Abstract 4463: Tumor-derived Cell-Free DNA from Bronchoalveolar Lavage Fluid (BALF): A Potential Liquid Biopsy Analysis in Lung Cancer Patients

Abstract Background: Bronchoalveolar lavage (BAL) is the most common technique for sampling the components of the alveolar space. Here, we evaluated the potential use of BAL fluid (BALF) in liquid biopsy in lung cancer. Methods: This study enrolled 56 lung cancer patients. And 57 BALF (separated supernatant and precipitate) samples and 56 peripheral blood lymphocytes samples were collected. 57 formalin-fixed Paraffin-embedded (FFPE) tissues were also obtain. We utilized a 1021-gene NGS panel in matched tissue DNA, BALF supernatant cfDNA and BALF precipitate DNA to identify somatic mutations with white blood cell DNA as a germline control. Results: Mutations were identified in 52 (~91.22%) BALF precipitate samples and 55 (~96.49%) BALF supernatant samples, comparing to 53 (92.98%) in tumor samples. EGFR mutations were observed in 22 BALF precipitate samples and 24 supernatant samples. Among these, 23 were also identified in matched tumor samples. One BALF precipitate samples specific and two BALF supernatant samples specific EGFR mutations were confirmed by Cobas assay. In addition, gene fusions including ALK, ROS1 and RET were found in 6 tumors, 4 BALF precipitate samples and 5 supernatant samples, respectively. In total, there were 195 mutations identified in the tumor samples, of which 147 (~75.4%) mutations were detected in the matched BALF precipitate samples, 168 (~86.1%) mutations were detected in the matched BALF supernatant samples and 145 (~74.4%) mutations were shared in three types of samples. Tumor mutation burden (TMB) were calculated, and the consistency between tissue and BALF precipitate was 90% and the consistency between tissue and BALF supernatant was 94%. Conclusions: Liquid biopsy using BALF shown high potential to profiling genetic alterations of patients with lung cancer, which might be implemented and standardized into clinical use. Citation Format: Yuhua Gong, Xinyu Zhang, Chun Li, Weiran Wang, Maosong Ye, Yancheng Zhao, Xin Yi, Yaping Xu, Qin Hu, Yanfang Guan, Ling Yang, Xuefeng Xia, Min Zhou, Jian'an Huang, Hua Zhang, Tao Ren, Qian Shen, Kai Wang, Yingyong Hou, Xin Zhang. Tumor-derived cell-free DNA from bronchoalveolar lavage fluid (BALF): A potential liquid biopsy analysis in lung cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4463.