KRAS and neoplasm: Circulating tumor DNA was detected in 50% of the samples, and the emergence of putative resistance mechanisms was confirmed, including gene amplifications (MET, EGFR, and KRAS) and other mutations (EGFR C797S, HER2 exon 20 insertion, MEK1, KRAS, PIK3CA, and JAK2), although the acquired EGFR T790M mutation was not observed.