Deciphering intra-tumor heterogeneity of lung adenocarcinoma confirms that dominant, branching, and private gene mutations occur within individual tumor nodules

Prediction of the Presence of Targetable Molecular Alteration(s) with Clinico-Metabolic 18 F-FDG PET Radiomics in Non-Asian Lung Adenocarcinoma Patients

This study aimed to investigate if combining clinical characteristics with pre-therapeutic 18 F-fluorodeoxyglucose (18 F-FDG) positron emission tomography (PET) radiomics could predict the presence of molecular alteration(s) in key molecular targets in lung adenocarcinoma. This non-interventional monocentric study included patients with newly diagnosed lung adenocarcinoma referred for baseline PET who had tumour molecular analyses. The data were randomly split into training and test datasets. LASSO regression with 100-fold cross-validation was performed, including sex, age, smoking history, AJCC cancer stage and 31 PET variables. In total, 109 patients were analysed, and it was found that 63 (57.8%) patients had at least one molecular alteration. Using the training dataset (n = 87), the model included 10 variables, namely age, sex, smoking history, AJCC stage, excessKustosis_HISTO, sphericity_SHAPE, variance_GLCM, correlation_GLCM, LZE_GLZLM, and GLNU_GLZLM. The ROC analysis for molecular alteration prediction using this model found an AUC equal to 0.866 (p < 0.0001). A cut-off value set to 0.48 led to a sensitivity of 90.6% and a positive likelihood ratio (LR+) value equal to 2.4. After application of this cut-off value in the unseen test dataset of patients (n = 22), the test presented a sensitivity equal to 90.0% and an LR+ value of 1.35. A clinico-metabolic 18 F-FDG PET phenotype allows the detection of key molecular target alterations with high sensitivity and negative predictive value. Hence, it opens the way to the selection of patients for molecular analysis.

Distinguishing multiple lung primaries from intra-pulmonary metastases and treatment implications

INTRODUCTION

The distinction between multiple primary lung cancers and intra-pulmonary metastases has been extensively investigated because of its important clinical and therapeutic implications.

AREAS COVERED

Rapidly improving imaging technology and genomic analysis has led to a finer discrimination between multiple primary lung tumors and pulmonary metastases. However, over the past few decades, standardized criteria for the identification of multiple lung tumors have been lacking. Therefore, in 2017 a multidisciplinary international committee composed of the Union for International Cancer Control (UICC), American Joint Committee on Cancer (AJCC) and International Association for the Study of Lung Cancer (IASLC) addressed this problem when drawing up the 8th edition of TMN stage classification, that now represents a specific consensus on this topic. The most advanced diagnostic strategies associated with screening allow for the detection of early stage synchronous lung cancers.

EXPERT OPINION

Although diagnostic confirmation relies on pathologic and clinical examination, new molecular analyses help in the discrimination between primary and secondary tumors. The treatment of multiple primary lung tumors remains, whenever possible, a local treatment based on surgical resection, providing the absence of distant or local (lymph node) metastases.

Recent advances in the molecular landscape of lung neuroendocrine tumors

INTRODUCTION

Neuroendocrine tumors of the lung (Lung-NETs) make up a heterogenous family of neoplasms showing neuroendocrine differentiation and encompass carcinoids and neuroendocrine carcinomas. On molecular grounds, they considered two completely distinct and separate tumor groups with no overlap of molecular alterations nor common developmental mechanisms. Areas covered: Two perspectives were evaluated based on an extensive review and rethinking of literature: (1) the current classification as an instrument to obtaining clinical and molecular insights into the context of Lung-NETs; and (2) an alternative and innovative interpretation of these tumors, proposing a tripartite separation into early aggressive primary high-grade neuroendocrine tumors (HGNET), differentiating or secondary HGNET, and indolent NET. Expert opinion: We herein provide an alternative outlook on Lung-NETs, which is a paradigm shift to current pathogenesis models and expands the understanding of these tumors.

