A diagnostic algorithm using EGFR mutation-specific antibodies for rapid response EGFR-TKI treatment in patients with non-small cell lung cancer

The lonely driver or the orchestra of mutations? How next generation sequencing datasets contradict the concept of single driver checkpoint mutations in solid tumours - NSCLC as a scholarly example

Driver mutations are considered to be responsible for the majority of cancers and several of those mutations provide targets in order to set up personalized therapies. So far the generally accepted opinion had been that driver mutations occur as stand-alone factors, but novel sequencing technologies induced an essential rethink. Next generation sequencing approaches have shown that double, triple or multiple concurrent mutations could occur within the same tumour and may by interaction influence sensitivity to anticancer drugs and therapy success. This review focusses on this novel concept and discusses the challenges for molecular pathology and laboratory diagnostics while providing putative solutions to overcome the present pitfalls, thereby taking NSCLC as an example.

Overexpression of mutant EGFR protein indicates a better survival benefit from EGFR-TKI therapy in non-small cell lung cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) is a novel target for therapy in a subset of non-small cell lung cancer (NSCLC). Tumors with EGFR mutations showed good response to EGFR tyrosine kinase inhibitors (TKIs). We aimed to identify the discriminating capacity of immunohistochemistry (IHC) to detect EGFR L858R and del E746-A750 mutations in NSCLC patients and predict EGFR TKIs response.

METHODS

We collected specimens from 200 patients with NSCLC whose EGFR mutation status had been validated by direct DNA sequencing. IHC analyses using EGFR mutation-specific antibodies were employed for all samples. After staining and scoring, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.

RESULTS

The sensitivity, specificity, PPV, and NPV of IHC using EGFR del E746-A750 and L858R mutation antibodies were 95.0%/95.1%, 85.7%/94.1%, 74.0%/91.8%, and 97.6%/96.5%, respectively. When score 2+ and 3+ were considered as positive, the sensitivity, specificity, PPV, and NPV were 53.3%/36.6%, 99.3%/100%, 97.0%/100%, and 83.2%/65.3%, respectively. The median progression-free survival (PFS) after the start of gefitinib treatment was significantly longer in patients with a high score for mutant EGFR expression than in those with a low score (31.0 versus 13.0 months, p <0.05).

CONCLUSIONS

IHC with EGFR mutation-specific antibodies is a promising screening method for detecting EGFR mutations in NSCLC patients. Otherwise, quantitative analysis of mutant EGFR expression might also predict the efficacy of TKIs treatment for NSCLC patients harboring sensitive EGFR mutation.

Detection of epidermal growth factor receptor mutations in lung adenocarcinoma cytological specimens by immunocytochemistry

Tyrosine kinase inhibitors of epidermal growth factor receptor (EGFR) improve the survival of patients with lung adenocarcinoma, and determine the EGFR mutation status before treatment is necessary. In contrast to biopsy samples, cytological specimens are obtained less invasively and are useful for EGFR mutation analyses. Recently, novel antibodies against two major EGFR mutations were developed: SP111, which is specific for the E746-A750 deletion in exon 19; and SP125, which is specific for the L858R mutation. To the best of our knowledge, no study has evaluated cytological specimens using the two novel antibodies, thus their specificity and sensitivity were examined in surgical resection, and cytological lung adenocarcinoma samples in the present study. Previous screening for EGFR mutation status by molecular testing identified delE746-A750 in 3 cases and the L858R mutation in 7 cases; the other cases did not have the L858R or the delE746-A750 mutation. Using a four-grade scoring system (score 0 to 3+), the immunohistochemistry (IHC) and immunocytochemistry (ICC) results were compared with those of molecular testing. Using a score of ≥2 as positive, IHC and ICC using SP111 demonstrated sensitivities of 100 and 33.3%, and specificities of 100 and 100%, respectively. IHC and ICC using SP125 revealed sensitivities of 100 and 71.4%, and specificities of 100 and 100%, respectively. Therefore, screening for EGFR mutations by ICC may facilitate therapeutic decision-making, particularly in medical centers that are unable to perform molecular testing.

