Utility of AMOY polymerase chain reaction panel in detecting non-small cell lung cancer using pleural cell block

BACKGROUND: Comprehensive biomarker testing is mandatory for advanced non-small cell lung cancer (NSCLC). Pleural effusion cell blocks are a minimally invasive alternative to biopsy. The AmoyDx pan lung cancer (PLC) polymerase chain reaction panel is a sensitive multiplex assay; however, its performance using pleural cell-block specimens with low tumor-cell content remains largely unexplored. METHODS: We conducted a retrospective study of 30 patients with advanced NSCLC and having known driver mutations, whose pleural effusion cell blocks were tested using the AmoyDx PLC panel at Kanagawa Cancer Center between 2021 and 2023. Tumor content was quantified using thyroid transcription factor 1 immunohistochemistry. DNA and RNA quality were assessed, and the panel results were compared with those of other molecular assays. RESULTS: The AmoyDx PLC panel achieved a detection success rate of 96.7% (29/30), with a sole discordant case owing to the absence of malignant cells. The concordance in confirmed malignant cases was 100%. Notably, the panel detected target mutations in specimens with tumor contents well below the recommended threshold. High detection performance was observed even when the nucleic acid concentrations were suboptimal or the purity levels were outside the reference range. The median tumor content was 8.5% (range, 0.2%-88.2%), with 74% samples below the 20% threshold. CONCLUSIONS: Pleural effusion cell blocks are a practical and reliable alternative for molecular testing of advanced NSCLC when biopsy is not feasible. The high sensitivity of the AmoyDx PLC panel even for specimens with low tumor cell content underscores its potential clinical utility.