Abstract Background & Objectives: Glioblastoma is the most common primary malignancy of the brain, the prognosis of which is poor. Immunotherapy with cancer/testis (CT) antigens is a novel therapeutic approach for glioblastoma. This study aimed to investigate the expression rate of MAGE-E1, GAGE, and SOX-6 in glioblastoma tumors using the immunohistochemistry (IHC) method. Materials & Methods: Expression of MAGE-E1, GAGE, and SOX-6 were determined by IHC in 50 paraffin blocks of glioblastoma. The results were compared between variables including age, gender, tumor location, and Karnofsky performance status (Kps) score. Survival analysis was also performed. Results: The expression levels of SOX-6, MAGE-E1, and GAGE were 82%, 78%, and 76%, respectively. The relationship between CT antigens and age, gender, and tumor location was not significant, while the association between MAGE-E1 expression and age was statistically significant (p =0.002). High expression levels of SOX-6 and MAGE-E1 were associated with low Kps scores (p =0.034 and p <0.001, respectively). Survival analysis showed that age >40 and Kps score p =0.005 and p =0.018, respectively). Expression of MAGE-E1 and GAGE was negatively associated with overall 2-year survival (p =0.001 and p =0.021, respectively). Conclusion: The expression of all the three CT antigens, especially MAGE-E1 and SOX-6, was high in patients with glioblastoma. It can be concluded that these markers are ideal targets for immunotherapy in these patients. MAGE-E1 and SOX-6 can be considered as important markers in determining the prognosis of glioblastoma.

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