FIG 2.

HPV ctDNA burden over time on the basis of (A) dPCR and (B) HPV-seq. Patients who are disease-free are depicted in gray; those who relapsed are depicted in red. The change in HPV ctDNA burden was determined using adjacent timepoints. Patients had (1) rapid clearance of HPV ctDNA at all three nonbaseline timepoints (end of CRT, 4-6 weeks post-CRT, and 3 months post-CRT); (2) a gradual decrease in HPV ctDNA; (3) an increase in HPV ctDNA level relative to an earlier adjacent timepoint; or (4) missing adjacent timepoints. PFS by HPV ctDNA kinetic patterns (1)-(3), on the basis of (C) dPCR and (D) HPV-seq. CRT, chemoradiation; dPCR, digital polymerase chain reaction; HPV ctDNA, human papilloma virus circulating tumor DNA; PFS, progression-free survival.