Expression and clinical significance of VISTA and PD-L1 in adrenocortical carcinoma.

Adrenocortical carcinoma (ACC) is a rare malignancy with a poor prognosis and challenging management. The present study aimed to investigate the expression of programmed death ligand-1 (PD-L1) and V-domain Ig-containing suppressor of T cell activation (VISTA) in ACC and their associations with clinicopathological features and survival outcomes. Immunohistochemistry was performed on formalin-fixed paraffin-embedded specimens from 54 ACC patients. Chi-square/Fisher's exact tests or independent samples t/Mann-Whitney U tests were performed to assess correlations between immunoscores and clinicopathological parameters. The Kaplan-Meier method and Cox regression were conducted for survival analysis and to identify independent predictors of overall (OS) and disease-free (DFS) survival. Results showed that VISTA was expressed in tumor cells (TCs) and tumor-infiltrating immune cells (TICs) in 81.5% (44/54) and 40.7% (22/54) of the patients, respectively. PD-L1 positivity was found in either TCs or TICs in 11.1% (6/54) of the patients. Patients with positive VISTA expression in TCs had a higher tumor stage (56.9% vs 20%, P = 0.036) and Ki-67 index (30.50 ± 23.51% vs 14.76 ± 11.75%, P = 0.006). However, PD-L1 positivity in either TCs or TICs had no association with patient clinicopathological features. A higher VISTA expression intensity, a larger area and a higher immunoscore were associated with increased risks of disease progression and overall mortality, but PD-L1 expression in TCs or TICs was not associated with OS or DFS. In conclusion, positive TC VISTA expression was correlated with pathological parameters related to malignancy in ACC patients. This finding provides novel evidence of the value of VISTA, in addition to PD-L1, as an immunotherapeutic target in ACC.