Faisabilité de la recherche de mutations EGFR et KRAS sur des prélèvements obtenus par EBUS-PTBA

[The role of endoscopy in exploration of the mediastinum, indications and results]

Since 2005, endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has emerged as a standard pulmonological tool. The procedure is safe and well tolerated by patients, with minimal morbidity and almost no mortality. A previous review on the technique was published in 2012. However, over the last ten years, a number of new studies have been published on "benign" (sarcoidosis, tuberculosis…) as well as "malignant" diseases (lung cancer, metastases of extra-thoracic cancers, search for mutations and specific oncogenic markers…). These developments have led to expanded indications for EBUS-TBNA, with which it is indispensable to be familiar, in terms of "staging" as well as "diagnosis". In view of optimizing lymph node sampling, several publications have described and discussed EBUS exploration by means of newly available tools (biopsy forceps, larger needles…), and proposed interpretation of the images thereby produced. Given the ongoing evolution of linear EBUS, it seemed indispensable that information on this marvelous tool be updated. This review is aimed at summarizing the novel elements we have found the most important.

Feasibility of comprehensive genotyping specimens from radial endobronchial ultrasonography and electromagnetic navigation bronchoscopy

Introduction

Mini-invasive bronchoscopic techniques (such as radial endobronchial ultrasonography (rEBUS) and electromagnetic navigation (EMN)) have been developed to reach the peripheral lung but result in small samples. The feasibility of an adequate molecular testing from these specimens has been very little studied.

Methods

We retrospectively reviewed EMN and rEBUS procedures performed in patients diagnosed with lung cancer in our institution in 2017 and 2018. We analysed the sensitivity for rEBUS and EMN and each sampling method, and the feasibility of a comprehensive molecular testing.

Results

In total, 317 rEBUS and 14 EMN were performed. Median sizes of tumours were 16 and 32 mm for EMN and rEBUS, respectively. Overall sensitivity for rEBUS and EMN was 84.3%. Cytology was found to be complementary with biopsies, with 13.3% of cancer diagnosed on cytology while biopsies were negative. Complication rate was 2.4% (pneumothorax 1.5%, mild haemoptysis 0.9%). Genotyping (immunohistochemistry for ROS1 and ALK followed by fluorescence in situ hybridisation if positive and hybrid capture next-generation sequencing covering 48 genes), when ordered (n=188), was feasible in 69.1% (EGFR 17.7%, KRAS 31.7%, BRAF 4.8%, ALK 1.2%, MET 3.1%, HER2 0.8%). PD-L1 (programmed death-ligand 1) expression, when ordered (n=232), could be analysed in 94% of cases. Overall, 56.9% (33 out of 58) of patients for whom genotyping was not feasible underwent a second sampling (12 pretreatment, 21 at progression), allowing for the detection of six actionable genotypes (five EGFR, one MET).

Conclusion

rEBUS and EMN are sensitive and safe procedures that result in limited samples, often not suitable for genotyping, highlighting the importance of integrating liquid biopsy in routine testing.

Radial EBUS and EMN bronchoscopies are safe and sensitive procedures for lung cancer diagnosis. Cytology is highly complementary with histology. These small samples are, however, not suitable for an exhaustive molecular testing in 30% of cases.https://bit.ly/3eZ7Xn0

Adequacy of Samples Obtained by Endobronchial Ultrasound with Transbronchial Needle Aspiration for Molecular Analysis in Patients with Non-Small Cell Lung Cancer. Systematic Review and Meta-Analysis

RATIONALE

Endobronchial ultrasound and transbronchial needle aspiration (EBUS-TBNA) are commonly used for the diagnosis and mediastinal staging of lung cancer. Molecular markers are becoming increasingly important in patients with lung cancer to define targetable mutations suitable for personalized therapy, such as epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), reactive oxygen species proto-oncogene (ROS1), and programmed death-ligand 1 (PD-L1).

OBJECTIVES

To evaluate the adequacy of EBUS-TBNA-derived tissue for molecular analysis.

METHODS

We searched the MEDLINE, LILACS, www.clinicaltrials.gov , and Epistemonikos databases through January 2018.

