Malignant pleural effusion supernatant is an alternative liquid biopsy specimen for comprehensive mutational profiling.

BACKGROUND: The clinical utility of malignant pleural effusion (MPE) to detect mutation has been well documented; however, routine practice of the use of MPE involves collection of the cell pellet to detect mutation, and limited studies have interrogated the MPE supernatant as an alternative source of tumor-derived DNA for mutation profiling. In this study, we investigated the potential of MPE supernatant as a liquid biopsy specimen by comparing its mutation profile with that of matched MPE cell pellets, tissue, and plasma samples.

METHODS: Sequencing data from 17 patients with matched lung tissue, plasma, and MPE samples were retrospectively analyzed. Capture-based targeted sequencing was performed on matched plasma and MPE supernatant samples obtained from 154 patients with advanced lung adenocarcinoma.

RESULTS: MPE supernatants had significantly higher median maximum allelic fractions (maxAFs) than their corresponding cell pellets (P = 0.008) and plasma samples (P = 0.036), and a comparable maxAF value to that of tissue samples (P = 0.675). Comparison of MPE supernatant and matched plasma samples from the larger cohort (n = 154) revealed a comparable mutation detection rate; however, MPE supernatant had a significantly higher median maxAF than plasma (20.3% vs. 1.13%; P < 0.001). Furthermore, the concordance rates between MPE supernatant and plasma for single-nucleotide and copy number variations were 56% and 18%, respectively, suggesting that MPE supernatant reveals a more comprehensive mutation spectrum, particularly for copy number variations.

CONCLUSION: Overall, our study shows that MPE supernatant is an optimal alternative source of tumor-derived DNA for comprehensive mutation profiling.