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

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.

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

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).

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.