The EGFR gain correlated excellently with an initial good response to anti-EGFR therapy as previously reported [19]–[21], because tumor markers CEA and CA19-9 decreased (Figure 2b) and when we repeated our plasma-Seq analysis two months later we observed an almost balanced copy number profile, indicating a very low ctDNA percentage (P2_2 in Figure 2a). The gene discussed is EGFR; the disease is neoplasm.