Improved detection of EGFR mutations in the tumor cells enriched from the malignant pleural effusion of non-small cell lung cancer patient

Detection of Tumor DNA in Bronchoscopic Fluids in Peripheral NSCLC: A Proof-of-Concept Study

Introduction

DNA genotyping from plasma is a useful tool for molecular characterization of NSCLC. Nevertheless, the false-negative rate justifies the development of methods with higher sensitivity, especially in difficult-to-reach peripheral lung tumors.

Methods

We aimed at comparing molecular analysis from the supernatant of guide sheath flush fluid collected during radial-EndoBronchial UltraSound (r-EBUS) bronchoscopy with plasma sampling and tumor biopsies in patients with peripheral NSCLC. The DNA was genotyped using high-throughput sequencing or the COBAS mutation test. There were 65 patients with peripheral lung tumors subjected to concomitant sampling of guide sheath flush supernatant, plasma tumor DNA, and tumor biopsy and cytology using r-EBUS. There were 33 patients (including 24 newly diagnosed with having NSCLC) with an identifiable tumor mutation in the primary lesion selected for the comparative analysis.

Results

Guide sheath flush-based genotyping yielded a mutation detection rate of 61.8% (17 of 24 mutated EGFR, one of two ERBB2, one of one KRAS, one of one MAP2K, one of four MET, and zero of one STK11), compared with 33% in plasma-based genotyping (p = 0.0151). Furthermore, in eight of 34 r-EBUS without tumor cells on microscopic examination, we were able to detect the mutation in four paired guide sheath flush supernatant, compared with only two in paired plasma.

Conclusion

The detection of tumor DNA in the supernatant of guide sheath flush fluid collected during r-EBUS bronchoscopy represents a sensitive and complementary method for genotyping NSCLC.

Malignant Pleural Effusions

Malignant pleural effusions have a significant burden on patients and the health care system. Diagnosis is typically via thoracentesis, although other times more invasive procedures are required. Management centers around relief of dyspnea and patient quality of life and can be done via serial thoracentesis, indwelling pleural catheter, or pleurodesis. This article focuses on the diagnosis and management of malignant pleural effusion.

Gene Alterations in Paired Supernatants and Precipitates from Malignant Pleural Effusions of Non-Squamous Non-Small Cell Lung Cancer

OBJECTIVE: This study investigated the feasibility of using malignant pleural effusion (MPE) supernatant and paired cell blocks (precipitate) for gene profiling in patients with non-small cell lung cancer (NSCLC) using next-generation sequencing (NGS) technique. METHODS: Stage IV non-squamous NSCLC patients with MPE were eligible in this prospective study and recruited from Zhejiang Cancer Hospital between May 2014 and October 2015. MPE supernatant and paired precipitate sample gene alterations were determined with NGS containing 14 cancer-related genes. Progression free survival (PFS) was evaluated using Kaplan–Meier method and compared using log-rank test. RESULTS: A total of 102 patients were enrolled in the present study. All pleural effusions were confirmed as malignant with cytological smears. A total of 77 paired MPE supernatant and precipitate samples were acquired from the 102 patients. The results revealed that there were no statistically significant differences in the detection rate and maximum allelic fraction between supernatant and precipitate samples (P = 1.0 and P = .6). Collectively, 172 and 158 genomic alterations with 112 shared mutations were identified in supernatant and precipitate samples, respectively. Comparable PFS was found in EGFR mutation patients according to the supernatant and precipitate sample results (14.0 vs.13.9 months, P = .90). CONCLUSIONS: These results demonstrated that MPE supernatants were comparable to precipitate samples for detection of genetic alterations. However, gene mutation heterogeneity was found between these two media types.

Digital PCR-Based Detection of EGFR Mutations in Paired Plasma and CSF Samples of Lung Adenocarcinoma Patients with Central Nervous System Metastases

BACKGROUND

The presence of specific mutations in the EGFR gene informs the clinical pathway of therapy for patients with lung adenocarcinoma (LAC), including those with central nervous system (CNS) metastases. Plasma circulating cell-free DNA (cfDNA) has been demonstrated to carry the mutational information of LACs, which serves as a biomarker to guide treatment. However, whether the cerebrospinal fluid (CSF) enriches circulating tumor DNA (ctDNA) released from CNS metastatic lesions of LAC, and whether the CSF ctDNA can be used to characterize these lesions remains unknown.

OBJECTIVE

To explore the EGFR status in CNS metastases of LAC patients, and to guide the treatment of intra- and extracranial tumors in these patients.

