Temozolomide, an orally administered alkylating agentmay have efficacy in the treatment of pituitary adenomas and carcinomas. Temozolomide methylates DNA through methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme, removes alkylating adducts induced by temozolomide, counteracting its effects. A recent review noted that there have been 19 reported cases of adenohypophyseal tumors treated with temozolomide, including 13 adenomas and 6 carcinomas. Ten of those 13 adenomas responded favorably, and 2 nonresponsive tumors had high-level MGMT immunoexpression. All 6 carcinomas responded to therapy, but data regarding MGMT expression were available for only 3 patients, and each had low MGMT expression. In 2 adenomas, morphologic studies were performed both before and after the patients received temozolomide. The responsive tumor had necrosis, hemorrhage, fibrosis, and neuronal differentiation. The nonresponsive tumor had no changes. There have been no reported complications attributable to temozolomide. The current results indicated that temozolomide is efficacious in the treatment of aggressive pituitary adenomas and pituitary carcinomas. Evidence indicated that low-level MGMT immunoexpression is correlated with a favorable response. A significant proportion of pituitary adenomas and carcinomas had low MGMT immunoexpression
Mohammed, Safraz M.B.B.S.; Kovacs, Kalman M.D., Ph.D.; Mason, Warren M.D., Ph.D.; Smyth, Harley M.D., Ph.D.; Cusimano, Michael D. M.D., Ph.D.
Use of Temozolomide in Aggressive Pituitary Tumors: Case Report Neurosurgery:
April 2009 – Volume 64 – Issue 4 – p E773-E774
Syro LV, Ortiz LD, Scheithauer BW, Lloyd R, Lau Q, Gonzalez R, Uribe H, Cusimano M, Kovacs K, Horvath ETreatment of pituitary neoplasms with temozolomide: a review. Cancer. 2011 Feb 1;117(3):454-62.