Clinically significant sub-clonality for common drivers can be detected in 26% of KRAS/EGFR mutated lung adenocarcinomas

Genetic sub-clonality has been described in multiple malignancies, however the presence of sub-clonality for major drivers in lung adenocarcinoma and its clinical significance is a subject under debate. Using molecular and morphometric approach, 347 lung adenocarcinoma samples were analyzed for KRAS and EGFR sub-clonality, which was further correlated with clinical and pathological variables.KRAS and EGFR mutations were identified in 100 (29%) and 82 (23%) cases, respectively. One hundred and forty four KRAS or EGFR positive cases were also available for morphometric analysis, among which 37 (26%) were defined as sub-clonal. The presence of sub-clonality was associated with shorter survival time (p=0.02). Interestingly, cases with sub-clonality were also associated with earlier disease stage (89% vs 66% stage I disease in sub-clonal vs clonal cases, respectively, p=0.01) and less lymph node involvement (8% vs 25% in sub-clonal vs clonal cases, respectively, p=0.02). Our findings demonstrate the presence of sub-clonality for mutations in common drivers in lung adenocarcinoma and link it both to earlier disease stage and to poor survival. These findings are in line with the different evolutionary models that can present with genetic sub-clonality.

The more the micropapillary pattern in stage I lung adenocarcinoma, the worse the prognosis-a retrospective study on digitalized slides

Although the majority of lung adenocarcinomas show mixed pattern, only the predominant component is taken into account according to the novel classification. We evaluated the proportion of different patterns and their impact on overall survival (OS) and disease-free survival (DFS). Patterns were recorded according to predominance and their proportions were rated and calculated by objective area measuring on digitalized, annotated slides of resected stage I lung adenocarcinomas. Spearman's rank correlation, Kaplan-Meier models and the log rank test were used for statistical evaluation. Two hundred forty-three stage I adenocarcinoma were included. Lepidic pattern is more frequent in tumours without recurrence (20 vs. 8%), and lepidic predominant tumours have favourable prognosis (OS 90.5%, DFS 89.4%), but proportions above 25% are not associated with improving outcome. Solid and micropapillary patterns are more frequent in patients with recurrence (48 vs. 5% and 13 vs. 4%) and predominance of each one is associated with unfavourable prognosis (OS 64.1%, DFS 56.3% and OS 28.1%, DFS 28.1%, respectively). Above 25%, a growing proportion of solid or micropapillary pattern is not associated with worsening prognosis. In contrast, tumours having micropapillary pattern as secondly predominant form a different intermediate group (OS 51.1%, DFS 57.8%). Our study was based on measured area of each growth pattern on all available slides digitalized. This is the most precise way of determining the size of each component from the material available. We propose using predominant and secondly predominant patterns for prognostic purposes, particularly in tumours having solid or micropapillary patterns.

EGFR, KRAS, BRAF and HER2 testing in metastatic lung adenocarcinoma: Value of testing on samples with poor specimen adequacy and analysis of discrepancies

Molecular testing on metastatic lung adenocarcinoma or on non-small cell non-squamous lung carcinoma often relies on small specimen. In this group of patient with poor specimen adequacy, we analyzed the rate of EGFR, KRAS, BRAF and HER2 mutations compared to their rate in optimal specimen. We analyzed discrepancies in molecular testing results in patients with iterative analysis on several samples. We performed a retrospective study of 1538 samples consecutively analyzed. 263/665 (39,5%) biopsies and 37/708 (5,2%) surgical specimens were considered as samples with poor specimen adequacy (p<0,0001). A lower tumor cell content was associated with a lower rate of KRAS mutation: 15,8% in samples with <10% of tumor cells or <100 tumor cells versus 29,8% in samples with >10% tumor cell and >100 tumor cells (p=0,001). KRAS mutational rate was at 11,1% in cytology specimens, significantly lower than in biopsy or surgical specimens respectively at 28,2% and 28,5% (p=0,0002). Tumor cell content was not associated with mutational rate for EGFR, BRAF and HER2 mutations. DNA quantity was not associated with mutational rate for EGFR, KRAS, BRAF and HER2. A discrepancy in molecular testing was found in 16 patients. For 5 patients there was also a discrepancy for TTF-1 expression. On the 11 without TTF-1 discrepancy, specimen adequacy was not fulfilled in 10 cases at least for tumor content. Discrepancies were found in the case of low cellularity, poor cell content or testing on cytological specimens. Tumor cell content is a crucial parameter for molecular analysis rather than the type of specimen or the DNA quantity. Discrepancies in molecular testing results are rare but might suggest the presence of another tumor type, the emergence of another clone or a molecular testing in a sample with low cell content.

