Feasibility of Bronchial Washing Fluid-Based Approach to Early-Stage Lung Cancer Diagnosis

Bronchial washing fluid sequencing is useful in the diagnosis of lung cancer with necrotic tumor

BACKGROUND

Early-stage lung cancers detected by low-dose computed tomography (CT) often require confirmation through invasive procedures due to the absence of endobronchial lesions. This study assesses the diagnostic utility of bronchial washing fluid (BW) sequencing, a less invasive alternative, aiming to identify patient characteristics most suited for this approach.

METHODS

From June 2017 to March 2018, we conducted a prospective cohort study by enrolling patients with incidental lung lesions suspected of early-stage lung cancer at two independent hospitals, and 114 were diagnosed with lung cancer while 50 were diagnosed with benign lesions. BW sequencing was performed using a targeted gene panel, and the clinical characteristics of patients detected with cancer through sequencing were identified.

RESULTS

Malignant cells were detected in 33 patients (28.9 %) through BW cytology. By applying specificity-focused mutation criteria, BW sequencing classified 42 patients (36.8 %) as having cancer. Among the cancer patients who were BW sequencing positive and BW cytology negative, 15 patients (75.0 %) showed necrosis on CT. The sensitivity of BW sequencing was particularly enhanced in patients with necrotic tumors, reaching 75 %.

CONCLUSIONS

BW sequencing presents a viable, non-invasive diagnostic option for early-stage lung cancer, especially valuable in patients with necrotic lesions. By potentially reducing the reliance on more invasive diagnostic procedures, this method could streamline clinical workflows, decrease patient burden, and improve overall diagnostic efficiency.

Variant Allele Frequency Analysis of Circulating Tumor DNA as a Promising Tool in Assessing the Effectiveness of Treatment in Non-Small Cell Lung Carcinoma Patients

Despite the different possible paths of treatment, lung cancer remains one of the leading causes of death in oncological patients. New tools guiding the therapeutic process are under scientific investigation, and one of the promising indicators of the effectiveness of therapy in patients with NSCLC is variant allele frequency (VAF) analysis. VAF is a metric characterized as the measurement of the specific variant allele proportion within a genomic locus, and it can be determined using methods based on NGS or PCR. It can be assessed using not only tissue samples but also ctDNA (circulating tumor DNA) isolated from liquid biopsy. The non-invasive characteristic of liquid biopsy enables a more frequent collection of material and increases the potential of VAF analysis in monitoring therapy. Several studies have been performed on patients with NSCLC to evaluate the possibility of VAF usage. The research carried out so far demonstrates that the evaluation of VAF dynamics may be useful in monitoring tumor progression, remission, and recurrence during or after treatment. Moreover, the use of VAF analysis appears to be beneficial in making treatment decisions. However, several issues require better understanding and standardization before VAF testing can be implemented in clinical practice. In this review, we discuss the difficulties in the application of ctDNA VAF analysis in clinical routine, discussing the diagnostic and methodological challenges in VAF measurement in liquid biopsy. We highlight the possible applications of VAF-based measurements that are under consideration in clinical trials in the monitoring of personalized treatments for patients with NSCLC.

Usefulness of bronchial washing fluid for detection of EGFR mutations in non-small cell lung cancer

INTRODUCTION

The implementation of bronchial washing fluid (BWF) as a diagnostic specimen may complement the low diagnostic yields of plasma in detecting EGFR mutation (mEGFR) in non-small cell lung cancer. However, the diagnostic value of BWF in detecting mEGFR has yet to be clarified.

MATERIALS AND METHODS

From March 2021 to August 2022, patients with histologically confirmed NSCLC with matched tumor tissue, BWF, and/or plasma samples were enrolled. Patients were classified into either initial diagnosis or rebiopsy groups. Diagnostic yields of mEGFR in BWF and plasma were evaluated using droplet digital polymerase chain reaction and compared to mEGFR in tumor tissue as standard.

