Epidermal growth factor receptor abnormalities in lung cancer. Pathogenetic and clinical implications

Pattern and Dynamics of FLT3 Duplications

FMS-like tyrosine kinase 3 (FLT3) is mutated in ∼30% of patients that suffer from acute myeloid leukemia (AML). In about 25% of all AML patients, in-frame insertions are observed in the sequence. Most of those insertions are internal tandem duplications (ITDs) of a sequence from the protein. The characteristics of such mutations in terms of length, sequence, and location were hitherto studied in different populations, but not in a comprehensive mutation database. Here, in-frame insertions into the FLT3 gene were extracted from the Catalogue of Somatic Mutations in Cancer (COSMIC) database. These were analyzed with respect to the length, location, and sequence of the mutations. Furthermore, characteristic strings (sequences) of different lengths were identified. Mutations were shown to occur most often in the juxtamembrane zipper (JM-Z) domain of FLT3, followed by the hinge domain and first tyrosine kinase domain (TKD1), upstream of the phosphate-binding loop (P-loop). Interestingly, there are specific hot spot residues where insertions are more likely to occur. The insertions vary in length between one and 67 amino acids, with the largest insertions spanning the phosphate binding loop. Insertions that occur downstream of the P-loop are shorter. Our analysis further shows that acidic and aromatic residues are enriched in the insertions. Finally, molecular dynamics simulations were run for FLT3 with ITD insertions in the hinge and tyrosine kinase domains. On the basis of the findings, a mechanism is proposed for activation by ITDs, according to which there is no direct coupling between the length of the insertion and the activity of the mutated protein. The effect of insertions on the sensitivity of FLT3 to kinase inhibitors is discussed based on our findings.

Exploring the Role of Novel Medical Therapies for Aggressive Pituitary Tumors: A Review of the Literature-"Are We There Yet?"

Aggressive pituitary tumors account for up to 10% of pituitary tumors and are characterized by resistance to medical treatment and multiple recurrences despite standard therapies, including surgery, radiotherapy, and chemotherapy. They are associated with increased morbidity and mortality, particularly pituitary carcinomas, which have mortality rates of up to 66% at 1 year after diagnosis. Novel targeted therapies under investigation include mammalian target of rapamycin (mTOR), tyrosine kinase, and vascular endothelial growth factor (VEGF) inhibitors. More recently, immune checkpoint inhibitors have been proposed as a potential treatment option for pituitary tumors. An increased understanding of the molecular pathogenesis of aggressive pituitary tumors is required to identify potential biomarkers and therapeutic targets. This review discusses novel approaches to the management of aggressive pituitary tumors and the role of molecular profiling.

Different subtypes of EGFR exon19 mutation can affect prognosis of patients with non-small cell lung adenocarcinoma

Aims

In this study, we determined whether different subtypes of epidermal growth factor receptor (EGFR) exon19 mutation are associated with the therapeutic effect of EGFR-tyrosine kinase inhibitors (TKIs) on advanced non-small cell lung adenocarcinoma.

Methods

A total of 122 patients with stage III or IV non-small cell lung adenocarcinoma were retrospectively reviewed. Clinical characteristics of these patients, including progression-free survival (PFS) outcome for EGFR-TKI treatment, were analyzed.

Results

According to the mutation pattern, we classified the in-frame deletions detected on EGFR Exon19 into three different types: codon deletion (CD), with a deletion of one or more original codons; codon substitution and skipping (CSS), with a deletion of one or two nucleotides but the residues could be translated into a new amino acid without changing following amino acid sequence; CD or CSS plus single nucleotide variant (SNV) (CD/CSS+SNV), exclude CD or CSS, there’s another SNV nearby the deletion region. The clinical characteristics of three groups were analyzed and as a result, no significant difference was found. By comparing the average number of missing bases and amino acids of the three mutation subtypes, it could be discovered that the number of missing bases and amino acids of the three mutation subtypes is diverse, and group CSS> group CD> group CD/CSS+SNV. Finally, survival analysis was performed between three groups of patients. The median PFS of group CD, group CSS and group CD/CSS+SNV was 11 months, 9 months and 14 months respectively. There was a distinct difference in the PFS between group CSS and group CD/CSS+SNV (P = 0.035<0.05), and the PFS of group CD/CSS+SNV was longer.

Conclusions

Different mutation subtypes of EGFR exon19 can predict the therapeutic effect of EGFR-TKIs on advanced non-small cell lung adenocarcinoma.

