e14554 Background: Malignant pleural effusion (MPE) from lung cancer is an attractive alternative for molecular testing due to advantages of non-invasiveness and less heterogeneity. Previously, cell pellet blocks of MPE are widely used. This study is to further address whether supernatants of MPE is a suitable source to identify key oncogenic mutants in lung cancer and provide more information for clinical molecular testing. Methods: MPE samples from 12 lung cancer patients were centrifuged to obtain supernatants and cell pellets, and DNA were extracted. The DNA samples were analyzed by a targeted next generation sequencing (NGS) panel using Illumina HiSeq platform. Results: In a pilot study, paired cancer tissue and MPE samples were obtained from 3 lung cancer patients and analyzed using a comprehensive 500-gene cancer panel. Nine mutants were identified both in the tissue samples and MPE samples. We then analyzed another 9 lung cancer patient samples to detect oncogenic mutants using an 18-gene panel. In total, 8 mutants including EGFR L858R, exon 19 deletion, or T790M mutants were identified in MPE samples. For the total 17 mutants from the 12 MPE samples, 10 mutants were observed in both matched supernatant and cell pellet of MPE, of which more pairs (6 out of 10) had supernatants with higher abundance of mutants than cell pellets. More importantly, 7 of the 17 mutants were only detected in the supernatants of the matched MPE. Taken together, these results suggest that supernatant of MPE is a more suitable source to detect key driver mutants of lung cancer. Interestingly, 2 patients had both tyrosine kinase inhibitor (TKI) resistant mutant T790M and TKI sensitive mutants detected in supernatants of MPE; both patients had prior treatment of EGFR TKI, consistent with the development of TKI resistant mutant and supporting the utility of supernatants of MPE in monitoring TKI resistance. Conclusions: This study suggest supernatant of MPE is a more suitable source for identifying key driver mutants for lung cancer and can also be used to monitor response to targeted therapy. The study provides evidence of using supernatant of MPE as alternative source for molecular testing and thus direct precise targeted therapy and effect surveillance.
Usefulness of the endosonography using 25 gauge core needles for immunohistochemistry and molecular testing in lung cancer patients: a feasibility study
