Worldwide Frequency of Commonly Detected EGFR Mutations

New Frontiers for Molecular Pathology

Lung cancer remains a serious oncological problem worldwide. The delayed diagnosis and a prevalence of advanced stages in up to 70% of cases at recognition are still observed. Thanks to targeted therapies and immunotherapy a significant progress in achieving prolonged survival in some lung cancer patients is reported. A precise histopathological diagnosis, especially the recognition of adenocarcinoma, and a progress in the methods of clinical staging underlie the proper qualification of patients for a tailored therapy. The deep molecular characteristics of lung cancer in liquid biopsy, for example blood, bronchoalveolar lavage fluid (BALF), cell suspension from needle aspirates, are currently available. The molecular characteristic has recently been extended with molecular aberrations of BRAF, KRAS, MET, ERBB2, RET, NTRK next to the well-known EGFR mutations and ALK, ROS-1 relocation. The present paper discusses the usefulness of adequate pathological methods and molecular testing for the identification of a broad spectrum of predictive biomarkers for a molecular-directed lung cancer therapy. Immunotherapy with immune checkpoint inhibitors (ICIs) is approved in the first line therapy of advanced non-small-cell lung cancer. To date only PD-L1 expression on tumor cells has been found to be a marker of response to ICIs. The efficacy of ICIs as well as the susceptibility to immune-related adverse events are highly individual, so immune biomarkers are widely investigated. The candidates for predictive factors for ICIs immunotherapy include cancer cell antigenicity, presence of regulatory/suppressory molecules on cancer cells, cancer stem cells or on exosomes, and, on the other hand, an immune status of the patient. Cancers with high immune infiltration in the tumor milieu, referred to as “hot” tumors, seem to ensure a better response to ICIs than the “cold” ones. BALF analysis may replace cancer tissue examination, which is of limited access in advanced stages, for the recognition of the nature of immune response in the tumor environment. Tumor mutational burden (TMB) was shown to correlate with a good response to ICIs, especially when combined with other anticancer therapies. The present paper demonstrates the results of recent studies on lung cancer characteristics which bring us closer to the definition of useful prognostic/predictive factors.

Impact of Asian ethnicity on outcome in metastatic EGFR-mutant non-small cell lung cancer

AIM

To determine factors associated with survival in de novo stage IV, non-small cell lung cancer (NSCLC) patients possessing epidermal growth factor receptor mutations (EGFRmut⁺ ) receiving tyrosine kinase inhibitors (TKI) in the first-line setting.

METHODS

The Glans-Look Lung Cancer Database was used to retrospectively review stage IV EGFRmut⁺ NSCLC patients diagnosed 2010-2016 receiving first-line TKI. Patients with overall survival times in the upper quartile (≥34 months) were designated "long-term survivors" (LTS), the remaining deemed "average-term survivors" and characteristics between these groups were compared in univariate analysis, and multivariable models constructed to determine predictors of outcome.

RESULTS

Of 170 eligible patients, median overall survival was 21 months. LTS were significantly more likely to be of Asian ethnicity, be never-smokers and not possess brain or bone metastases at diagnosis. Asian and non-Asian patients were comparable, save for an increased propensity of Asian patients to be never smokers and have normal-range BMI. Multivariable analysis revealed Asian ethnicity [hazard ratio (HR) = 0.65; P = 0.016] and never-smoking history (HR = 0.65; P = 0.034) as indicators of improved outcome, and presence of brain metastasis at diagnosis an indicator of poor outcome (HR = 2.21; P < 0.001).

CONCLUSIONS

Analysis of this population-based cohort identifies never-smoking history and absence of brain metastasis along with Asian ethnicity as an independent prognosticators of favorable outcome, and reveals Asian patients to be clinicopathologically similar to non-Asian patients. These findings suggest Asian patients represent a unique subpopulation within EGFRmut⁺ NSCLC who may possess different biological underpinnings of NSCLC.

