title: Aggressive pituitary tumours: the role of temozolomide and the assessment of MGMT status.
abstract: BACKGROUND
  Aggressive pituitary tumours are associated with substantial morbidity and mortality. Treatment options are often limited, and chemotherapy has been reserved as salvage therapy although historically results have often been disappointing. However, temozolomide, an oral alkylating agent, has recently demonstrated significant activity against these tumours. A DNA repair protein, 06-methylguanine-DNA methyltransferase (MGMT) has been suggested as a biomarker to predict response to temozolomide in pituitary tumours.
  
  
  METHODS
  This paper will review the current literature on temozolomide and pituitary tumours and discuss the recent controversy surrounding the value of determining the MGMT status in this tumour group. A PubMed search was performed to retrieve articles, using the terms 'pituitary tumour' and 'temozolomide'.
  
  
  RESULTS
  Overall, 24/40 (60%) of the published cases demonstrated a response to temozolomide therapy. The highest response rates were seen amongst prolactinomas (73%) and ACTH-secreting tumours (60%), whilst nonfunctioning pituitary tumours exhibit lower response rates (40%). Responsivity is typically evident in the first 3 months of therapy and may be dramatic and sustained. Low MGMT expression, as determined by immunohistochemistry, is associated with a high response rate (76%), whilst high MGMT expression has not been associated with responses. MGMT promoter methylation does not correlate with temozolomide response.
  
  
  CONCLUSIONS
  Temozolomide is the first chemotherapeutic agent to show substantial response rates in aggressive pituitary tumours. MGMT immunohistochemistry, but not MGMT methylation analysis, shows promise as a predictive tool. Prospective clinical trials are now necessary to more accurately determine the efficacy of this agent in this patient group.
authors.affiliation: Cancer Genetics Unit, Hormones and Cancer Group, Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, NSW, Australia.
authors.forename: Ann I
authors.initials: AI
authors.lastname: McCormack
authors.forename: John A H
authors.initials: JA
authors.lastname: Wass
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Grossman
mesh_terms: D000236:Adenoma / Q000188:drug therapy* / Q000378:metabolism; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000378:metabolism; D002296:Carcinosarcoma / Q000188:drug therapy* / Q000378:metabolism; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D000077204:Temozolomide
chemical_list: D018906:Antineoplastic Agents, Alkylating; D014408:Biomarkers, Tumor; D003606:Dacarbazine; D019853:O(6)-Methylguanine-DNA Methyltransferase; D000077204:Temozolomide