Exosome-Based Detection of EGFR T790M in Plasma from Non–Small Cell Lung Cancer Patients

Abstract

Tumor tissue biopsies carry risks and are not always possible, making liquid biopsies an attractive way to acquire molecular information from cancer patients. The EGFR T790M mutation is a critical biomarker in non-small cell lung cancer and has introduced new challenges in how these patients are managed. With the approval of osimertinib for patients failing first generation EGFR inhibitor therapy, the use of a liquid biopsy to detect EGFR T790M would reduce the number of unnecessary repeat biopsies. Detection of EGFR T790M using cfDNA has proved to be challenging due to low abundance in blood. Here we present a novel EGFR T790M assay based on a platform validated in a CLIA laboratory that simultaneously monitors the mutation on exosomal RNA/DNA and cfDNA from plasma that achieves 92% sensitivity and 89% specificity.Research. AbstractPurpose: About 60% of non-small cell lung cancer (NSCLC) patients develop resistance to targeted epidermal growth factor receptor (EGFR) inhibitor therapy through the EGFR T790M mutation. Patients with this mutation respond well to third generation tyrosine kinase inhibitors, but obtaining a tissue biopsy to confirm the mutation poses risks and is often not feasible. Liquid biopsies using circulating free tumor DNA (cfDNA) have emerged as a non-invasive option to detect the mutation, however sensitivity is low as many patients have too few detectable copies in circulation. Here we have developed and validated a novel test that overcomes the limited abundance of the mutation by simultaneously capturing and interrogating exosomal RNA/DNA and cfDNA (exoNA) in a single step followed by a sensitive allele specific qPCR.Experimental design: ExoNA was extracted from the plasma of NSCLC patients with biopsy-confirmed T790M-positive (N = 102) and T790M-negative (N = 108) samples.The T790M mutation status was determined using an analytically validated allelespecific qPCR assay in a CLIA laboratory.Results: Detection of the T790M mutation on exoNA achieved 92% sensitivity and 89% specificity using tumor biopsy results as gold standard. We also obtained high sensitivity (88%) in patients with intrathoracic disease (M0/M1a), for whom detection by liquid biopsy has been particularly challenging.Research.on March 26,

Circulating microRNA‐590‐5p functions as a liquid biopsy marker in non‐small cell lung cancer

“…Therefore, liquid biopsy is greatly explored in current oncology research due to its minimally invasive approach for early cancer detection and for responses to cancer treatment. 3,12 Circulating or cf-miRNAs disseminate from tumor tissue into the peripheral circulation 1 and are present in all body fluids, including whole blood, plasma, serum, sputum, saliva, urine, and cerebrospinal fluids. 2,13 These miRNAs are stable under harsh conditions, such as extreme pH, temperature, multiple freeze-thaw cycles, long-term storage, and even against RNase degradation.…”

Immunoregulatory Potential of Exosomes Derived from Cancer Stem Cells

“…These findings highlight the potential use of TEX diagnostic biomarkers for HNSCC [81,82]. Indeed, such TEX-based biomarkers as liquid biopsy diagnostics from Exosome Diagnostics were recently approved for clinical use for prostate and lung cancer [83,84]. These diagnostics aid clinicians in detecting, diagnosing, and monitoring cancer progression in addition to identifying the unique genetic composition of each patient's tumor.…”

Extracellular Vesicles in Non-Small-Cell Lung Cancer: Functional Role and Involvement in Resistance to Targeted Treatment and Immunotherapy

“…Hence, analysis of tumor-derived EVs has emerged as an alternative approach to ctDNA to evaluate therapeutic effect of targeted therapy. Specifically, it has been reported that exosomal RNA can be a useful biomarker for detecting development of the T790M and other activating EGFR mutations, increasing sensitivity and specificity of traditional ctDNA analysis [89,90]. The importance of tumor EVs as clinical biomarkers is supported by the fact that EVs are directly implicated in the propagation of resistance mechanisms between cancer cells.…”