimate goal of gene therapy is to target cancerous stem cells, the importance of which is beginning to be recognized in NSCLC through the study of abnormalities in the wingless (Wnt) pathway. At the preclinical level, small interfering RNA sequences have been used successfully to neutralize multiple abnormal components of the Wnt pathway.

Treatment of non-small-cell lung cancer and pharmacogenomics: where we are and where we are going

PURPOSE OF REVIEW

This review highlights the numerous molecular biology findings in the field of lung cancer with potential therapeutic impact in both the near and distant future.

RECENT FINDINGS

Abundant preclinical and clinical data indicate that BRCA1 mRNA expression is a differential modulator of chemotherapy sensitivity. Single nucleotide polymorphisms in the excision repair cross-complementing 1 gene (ERCC1) influence survival with cisplatin-based chemotherapy. For the first time, epidermal growth factor receptor (EGFR) mutations have been shown to predict dramatic responses in metastatic lung adenocarcinomas. The crosstalk between estrogen and EGFR pathways have also been revealed. MicroRNAs control the expression of cognate target genes and predict relapse in surgically resected non-small-cell lung cancer patients. Overexpression of the Wingless-type (Wnt) genes and methylation of Wnt antagonists have been documented in non-small-cell lung cancer.

SUMMARY

Understanding the relevance of these findings can help to change the clinical practice in oncology towards customizing chemotherapy and targeted therapies, leading to improvement both in survival and in cost-effectiveness.

EGFR amplification and lack of activating mutations in metaplastic breast carcinomas

Metaplastic breast carcinomas are reported to harbour epidermal growth factor receptor (EGFR) overexpression in up to 80% of the cases, but EGFR gene amplification is the underlying genetic mechanism in around one-third of these. In this study, EGFR gene amplification as defined by chromogenic in situ hybridization and protein overexpression was examined in a cohort of 47 metaplastic breast carcinomas. Furthermore, the presence of activating EGFR mutations in exons 18, 19, 20, and 21 was investigated. Thirty-two cases showed EGFR overexpression and of these, 11 (34%) harboured EGFR gene amplification. In addition, EGFR amplification showed a statistically significant association with EGFR overexpression (p < 0.0094) and was restricted to carcinomas with homologous metaplasia. Ten cases, five with and five without EGFR amplification, were subjected to microarray-based CGH, which demonstrated that EGFR copy number gain may occur by amplification of a discrete genomic region or by gains of the short arm of chromosome 7 with a breakpoint near the EGFR gene locus, the minimal region of amplification mapping to EGFR, LANCL2, and SEC61G. No activating EGFR mutations were identified, suggesting that this is unlikely to be a common alternative underlying genetic mechanism for EGFR expression in metaplastic breast carcinomas. Given that metaplastic breast carcinomas are resistant to conventional chemotherapy or hormone therapy regimens and that tumours with EGFR amplification are reported to be sensitive to EGFR tyrosine kinase inhibitors, these findings indicate that further studies are warranted to explore EGFR tyrosine kinase inhibitors as potential therapeutic agents for metaplastic breast carcinomas harbouring amplification of 7p11.2.

Metaplastic breast carcinomas exhibit EGFR, but not HER2, gene amplification and overexpression: immunohistochemical and chromogenic in situ hybridization analysis

INTRODUCTION

Metaplastic breast carcinomas constitute a heterogeneous group of neoplasms, accounting for less than 1% of all invasive mammary carcinomas. Approximately 70-80% of metaplastic breast carcinomas overexpress the epidermal growth factor receptor (EGFR). Human epidermal growth factor receptor (HER)2 and EGFR have attracted much attention in the medical literature over the past few years owing to the fact that humanized monoclonal antibodies against HER2 and therapies directed against the extracellular ligand-binding domain or the intracellular tyrosine kinase domain of EGFR have proven successful in treating certain types of human cancer. We investigated whether HER2 and EGFR overexpression was present and evaluated gene amplification in a series of metaplastic breast carcinomas.

METHOD

Twenty-five metaplastic breast carcinomas were immunohistochemically analyzed using a monoclonal antibody (31G7) for EGFR and two antibodies for HER2 (Herceptest and CB11) and scored using the Herceptest scoring system. Gene amplification was evaluated by chromogenic in situ hybridization using Zymed Spot-Light EGFR and HER2 amplification probe. The results were evaluated by bright field microscopy under 40x and 63x objective lenses.

RESULTS

Nineteen (76%) metaplastic breast carcinomas exhibited EGFR ovexpression, and among these EGFR amplification (defined either by large gene clusters or >5 signals/nucleus in >50% of neoplastic cells) was detected in seven cases (37%): three carcinomas with squamous differentiation and four spindle cell carcinomas. One case exhibited HER2 overexpression of grade 2+ (>10% of cells with weak to moderate complete membrane staining), but HER2 gene amplification was not detected.

CONCLUSION

Metaplastic breast carcinomas frequently overexpressed EGFR, which was associated with EGFR gene amplification in one-third of cases. Our findings suggest that some patients with metaplastic breast carcinomas might benefit from novel therapies targeting EGFR. Because most metaplastic breast carcinomas overexpress EGFR without gene amplification, further studies to evaluate EGFR activating mutations are warranted.