Background: Immune checkpoint inhibitors (ICI) have achieved astonishing results and
improved overall survival (OS) in several types of malignancies, including advanced melanoma. However,
due to a peculiar type of anti-cancer activity provided by these drugs, the response patterns during
ICI treatment are completely different from that with “old” chemotherapeutic agents.
Objective: To provide an overview of the available literature and potentials of 18F-FDG PET/CT in
advanced melanoma during the course of therapy with ICI in the context of treatment response
Method: Morphologic criteria, expressed by Response Evaluation Criteria in Solid Tumors (RECIST),
immune-related response criteria (irRC), irRECIST, and, more recently, immune-RECIST (iRECIST),
along with response criteria based on the metabolic parameters with 18F-Fluorodeoxyglucose (18FFDG),
have been explored.
Results: To overcome the limits of traditional response criteria, new metabolic response criteria have
been introduced on time and are being continuously updated, such as the PET/CT Criteria for the early
prediction of Response to Immune checkpoint inhibitor Therapy (PECRIT), the PET Response Evaluation
Criteria for Immunotherapy (PERCIMT), and “immunotherapy-modified” PET Response Criteria
in Solid Tumors (imPERCIST). The introduction of new PET radiotracers, based on monoclonal antibodies
combined with radioactive elements (“immune-PET”), are of great interest.
Conclusion: Although the role of 18F-FDG PET/CT in malignant melanoma has been widely validated
for detecting distant metastases and recurrences, evidences in course of ICI are still scarce and larger
multicenter clinical trials are needed.