Metabolic tumor parameters on 18F-FDG PET/CT can predict the expression of PD-L1 and prognosis in patients with fumarate hydratase-deficient renal cell carcinoma

Abstract

Objective: This study aimed to comprehensively evaluate the performance of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and investigate the association between metabolic parameters, programmed cell death ligand 1 (PD-L1) expression, and prognosis in patients with fumarate hydratase-deficient renal cell carcinoma (FHRCC).

Methods: Twenty-nine patients with FHRCC were prospectively enrolled from May 2020 to February 2023 for ¹⁸F-FDG PET/CT. The maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of primary/recurrent tumors were analyzed. The relationship between PET metabolic parameters, clinicopathological features and prognosis were evaluated.

Results: Primary/recurrent and metastatic lesions showed FDG avidity, without metabolic differences between them. In our analysis, SUVmax of whole body (WB-SUVmax), SUVpeak of whole body (WB-SUVpeak), MTV of whole body (WB-MTV), and TLG of whole body (WB-TLG) were associated with the expression of PD-L1. The optimal cut-off values of WB-SUVmax, WB-SUVpeak, WB-MTV, and WB-TLG for predicting positive PD-L1 expression were 9.86 (AUC 0.814), 6.92 (AUC 0.848), 19.61 cm³ (AUC 0.803), and 58.39 g (AUC 0.841), respectively. Survival analysis further demonstrated that patients with WB-SUVpeak ≥ 8.92 had shorter time to progression than those with WB-SUVpeak < 8.92 (11.0 mo vs. 21.0 mo, P = 0.047).

Conclusions: ¹⁸F-FDG PET/CT is effective in detecting FHRCC lesions due to their hypermetabolic nature. PET metabolic parameters can serve as predictors of positive PD-L1 expression, with higher values observed in FHRCC patients with positive PD-L1 expression. Additionally, WB-SUVpeak is a significant predictor of prognosis in patients with FHRCC.

Keywords: Fluorodeoxyglucose; Fumarate hydratase-deficient renal cell carcinoma; Metabolic parameters; Positron emission tomography/computed tomography; Programmed cell death ligand 1.