Fig. 4

The association of ctDNA status with clinical outcomes. a Dynamics of HER2-mutant ctDNA between baseline and first radiological evaluation. b log10 of the change of HER2-mutant VAF according to response to pyrotinib treatment. c, d Kaplan–Meier estimates of PFS c and OS d for 34 patients stratified by ctDNA status at the first radiographic evaluation (40 days after start of targeted therapy). e Duration of pyrotinib treatment in patients with ctDNA nonshedding, clearance and remained. f–h Representative cases in which ctDNA can be used to monitor patients' response to pyrotinib treatment in three different conditions. VAF variant allele frequency, PFS progression free survival, OS overall survival, HR hazard ratio