RESULTS

The study included 123 patients (74.1 %) in the initial diagnosis and 43 patients (25.9 %) in the rebiopsy group. BWF showed higher sensitivity, specificity, and concordance rates than plasma in both the initial diagnosis (57.4 %, 96.4 %, and 74.0 % vs. 16.4 %, 96.2 %, and 53.1 %) and the rebiopsy group (87.9 %, 60.0 %, and 81.4 % vs. 25.0 %, 75.0 %, and 41.7 %). In the initial diagnosis group, mEGFR was detected in the BWF of 13 out of 16 patients, even in the absence of tumor cells in the tissue biopsy. In these cases, EGFR test results obtained from BWF showed concordance with EGFR test results from the tumor tissue obtained through repeated biopsy or surgery later. In the rebiopsy group, T790M was detected in 16 patients (37.2 %) by tissue biopsy. The combined use of tissue biopsy and BWF increased detection, confirming T790M in 22 patients (51.2 %).

DISCUSSION

The detection of mEGFR using BWF shows higher diagnostic yields than plasma for both initial diagnosis and rebiopsy. T790M was detected earlier in BWF than in tissue rebiopsy in some cases, providing patients with an early opportunity to access third-generation EGFR-TKIs. The complementary use of BWF with tumor tissue may improve precision in EGFR-mutated NSCLC treatment strategies.

Utility of cell-free DNA from bronchial washing fluid in diagnosis and genomic determination for radiology-suspected pulmonary nodules

BACKGROUND

Bronchial washing fluid (BWF) is a less-invasive specimen. Due to the limited sensitivity of BWF cellular component diagnosis, the aim of this study was to explore the potential role of BWF supernatant as a source of liquid biopsy of lung cancer.

METHODS

This prospective study enrolled 76 suspected and 5 progressed lung cancer patients. Transbronchial biopsy tissues, BWF supernatant (BWF_Sup) and BWF precipitant (BWF_Pre) were tested by a targeted panel of 1021 genes.

RESULTS

BWF_Sup cell-free DNA (cfDNA) was superior to tissue biopsy and BWF_Pre in determining mutational allele frequency, tumour mutational burden, and chromosomal instability. Moreover, BWF_Sup and BWF_Pre achieved comparable efficacy to tissue samples in differentiating malignant and benign patients, but only BWF_Sup persisted differentiated performance after excluding 55 malignancies pathologically diagnosed by bronchoscopic biopsy. Among 67 malignant patients, 82.1% and 71.6% of tumour-derived mutations (TDMs) were detected in BWF_Sup and BWF_Pre, respectively, and the detectability of TDMs in BWF_Sup was independent of the cytological examination of BWF. BWF_Sup outperformed BWF_Pre in providing more subclonal information and thus might yield advantage in tracking drug-resistant markers.

CONCLUSIONS

BWF_Sup cfDNA is a reliable medium for lung cancer diagnosis and genomic profiles and may provide important information for subsequent therapeutic regimens.

Genomic Profiling of Bronchoalveolar Lavage Fluid in Lung Cancer

Genomic profiling of bronchoalveolar lavage (BAL) samples may be useful for tumor profiling and diagnosis in the clinic. Here, we compared tumor-derived mutations detected in BAL samples from subjects with non-small cell lung cancer (NSCLC) to those detected in matched plasma samples. Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq) was used to genotype DNA purified from BAL, plasma, and tumor samples from patients with NSCLC. The characteristics of cell-free DNA (cfDNA) isolated from BAL fluid were first characterized to optimize the technical approach. Somatic mutations identified in tumor were then compared with those identified in BAL and plasma, and the potential of BAL cfDNA analysis to distinguish lung cancer patients from risk-matched controls was explored. In total, 200 biofluid and tumor samples from 38 cases and 21 controls undergoing BAL for lung cancer evaluation were profiled. More tumor variants were identified in BAL cfDNA than plasma cfDNA in all stages (P < 0.001) and in stage I to II disease only. Four of 21 controls harbored low levels of cancer-associated driver mutations in BAL cfDNA [mean variant allele frequency (VAF) = 0.5%], suggesting the presence of somatic mutations in nonmalignant airway cells. Finally, using a Random Forest model with leave-one-out cross-validation, an exploratory BAL genomic classifier identified lung cancer with 69% sensitivity and 100% specificity in this cohort and detected more cancers than BAL cytology. Detecting tumor-derived mutations by targeted sequencing of BAL cfDNA is technically feasible and appears to be more sensitive than plasma profiling. Further studies are required to define optimal diagnostic applications and clinical utility.

