Relationship between PD-L1 expression and ¹⁸F-FDG uptake in gastric cancer

Immunotherapy has been successfully utilized for treatment of gastric cancer, so the identification of clinicopathologic features that are predictive of response to this therapy is crucial. ¹⁸F-FDG PET/CT can provide information on the molecular phenotype of many malignant tumors. The correlation between ¹⁸F-FDG accumulation and PD-L1/PD-L1-TILs status in gastric cancer patients has not been investigated. The aim of the current study is to assess whether ¹⁸F-FDG accumulation is associated with PD-L1/PD-L1-TILs status, and whether ¹⁸F-FDG PET/CT may be useful for predicting PD-L1/PD-L1-TILs expression of gastric cancer.

Tumors with positive PD-L1 expression had higher SUVmax than in tumors with negative PD-L1 expression (15.0 ± 8.0 vs. 7.2 ± 4.2, respectively; P = 0.004). Tumors with positive PD-L1-TILs expression also had higher SUVmax than in tumors with negative PD-L1-TILs expression (10.3 ± 6.5 vs. 6.6 ± 3.7, respectively; P = 0.034). Multivariate analysis suggested that SUVmax remained significantly correlated with the status of PD-L1 (P = 0.043) and PD-L1-TILs (P = 0.016). PD-L1 expression was predicted with an accuracy of 67.2% when a SUVmax value of 8.55 was used as a cutoff point for analysis. Similarly, PD-L1-TILs expression was predicted with an accuracy of 64.2%, when a SUVmax value of 7.9 was used as the threshold for analysis.

Higher ¹⁸F-FDG accumulation in gastric cancers is correlated with positive PD-L1/PD-L1-TILs expression. ¹⁸F-FDG PET/CT may be used to predict the status of PD-L1/PD-L1-TILs and thus aid in optimal treatment decision.

A retrospective analysis was conducted on 64 patients with gastric cancer who underwent ¹⁸F-FDG PET/CT. SUVmax was calculated from the ¹⁸F-FDG accumulation of the primary tumor. The relationship between SUVmax and PD-L1/PD-L1-TILs status was analyzed.