Usefulness of nanofluidic digital PCR arrays to quantify T790M mutation in EGFR-mutant lung adenocarcinoma.

AIM: The present pilot study assessed the usefulness of nanofluidic digital polymerase chain reaction (PCR) arrays in epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma after tyrosine kinase inhibitor (TKI) resistance. PATIENTS AND METHODS: We enrolled 12 patients with primary lung adenocarcinoma with sensitive EGFR mutation-confirmed T790M status by re-biopsy after TKI resistance. Nanofluidic digital PCR arrays were used to quantify T790M in genomic DNA from the pre-treatment primary site and in serum cell-free DNA (cfDNA). RESULTS: On digital PCR, quantified T790M at the pre-treatment primary site was higher in re-biopsy-positive T790M patients (n=4) than in re-biopsy-negative patients (n=8) (0.78%±0.36% vs. 0.07%±0.09%, p<0.01). T790M at the pre-treatment primary site correlated with progression-free survival (PFS) after gefitinib therapy (r=0.67, p=0.016). CONCLUSION: Use of digital PCR to quantify T790M at the primary site of EGFR-mutant lung adenocarcinoma predicted T790M emergence in re-biopsies after TKI resistance and PFS after gefitinib therapy.