In our cohort of patients, high mutant EGFR ctDNA copy number at baseline and increased clearance of ctDNA, as evidenced by a lower mutant EGFR AF as early as Day 7 of treatment, but not the tumor volume, were associated with PFS, suggesting that ctDNA “shedding” may indicate the existence of more aggressive tumors that are likely to develop resistance to therapy faster. Here, EGFR is linked to neoplasm.