SIGNIFICANCE

Hybrid-capture, targeted deep sequencing of lung cancer mutational burden in cell-free BAL fluid identifies more tumor-derived mutations with increased allele frequencies compared with plasma cell-free DNA. See related commentary by Rolfo et al., p. 2826.

The Diagnostic Utility of Cell-Free DNA from Ex Vivo Bronchoalveolar Lavage Fluid in Lung Cancer

Simple Summary

This study aims to detect cell-free DNA released from lung cancer cells into the airway using the ex vivo BAL model of our own establishing. We finally demonstrated that cell-free DNA released from lung cancer cells is more abundant in the airway than in the blood, and the efficient collection of cell-free DNA derived from lung cancer in the airway by BAL and its genomic analysis could allow the accurate diagnosis of lung cancer. We believe that this approach will possibly make a breakthrough in the currently unsatisfactory diagnostic yield for lung cancer, since it is a new and constitutive diagnostic focusing on the gene mutations of lung cancer and their release into the airway in the form of cell-free DNA.

Abstract

Although bronchoscopy is generally performed to diagnose lung cancer, its diagnostic yield remains unsatisfactory. Assuming that lung cancer cells release cell-free DNA into the epithelial lining fluid, we hypothesized that lung cancer could be diagnosed by analyzing gene mutations in cell-free DNA in this fluid. This study included 32 patients with lung cancer who underwent surgery at our hospital. Bronchoalveolar lavage (BAL) was performed on the resected lung samples (ex vivo BAL model) after lobectomy. Each DNA sample (i.e., BAL fluid, primary lesion, and plasma) underwent deep targeted sequencing. Gene mutation analyses in the BAL fluid samples identified mutations identical to those in the primary lesions in 30 (93.8%) of 32 patients. In contrast, the microscopic cytology of the same BAL fluid samples yielded a diagnosis of lung cancer in only one of 32 patients, and the analysis of plasma samples revealed gene mutations identical to those in the primary lesions in only one of 32 patients. In conclusion, cell-free DNA released from lung cancer cells exists more abundantly in the airway than in the blood. The collection and analysis of the BAL fluid containing cell-free DNA derived from lung cancer can thus allow lung cancer diagnosis and the screening of driver mutations.

Sensitive cell-free tumor DNA analysis in supernatant pleural effusions supports therapy selection and disease monitoring of lung cancer patients

Supernatant pleural effusions (PE) have shown to be a valuable source for the detection of driver mutations in circulating tumor DNA (ctDNA). In this prospective study, the clinical value of ctDNA analysis in supernatant PE to support therapy selection and disease monitoring in lung cancer patients is assessed. Paired PE and plasma samples were collected from lung cancer patients before initiation of therapy (N = 2) and from EGFR positive patients during therapy (N = 3). Supernatant PE and plasma were tested for mutations in EGFR, KRAS and BRAF by droplet digital PCR. In PE of two patients with suspected lung cancer, a KRAS mutation was detected with a 5- and 8-fold higher fractional abundance (FA) compared to plasma. For three patients with progressive disease during therapy, both the EGFR L858R and T790M mutations were detected in PE. However, in plasma only for two of these patients the L858R mutation was detected with a 46- and 14- fold lower FA, and only for one patient the T790M mutation was detected with a 8-fold lower FA. For one patient, longitudinal ctDNA analysis in PE revealed the T790M and L858R mutations already two months prior to detection of progressive disease by CT-scan. In this study, a higher ctDNA concentration and FA was obtained from PE compared to the corresponding blood samples, which enables more sensitive mutation analysis. Thus, PE is a valuable liquid biopsy, complementing plasma, for ctDNA analysis to support therapy selection and disease monitoring in lung cancer patients.

