Clinical course and ctDNA measurements for patient #01, a 68-year-old woman with biopsy-proven unresectable melanoma of the left neck and left supraclavicular regions. She received ipilimumab as first-line therapy, to which she had an “immune-related” response. A) Treatment timeline. Ipilimumab (anti-CTLA-4, 3 mg/kg) was administered intravenously every 3 weeks for 3 doses. ctDNA levels (TERTmut) increased initially as metastatic lymph nodes enlarged on physical examination (week 3), but ctDNA became undetectable at week 6 even though metastatic lymph nodes were still palpable. Significant disease regression was noted clinically 3 weeks later and complete disease resolution was demonstrated on CT and FDG-PET scans performed 4 months after treatment initiation. B) CT and FDG-PET images demonstrating the resolution of palpable cervical lymphadenopathy after administration of ipilimumab.