Be Active or Not: the Relative Contribution of Active and Passive Tumor Targeting of Nanomaterials

Malignant tumor (cancer) remains as one of the deadliest diseases throughout the world, despite its overall mortality drops. Nanomaterials (NMs) have been widely studied as diagnostic and/or therapeutic agents for tumors. A feature of NMs, compared to small molecules, is that NMs can be concentrated passively in tumors through enhanced permeability and retention (EPR) effect. In the meantime, NMs can be engineered to target toward tumor specific markers in an active manner, e.g., receptor-mediated targeting. The relative contribution of the EPR effect and the receptor-mediated targeting to NM accumulation in tumor tissues has not been clearly defined yet. Here, we tackle this fundamental issue by reviewing previous studies. First, we summarize the current knowledge on these two tumor targeting strategies of NMs, and on how NMs arrive to tumors from blood circulation. We then demonstrate that contribution of the active and passive effects to total accumulation of NMs in tumors varies with time. Over time, the receptor-mediated targeting contributes more than the EPR effect with a ratio of 3 in the case of urokinase-type plasminogen activator receptor (uPAR)-mediated targeting and human serum albumin (HSA)-mediated EPR effect. Therefore, this review highlights the dynamics of active and passive targeting of NMs on their accumulation at tumor sites, and is valuable for future design of NMs in cancer diagnosis and treatment.

Circulating Cell-Free Tumour DNA in the Management of Cancer

With the development of new sensitive molecular techniques, circulating cell-free tumour DNA containing mutations can be identified in the plasma of cancer patients. The applications of this technology may result in significant changes to the care and management of cancer patients. Whilst, currently, these "liquid biopsies" are used to supplement the histological diagnosis of cancer and metastatic disease, in the future these assays may replace the need for invasive procedures. Applications include the monitoring of tumour burden, the monitoring of minimal residual disease, monitoring of tumour heterogeneity, monitoring of molecular resistance and early diagnosis of tumours and metastatic disease.

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.

Reliable detection of rare mutations in EGFR gene codon L858 by PNA-LNA PCR clamp in non-small cell lung cancer

PNA-LNA PCR clamp real-time PCR method represents allele-specific approach to mutation analysis of EGFR gene in NSCLC. Due to its unique design, it is characterized by exceptionally high specificity and sensitivity but also allows detection of rare or not specifically-targeted EGFR mutations within examined exons, otherwise undetectable by other mutation-specific fluorescent probes. We herein present two cases of rare mutations revealed by PNA-LNA PCR clamping of NSCLC samples referred for routine EGFR gene molecular diagnostics. In one, the EGFR gene L858 codon mutation was detected by standard PNA-LNA PCR clamping, subsequently reconfirmed and characterized by direct sequencing of allele specific amplification products as the missense mutation c.2572C>A (p.L858M) paired with L861Q mutation on the same allele (in cis). In the second sample, low quality FFPE material from pleural biopsy, c.2573C>T missense mutation (p.L858P) was revealed. Still, repeated DNA analysis by PNA-LNA PCR clamp and direct sequencing demonstrated low level of mutant allele existing in a total allele pool suggesting rather artifactual c.2572C>T transition, a phenomenon quite frequent in low-volume FFPE samples upon fixation procedures. In conclusion, superior sensitivity and unique design of PNA-LNA PCR clamping are crucial for its excellent diagnostic effectiveness. As we demonstrated, the method allows detecting rare EGFR mutations, although it increases the risk of detection of a very low signal, e.g., generated by a small pool of mutated allele. Therefore, applicability of PNA-LNA PCR clamp product for the direct sequencing reevaluation is of key importance enabling reliable validation of results.

Intratumor heterogeneity and chemotherapy-induced changes in EGFR status in non-small cell lung cancer

INTRODUCTION

Biomarker expression is increasingly being used to customize treatment in non-small cell lung cancer (NSCLC). The choice of systemic treatment usually depends on biomarker expression in the initial diagnostic biopsy taken before initiation of first-line treatment. Chemotherapy induces DNA damages in the tumor cells, and thus, biomarker expression in the tumor after systemic treatment might not be identical to biomarker expression in the diagnostic biopsy. NSCLC is highly heterogeneous and biomarker expression may vary in different areas within the same tumor. This review explores the tumor heterogeneity and chemotherapy-induced changes in EGFR biomarker status in NSCLC.

METHODS

A literature search was performed in August 2011 using pubmed.

RESULTS

Fifteen trials explored EGFR status in primary tumor and subsequent resected primary tumor, lymph node metastases, or organ metastases. Four papers compared EGFR status in primary tumor or metastases before and after systemic treatment. All trials included relatively few patients and used different chemotherapy regimes, biopsy locations, or time intervals between biopsies.

