Longitudinal assessment of mutation abundance in plasma cfDNA upon R-CHOP treatment. The graphs represent the variant allele frequency of nonsynonymous somatic mutations in plasma cfDNA at baseline before the start of treatment, before each R-CHOP course, and at the end of treatment. Responding (A) and nonresponding (B) patients are pooled in the graphs. Each dot represents 1 single individual mutation. Among responding patients (A), baseline mutations (n = 102; mean allele frequency: 12.6%, range: 0.17%-80.4%) disappeared from plasma cfDNA. Among nonresponding patients (B), baseline mutations (n = 27; mean allele frequency: 14.3%, range: 0.14%-53.9%) remain detectable in plasma cfDNA before R-CHOP cycle 2 (mean allele frequency: 20.2%, range: 0.65%-65.3%), before R-CHOP cycle 3 (mean allele frequency: 18.8%, range: 1.1-61.1%), and at the end of treatment (mean allele frequency: 8.2%, range: 0.1%-34.2%).