Apport de la TEP-TDM au 18F-FDG chez des patients avec cancer bronchique non à petites cellules ou mélanome métastatique traités par immunothérapie

Abstract

Immune checkpoints inhibitors have become the benchmark for treating many different types of cancer, as well as melanoma or non-small cell lung cancer. Unlike chemotherapies or targeted therapies, immunotherapy does not specifically target tumor cells and can restore anti-tumor immunity. This paradigm shift directly impacts onco-imaging and especially 18fluor-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Indeed, novel patterns of response or progression have been identified, such as “pseudo-progression”, “hyper-progression”, “dissociated response”, “durable response” and “abscopal effect” (immunotherapy+radiotherapy). These atypical patterns have led to specific changes of criteria dedicated to therapeutic assessment. Furthermore, several biomarkers extracted from 18F-FDG PET imaging could help selecting appropriate candidates to immunotherapy early, which is currently a major clinical challenge. From a more fundamental point of view, deciphering the cross talk between tumor, its microenvironment and lymphoid organs (spleen and bone marrow) could help better understand pathophysiologic mechanisms of immunoresistance. Increased bone marrow glucose metabolism on 18F-FDG-PET could be associated with tumor immune transcriptome and an upregulation of genes associated with cell populations involved in immunosuppressive phenotypes. Finally, imaging with immuno-PET, using several labeled antibodies targeted against immune checkpoints, general T cell markers or biomarkers of the immune response, may offer an indispensable theranostic approach in the era of precision medicine.