18 F-FDG PET/CT for response assessment in Hodgkin lymphoma undergoing immunotherapy with checkpoint inhibitors.

Our aim was to evaluate Hodgkin Lymphoma (HL) response to checkpoint inhibitors with 18 F-FDG PET/CT. Forty three refractory or relapsed HL patients were investigated before immunotherapy, 8 weeks and 17 weeks after administration of either nivolumab or pembrolizumab. The median follow-up was 19 months. Best clinical response was complete response (CR) in 26 patients, partial response (PR) in 5 patients, stable disease (SD) in 8 patients, and progression disease (PD) in 4 patients. At the early assessment, Deauville Score (DS) resulted significantly different in responder group compared to nonresponders. SUVmax was significantly lower in responders, while there was no relevant modification in the tumor burden. At interim evaluation, DS well differentiated responder group. A significant decrease in glucose metabolism and tumor burden parameters was observed in responder patients, who presented with a longer progression-free survival then nonresponders. 18 F-FDG PET/CT provides a reliable indication of treatment response under checkpoints inhibitors, even at an early assessment.