Conclusions
ARAF amplification was identified in 5-8% of EGFR-TKI-resistant tumors. The possible roles of ARAF in SCLC transformation warrant further investigation.
Methods
We conducted a single-center retrospective analysis of the presence of ARAF amplification in re-biopsied samples in patients with EGFR-mutant NSCLC resistant to EGFR-TKIs. Demographic data, treatment course, and clinical molecular testing reports were extracted from electronic medical records. ARAF amplification was determined using a gene copy number assay. RNA sequence analysis was performed in patients with ARAF amplification as well as presenting histologic transformations to small-cell lung carcinoma (SCLC).
Results
ARAF amplification was identified in five of ninety-seven patients resistant to erlotinib or gefitinib, and four of forty-eight patients resistant to Osimertinib. ARAF amplification was dominantly observed in female patients with EGFR exon 19 deletion. All ARAF-amplified tumors retained their founder EGFR mutation and were absent of secondary mutations. Two cases were found where ARAF amplification correlated with a histological transformation to SCLC. Conclusions: ARAF amplification was identified in 5-8% of EGFR-TKI-resistant tumors. The possible roles of ARAF in SCLC transformation warrant further investigation.