The genomic dynamics during progression of lung adenocarcinomas

Intra-tumor heterogeneity is a big barrier to precision medicine. To explore the underlying clonal diversity in lung adenocarcinomas, we selected nine individuals with whole-genome sequencing data from primary and matched metastatic tumors as a cohort for study. Similar global pattern of arm-level copy number changes and large variations of somatic single-nucleotide variant between the primary and metastasis are observed in the majority of cases. Importantly, we found breakage-fusion-bridge (BFB) cycles acting as an important mechanism for underlying cancer gene amplification, such as amplification of CDK4, CDKN3 and FGFR1 in early stage. We also identified recurrent focal amplification of gene CCNY derived from BFB in two metastatic tumors, but not in primary tumor. Clonal analysis of case 236T demonstrated that mutational processes are varying with tumor progression. Collectively, our data provide new insights into genetic diversity and potential therapeutic target in lung adenocarcinoma.

Thymus neuroendocrine tumors with CTNNB1 gene mutations, disarrayed ß-catenin expression, and dual intra-tumor Ki-67 labeling index compartmentalization challenge the concept of secondary high-grade neuroendocrine tumor: a paradigm shift

We herein report an uncommon association of intimately admixed atypical carcinoid (AC) and large cell neuroendocrine (NE) carcinoma (LCNEC) of the thymus, occurring in two 20- and 39-year-old Caucasian males. Both tumors were treated by maximal thymectomy. The younger patient presented with a synchronous lesion and died of disease after 9 months, while the other patient was associated with a recurrent ectopic adrenocorticotropic hormone Cushing's syndrome and is alive with disease at the 2-year follow-up. MEN1 syndrome was excluded in either case. Immunohistochemically, disarrayed cytoplasmic and nuclear ß-catenin expression was seen alongside an intra-tumor Ki-67 antigen labeling index (LI) ranging from 2 to 80% in the younger patient's tumor and from 3 to 45% in the other. Both exhibited upregulated cyclin D1 and retinoblastoma, while vimentin was overexpressed in the recurrent LCNEC only. Next-generation sequencing revealed CTNNB1, TP53, and JAK3 mutations in the synchronous tumor and CTNNB1 mutation alone in the metachronous tumor (the latter with the same mutation as the first tumor of 17 years prior). None of the 23 T-NET controls exhibited this hallmarking triple alteration (p = 0.003). These findings suggested that LCNEC components developed from pre-existing CTNNB1-mutated AC upon loss-of-function TP53 and gain-of-function JAK3 mutations in one case and an epithelial-mesenchymal transition upon vimentin overexpression in the other case. Both tumors maintained intact cyclin D1-retinoblastoma machinery. Our report challenges the concept of secondary LCNEC as an entity that develops from pre-existing AC as a result of tumor progression, suggesting a paradigm shift to the current pathogenesis of NET.

