Composite Clonal Analysis Reveals Transition of NSCLC Subtypes Through Accumulation of Gene Mutations: A Case Report

We analyzed an EGFR-mutated lung cancer with a pathologic diagnosis of combined large cell neuroendocrine carcinoma with mixed adenocarcinoma subtypes. Targeted next-generation sequencing of each component suggested that mutations in RB1, TP53, and SMAD4 and apparent loss of heterozygosity of TP53 and SMAD4 accompanied the transition of different adenocarcinoma subtypes. Additional gene mutations including PTEN, MST1R, and PIK3CA were noted during transdifferentiation from acinar adenocarcinoma to large cell neuroendocrine carcinoma. Combined DNA and RNA analysis using Todai OncoPanel revealed that transdifferentiation to different pathologic subtypes occurred in a single tumor through the accumulation of gene mutations.