Is EGFR expression altered following postoperative chemotherapy for colorectal adenocarcinoma?

BACKGROUND: There is immunohistochemical evidence to suggest that expression of epidermal growth factor receptor (EGFR) in primary colorectal adenocarcinoma predicts its expression in recurrent disease. This study investigates whether postoperative chemotherapy affects the degree of concordance between EGFR statuses of the two tumors. METHODS: Thirty-three patients were identified from the files of Sunnybrook Health Sciences Center from July 1994 to June 2005. All patients had resection of their primary tumors and their distant recurrences. Eighteen patients received postoperative chemotherapy, 3 of which also received postoperative radiation therapy. Representative primary and recurrent tumor sections were stained using mouse anti-EGFR antibodies and only membranous staining of malignant cells was recorded. Results were reported as negative (no staining), 1+ (positivity in <50% of cells) or 2+ (positivity in >50% of cells). RESULTS: EGFR immunostaining in the 15 patients, who received no postoperative chemotherapy, was decreased in 3 recurrences, remained the same in 10 and increased in 2. In the group of 18 patients who received postoperative chemotherapy, EGFR immunostaining was decreased in 6 recurrences, remained the same in 9 and increased in 3 (p = 0.6598). In patients who received postoperative chemotherapy, the odds ratio for a recurrence to show lower levels of EGFR immunostaining compared to its originally resected primary was 4.75 (CI = 0.94 – 26.73). CONCLUSION: These preliminary data suggest that recurrences following postoperative chemotherapy are likely to have lower levels of EGFR expression compared to cases who receive no chemotherapy. Although the difference of immunostaining profiles between the two groups was not statistically significant, this observation might impact the management of these patients by targeted biologic therapies and its practical implications need further validation in larger series

Targeting the EGFR in ovarian cancer with the tyrosine kinase inhibitor ZD1839 (“Iressa”).

The modulating effects of the orally active epidermal growth factor receptor-specific tyrosine kinase inhibitor ZD 1839 (‘Iressa’) on cell growth and signalling were evaluated in four ovarian cancer cell lines (PE01, PE04, SKOV-3, OVCAR-5) that express the epidermal growth factor receptor, and in A2780, which is epidermal growth factor receptor-negative. Transforming growth factor-α stimulated growth was completely inhibited by concentrations of ZD 1839 ⩾0.3 μM in the epidermal growth factor receptor-expressing cell lines, as were transforming growth factor-α stimulated phosphorylation of the epidermal growth factor receptor and downstream components of the MAP kinase and PI-3 kinase signalling cascades. Growth inhibition in the absence of added transforming growth factor-α was also observed which could be consistent with suppression of action of autocrine epidermal growth factor receptor-activating ligands by ZD 1839. In support of this, transforming growth factor-α, EGF and amphiregulin mRNAs were detected by RT–PCR in the epidermal growth factor receptor-expressing cell lines. ZD 1839 inhibited growth of the PE04 ovarian cancer xenograft at 200 mg kg(−1) day(−1). These data lend further support to the view that targeting the epidermal growth factor receptor in ovarian cancer could have therapeutic benefit. British Journal of Cancer (2002) 86, 456–462. DOI: 10.1038/sj/bjc/6600058 www.bjcancer.com © 2002 The Cancer Research Campaig

The in vitro effect of gefitinib ('Iressa') alone and in combination with cytotoxic chemotherapy on human solid tumours

BACKGROUND: Activation of the epidermal growth factor receptor (EGFR) triggers downstream signaling pathways that regulate many cellular processes involved in tumour survival and growth. Gefitinib ('Iressa') is an orally active tyrosine kinase inhibitor (TKI) targeted to the ATP-binding domain of EGFR (HER1; erbB1). METHODS: In this study we have used a standardised ATP-based tumour chemosensitivity assay (ATP-TCA) to measure the activity of gefitinib alone or in combination with different cytotoxic drugs (cisplatin, gemcitabine, oxaliplatin and treosulfan) against a variety of solid tumours (n = 86), including breast, colorectal, oesophageal and ovarian cancer, carcinoma of unknown primary site, cutaneous and uveal melanoma, non-small cell lung cancer (NSCLC) and sarcoma. The IC50 and IC90 were calculated for each single agent or combination. To allow comparison between samples the Index(SUM )was calculated based on the percentage tumour growth inhibition (TGI) at each test drug concentration (TDC). Gefitinib was tested at concentrations ranging from 0.0625–2 microM (TDC = 0.446 microg/ml). This study represents the first use of a TKI in the assay. RESULTS: There was heterogeneity in the degree of TGI observed when tumours were tested against single agent gefitinib. 7% (6/86) of tumours exhibited considerable inhibition, but most showed a more modest response resulting in a low TGI. The median IC50 value for single agent gefitinib in all tumours tested was 3.98 microM. Interestingly, gefitinib had both positive and negative effects when used in combination with different cytotoxics. In 59% (45/76) of tumours tested, the addition of gefitinib appeared to potentiate the effect of the cytotoxic agent or combination (of these, 11% (5/45) had a >50% decrease in their Index(SUM)). In 38% of tumours (29/76), the TGI was decreased when the combination of gefitinib + cytotoxic was used in comparison to the cytotoxic alone. In the remaining 3% (2/76) there was no change observed. CONCLUSION: The in vitro model suggests that gefitinib may have differential effects in response to concomitant cytotoxic chemotherapy with the agents tested during this study. The mechanism involved may relate to the effect of TKIs on growth rate versus their effect on the ability of the cell to survive the stimulus to apoptosis produced by chemotherapy