CONCLUSIONS

Tumor heterogeneity and probably also previous systemic treatment may be an obstacle for correct interpretation of EGFR status in NSCLC. Heterogeneity regarding EGFR mutations is probably rare and previously reported intra and intertumor heterogeneity may be due to methodological issues. In the current and future clinical scenario with many different options for systemic treatment both as 2nd line and beyond, it is increasingly important to further elucidate the role extent of chemotherapy-induced changes in biomarker expression for proper use of biomarkers in order to customize treatment and thus improve prognosis.

Recurrent genomic gains in preinvasive lesions as a biomarker of risk for lung cancer

Lung carcinoma development is accompanied by field changes that may have diagnostic significance. We have previously shown the importance of chromosomal aneusomy in lung cancer progression. Here, we tested whether genomic gains in six specific loci, TP63 on 3q28, EGFR on 7p12, MYC on 8q24, 5p15.2, and centromeric regions for chromosomes 3 (CEP3) and 6 (CEP6), may provide further value in the prediction of lung cancer. Bronchial biopsy specimens were obtained by LIFE bronchoscopy from 70 subjects (27 with prevalent lung cancers and 43 individuals without lung cancer). Twenty six biopsies were read as moderate dysplasia, 21 as severe dysplasia and 23 as carcinoma in situ (CIS). Four-micron paraffin sections were submitted to a 4-target FISH assay (LAVysion, Abbott Molecular) and reprobed for TP63 and CEP 3 sequences. Spot counts were obtained in 30-50 nuclei per specimen for each probe. Increased gene copy number in 4 of the 6 probes was associated with increased risk of being diagnosed with lung cancer both in unadjusted analyses (odds ratio = 11, p<0.05) and adjusted for histology grade (odds ratio = 17, p<0.05). The most informative 4 probes were TP63, MYC, CEP3 and CEP6. The combination of these 4 probes offered a sensitivity of 82% for lung cancer and a specificity of 58%. These results indicate that specific cytogenetic alterations present in preinvasive lung lesions are closely associated with the diagnosis of lung cancer and may therefore have value in assessing lung cancer risk.

Recent advances of novel targeted therapy in non-small cell lung cancer

Lung cancer is the leading cause of cancer deaths world-wide. Recent advances in cancer biology have led to the identification of new targets in neoplastic cells and the development of novel targeted therapies. At this time, two targeted agents are approved by the FDA in advanced non-small cell lung cancer (NSCLC): the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) erlotinib, and the anitangiogenic bevacizumab. A third agent, cetuximab, which was recently shown to enhance survival when used with cisplatin and vinorelbine as first line therapy for advanced NSCLC, will likely be approved by regulatory agencies. With more than 500 molecularly targeted agents under development, the prospects of identifying novel therapies that benefit individual patients with lung cancer are bright.

Gold nanoparticles: From nanomedicine to nanosensing

Because of their photo-optical distinctiveness and biocompatibility, gold nanoparticles (AuNPs) have proven to be powerful tools in various nanomedicinal and nanomedical applications. In this review article, we discuss recent advances in the application of AuNPs in diagnostic imaging, biosensing and binary cancer therapeutic techniques. We also provide an eclectic collection of AuNPs delivery strategies, including assorted classes of delivery vehicles, which are showing great promise in specific targeting of AuNPs to diseased tissues. However, successful clinical implementations of the promised applications of AuNPs are still hampered by many barriers. In particular, more still needs to be done regarding our understanding of the pharmacokinetics and toxicological profiles of AuNPs and AuNPs-conjugates.

Flavonoids as RTK inhibitors and potential anticancer agents

Tyrosine kinase receptors (RTKs) play a crucial role in the regulation of the cell division cycle. Currently more than 50 RTKs divided into several subfamilies have been described. The inhibition of these enzymes has emerged as an important research-area. Compounds able to inhibit the activity of these enzymes are expected to display antiproliferative properties. Flavonoids are representative of various small molecules acting as RTK inhibitors. These naturally occurring compounds are able to bind to the ATP-binding site of several kinases. The most plausible current hypothesis explaining the action of these substances on kinases is that the chromenone moiety of the flavonoid acts as a mimetic of the adenine moiety of ATP, the receptor co-factor. In this review, we report recent results on the activity of natural and synthetic derivatives of flavonoids as inhibitors of RTKs. Mechanistic aspects, the therapeutic usefulness, and the potential clinical use are discussed.