Understanding the Mechanisms of Resistance in EGFR-Positive NSCLC: From Tissue to Liquid Biopsy to Guide Treatment Strategy

Liquid biopsy has emerged as an alternative source of nucleic acids for the management of Epidermal Growth Factor Receptor (EGFR)-mutant non-Small Cell Lung Cancer (NSCLC). The use of circulating cell-free DNA (cfDNA) has been recently introduced in clinical practice, resulting in the improvement of the identification of druggable EGFR mutations for the diagnosis and monitoring of response to targeted therapy. EGFR-dependent (T790M and C797S mutations) and independent (Mesenchymal Epithelial Transition [MET] gene amplification, Kirsten Rat Sarcoma [KRAS], Phosphatidyl-Inositol 4,5-bisphosphate 3-Kinase Catalytic subunit Alpha isoform [PI3KCA], and RAF murine sarcoma viral oncogene homolog B1 [BRAF] gene mutations) mechanisms of resistance to EGFR tyrosine kinase inhibitors (TKIs) have been evaluated in plasma samples from NSCLC patients using highly sensitive methods (i.e., digital droplet PCR, Next Generation Sequencing), allowing for the switch to other therapies. Therefore, liquid biopsy is a non-invasive method able to detect the molecular dynamic changes that occur under the pressure of treatment, and to capture tumor heterogeneity more efficiently than is allowed by tissue biopsy. This review addresses how liquid biopsy may be used to guide the choice of treatment strategy in EGFR-mutant NSCLC.

A rare epidermal growth factor receptor H773L/V774M compound mutation in advanced non-small-cell lung cancer with poor response to epidermal growth factor receptor tyrosine kinase inhibitor

Uncommon mutations account for 10-15% of epidermal growth factor receptor (EGFR) mutations in patients with non-small-cell lung cancer. Afatinib is currently the most efficient EGFR-tyrosine kinase inhibitor (TKI) against uncommon EGFR mutations. Here we report a 56-year-old woman presenting with persistent cough for one month. She was diagnosed with stage IV lung adenocarcinoma by bronchoscopic biopsy to the left lower lung tumour and serial image modalities. A rare H773L/V774M compound mutation in exon 20 was detected by gene sequencing. The patient received first-line afatinib but primary resistance was noted with rapid left lower lung tumour progression. Second-line chemotherapy combined with bevacizumab, pemetrexed, and cisplatin demonstrated more durable response. Our case suggests that H773L/V774M may be one of the EGFR-TKI-resistant uncommon EGFR mutations.

Computational algorithms for in silico profiling of activating mutations in cancer

Methods to catalog and computationally assess the mutational landscape of proteins in human cancers are desirable. One approach is to adapt evolutionary or data-driven methods developed for predicting whether a single-nucleotide polymorphism (SNP) is deleterious to protein structure and function. In cases where understanding the mechanism of protein activation and regulation is desired, an alternative approach is to employ structure-based computational approaches to predict the effects of point mutations. Through a case study of mutations in kinase domains of three proteins, namely, the anaplastic lymphoma kinase (ALK) in pediatric neuroblastoma patients, serine/threonine-protein kinase B-Raf (BRAF) in melanoma patients, and erythroblastic oncogene B 2 (ErbB2 or HER2) in breast cancer patients, we compare the two approaches above. We find that the structure-based method is most appropriate for developing a binary classification of several different mutations, especially infrequently occurring ones, concerning the activation status of the given target protein. This approach is especially useful if the effects of mutations on the interactions of inhibitors with the target proteins are being sought. However, many patients will present with mutations spread across different target proteins, making structure-based models computationally demanding to implement and execute. In this situation, data-driven methods-including those based on machine learning techniques and evolutionary methods-are most appropriate for recognizing and illuminate mutational patterns. We show, however, that, in the present status of the field, the two methods have very different accuracies and confidence values, and hence, the optimal choice of their deployment is context-dependent.

Epidermal Growth Factor Receptor Gene Mutation Status in Primary Lung Adenocarcinoma and Corresponding Bone Metastases

BACKGROUND

The aim of this study was to compare epidermal growth factor receptor (EGFR) mutations between primary tumors and corresponding bone metastases (BMs) in lung adenocarcinoma.

MATERIALS AND METHODS

In total, 115 paired primary lung adenocarcinoma and corresponding BM tumors were analyzed for EGFR mutations by Amplification Refractory Mutation System.

RESULTS

EGFR mutations were detected in 61 primary lung adenocarcinomas (53.04%) and in 67 corresponding metastases (58.26%), respectively. The EGFR mutation rate was significantly higher in female and in never-smoker patients. The consistency of EGFR mutations between the 115 matched BMs and primary tumor tissue samples reached to 80.87%, and the disparity was 19.13%. Mutations in exons 19 (19-del) and 21 (point mutation L858R) were the predominant mutation type.

CONCLUSIONS

The concordance rate demonstrated the feasibility of EGFR mutations in corresponding metastases using Amplification Refractory Mutation System when the primary tumor tissue is unavailable in the lung adenocarcinoma patients, and the inconsistency indicates that corresponding metastasis being screened simultaneously with the primary tumor samples may present some supplementary information for the patients.

