Prognostic value of indoleamine 2, 3-dioxygenase-1 expression in glial tumors

Abstract

Background and purpose – Gliomas are the most common primary malignant central nervous system tumors in adults, exhibiting a poor prognosis. Indoleamine 2, 3-dioxygenase-1 (IDO-1) has important functions in cancer immunotherapy due to its role in escaping cancer cells from the immune system. In this study we purposed to evaluate the correlation between IDO1 expression and clinicopathological parameters in gliomas, and whether IDO-1 can be a prognostic marker. Methods – n=75 patients in total, n=25 patients with low grade glial tumors (LGG, grade 1-2), n=25 patients with high grade glial tumors (HGG, grade 3-4), and n=25 persons with normal brain tissue as control group were included in this study. IDO1 expression was categorized by using immunohistochemical staining in biopsy specimens as high (H) and low (L) groups among the patients with gliomas. We used a 95% percent confidence interval and p <0.05 to analyze the association between the degree of IDO-1 expression, clinicopathological characteristics, and survival rates in glioma patients. Results – In HGG, IDO-1 levels were higher than in control brain tissue and LGG (p< 0.001). The mean overall survival (OS) was longer in the L-IDO-1 group (64.53 ± 3.34) in months (95% CI: 57.969-71.098) compared to the H-IDO-1 group (43.74 ± 4.36) in months, (95% CI: 35.218-52.330) (p< 0.05). Conclusion – IDO-1 expression is an independent prognostic biomarker to predict OS and progression in HGG. IDO-1 can be evaluated as an alternative instrument for precision medicine in the treatment of gliomas.