A novel, rapid point-of-care test for lung cancer patients to detect epidermal growth factor receptor gene mutations by using real-time droplet-PCR and fresh liquid cytology specimens

Epidermal growth factor receptor gene (EGFR) mutations are associated with response to tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). We developed a novel, rapid EGFR mutation assay using a real-time droplet-polymerase chain reaction machine (EGFR d-PCR assay). The purpose of this study was to validate the performance of the EGFR d-PCR assay using fresh liquid cytology specimens. We analyzed three major EGFR mutations (L858R in exon 21, E746_A750del in exon 19 and T790M in exon 20) in 80 fresh liquid cytology specimens of adenocarcinoma (ADC) or NSCLC-not otherwise specified (NOS) via the EGFR d-PCR assay and conventional real-time PCR assay using the therascreen® EGFR RGQ PCR kit (Therascreen assay). In addition, we performed sensitivity assays using cell lines with EGFR mutations. The EGFR d-PCR assay detected 16 L858Rs, 8 E746_A750dels and 1 T790M mutation and the Therascreen assay detected 16 L858Rs, 11 deletions in exon 19 and 1 T790M mutation. The results were concordant between the two assays. The reaction time of the EGFR d-PCR assay was 8 min and 10 sec, but that of the Therascreen assay was 1 h and 45 min. Sensitivity, as assessed by the detection limit of the EGFR d-PCR assay was 0.5, 0.05 and 0.5% for L858R, E746_A750del and T790M, respectively. The EGFR d-PCR assay markedly reduced the detection time of major EGFR mutations with high sensitivity compared with the conventional Therascreen assay and is expected to expedite EGFR-TKI therapy for lung cancer patients, especially those in advanced stages.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.

The Contrasting Role of p16Ink4A Patterns of Expression in Neuroendocrine and Non-Neuroendocrine Lung Tumors: A Comprehensive Analysis with Clinicopathologic and Molecular Correlations

Lung cancer encompasses a constellation of malignancies with no validated prognostic markers. p16Ink4A expression has been reported in different subtypes of lung cancers; however, its prognostic value is controversial. Here, we sought to investigate the clinical significance of p16Ink4A immunoexpression according to specific staining patterns and its operational implications. A total of 502 tumors, including 277 adenocarcinomas, 84 squamous cell carcinomas, 22 large cell carcinomas, 47 typical carcinoids, 12 atypical carcinoids, 28 large cell neuroendocrine carcinomas, and 32 small cell carcinomas were reviewed and subjected to immunohistochemical analysis for p16Ink4A and Ki67. The spectrum of p16Ink4A expression was annotated for each case as negative, sporadic, focal, or diffuse. Expression at immunohistochemical level showed intra-tumor homogeneity, regardless tumor histotype. Enrichments in cells expressing p16Ink4A were observed from lower- to higher-grade neuroendocrine malignancies, whereas a decrease was seen in poorly and undifferentiated non-neuroendocrine carcinomas. Tumor proliferation indices were higher in neuroendocrine tumors expressing p16Ink4A while non-neuroendocrine malignancies immunoreactive for p16Ink4A showed a decrease in Ki67-positive cells. Quantitative statistical analyses including each histotype and the p16Ink4A status confirmed the independent prognostic role of p16Ink4A expression, being a high-risk indicator in neuroendocrine tumors and a marker of good prognosis in non-neuroendocrine lung malignancies. In this study, we provide circumstantial evidence to suggest that the routinary assessment of p16Ink4A expression using a three-tiered scoring algorithm, even in a small biopsy, may constitute a reliable, reproducible, and cost-effective substrate for a more accurate risk stratification of each individual patient.

Detection of EGFR-TK domain-activating mutations in NSCLC with generic PCR-based methods

Somatic mutations in the epidermal growth factor receptor-tyrosine kinase (EGFR-TK) domain of non-small cell lung cancer (NSCLC) influence the responsiveness of these tumors to EGFR-TK inhibitors, indicating their usefulness as a predictive molecular marker. However, for mutation analysis, the amount of clinical material available from NSCLC patients is often very limited, suboptimally preserved, and composed of both normal and tumor cells. As a consequence, the total amount of recovered DNA is frequently very limited, with mutant alleles being often strongly underrepresented, and thus requiring highly sensitive methods for the detection of mutations. In the present study, EGFR mutation screening was performed on 210 NSCLC clinical samples by heminested polymerase chain reaction (PCR), followed by denaturing gradient gel electrophoresis (DGGE). Candidate mutations were further characterized by sequencing. Seventeen different types of pathogenic EGFR-TK domain mutations were detected in 55 of the 210 samples (26%). We reanalyzed 149 of the 155 samples in which no mutation was found by real-time PCR for the presence of recurrent exon 21 and exon 19 mutations using peptide nucleic acid probes in the PCR mix to increase sensitivity by mutant allele enrichment. Four additional samples with exon 19 mutations were detected. Thus, it is found that the relatively simple and inexpensive PCR-DGGE assay is already very sensitive for the detection of mutations in clinical samples, including samples with low tumor cellularity (10% or higher tumor cell content), although the sensitivity and speed of the assay can be further increased for a restricted panel of mutations by introducing peptide nucleic acid probes in the DGGE or real-time PCR-based assay.

