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ctDNA ICI Cessation — SCE Medical Oncology MCQ

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HardImmunotherapy & Targeted TherapyctDNA ICI CessationSCE Medical Oncology

A patient with metastatic melanoma has a complete radiological response and undetectable personalised ctDNA after two years of anti-PD-1 treatment. What is the current role of ctDNA in deciding whether to stop treatment?

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Correct answer: E — Treat ctDNA clearance as investigational, not as a stand-alone checkpoint stopping rule

ctDNA clearance is prognostic but remains investigational for checkpoint duration and cannot serve as a stand-alone stopping, imaging or restart rule. Treat ctDNA clearance as sufficient evidence to stop checkpoint treatment at one year: no validated stand-alone ctDNA stopping threshold exists. Treat ctDNA persistence as sufficient evidence to continue checkpoint treatment indefinitely: persistent detection does not independently define duration or benefit. Treat ctDNA clearance as sufficient evidence to replace cross-sectional imaging: ctDNA cannot yet substitute for anatomical response and surveillance imaging. Treat ctDNA recurrence as sufficient evidence to restart checkpoint treatment immediately: a low-level molecular result requires confirmation and clinical context.

Reference: ESMO recommendations on circulating tumour DNA assays in cancer (Published July 2022): https://pubmed.ncbi.nlm.nih.gov/35809752/; SITC clinical practice guideline on immunotherapy for melanoma, version 3.0 (Published October 2023): https://pmc.ncbi.nlm.nih.gov/articles/PMC10603365/; NICE NG14 melanoma: recommendations (Updated July 2022; minor amendment January 2024): https://www.nice.org.uk/guidance/ng14/chapter/recommendations