ITA-IMMUNO-PET: The Role of [18F]FDG PET/CT for Assessing Response to Immunotherapy in Patients with Some Solid Tumors

Abstract

AIM: To examine the role of [18F]FDG PET/CT for assessing response to immunotherapy in patients with some solid tumors. METHODS: Data recorded in a multicenter (n = 17), retrospective database between March and November 2021 were analyzed. The sample included patients with a confirmed diagnosis of a solid tumor who underwent serial [18F]FDG PET/CT (before and after one or more cycles of immunotherapy), who were >18 years of age, and had a follow-up of at least 12 months after their first PET/CT scan. Patients enrolled in clinical trials or without a confirmed diagnosis of cancer were excluded. The authors classified cases as having a complete or partial metabolic response to immunotherapy, or stable or progressive metabolic disease, based on a visual and semiquantitative analysis according to the EORTC criteria. Clinical response to immunotherapy was assessed at much the same time points as the serial PET scans, and both the obtained responses were compared. RESULTS: The study concerned 311 patients (median age: 67; range: 31–89 years) in all. The most common neoplasm was lung cancer (56.9%), followed by malignant melanoma (32.5%). Nivolumab was administered in 46.3%, and pembrolizumab in 40.5% of patients. Baseline PET and a first PET scan performed at a median 3 months after starting immunotherapy were available for all 311 patients, while subsequent PET scans were obtained after a median 6, 12, 16, and 21 months for 199 (64%), 102 (33%), 46 (15%), and 23 (7%) patients, respectively. Clinical response to therapy was recorded at around the same time points after starting immunotherapy for 252 (81%), 173 (56%), 85 (27%), 40 (13%), and 22 (7%) patients, respectively. After a median 18 (1–137) months, 113 (36.3%) patients had died. On Kaplan–Meier analysis, metabolic responders on the first two serial PET scans showed a better prognosis than non-responders, while clinical response became prognostically informative from the second assessment after starting immunotherapy onwards. CONCLUSIONS: [18F]FDG PET/CT could have a role in the assessment of response to immunotherapy in patients with some solid tumors. It can provide prognostic information and thus contribute to a patient’s appropriate treatment. Prospective randomized controlled trials are mandatory.

The prognostic value of [18F]FDG PET/CT based response monitoring in metastatic melanoma patients undergoing immunotherapy: comparison of different metabolic criteria

“…Moreover, patterns of [ 18 F]FDG uptake on interim and late PET/CT suggestive of manifestations of irAEs to immunotherapy were documented. Given the lack of a standard definition for immunotherapy-induced organ inflammation, PET-irAEs were defined visually as sites of newly emerging or markedly increased compared to baseline imaging, non-malignant [ 18 F]FDG accumulation in organs known to exhibit immune-related signs on PET/CT [ 21 , 24 - 26 ]. In specific, a diffusely enhanced tracer uptake in the gastrointestinal tract, the thyroid gland, the lungs and the bone marrow, or, respectively, a relatively symmetrical, increased uptake in lymph nodes (e.g.…”

Lymphoid organs’ metabolism and its role in predicting the outcomes of patients with malignant melanoma treated with immunotherapy: an exploratory study

“…Patients who were participating in clinical trials or lacked a con rmed diagnosis of malignant melanoma were excluded from the study. It is worth noting that some patients included in this study were previously analyzed in other reports [14][15].…”

Can physiologic colonic [18F]FDG uptake in PET/CT imaging predict response to immunotherapy in metastatic melanoma?

“…18 F-fluorodeoxyglucose ([ 18 F]FDG) positron emission tomography/computed tomography (PET/CT) is the elective imaging modality in detection of metastatic disease in advanced melanoma [ 21 , 22 ], with, moreover, an upgraded role in recent years as a tool for treatment response evaluation and prognosis, mainly in the immunotherapy setting [ 23 – 25 ]. In particular, apart from monitoring tumor/target lesions [ 26 , 27 ], [ 18 F]FDG PET/CT has been applied in the investigation of the metabolism and signs of immune activation in otherwise healthy tissues, showing promising results in prediction of response to ICIs [ 28 – 30 ]. In this context, several PET parameters have been recognized to unfavorably influence melanoma survival, including the number of tumor lesions [ 31 ], the intensity of tracer uptake in melanoma lesions reflected by standardized uptake value (SUV) [ 32 , 33 ], volumetric parameters of tumor burden reflected by metabolic tumor volume (MTV), and total lesion glycolysis (TLG) [ 34 – 37 ], as well as changes in the metabolism of organs not infiltrated by tumor cells such as the colon, the bone marrow, and the spleen [ 30 , 38 – 41 ].…”