Epidermal growth factor receptor mutation status in cell-free DNA supernatant of bronchial washings and brushings

BACKGROUND

The aim of the current study was to examine whether it would be possible to detect epidermal growth factor receptor (EGFR) mutations in cytology cell-free DNA (ccfDNA) from the supernatant fluids of bronchial cytology samples.

METHODS

This study investigated cell damage via immunostaining with a cleaved caspase 3 antibody and the quantity of cell-free DNA in supernatant fluid from 2 cancer cell lines, and the EGFR mutation status was evaluated via polymerase chain reaction (PCR) analysis. EGFR mutations were also evaluated via PCR analysis in 74 clinical samples of ccfDNA from bronchial washing samples with physiological saline or from bronchial brushing liquid-based cytology samples with CytoRich Red.

RESULTS

The quantity and fragmentation of cell-free DNA in the supernatant fluid and the cell damage and cleaved caspase 3 expression in the sediment gradually increased in a time-dependent manner in the cell lines. In the 74 clinical samples, the quantity of ccfDNA extracted from the supernatant was adequate to perform the PCR assay, whereas the quality of ccfDNA in physiological saline was often decreased. The detection of EGFR mutations with ccfDNA showed a sensitivity of 88.0%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 89.7%, and an accuracy of 94.1% in samples with malignant or atypical cells.

CONCLUSIONS

These results suggest that activating EGFR mutations can be detected with ccfDNA extracted from the supernatant fluid of liquid-based samples via a PCR assay. This could be a rapid and sensitive method for achieving a parallel diagnosis by both morphology and DNA analysis in non-small cell lung cancer patients.

The use of a two-tiered testing strategy for the simultaneous detection of small EGFR mutations and EGFR amplification in lung cancer

Lung cancer is the leading cause of cancer-related death worldwide. Recent progress in lung cancer diagnosis and treatment has been achieved due to a better understanding the molecular mechanisms of the disease and the identification of biomarkers that allow more specific cancer treatments. One of the best known examples of personalized therapy is the use of tyrosine kinase inhibitors, such as gefitinib and erlotinib, for the successful treatment of non-small-cell lung cancer patients selected based on the specific EGFR mutations. Therefore, the reliable detection of mutations is critical for the application of appropriate therapy. In this study, we tested a two-tiered mutation detection strategy using real-time PCR assays as a well-validated high-sensitivity method and multiplex ligation-dependent probe amplification (MLPA)-based EGFRmut+ assay as a second-tier standard-sensitivity method. One additional advantage of the applied MLPA method is that it allows the simultaneous detection of EGFR mutations and copy-number alterations (i.e., amplifications) in EGFR, MET and ERBB2. Our analysis showed high concordance between these two methods. With the use of this two-tier strategy, we reliably determined the frequency of EGFR mutations and EGFR, MET and ERBB2 amplifications in over 200 lung cancer samples. Additionally, taking advantage of simultaneous copy number and small mutation analyses, we showed a very strong correlation between EGFR mutations and EGFR amplifications and a mutual exclusiveness of EGFR mutations/amplifications with MET and ERBB2 amplifications. Our results proved the reliability and usefulness of the two-tiered EGFR testing strategy.

Identification of EGFR Mutations by Immunohistochemistry with EGFR Mutation-Specific Antibodies in Biopsy and Resection Specimens from Pulmonary Adenocarcinoma

Purpose

Mutation-specific antibodies have recently been developed for identification of epidermal growth factor receptor (EGFR) mutations by immunohistochemistry (IHC). This study was designed to investigate whether the type of specimen (biopsy vs. resection) would make a difference in determining mutation status by IHC, and to evaluate whether biopsies are suitable for detection of mutant EGFR protein.

