ALK and neoplasm: To identify putative resistance mutations, we performed tumor-naïve variant calling39 on the post-TKI plasma sample, retaining mutations in genes known to be associated with resistance mutations (exonic SNVs, EGFR, PIK3CA, KRAS, CDKN2A, RB1, ALK, KIT, and MET; copy number variants, MET, ERBB2, and EGFR)40.