Expression of cancer testis antigens CT10 (MAGE-C2) and GAGE in gastrointestinal stromal tumors

INTRODUCTION: Expression of cancer testis antigens (CTAs) has been associated with prognosis in gastrointestinal stromal tumors (GIST) and other malignancies. CTAs are currently being investigated for cancer immunotherapy.

MATERIALS AND METHODS: We analyzed two CTAs, CT10/MAGE-C2 and GAGE, in 51 GIST by immunohistochemistry and correlated it with established histopathological criteria for malignancy.

RESULTS: GAGE expression was found in 6/51 (12%) patients, whereas 5/51 (10%) patients expressed CT10/MAGE-C2. 7/51(14%) patients expressed at least one of both CTAs, in 4/51 (8%) patients both CTAs were positive. High-grade GIST are more likely to express GAGE (p = 0.002) and CT10/MAGE-C2 (p = 0.007) compared to less aggressive tumors. All patients with GAGE or CT10/MAGE-C2 expression had moderate- or high-risk of recurrence according to the established risk criteria. The presence of GAGE correlates with mitotic rate (p = 0.001) and tumor size (p = 0.02), but not with tumor location (p = 0.60). CT10/MAGE-C2 also significantly correlates with mitotic rate (p = 0.004) and tumor size (p = 0.002), whereas no correlation could be found with tumor location (p = 0.36).

DISCUSSION: CT10/MAGE-C2 and GAGE should be explored together with other previously described CTAs as targets for immunotherapy of GIST in cases, which are refractory to conventional therapy.