Prognostic role of indoleamine 2,3-dioxygenase in endometrial carcinoma

Abstract Objective Indoleamine-2,3-dioxygenase (IDO) suppresses the function of T-lymphocytes and is an important immune escape mechanism for cancer. Therefore, it is to be expected that IDO influences prognosis of cancer patients. This study aimed to investigate the prognostic role of IDO expression in a large cohort of endometrial carcinoma (EC) patients. Methods A tissue microarray containing primary EC tissue of 355 patients treated in a single institution was used to evaluate IDO expression. Expression of IDO was associated with clinicopathological characteristics, survival and previously determined numbers of CD8 + and Foxp3 + T-lymphocytes. Results IDO high expression was associated with lower numbers of intratumoral CD8 + T-lymphocytes (p=0.031). Next to well-known prognostic parameters, IDO high expression was independently associated with poor disease specific survival in the general cohort of EC patients (HR 2.62, 95% C.I. 1.48–4.66, p=0.001) and among patients with early stage EC (HR 3.06, 95% C.I. 1.10–8.54, p=0.032). Conclusion Our results show that IDO expression is associated with poor survival. This provides evidence that further research into the use of IDO blocking agents in cancer treatment is valid where it might be a promising new therapeutic strategy.