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

ObjectiveIndoleamine-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.MethodsA 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.ResultsIDOhigh expression was associated with lower numbers of intratumoral CD8+ T-lymphocytes (p = 0.031). Next to well-known prognostic parameters, IDOhigh 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).ConclusionOur 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.

► An IFN-γ dependent increase of IDO expression was observed in human cancer cells in several experiments.
► Endometrial carcinoma tissue with IDOhigh expression contained lower number of intratumoral CD8+ T-lymphocytes compared to tumors with IDOlow expression.
► IDOhigh expression was independently associated with poor disease specific survival for endometrial carcinoma patients.