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The prevalence of favorable PTEN and MGMT biomarker status in 66 glioblastomas
Author(s) -
Jesus Jason A,
Lam Dia,
Tinajero Yolanda L,
Kavafyan Lorie,
Zhang Haijing,
Taieb Philippe,
Deguzman Victoria C,
Mischel Paul S,
Cloughesy Timothy F,
Yong William H
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.706.16
Subject(s) - pten , tensin , cancer research , biomarker , immunostaining , immunohistochemistry , tissue microarray , phosphatase , medicine , biology , pathology , pi3k/akt/mtor pathway , signal transduction , enzyme , genetics , biochemistry
Glioblastomas are genetically heterogeneous neoplasms with variable responses to therapy. Biomarkers that predict response to therapy include O6‐methylguanine‐DNA methyl transferase (MGMT) and phosphatase and tensin homolog (PTEN). MGMT is a DNA repair enzyme and low levels of MGMT expression in tumors have been associated with response to Temazolamide, an alkylating agent. PTEN is a phosphatase that modulates signaling pathways downstream from EGFR and loss of PTEN predicts a poor response to small molecule EGFR kinase inhibitors. In this study, we attempt to assess the prevalence of a favorable biomarker status in 66 glioblastomas. The glioblastomas are sampled in triplicate on a tissue microarray. Sections are then assayed for MGMT and PTEN by immunohistochemistry. The extent of tumor cell staining is semi‐quantitatively scored as percentages. PTEN loss greater than 25% is considered deficient as previously reported. By published criteria, MGMT immunostaining in less than 20% of tumor cells is considered favorable. 72.7% (48/66) of the tumors have a favorable PTEN status. 37.8% (25/66) have a favorable MGMT status. 27.3% (18/66) of the glioblastomas have both a favorable PTEN and MGMT status. Therefore, only a minority of patients are predicted to have available two lines of therapy. To avoid use of possibly ineffective therapies, more work is needed to identify other predictive biomarkers.