Droplet digital PCR as an alternative method for detecting MET amplification in patients with non-small cell lung cancer.

Abstract

e15107 Background: Mesenchymal-epithelial transition (MET) amplification is associated with resistance to epidermal growth factor receptor tyrosine kinase inhibitors in lung cancer patients and poor prognosis. Fluorescence in situ hybridization (FISH) is the most commonly used method for detecting MET amplification but is not possible in cases where tissue samples are unavailable. Here, we evaluated the utility of droplet digital PCR (ddPCR) in detecting MET amplification in non-small cell lung cancer (NSCLC) patients. Methods: We evaluated a c-Met: EFTUD ddPCR assay of the c-Met gene and using EFTUD as the reference gene to determine c-Met amplification in plasma cfDNA samples from 80 advanced NSCLC patients. A total of 84 plasma samples were collected for MET amplification detection using ddPCR. Paired tissue samples using FISH were to evaluate the correlation between the MET-ddPCR ratio and MET FISH. Results were correlated with clinical findings. Results: We found that ddPCR had an 88.1% concordance rate with FISH in detecting MET CNG, with an area under the curve (AUC) of 0.84. Eleven patients were positive for MET amplification by FISH prior to MET inhibitor treatment, and these patients had a partial response rate (PR) of 45.5% and a median progression-free survival (PFS) of 12.1 months. However, MET amplification identified by ddPCR failed to distinguish significant clinical outcomes. The PR rate and median PFS for ddPCR-positive vs. negative patients were 57.1% vs. 50.0% and 12.1 months vs. 2.1 months (P = 0.276). Conclusions: Our results suggest that ddPCR is a reliable alternative to detect MET amplification in plasma cfDNA samples. Met status determined in cfDNA may have potential as a predictive factor for PFS after c-Met inhibitor therapy.