Materials and Methods

IHC was performed using mutation-specific antibodies for E746-A750 deletion (DEL) and L858R point mutation (L858R) in biopsies and tissue microarrays of resected tumors from 154 patients with pulmonary adenocarcinoma. Results were then compared with DNA sequencing data.

Results

Molecular-based assays detected EGFR mutations in 62 patients (40.3%), including 14 (9.1%) with DEL, and 31 (20.1%) with L858R. IHC with two mutation-specific antibodies showed a homogeneous staining pattern, and correctly identified EGFR mutation status in 89% (137/154). Overall (biopsy/resection) sensitivity, specificity, positive predictive value, and negative predictive value were 75.6% (78.3%/72.7%), 94.5% (90.9%/96.3%), 85% (78.3%/88.9%), and 90.4% (90.9%/89.7%), respectively.

Conclusion

Our data showed that IHC using EGFR mutation–specific antibodies is useful for detection of EGFR mutations with high specificity and good sensitivity not only for resection specimens but also for biopsy materials. Therefore, IHC using EGFR mutation–specific antibodies may preclude a second biopsy procedure to obtain additional tissues for identification of EGFR mutations by molecular assays in biopsies from advanced cancer, particularly when tumor cells in the samples are limited.

Immunohistochemical detection of BRAF V600E mutant protein using the VE1 antibody in colorectal carcinoma is highly concordant with molecular testing but requires rigorous antibody optimization

The BRAF V600E mutation occurs in 15% of colorectal carcinomas (CRCs) and has important genetic, prognostic, and therapeutic implications. A monoclonal antibody (VE1) targeting the BRAF V600E mutant protein has become available with variable efficacy in literature reports. We investigated the utility of the VE1 antibody in detecting BRAF V600E mutant protein in two cohorts: (1) a retrospectively accrued series of 103 resected CRCs with (N = 57) and without (N = 46) known BRAF V600E mutation status by PCR and (2) a prospective series of 25 CRCs requiring BRAF analysis during routine screening for Lynch syndrome. All 74 cases with positive BRAF V600E mutation demonstrated cytoplasmic positivity with the VE1 antibody with most tumors (70/74, 95%) demonstrating moderate to strong staining. Of the 54 BRAF V600E-negative cases, 51/54 CRCs (94%) were negative with the VE1 antibody while 3 CRCs (6%) demonstrated weak cytoplasmic staining. The sensitivity and specificity of VE1 was 100% and 94%, respectively. Ten BRAF V600E-mutated CRCs had adjacent precursor lesions including 7 sessile serrated adenomas associated with CRCs with high-level microsatellite instability (MSI-H). All 10 precursor adenomas were positive for VE1 staining with the 7 sessile serrated adenomas maintaining preserved MLH1 expression. Our results indicate that VE1 immunohistochemistry is a useful surrogate for the detection of the BRAF V600E mutation in CRC, although weak staining must be evaluated by BRAF PCR analysis to exclude a false positive result. In addition, the BRAF V600E mutation appears to be an early event before the divergent development into MSS and MSI-H pathways.

Biopsy and mutation detection strategies in non-small cell lung cancer

The emergence of new therapeutic agents for non-small cell lung cancer (NSCLC) implies that histologic subtyping and molecular predictive testing are now essential for therapeutic decisions. Histologic subtype predicts the efficacy and toxicity of some treatment agents, as do genetic alterations, which can be important predictive factors in treatment selection. Molecular markers, such as epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangement, are the best predictors of response to specific tyrosine kinase inhibitor treatment agents. As the majority of patients with NSCLC present with unresectable disease, it is therefore crucial to optimize the use of tissue samples for diagnostic and predictive examinations, particularly for small biopsy and cytology specimens. Therefore, each institution needs to develop a diagnostic approach requiring close communication between the pulmonologist, radiologist, pathologist, and oncologist in order to preserve sufficient biopsy materials for molecular analysis as well as to ensure rapid diagnosis. Currently, personalized medicine in NSCLC is based on the histologic subtype and molecular status. This review summarizes strategies for tissue acquisition, histologic subtyping and molecular analysis for predictive testing in NSCLC.