PATIENTS AND METHODS

The EGFR mutational status in the cfDNA from paired CSF and plasma samples from LAC patients with CNS metastases, including 20 brain metastases (BM) and 15 leptomeningeal metastases (LM), was assessed by droplet digital polymerase chain reaction (ddPCR). The clinical outcomes of the EGFR status-based intervention were investigated.

RESULTS

EGFR mutations were detected in 23/35 LAC patients (65.7%). EGFR mutations in the plasma or CSF were detected in 6/11 (54.5%) and 5/10 (50%) BM patients, and in 4/11 (36.4%) and 9/12(75%) LM patients, respectively. The prevalence of the T790M mutation was significantly higher in plasma (9/23) than in CSF (3/23) samples. The sensitivity and specificity of the ddPCR-based EGFR mutation test in CSF or plasma samples versus the primary tumor samples were 56% and 89% versus 46% and 100%, respectively. Twelve patients received a first-generation EGFR TKI (tyrosine kinase inhibitor) after the detection of sensitive EGFR mutations in their CSF or plasma, and five patients were switched from a first-generation EGFR TKI to osimertinib after the detection of the T790M mutation.

CONCLUSIONS

The EGFR T790M mutation in plasma cfDNA is a sensitive marker for EGFR TKI resistance when CNS metastases progressed. CSF ctDNA increases the diagnostic validity for EGFR genotyping of lung cancer brain metastasis. ddPCR in CSF and plasma samples could provide less invasive and close monitoring of the EGFR status of LAC patients with CNS metastases.

Detecting EGFR mutations and ALK/ROS1 rearrangements in non-small cell lung cancer using malignant pleural effusion samples

Background

The study was conducted to evaluate the feasibility of using malignant pleural effusion (MPE) as a substitute specimen for genetic testing and to determine the significance of genetic profiling of MPE tumor cells to monitor non‐small cell lung cancer (NSCLC) progression and therapeutic response.

Methods

We selected 168 NSCLC patients with MPE. We extracted MPE and enriched tumor cells using a custom‐designed device. EGFR mutations and ALK/ROS1 fusions were then detected by quantitative real‐time PCR, and the results were used to guide targeted therapy. We investigated drug responses through imaging.

Results

MPE tumor cells were detected in all patients. EGFR mutations and ALK/ROS1 rearrangements were detected in biopsy samples, treated MPE, and untreated MPE. We found that treated MPE had higher sensitivity and specificity than biopsy or untreated MPE. Among the 26 EGFR inhibitor patients, 13 showed a partial response, 7 had progressive disease, and 6 showed stable disease. Among the 16 patients that received ALK/ROS1 inhibitors, 8 had a partial response, 4 had progressive disease, and 4 showed stable disease.

Conclusion

Our study provides a new, less invasive, and highly repeatable method of analyzing MPE tumor cells in NSCLC that facilitates precision medicine and genetic testing.

Liquid Biopsy for Advanced Non-Small Cell Lung Cancer (NSCLC): A Statement Paper from the IASLC

The isolation and analysis of circulating cell-free tumor DNA in plasma is a powerful tool with considerable potential to improve clinical outcomes across multiple cancer types, including NSCLC. Assays of this nature that use blood as opposed to tumor samples are frequently referred to as liquid biopsies. An increasing number of innovative platforms have been recently developed that improve not only the fidelity of the molecular analysis but also the number of tests performed on a single specimen. Circulating tumor DNA assays for detection of both EGFR sensitizing and resistance mutations have already entered clinical practice and many other molecular tests - such as detection of resistance mutations for Anaplastic Lymphoma Kinase (ALK) receptor tyrosine kinase rearrangements - are likely to do so in the near future. Due to an abundance of new evidence, an appraisal was warranted to review strengths and weaknesses, to describe what is already in clinical practice and what has yet to be implemented, and to highlight areas in need of further investigation. A multidisciplinary panel of experts in the field of thoracic oncology with interest and expertise in liquid biopsy and molecular pathology was convened by the International Association for the Study of Lung Cancer to evaluate current available evidence with the aim of producing a set of recommendations for the use of liquid biopsy for molecular analysis in guiding the clinical management of advanced NSCLC patients as well as identifying unmet needs. In summary, the panel concluded that liquid biopsy approaches have significant potential to improve patient care, and immediate implementation in the clinic is justified in a number of therapeutic settings relevant to NSCLC.