DATA EXTRACTION

Two independent reviewers performed the data search, quality assessment, and data extraction. We included both prospective and retrospective studies; risk of bias was evaluated using the ROBINS-I tool. The primary outcome was the proportion of adequate samples obtained by EBUS-TBNA for molecular analysis. Data were pooled by using a binary random effects model. Finally, evidence was rated by using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach.

RESULTS

A total of 33 studies including 2,698 participants were analyzed. In 28 studies that evaluated EBUS-TBNA for the identification of EGFR mutations, the pooled probability of obtaining a sufficient sample was 94.5% (95% confidence interval CI], 93.2-96.4%). For identification of ALK mutations, the pooled probability was 94.9% (95% CI, 89.4-98.8%). Finally, the prevalence of EGFR mutation was 15.8% (95% CI, 12.1-19.4%), and the prevalence of ALK mutation was 2.77% (95% CI, 1.0-4.8%). Data for ROS1 and PD-L1 mutations were not suitable for meta-analysis.

CONCLUSIONS

EBUS-TBNA has a high yield for molecular analysis of both EGFR and ALK mutations. However, the suitability of TBNA samples for next-generation sequencing is uncertain and should be explored in further studies. Clinical trial registered with PROSPERO (CRD42017080008).

Molecular biomarkers for lung adenocarcinoma

The identification of oncogenic driver alterations that underlie sensitivity to small inhibitors has led to growing interest in identifying additional targetable oncogenes in nonsmall cell lung cancer. Although the therapeutic impact of the discovery of these alterations has now been widely demonstrated, the epidemiological data associated with each of these biomarkers remain insufficiently studied. In this review, we discuss the techniques used to discover each of these candidate oncogenes, their prevalence in nonsmall cell lung cancer, and briefly outline the epidemiological features of the major oncogenes and ways in which their identification can determine therapeutic strategies.

[Endobronchial ultrasonography (EBUS) for the internist]

Endobronchial ultrasonography (EBUS) is a recent mini-invasive technique allowing transbronchial needle aspiration (TBNA) of mediastinal lymph nodes as well as peribronchial lesions. EBUS was initially developed for lung cancer mediastinal staging. Over the years, indications for EBUS have been progressively extended to the scope of inflammatory disorders, mediastinal lymphomas, and infectious diseases. Particularly in immunosuppressed patients, including HIV-infected patients, EBUS allows the diagnosis of several diseases that involve the mediastinum, avoiding invasive surgical explorations such as mediastinoscopy or thoracoscopy. This review aims at discussing the technical aspects, and specifies indications, results, and limits of EBUS for the internist.

Adequacy of endobronchial ultrasound-guided transbronchial needle aspiration samples processed as histopathological samples for genetic mutation analysis in lung adenocarcinoma

Phenotyping non-small-cell lung cancer is becoming increasingly important with the advent of molecular testing. Tumours harbouring somatic mutations in the gene that encodes for the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) have been found to increase responsiveness to tyrosine kinase inhibitors. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive technique for mediastinal node sampling. The available prospective data on EBUS-TBNA sample suitability for molecular profiling are currently limited. The aim of this prospective study was to evaluate the adequacy of EBUS-TBNA samples for EGFR and anaplastic lymphoma kinase (ALK) genetic mutation analysis in confirmed primary lung adenocarcinomas. We conducted a prospective analysis of 410 consecutive patients referred for EBUS-TBNA between 2010 and 2014. Rapid on-site cytological evaluation was not used. The samples were obtained using 21-gauge (21G) or 22G needles and were prepared as histopathological samples. A total of 91 samples were confirmed as lung adenocarcinomas and 80 of these samples were sent for EGFR mutation analysis. EBUS-TBNA had a diagnostic accuracy of 98.3% for malignancy. EGFR mutation testing was possible in 79/80 cases (98.75%). EGFR mutations were detected in 5/80 (6.3%) samples. ALK gene analysis, which became available during the study period, was requested and successfully performed in 21/21 samples (100%). The total combined genotyping success rate was 100/101 (99.0%). This UK study confirmed the high clinical utility of EBUS-TBNA samples processed as histopathological specimens for EGFR and ALK genotyping in primary lung adenocarcinoma. The needle gauge did not affect genotyping efficacy.