Clinical significance of EGFR amplification and the aberrant EGFRvIII transcript in conventionally treated astrocytic gliomas.

The aim of this study was to evaluate the clinical value of assessing epidermal growth factor receptor (EGFR) amplification and the common 5' rearrangement of EGFR resulting in the EGFRvIII transcript in astrocytic gliomas. Data from 221 tumours were correlated with patient survival. The majority of previous studies evaluated amplification alone and provided contradictory results. Amplification was analysed by a densitometry of Southern blot analysis or quantitative polymerase chain reaction (PCR). EGFR transcripts were examined by reverse transcription PCR and subsequent sequencing. A ribonuclease (RNase) protection assay was carried out on a subgroup to confirm PCR results. Amplification of EGFR was found in 41% (65/160) of glioblastomas (GBs) and 10% (4/41) of anaplastic astrocytomas (AAs). The EGFRvIII rearrangement was identified in 54% (35/65) of GBs and 75% (3/4) of AAs with amplification, as well as in 8% (8/95) of GBs and 5% (2/37) of AAs without amplification (confirmed by RNase protection assay). There were no abnormalities of the EFGR or its transcript in grade II astrocytoma (AII). We found no significant association between EGFR amplification or rearrangement, and age or survival in the 160 GB patients. We noted a tendency towards decreased survival with any EGFR abnormality in the 41 patients with AAs. This was most marked in the five cases with the EGFRvIII transcript (p=0.069), but these were significantly older than those without (p=0.023). No abnormalities of EGFR were identified in AII patients. We conclude that neither EGFR amplification nor the presence of the EGFRvIII transcript predicts patient outcome in conventionally treated GBs. However, in AAs, although uncommon, EGFR aberrations appear to be associated with shorter survival.

Short postoperative survival for glioblastoma patients with a dysfunctional Rb1 pathway in combination with no wild-type PTEN.

PURPOSE: Glioblastoma (GB, WHO grade IV) is the most common primary brain tumor in adults. Survival is typically <1 year but varies between a few months and a couple of years. The aim of the study was to find novel genetic prognostic factors in a well-defined GB series. EXPERIMENTAL DESIGN: The survival data on 129 GBs were correlated with the results of a detailed analysis of 9 genes. These included 3 genes coding for proteins in the p53 pathway (i.e., TP53, p14(ARF), and MDM2), 4 in the Rb1 pathway (i.e., CDKN2A, CDKN2B, RB1, and CDK4), as well as PTEN and epidermal growth factor receptor. RESULTS: We found that abnormalities in any of the four genes (CDKN2A, CDKN2B, RB1, and CDK4) coding for components of the Rb1 pathway were associated with shorter survival (P = 0.002). In combination with loss of wild-type PTEN, the association was even stronger (P < 0.001), the median survival being 166 days as compared with the group without these abnormalities where the median postoperative survival was 437 days. The survival difference remained statistically significant in Cox' regression analysis adjusting for age (P = 0.012). CONCLUSIONS: The findings indicate that knowledge of the molecular genetic abnormalities in GBs provides important data in assessing individual patients. As additional advances in our understanding of the molecular genetics and cell biology of gliomas are made, in addition to providing prognostic information, such data may also provide targets for innovative therapy in the individual case.