Gefitinib (IRESSA) sensitive lung cancer cell lines show phosphorylation of Akt without ligand stimulation

BACKGROUND: Phase III trials evaluating the efficacy of gefitinib (IRESSA) in non-small cell lung cancer (NSCLC) lend support to the need for improved patient selection in terms of gefitinib use. Mutation of the epidermal growth factor receptor (EGFR) gene is reported to be associated with clinical responsiveness to gefitinib. However, gefitinib-sensitive and prolonged stable-disease-defined tumors without EGFR gene mutation have also been reported. METHODS: To identify other key factors involved in gefitinib sensitivity, we analyzed the protein expression of molecules within the EGFR family, PI3K-Akt and Ras/MEK/Erk pathways and examined the sensitivity to gefitinib using the MTT cell proliferation assay in 23 lung cancer cell lines. RESULTS: We identified one highly sensitive cell line (PC9), eight cell lines displaying intermediate-sensitivity, and 14 resistant cell lines. Only PC9 and PC14 (intermediate-sensitivity) displayed an EGFR gene mutation including amplification. Eight out of the nine cell lines showing sensitivity had Akt phosphorylation without ligand stimulation, while only three out of the 14 resistant lines displayed this characteristic (P = 0.0059). Furthermore, the ratio of phosphor-Akt/total Akt in sensitive cells was higher than that observed in resistant cells (P = 0.0016). Akt phosphorylation was partially inhibited by gefitinib in all sensitive cell lines. CONCLUSION: These results suggest that Akt phosphorylation without ligand stimulation may play a key signaling role in gefitinib sensitivity, especially intermediate-sensitivity. In addition, expression analyses of the EGFR family, EGFR gene mutation, and FISH (fluorescence in situ hybridization) analyses showed that the phosphorylated state of EGFR and Akt might be a useful clinical marker of Akt activation without ligand stimulation, in addition to EGFR gene mutation and amplification, particularly in adenocarcinomas

Expression of RFC/SLC19A1 is Associated with Tumor Type in Bladder Cancer Patients

Urinary bladder cancer (UBC) ranks ninth in worldwide cancer. In Egypt, the pattern of bladder cancer is unique in that both the transitional and squamous cell types prevail. Despite much research on the topic, it is still difficult to predict tumor progression, optimal therapy and clinical outcome. The reduced folate carrier (RFC/SLC19A1) is the major transport system for folates in mammalian cells and tissues. RFC is also the primary means of cellular uptake for antifolate cancer chemotherapeutic drugs, however, membrane transport of antifolates by RFC is considered as limiting to antitumor activity. The purpose of this study was to compare the mRNA expression level of RFC/SLC19A1 in urothelial and non-urothelial variants of bladder carcinomas. Quantification of RFC mRNA in the mucosa of 41 untreated bladder cancer patients was performed using RT-qPCR. RFC mRNA steady-state levels were ∼9-fold higher (N = 39; P<0.0001) in bladder tumor specimens relative to normal bladder mRNA. RFC upregulation was strongly correlated with tumor type (urothelial vs. non-urothelial; p<0.05) where median RFC mRNA expression was significantly (p<0.05) higher in the urothelial (∼14-fold) compared to the non-urothelial (∼4-fold) variant. This may account for the variation in response to antifolate-containing regimens used in the treatment of either type. RFC mRNA levels were not associated with tumor grade (I, II and III) or stage (muscle-invasive vs. non-muscle invasive) implying that RFC cannot be used for prognostic purposes in bladder carcinomas and its increased expression is an early event in human bladder tumors pathogenesis. Further, RFC can be considered as a potential marker for predicting response to antifolate chemotherapy in urothelial carcinomas

Gene expression profiles of prostate cancer reveal involvement of multiple molecular pathways in the metastatic process

BACKGROUND: Prostate cancer is characterized by heterogeneity in the clinical course that often does not correlate with morphologic features of the tumor. Metastasis reflects the most adverse outcome of prostate cancer, and to date there are no reliable morphologic features or serum biomarkers that can reliably predict which patients are at higher risk of developing metastatic disease. Understanding the differences in the biology of metastatic and organ confined primary tumors is essential for developing new prognostic markers and therapeutic targets. METHODS: Using Affymetrix oligonucleotide arrays, we analyzed gene expression profiles of 24 androgen-ablation resistant metastatic samples obtained from 4 patients and a previously published dataset of 64 primary prostate tumor samples. Differential gene expression was analyzed after removing potentially uninformative stromal genes, addressing the differences in cellular content between primary and metastatic tumors. RESULTS: The metastatic samples are highly heterogenous in expression; however, differential expression analysis shows that 415 genes are upregulated and 364 genes are downregulated at least 2 fold in every patient with metastasis. The expression profile of metastatic samples reveals changes in expression of a unique set of genes representing both the androgen ablation related pathways and other metastasis related gene networks such as cell adhesion, bone remodelling and cell cycle. The differentially expressed genes include metabolic enzymes, transcription factors such as Forkhead Box M1 (FoxM1) and cell adhesion molecules such as Osteopontin (SPP1). CONCLUSION: We hypothesize that these genes have a role in the biology of metastatic disease and that they represent potential therapeutic targets for prostate cancer