Identifying Genomic Alterations in Small Cell Lung Cancer Using the Liquid Biopsy of Bronchial Washing Fluid

Objective: With the rapid development of cancer genomics and immunomics, some new treatments of small cell lung cancer (SCLC) are emerging. However, there are limitations to the clinical use of tumor tissue. Our study aimed to evaluate the potential use of bronchial washing fluid (BWF) in the liquid biopsy of SCLC. Methods: Twenty-one extensive SCLC (ES-SCLC) patients were enrolled in this study. For all patients, four sample types, BWF supernatant (BWFs), BWF precipitate (BWFp), plasma and tumor tissue, were collected before receiving chemotherapy, and one type, plasma, was collected after chemotherapy. All samples were conducted to NGS using the 1021-gene panel. The concordance rates of genomic profiling using NGS in the four types of samples were evaluated. Multiple clinical information was analyzed for correlation. Results: We successfully tested 20 BWFs samples, 21 BWFp samples, 21 tumor tissue samples, 20 pre-treatment plasma, and 13 post-treatment plasma of these 21 patients. The detectability of somatic mutations was 100% for BWFs, BWFp, tumor tissues, and post-treatment plasma, and only one pre-treatment plasma was absent with any mutation. Matched tumor tissue, BWFs, BWFp, and pre-treatment plasma samples were subsistent for 19 patients. For these patients, 204 genomic alterations were identified in tissue samples, while 189 (92.6%), 175 (85.5%), and 163 (79.9%) alterations were detected in the matched BWFs, BWFp, and pre-treatment plasma, respectively. Moreover, we found that the three tumor markers associated with SCLC have a lower sensitivity than genomic alterations. The endocrine resistance pathway was found enriched in hyponatremia patients which may be related to the hyponatremia. The TMBs of BWF, BWFp, and pre-treatment plasma samples all had a strong correlation with that of tissue samples. Both the VAF and the MVAF of mutations in post-treatment plasma were less than those in pre-treatment plasma, which was in accordance with the evaluation of curative effect. Conclusions: For ES-SCLC patients, the liquid biopsy of BWF showed a highly potential advantage to identify DNA alterations, which suggested that genomic analysis of BWF liquid biopsy may have clinical value as a supplement for tissue and blood detection. Through the restricted validation, it can be widely used in routine clinical practice.

Bronchial Washing Fluid Versus Plasma and Bronchoscopy Biopsy Samples for Detecting Epidermal Growth Factor Receptor Mutation Status in Lung Cancer

Background

Bronchial washing fluid (BWF) is a common specimen collected during bronchoscopy and has been suggested to contain both tumor cells and cell-free DNA. However, there is no consensus on the feasibility of BWF in epidermal growth factor receptor (EGFR) genetic analysis because of the limited sample size and varying results in previous studies. This study compared the feasibility, sensitivity, and specificity of detecting EGFR mutation using BWF, bronchoscopy biopsy, and plasma samples in patients with lung cancer (LC).

Materials and Methods

A total of 144 patients (110 with LC and 34 without LC) were enrolled in the study. During diagnostic bronchoscopy for suspected LC lesions, bronchial washing with saline was performed directly or through a guide sheath. BWF was collected as well as paired bronchoscopy biopsy and plasma samples, and EGFR mutation testing was performed via highly sensitive blocker polymerase chain reaction. The EGFR mutation status of histologic samples was set as the standard reference.

