Cutaneous Squamous Cell Carcinoma Subjected to Anti PD-1 Immunotherapy: Monitoring Response Through Serial PET/CT Scans with F-18-FDG

Background: The effectiveness of F-18-fluorodeoxyglucose (F-18-FDG) positron emission computed tomography (PET/CT) for monitoring response to immunotherapy (IT) with cemiplimab in patients affected by cutaneous squamocellular carcinoma (cSCC) was investigated.Materials and Methods: Thirteen cSCC patients performed PET/CT at baseline (PET-1) and 3 months after IT (PET-2). According to immune PET Response Criteria in Solid Tumors (iPERCIST), patients showing progressive disease at PET-2 were classified as having unconfirmed progressive metabolic disease (uPMD) and were scheduled to perform a further PET/CT (PET-3) after 4 weeks. PET/CT's results were correlated with best clinical response (BCR) categorized, within 6 months from the start of IT, as clinical benefit (CB) or no clinical benefit (NCB) according to clinical follow-up.Results: At PET-2, 9 subjects (69.2%) showed metabolic response, whereas four (30.8%) were classified as uPMD. After 4 weeks, three uPMD patients were subjected to PET-3, which confirmed progressive disease in all cases, whereas 1 patient with uPMD did not undergo PET-3 due to clinical deterioration. All subjects with metabolic response at PET-2 were classified as having CB and continued IT in 8 out of 9 cases, whereas all patients with uPMD were categorized as NCB and discontinued IT.Conclusions: PET/CT, performed in cSCC patients after 3 months of cemiplimab, resulted capable to identify responders from nonresponders.

Automated summary

The effectiveness of F-18-FDG PET/CT for monitoring response to cemiplimab immunotherapy in patients with cutaneous squamocellular carcinoma was investigated. PET/CT was found to be capable of identifying responders and nonresponders.