, Volume 22, Issue 6, pp 614–619 | Cite as

MGMT immunohistochemistry in pituitary tumors: controversies with clinical implications

  • George KontogeorgosEmail author
  • Eleni Thodou
  • Mary Koutourousiou
  • Gregory Kaltsas
  • Andreas Seretis



Temozolomide (TMZ) is currently considered as a rational therapeutic option for patients with progressively aggressive pituitary adenomas and carcinomas not responding to conventional therapies. Administration of TMZ results in clinical response and improvement in survival of many of these patients depending upon the expression of the DNA repair enzyme O-6 methylguanine DNA transferase (MGMT). Low or negative MGMT immunoreactivity predicts responsiveness to TMZ therapy. Therefore, MGMT serves as a criterion to select candidate patients anticipating response to treatment.

Materials and Methods

The MGMT expression was investigated in 25 pituitary adenomas with Ki-67 labeling index more that 3% and p53 expression, using various antigen retrieval protocols. After direct application of the antibody, only one adenoma yielded positive for MGMT. However, after pretreatment of tissue sections with antigen retrieval protocols, another 3 adenomas, initially negative turned to positive.


These findings could explain lack of response to TMZ treatment in patients with false negative MGMT immunohistochemistry. Evaluation of tumor samples for MGMT expression should carefully be carried-out using the optimum immunohistochemical protocol to obtain consistent and reliable results that help to identify patients that could respond to TMZ therapy.


Antigen retrieval protocols Immunohistochemistry Ki-67 MGMT p53 Temozolomide 



No funding from official organization was received. We thank Mrs. Magda Pateraki and Soula Roumelioti for excellent technical support.

Compliance with ethical standards

Conflict of interest

The authors certify that they have NO involvement in any organization or entity with any financial interest in the context or materials discussed in this manuscript.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • George Kontogeorgos
    • 1
    • 2
    Email author
  • Eleni Thodou
    • 3
  • Mary Koutourousiou
    • 4
  • Gregory Kaltsas
    • 1
  • Andreas Seretis
    • 5
    • 6
  1. 1.First Propaepeudic Department of Internal Medicine, Laikon HospitalNational and Kapodistrian University of AthensAthensGreece
  2. 2.Department of Pathology“G. Gennimatas” Athens General HospitalAthensGreece
  3. 3.Department of Pathology, School of MedicineUniversity of Thessaly, ViopolisLarissaGreece
  4. 4.Department of Neurological SurgeryUniversity of LouisvilleLouisvilleUSA
  5. 5.Neurosurgery DepartmentHenry Dunant HospitalAthensGreece
  6. 6.Department of Neurosurgery“G. Gennimatas” Athens General HospitalAthensGreece

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