Results

Compared with the histologic samples, the sensitivity, specificity, and concordance rate of EGFR mutation detected in BWF samples were 92.5%, 100%, and 97.9%, respectively. Moreover, BWF showed a higher sensitivity in EGFR mutation testing than both plasma (100% [8/8] vs. 62.5% [5/8], p = 0.095) and bronchoscopy biopsy samples (92.5% [37/40] vs. 77.5% [31/40], p = 0.012) and identified EGFR mutations in 6 cases whose biopsy failed to establish an LC diagnosis. The diameter of the target lesion and its contact degree with BWF were positive predictive factors for EGFR testing results.

Conclusions

BWF yields a high sensitivity in EGFR mutation testing, having high concordance with histologic samples, and presenting the benefit of rapid EGFR mutation detection in LC patients.

Liquid Biopsy of Non-Plasma Body Fluids in Non-Small Cell Lung Cancer: Look Closer to the Tumor!

Liquid biopsy is a rapidly emerging field due to an increasing number of oncogenic drivers and a better understanding of resistance mechanisms to targeted therapies in non-small cell lung cancer (NSCLC). The sensitivity of the most widely used blood-based assays is, however, limited in particular in cases of low tumor volume where shed of tumor-derived material can be limited. A negative result thus requires biopsy confirmation using minimally invasive sampling procedures that can result in small specimens, which are often not suitable for genotyping. Liquid biopsy is not limited to plasma, and tumor DNA circulating in other body fluids such as urine, pleural fluid, cerebrospinal fluid, or cytology specimen-derived supernatant can be exploited. In comparison to cell blocks, these fluids in close contact to the tumor may contain a more abundant and less analytically demanding tumor DNA. In this review, we discuss the potential applications of circulating tumor DNA derived from cytology samples in NSCLC, from early stage (screening, nodule characterization) to metastatic disease.

Detection of EGFR Mutations Using Bronchial Washing-Derived Extracellular Vesicles in Patients with Non-Small-Cell Lung Carcinoma

Simple Summary

Considering the spatiotemporal heterogeneity, more frequent monitoring of the disease progress using less-invasive liquid biopsy technologies is highly desired. Here, we demonstrate that epidermal growth factor receptor (EGFR) mutations could be readily detected from minimally invasive bronchial washing (BW)-derived EVs with good accuracy. The acquisition of T790M resistance mutation was detected earlier in BW-derived EVs than in plasma or tissue samples. The longitudinal analysis of BW-derived EVs showed excellent correlation with the disease progression measured by CT images. We demonstrate the clinical potential of BW-derived EVs as a liquid-biopsy sample for prognosis and precision medicine in patients with lung cancer.

Abstract

The detection of epidermal growth factor receptor (EGFR) mutation, based on tissue biopsy samples, provides a valuable guideline for the prognosis and precision medicine in patients with lung cancer. In this study, we aimed to examine minimally invasive bronchial washing (BW)-derived extracellular vesicles (EVs) for EGFR mutation analysis in patients with lung cancer. A lab-on-a-disc equipped with a filter with 20-nm pore diameter, Exo-Disc, was used to enrich EVs in BW samples. The overall detection sensitivity of EGFR mutations in 55 BW-derived samples was 89.7% and 31.0% for EV-derived DNA (EV-DNA) and EV-excluded cell free-DNA (EV-X-cfDNA), respectively, with 100% specificity. The detection rate of T790M in 13 matched samples was 61.5%, 10.0%, and 30.8% from BW-derived EV-DNA, plasma-derived cfDNA, and tissue samples, respectively. The acquisition of T790M resistance mutation was detected earlier in BW-derived EVs than plasma or tissue samples. The longitudinal analysis of BW-derived EVs showed excellent correlation with the disease progression measured by CT images. The EGFR mutations can be readily detected in BW-derived EVs, which demonstrates their clinical potential as a liquid-biopsy sample that may aid precise management, including assessment of the treatment response and drug resistance in patients with lung cancer.