Temozolomide in Treating Patients With Invasive Pituitary Tumors

RATIONALE: Drugs used in chemotherapy, such as temozolomide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. PURPOSE: This phase II trial is studying how well temozolomide works in treating patients with invasive pituitary tumors.

OBJECTIVES: Primary * To assess the effect of temozolomide on pituitary tumor growth in patients with invasive pituitary tumors. * To assess the effect of temozolomide on pituitary tumor response and the duration of tumor response in these patients. Secondary * To assess the effect of temozolomide on pituitary tumor hormone secretion in these patients. * To assess the effect of temozolomide on other aspects of pituitary function in these patients. * To assess the overall safety and tolerability of temozolomide in these patients. * To assess the overall quality of life of patients treated with temozolomide. OUTLINE: This is a multicenter study. Patients receive oral temozolomide once daily on days 1-5. Treatment repeats every 28 days for up to 12 courses in the absence of disease progression or unacceptable toxicity. After completion of 12 courses, patients achieving a complete or partial tumor response may continue to receive temozolomide at the investigator's discretion in the absence of disease progression or unacceptable toxicity. Tumor tissue samples are collected periodically to assess methylation status of the methyl-guanine methyl-transferase promoter (MGMT) gene and to quantitate immunocytochemical expression of the tumor suppressor proteins p53, p16, and p27. Tissue samples are also analyzed by microarray and proteomics to determine a genetic "signature" of invasive vs non-invasive pituitary tumors and to determine if this signature correlates with response to temozolomide. Blood samples are also periodically for biomarker laboratory studies. Patients complete a quality of life questionnaire periodically. After completion of study therapy, patients are followed for 28 days.