Liquid biopsy for the detection of resistance mutations to ROS1 and RET inhibitors in non-small lung cancers: A case series study

Liquid biopsy can identify gene alterations that are associated with resistance to fusion gene-targeted treatments. In this study, we present three cases of advanced non-small cell lung cancer (NSCLC) harboring gene fusions; cell-free DNA (cfDNA) was used to assess the resistance mutations. A patient with MET amplification underwent RET-fusion NSCLC treatment with selpercatinib. A patient with ROS1 G2032R underwent ROS1-fusion NSCLC treatment with crizotinib. A patient who underwent ROS1-fusion NSCLC treatment with crizotinib harbored no somatic mutations. This case series shows that cfDNA analysis can identify potentially actionable genomic alterations, after disease progression, in targeted therapy for fusion genes. Trial registration The study was registered in the UMIN Clinical Trial Registry (UMIN 000017581).