18F-FDG PET/CT in Relapsed Endometrial Cancer Treated with Preoperative PD-1 Inhibitor Dostarlimab.

Dostarlimab is an immune checkpoint inhibitor (ICI) targeting the Programmed-Death-1 (PD-1) co-receptor, recently approved by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) as a novel therapy for recurrent or advanced endometrial cancer. We report the case of a 64-year-old woman, experiencing vaginal recurrence with microsatellite instability high/hypermutated of a FIGO stage IA grade 2 endometrial endometrioid adenocarcinoma. She received preoperative chemotherapy with four cycles of carboplatin plus paclitaxel, with stable disease on pelvic magnetic resonance imaging (MRI) and fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT). Dostarlimab (500 mg intravenously every 3 weeks) was then introduced. The subsequent evaluation after three perfusions demonstrated a complete metabolic response on 18F-FDG PET/CT according to immunotherapy-modified PET response criteria in solid tumors (imPERCIST) criteria, then confirmed by MRI according to immune response evaluation criteria in solid tumors (iRECIST). This clinical description suggests that 18F-FDG PET/CT might take place among available tools for guiding the preoperative management for recurrent endometrial cancer patients receiving dostarlimab immunotherapy that should be further explored through clinical trials.