MET gene copy number in non-small cell lung cancer: molecular analysis in a targeted tyrosine kinase inhibitor naïve cohort

INTRODUCTION

Recent clinical success of epidermal growth factor (EGFR)-tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) have raised hopes that targeting other deregulated growth factor signaling, such as the hepatocyte growth factor/MET pathway, will lead to new therapeutic options for NSCLC. Furthermore, NSCLC present secondary EGFR-TKIs resistance related to exons 20 and 19 EGFR mutations or more recently to MET amplification. The aim of this study was to determine MET copy number related to EGFR copy number and K-Ras mutations in a targeted TKI naive NSCLC cohort.

METHODS

We investigated 106 frozen tumors from surgically resected NSCLC patients. Genes copy number of MET and EGFR were assessed by quantitative relative real-time polymerase chain reaction and K-Ras mutations by sequencing.

RESULTS

MET is amplified in 22 cases (21%) and deleted in nine cases (8.5%). EGFR is amplified in 31 cases (29%). K-Ras is mutated in 11 cases (10.5%). As observed for EGFR amplification, MET amplification is never associated with K-Ras mutation. MET amplification could be associated with EGFR amplification. MET amplification is not related to clinical and pathologic features. MET amplification and EGFR amplification showed a trend toward poor prognosis in adenocarcinomas.

CONCLUSION

In EGFR-TKIs naive NSCLC patients, MET amplification is a frequent event, which could be associated with EGFR amplification, but not with K-Ras mutation. MET amplification may identify a subset of NSCLC for new targeted therapy. It will also be important to evaluate MET copy number to properly interpret future clinical trials.

[Clinical and molecular predictors of response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer]

Up to 10% of patients with non-small cell lung carcinoma (NSCLC) achieve an objective response to EGFR tyrosine kinase inhibitors (EGFR-TKI) such as erlotinib or gefitinib. This rate of response is related to non-smoker status, female gender, adenocarcinoma subtype, and Asian ethnicity. Molecular analysis showed that EGFR tyrosine kinase domain somatic mutations appear to be a strong predictor of response to EGFR-TKI. The L858R point mutation and the E746-A750 deletion represent 90% of the mutations encountered in responding patients. The amplification of EGFR gene also seems to be predictive of the response to EGFR-TKI, whereas T790M point mutation induces secondary resistance to EGFR-TKI. Nevertheless, objective responses or strong long-term stabilizations are observed in patients without any EGFR abnormality. Thus, the assessment of the EGFR status in patients with NSCLC remains controversial for clinical practice. The assessment of EGFR abnormalities should be targeted to identify reliable biomarkers of the NSCLC response to EGFR-TKI. This review presents the current knowledge on predictive biomarkers of NSCLC response to EGFR-TKI and the methods available for the assessment of EGFR status.

Detection of epidermal growth factor receptor gene mutations in cytology specimens from patients with non-small cell lung cancer utilising high-resolution melting amplicon analysis

Background:

Activating epidermal growth factor receptor (EGFR) mutations have been implicated in non-small cell lung cancer (NSCLC), and have also been clinically correlated with patient sensitivity to targeted EGFR inhibitors.

Aim:

To describe a technique for determining EGFR mutation status on archival fine needle aspirate (FNA) specimens from advanced NSCLC patients.

Methods:

Eleven archival FNA slides from patients with advanced NSCLC were examined for diagnostic material to identify tumour cell-enriched regions. EGFR mutation status was determined using a slide-scrape DNA extraction protocol of selected tumour cell regions on the smear slides, followed by real time PCR and high resolution melt analysis (HRMAA) of EGFR exons 18, 19, 20, and 21, followed by sequence analysis.

Results:

All DNA samples were successfully amplified by PCR. Three adenocarcinoma patient samples contained EGFR mutations in exon 19 (L747-P753insS). One of the three had an additional exon 19 mutation (A755D).

Conclusions:

Archival cytology slides from patients with NSCLC can be used to determine EGFR mutation status by PCR, HRMAA, and sequencing. The ability to use archival cytology slides greatly increases the potential material available for molecular analysis in diagnosis and selection of patients for targeted therapeutic agents.

EGFR expression as an ancillary tool for diagnosing lung cancer in cytology specimens