Targeted sequencing may facilitate differential diagnostics of pulmonary tumours: a case series

Background

Histopathological diagnosis is important for prognostication and choice of treatment in patients with cancer in the lung. Metastases to the lungs are common and need to be distinguished from primary lung cancer. Furthermore, cases with synchronous or metachronous primary lung cancers (although infrequent) are often handled differently than cases with lung cancer with intrapulmonary metastasis or relapse, respectively. In some cases, morphology and immunohistochemical staining is not sufficient for certain diagnosis.

Methods

The present study included six cases where molecular genetic analysis in form of pyrosequencing or targeted next-generation sequencing was of value for certain diagnosis of selected tumours in the lung.

Results

Two of the included cases were rare metastases to the lung; colorectal cancer with IHC profile consistent with primary lung cancer and malignant adenomyoepithelioma of the breast, respectively, where molecular genetic analysis was of aid for proving the relationship to the primary tumour. The other four cases were multiple lung adenocarcinomas where molecular genetic analysis was of aid to distinguish between intrapulmonary metastasis and synchronous tumour.

Conclusions

Comparison of molecular genetic profile may be an important tool for determination of relationship between tumours in some situations and should always be considered in unclear cases. Further studies on concordance and discordance of molecular genetic profiles between spatially or temporally different tumours with common origin may be helpful for improved diagnostics of pulmonary tumours.

Pulmonary adenocarcinoma with mucin production modulates phenotype according to common genetic traits: a reappraisal of mucinous adenocarcinoma and colloid adenocarcinoma

Whether invasive mucinous adenocarcinoma (IMA) and colloid adenocarcinoma (ICA) of the lung represent separate tumour entities, or simply lie within a spectrum of phenotypic variability, is worth investigating. Fifteen ICA, 12 IMA, 9 ALK‐rearranged adenocarcinomas (ALKA), 8 non‐mucinous KRAS‐mutated adenocarcinomas (KRASA) and 9 mucinous breast adenocarcinomas (MBA) were assessed by immunohistochemistry for alveolar (TTF1, cytoplasmic MUC1), intestinal (CDX‐2, MUC2), gastric (membrane MUC1, MUC6), bronchial (MUC5AC), mesenchymal (vimentin), neuroendocrine (chromogranin A, synaptophysin), sex steroid hormone‐related (oestrogen and progesterone receptors), pan‐mucinous (HNF4A) and pan‐epithelial (keratin 7) lineage biomarkers and by targeted next generation sequencing (TNGS) for 50 recurrently altered cancer genes. Unsupervised clustering analysis using molecular features identified cluster 1 (IMA and ICA), cluster 2 (ALKA and KRASA) and cluster 3 (MBA) (p < 0.0001). Cluster 1 showed four histology‐independent sub‐clusters (S1 to S4) pooled by HFN4A and MUC5AC but diversely reacting for TTF1, MUC1, MUC2, MUC6 and CDX2. Sub‐cluster S1 predominantly featured intestinal‐alveolar, S2 gastrointestinal, S3 gastric and S4 alveolar differentiation. In turn, KRASA and ALKA shared alveolar lineage alongside residual MUC5AC expression, with additional focal CDX2 and diffuse vimentin, respectively. A proximal‐to‐distal scheme extending from terminal (TB) and respiratory (RB) bronchioles to alveolar cells was devised, where S3 originated from distal TB (cellular mucinous adenocarcinoma), S2 from proximal RB (secreting mucinous adenocarcinoma), S1 from intermediate RB (mucin lake‐forming colloid adenocarcinoma), S4 from distal RB (colloid alveolar adenocarcinoma), KRASA from juxta‐alveolar RB (KRAS‐mutated non‐mucinous adenocarcinoma) and ALKA from juxta‐bronchial alveolar cells (ALK‐translocated adenocarcinoma). TNGS analysis showed KRAS, LKB1, TP53, APC and CDKN2A mutation predominance. In conclusion, IMA and ICA are basket categories, which likely originate from distinct domains of stem/progenitor cells spatially distributed along bronchioles upon common molecular features and genetic alterations.

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.