Evaluation of Indoleamine 2,3-Dioxygenase (IDO) Expression in Osteosarcoma: Insights From a 10-Year Retrospective Cohort.

Abstract

Introduction: Osteosarcoma, a prevalent bone malignancy in children and adolescents, is currently treated through surgical resection and chemotherapy. Advancements in cancer research are targeting immune checkpoint molecules, such as indoleamine 2,3-dioxygenase, to advance the development of immunotherapy. However, the scarcity of research on IDO in osteosarcoma results in an absence of comprehensive data, highlighting the conflicting findings surrounding IDO's role in various cancers. Our study aims to explore IDO expression in primary tumors and metastatic lesions among osteosarcoma patients, investigating its association with clinicopathological characteristics and assessing its impact on survival outcomes.

Methods: 150 patients diagnosed with osteosarcoma were selected between 2009 and 2019 from the Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan. FFPE tissue samples of primary tumors and metastatic lesions were retrieved to conduct immunohistochemical analysis. Moreover, the clinicopathological data of these patients were gathered from the hospital information system.

Results: Out of 150 patients, primary tumors were accessible for 134 individuals, while metastatic lesions were available for 49 patients. IDO expression was identified in 9 (6.71%) primary tumors and 2 (4.08%) metastatic lesions among osteosarcoma patients. Furthermore, 3 patients exhibited high expression (27.3%), while 8 displayed low IDO expression (72.7%).

Conclusion: Our comprehensive study findings indicate that most osteosarcoma patients do not exhibit expression of IDO. This absence of expression aligns with the characteristic "cold" tumor microenvironment observed in osteosarcoma. Further investigations are imperative to provide deeper insights into the intricacies of this immunomodulatory factor in the context of osteosarcoma.