In situ Protein Detection for Companion Diagnostics

The emergence of targeted therapies for cancer has created a need for the development of companion diagnostic tests. Assays developed in recent years are aimed at determining both the effectiveness and safety of specific drugs for a defined group of patients, thus, enabling the more efficient design of clinical trials and also supporting physicians when making treatment-related decisions. Immunohistochemistry (IHC) is a widely accepted method for protein expression analyses in human tissues. Immunohistochemical assays, used to localize and quantitate relative protein expression levels within a morphological context, are frequently used as companion diagnostics during clinical trials and also following drug approval. Herein, we describe established immunochemistry-based methods and their application in routine diagnostics. We also explore the possibility of using IHC to detect specific protein mutations in addition to DNA-based tests. Finally, we review alternative protein binders and proximity ligation assays and discuss their potential to facilitate the development of novel, targeted therapies against cancer.

Fixation effect of SurePath preservative fluids using epidermal growth factor receptor mutation-specific antibodies for immunocytochemistry

BACKGROUND

Cytological diagnosis of respiratory disease has become important, not only for histological typing using immunocytochemistry (ICC) but also for molecular DNA analysis of cytological material. The aim of this study was to investigate the fixation effect of SurePath preservative fluids.

METHODS

Human lung cancer PC9 and 11-18 cell lines, and lung adenocarcinoma cells in pleural effusion, were fixed in CytoRich Blue, CytoRich Red, 15% neutral-buffered formalin, and 95% ethanol, respectively. PC9 and 11-18 cell lines were examined by ICC with epidermal growth factor receptor (EGFR) mutation-specific antibodies, the EGFR mutation DNA assay, and fluorescence in situ hybridization. The effect of antigenic storage time was investigated in lung adenocarcinoma cells in pleural effusion by ICC using the lung cancer detection markers.

RESULTS

PC9 and 11-18 cell lines in formalin-based fixatives showed strong staining of EGFR mutation-specific antibodies and lung cancer detection markers by ICC as compared with ethanol-based fixatives. DNA preservation with CytoRich Blue and CytoRich Red was superior to that achieved with 95% ethanol and 15% neutral-buffered formalin fixatives, whereas EGFR mutations by DNA assay and EGFR gene amplification by fluorescence in situ hybridization were successfully identified in all fixative samples. Although cytoplasmic antigens maintained high expression levels, expression levels in nuclear antigens fell as storage time increased.

CONCLUSIONS

These results indicate that CytoRich Red is not only suitable for ICC with EGFR mutation-specific antibodies, but also for DNA analysis of cytological material, and is useful in molecular testing of lung cancer, for which various types of analyses will be needed in future.

Ascertaining an appropriate diagnostic algorithm using EGFR mutation-specific antibodies to detect EGFR status in non-small-cell lung cancer

Background

Epidermal growth factor receptor (EGFR) mutation status is the most valuable indicator in the screening of non-small-cell lung cancer (NSCLC) patients for tyrosine kinase inhibitor (TKI) therapy. Accurate, rapid and economical methods of detecting EGFR mutations have become important. The use of two mutation-specific antibodies targeting the delE746-A750 mutation in exon 19 and L858R mutation in exon 21 makes this task possible, but the lack of consensually acceptable criteria for positive results limits the application of this antibody based mutation detection.

Methods

We collected 399 specimens from NSCLC patients (145 resection specimens, 220 biopsy specimens, and 34 cytology specimens) whose EGFR mutation status had been detected by TaqMan PCR assay. Immunohistochemical (IHC) analyses using EGFR mutation-specific antibodies were employed for all samples. After staining and scoring, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated in accordance with different levels of positive grades in comparison with the results of PCR-based assay.

Results

In IHC-based analyses, 144 cases were scored 0, 104 cases were scored 1+, 103 cases were scored 2+, and 48 cases were scored 3+. With the molecular-based results were set as the “gold standard”, the prevalence of mutation was 6.94% (10/144), 23.08% (24/104), 67.96% (70/103) and 100% (48/48), respectively, for samples with scores 0, 1+, 2+ and 3+. When score 3+ was considered positive, the specificity and PPV were 100%; if only score 0 was considered negative, 93.06% NPV was obtained.

Conclusion

Patients with score 3+ have a perfect PPV (100%), and may accept TKI treatment directly without any molecular-based assays. Patients with score 0 had high NPV (93.06%), which could reach 97.22% when the detection of total EGFR was applied. However, samples with score 1+ or 2+ are unreliable and need further verification of EGFR mutation status by molecular-based assays.