Resistances to EGFR tyrosine kinase inhibitors in lung cancer-how to routinely track them in a molecular pathology laboratory?

Patients with advanced or metastatic forms of lung cancer with an activating mutation in epidermal growth factor receptor (EGFR) are given tyrosine kinase inhibitors (TKIs) targeted therapies that are more efficient than chemotherapy. These patients are excluded from first-line immunotherapy. After a phase of regression these tumors develop systematically resistance requiring a rapid change in therapy. At present two strategies are being discussed. The first strategy, so called "historical' sequential treatment strategy, is based on the administration of first- or second-generation TKIs until the emergence of therapeutic resistance and, in the case of a EGFR T790M mutation, on the administration of third-generation TKIs. The recently proposed second strategy, so called the "next-generation" TKIs strategy, concerns initial treatment with third-generation TKIs. This latter strategy appears to be promising but needs to be confirmed by data comparing survival curves of patients treated in a sequential manner. Several criteria influence the choice of these strategies, in particular the presence of brain metastases, the potential toxicity and the economic model. The selected therapeutic algorithm has certainly an impact on the activity of laboratories. The sequential approach requires investigation into EGFR T790M resistance mutations, using blood and then possibly a tissue biopsy, or into other mechanisms of resistance in the absence of this mutation. In the case of tumor progression under treatment with third-generation TKIs the EGFR C797S mutation in the cis or trans positions is looked for. In the absence of this latter mutation other mechanisms of resistance are then investigated. We describe here the different methodological approaches used to identify resistance mechanisms linked to treatment with TKIs targeting mutations in EGFR.

Comprehensive analysis of HPV infection, EGFR exon 20 mutations and LINE1 hypomethylation as risk factors for malignant transformation of sinonasal-inverted papilloma to squamous cell carcinoma

Different risk factors are suspected to be involved in malignant transformation of sinonasal papillomas and include HPV infection, tobacco smoking, occupational exposure, EGFR/KRAS mutations and DNA methylation alterations. In our study, 25 inverted sinonasal papillomas (ISPs), 5 oncocytic sinonasal papillomas (OSP) and 35 squamous cell carcinomas (SCCs) from 54 patients were genotyped for 10 genes involved in EGFR signalling. HPV-DNA detection was performed by in-situ hybridisation and LINE-1 methylation was quantitatively determined by bisulphite-pyrosequencing. High-risk HPV was observed only in 13% of ISP-associated SCC and in 8% of de novo-SCC patients. EGFR mutations occurred in 72% of ISPs, 30% of ISP-associated SCCs and 17% of de novo-SCCs. At 5-year follow-up, SCC arose in only 30% (6/20) of patients with EGFR-mutated ISPs compared to 76% (13/17) of patients with EGFR-wild-type ISP (p = 0.0044). LINE-1 hypomethylation significantly increased from papilloma/early stage SCC to advanced stage SCC (p = 0.03) and was associated with occupational exposure (p = 0.01) and worse prognosis (p = 0.09). In conclusion, our results suggest that a small subset of these tumours could be related to HPV infection; EGFR mutations characterise those ISPs with a lower risk of developing into SCC; LINE-1 hypomethylation is associated with occupational exposure and could identify more aggressive nasal SCC.

Diagnostic and Predictive Immunohistochemistry for Non-Small Cell Lung Carcinomas

Non-small cell lung carcinoma (NSCLC) accounts for significant morbidity and mortality worldwide, with most patients diagnosed at advanced stages and managed increasingly with targeted therapies and immunotherapy. In this review, we discuss diagnostic and predictive immunohistochemical markers in NSCLC, one of the most common tumors encountered in surgical pathology. We highlight 2 emerging diagnostic markers: nuclear protein in testis (NUT) for NUT carcinoma; SMARCA4 for SMARCA4-deficient thoracic tumors. Given their highly aggressive behavior, proper recognition facilitates optimal management. For patients with advanced NSCLCs, we discuss the utility and limitations of immunohistochemistry (IHC) for the "must-test" predictive biomarkers: anaplastic lymphoma kinase, ROS1, programmed cell death protein 1, and epidermal growth factor receptor. IHC using mutant-specific BRAF V600E, RET, pan-TRK, and LKB1 antibodies can be orthogonal tools for screening or confirmation of molecular events. ERBB2 and MET alterations include both activating mutations and gene amplifications, detection of which relies on molecular methods with a minimal role for IHC in NSCLC. IHC sits at the intersection of an integrated surgical pathology and molecular diagnostic practice, serves as a powerful functional surrogate for molecular testing, and is an indispensable tool of precision medicine in the care of lung cancer patients.