Modification in expression of EGFr, p53, and pTEN in non small cell lung cancer (NSCLC)

Abstract

13151 Background: Treatment inhibiting tyrosine kinase domain of EGFr have proved dramatically efficient in NSCLC. Even if several studies have revealed predictors of treatment response, - such as gender, adenocarcinoma histology, gene mutations, or Asian origin-, response to treatment remains random and is not correlated with an initial overexpression of EGFr by the tumor. The efficiency of those EGFr inhibitors was only shown in second- or third-line treatments, and studies using them in first-line treatments, particularly when combined, had no positive outcome. We have therefore assessed the expression of EGFr in NSCLC before and after cisplatin-based chemotherapy to see if it modified the level of expression of either EGFr, or of molecules including its chain of activation, such as P53 or pTEN. Methods: Tumor samples were obtained from patients treated for NSCLC. We retrospectively studied the bronchial samples of all the patients treated for NSCLC in Brest University Hospital for 6 months. Patients with treatment response whose control samples were negative were not included. We extracted paraffin embedded samples from NSCLC before and after cisplatin-based chemotherapy. For all cases EGFr expression has been assessed with the Ventana CONFIRM TM EGFr 3C6 antibody, P53 expression with the DAKO P53 D07 kit, and pTEN expression with Novocastra antibody. Intensity was scored 0, 1+, 2+, 3+. Results: Data on 30 patients are available, 27 males and 3 females. 70% of tumors show overexpression of EGFr before chemotherapy, and 63.3% after, which has no stastistical significance. The same was observed for pTEN and P53, whose level of expression is similar before and after treatment. The level of expression of P53, pTEN, and EGFr is not correlated with gender or histological type. However, EGFr expression tends to increase after chemotherapy for the subsets of adenocarcinoma and women, but this remains statistically non-significant. Conclusions: Cisplatin-based chemotherapy does not seem to modify the expression of EGFr nor its chain of activation. However, the level of expression, particularly for EGFr, seems to be higher after chemotherapy for the subsets of adenocarcinoma and women. No significant financial relationships to disclose.