MGMT immunoexpression in adamantinomatous craniopharyngiomas

At present, no effective medical treatment exists for recurrent and aggressive craniopharyngiomas that are resistant to conventional therapies, including surgery and adjuvant radiotherapy. Temozolomide is an alkylating chemotherapeutic agent used routinely in the management of high grade gliomas. The response to temozolomide is suggested to be dependent on the tumoral expression of O-6 methylguanine DNA methyltransferase (MGMT). Evidence supports that low MGMT immunoexpression correlates with positive response to temozolomide. Therefore, we aimed to assess MGMT immunoexpression in adamantinomatous craniopharyngiomas, in an effort to predict the likelihood of response to temozolomide. The MGMT immunostaining was performed on 23 adamantinomatous craniofaryngiomas operated at the Sisli Etfal Training and Research Hospital and identified by histological analysis. Paraffin embedded tissue sections were immunostained for MGMT and were evaluated semi-quantitatively. Of the 23 cases evaluated, 22 (96%) demonstrated negative (<10%) and 1 (4%) demonstrated low (10%) MGMT immunoexpression. Data from this study suggest a high proportion of adamantinomatous craniopharyngiomas exhibit negative/low MGMT immunoreactivity and could be treated with temozolomide, if conventional therapy fails.