Lung cancer evolves in a multistep process, and its early detection portends a better prognosis. Bronchial washings/brushings and fine-needle aspirations are often used as early screening and cytological diagnosis of lung cancer. In some cases, it is difficult to differentiate morphologically malignant from reactive cells. Epidermal growth factor receptor (EGFR) is a transmembrane receptor overexpressed in high percentage lung cancers, and contributes to tumor growth. Assessing EGFR expression levels by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) may provide critical information of tumor marker abnormalities, assist in the cytological diagnosis, and stratify patients for EGFR inhibitor therapy. Fifty patients with bronchial washings/brushings or fine-needle aspiration specimens, and corresponding histologically confirmed lung biopsies, were studied for EGFR expression with FISH and IHC. Copy numbers of the EGFR gene locus were analyzed with those of chromosome 7 by FISH. EGFR and FISH results were compared to our FISH data with combined EGFR, c-myc, 5p15.2, and chromosome 6 probes in selected cases. Cell blocks, if available, and tissue biopsy sections were used for EGFR IHC. The intensity of IHC was scored, and quantified. Only balanced aneuploidy of EGFR was identified by FISH. Gene amplification was not detected. The chromosomal abnormalities of EGFR were often accompanied by other chromosomal aneuploidies demonstrated in c-myc (8q24), 5p15.2 or 6p, indicating a general genomic instability. About half of the specimens with confirmed malignancy showed EGFR balanced aneuploidy by FISH, and gene copy number was not coupled with protein expression in many cases. The benign or reactive cytology specimens confirmed by biopsies had high specificity by FISH (96%) and IHC (88%). FISH and IHC analysis of EGFR, possibly along with other tumor markers, may be a useful ancillary tool to classify difficult cytology cases and inform clinicians arranging targeted chemotherapy.

Molecular pathogenesis of early-stage non-small cell lung cancer and a proposal for tissue banking to facilitate identification of new biomarkers

Non-small cell lung carcinoma (NSCLC) is one of the leading causes of death from cancer in both Eastern and Western countries. For patients with stage I NSCLC, full lobar or more extensive surgical resection is the treatment of choice. However, even among patients with surgically resected, stage I NSCLC, up to 30% of patients die of the disease within 5 years. At present, apart from clinical stage, there are no established cancer-specific clinical variables or biomarkers that reliably identify individuals at increased risk of death after surgical resection-individuals who could be candidates for adjuvant therapy or alternative management strategies. At a recent international workshop, participants discussed a clinical trial to compare radiation therapy with surgery among patients with stage I NSCLC. This study offers the opportunity to prospectively obtain, bank, and analyze tissue and other clinical specimens, which should facilitate the identification of new biomarkers for early detection, prognosis, and therapy in lung cancer.

Inhibition of epidermal growth factor receptor signalling reduces hypercalcaemia induced by human lung squamous-cell carcinoma in athymic mice

The purpose of this study was to evaluate the role of the epidermal growth factor receptor (EGFR) in parathyroid hormone-related protein (PTHrP) expression and humoral hypercalcaemia of malignancy (HHM), using two different human squamous-cell carcinoma (SCC) xenograft models. A randomised controlled study in which nude mice with RWGT2 and HARA xenografts received either placebo or gefitinib 200 mg kg⁻¹ for 3 days after developing HHM. Effectiveness of therapy was evaluated by measuring plasma calcium and PTHrP, urine cyclic AMP/creatinine ratios, and tumour volumes. The study end point was at 78 h. The lung SCC lines, RWGT2 and HARA, expressed high levels of PTHrP mRNA as well as abundant EGFR protein, but very little erbB2 or erbB3. Both lines expressed high transcript levels for the EGFR ligand, amphiregulin (AREG), as well as, substantially lower levels of transforming growth factor-α (TGF-α), and heparin binding-epidermal growth factor (HB-EGF) mRNA. Parathyroid hormone-related protein gene expression in both lines was reduced 40–80% after treatment with 1 μM of EGFR tyrosine kinase inhibitor PD153035 and precipitating antibodies to AREG. Gefitinib treatment of hypercalcaemic mice with RWGT2 and HARA xenografts resulted in a significant reduction of plasma total calcium concentrations by 78 h. Autocrine AREG stimulated the EGFR and increased PTHrP gene expression in the RWGT2 and HARA lung SCC lines. Inhibition of the EGFR pathway in two human SCC models of HHM by an anilinoquinazoline demonstrated that the EGFR tyrosine kinase is a potential target for antihypercalcaemic therapy.

Epidermal growth factor receptor mutations in lung cancer

The development and clinical application of inhibitors that target the epidermal growth factor receptor (EGFR) provide important insights for new lung cancer therapies, as well as for the broader field of targeted cancer therapies. We review the results of genetic, biochemical and clinical studies focused on somatic mutations of EGFR that are associated with the phenomenon of oncogene addiction, describing 'oncogenic shock' as a mechanistic explanation for the apoptosis that follows the acute treatment of susceptible cells with kinase inhibitors. Understanding the genetic heterogeneity of epithelial tumours and devising strategies to circumvent their rapid acquisition of resistance to targeted kinase inhibitors are essential to the successful use of targeted therapies in common epithelial cancers.