Radiological features of IDO1⁺/PDL1⁺ lung adenocarcinoma: A retrospective single-institution study

Aim: A combination of immune-checkpoint inhibitors that target the programmed cell death 1 (PD1)/programmed cell-death ligand 1 (PDL1) pathway and indoleamine 2,3-dioxygenase 1 (IDO1) is a promising treatment for non-small-cell lung cancer. Herein, we investigated clinical features of IDO1⁺/PDL1⁺ primary lung adenocarcinoma. Materials and Methods: IDO1 and PDL1 expression in 388 resected primary lung adenocarcinoma samples was evaluated using immunohistochemistry, and the radiological features of patients with IDO1⁺/PDL1⁺ lung adenocarcinoma were analyzed. Results: Of 388 specimens, 229 (59.0%) were IDO1⁺, 131 (33.8%) were PDL1⁺, and 109 (28.1%) were IDO1⁺/PDL1⁺. In multivariate analysis, vascular convergence and the absence of surrounding ground glass opacity were significantly associated with IDO1⁺/PDL1⁺ tumors. Fisher’s exact test showed high consolidation/tumor ratio was also significantly associated with IDO1⁺/PDL1⁺ tumors. Moreover, maximum standardized uptake in¹⁸F-fluorodeoxyglucose positron-emission tomography/computed tomography was significantly higher in patients with IDO1⁺/PDL1⁺ tumors than in those with IDO1⁻ or PDL1⁻ tumors. Conclusion: IDO1/PDL1 co-expression was significantly related to radiological invasiveness and malignancy in lung adenocarcinoma. This study may help select patients likely to benefit from combination therapy using immune-checkpoint inhibitors.