Epidermal growth factor receptor (EGFR) status in primary colorectal tumors does not correlate with EGFR expression in related metastatic sites: implications for treatment with EGFR-targeted monoclonal antibodies

Molecular prognostic markers in resectable colorectal liver metastases: a systematic review

BACKGROUND

Determination of prognosis in patients with resectable colorectal liver metastases (CLM) is desirable in order to improve case selection for surgery and tailor adjuvant treatment according to individual recurrence risk. Conventional clinicopathological factors lack the sensitivity to accurately achieve this goal. Consideration of tumour biology and the identification of molecular prognostic markers may allow more accurate risk stratification.

METHOD

This systematic review examines evidence from published manuscripts looking at molecular markers in resectable colorectal liver metastases and their correlation with disease recurrence and survival following hepatectomy.

RESULTS

Studies have yielded promising results in the search for prognostic molecular markers of CLM. Molecular biomarkers from varied aspects of tumour biology have been examined and a number of these, including proliferation indices, telomerase, thymidylate synthase, microvessel density and thrombospondin-1 appear to have prognostic utility in this context. Validation of other markers, notably p53, has been limited by a failure of methodologies to account for their biological complexity.

CONCLUSIONS

A biomarker-based approach may yield significant benefits through informed treatment of resectable metastatic colorectal malignancy. Standardised retrospective analyses are necessary to confirm preliminary findings and identify existing and novel markers for inclusion into prospective studies. Assessment and verification of multiple molecular markers in this manner may allow molecular profiling of metastases and tailoring of therapy according to the biological aggressiveness of individual tumours. The advent of genomic- and proteomic-based technologies will allow the simultaneous analysis of multiple molecular markers and the derivation of disease profiles associated with disease recurrence and poor survival.

Targeting the Epidermal Growth Factor Receptor in Colorectal Cancer: Advances and Controversies

Colorectal cancer (CRC) is the second leading cause of cancer death in the western world. Even with the significant improvement in traditional chemotherapy, there remain limitations with this treatment. One of the most promising new targets in the treatment of CRC is the epithelial growth factor receptor (EGFR). Agents that inhibit the EGFR have demonstrated clinical activity as single agents and in combination with chemotherapy and the most promising of these agents is cetuximab, which blocks the binding of EGF and transforming growth factor-alpha (TGF-alpha) to EGFR. Thus, the finding that monoclonal antibodies against EGFR caused a response in patients, and reversed resistance to chemotherapy, was exciting news. However, expression of EGFR did not correlate with clinical benefit. Clearly, the search for markers of response to treatment against EGFR must go on.

Assessment of epidermal growth factor receptor (EGFR) expression in primary colorectal carcinomas and their related metastases on tissue sections and tissue microarray

Metastatic colorectal carcinomas (CRC) resistant to chemotherapy may benefit from targeting monoclonal therapy cetuximab when they express the epidermal growth factor receptor (EGFR). Because of its clinical implications, we studied EGFR expression by immunohistochemistry on tissue sections of primary CRC (n=32) and their related metastases (n=53). A tissue microarray (TMA) was generated from the same paraffin blocks to determine whether this technique could be used for EGFR screening in CRC. On tissue sections, 84% of the primary CRC and 94% of the metastases were EGFR-positive. When matched, they showed a concordant EGFR-positive status in 78% of the cases. Moreover, staining intensity and extent of EGFR-positive cells in the primary CRC correlated with those observed in the synchronous metastases. On TMA, 65% of the primary CRC, 66% of the metastases, and 43% of the matched primary CRC metastases were EGFR-positive. There was no concordant EGFR status between the primary and the metastatic sites. A strong discrepancy of EGFR status was noted between TMA and tissue sections. In conclusion, EGFR expression measured in tissue sections from primary CRC and their related metastases was found to be similar and frequent, but it was significantly underestimated by the TMA technique.

Links between Biology, Prognosis and Prediction of Response to Chemotherapy in Colorectal Cancer

Compared with the progress achieved in breast cancer, the use of prognostic and predictive parameters in colorectal cancer is lagging behind. One of the reasons is the limited information provided by 'classic' mutations as markers for response to therapy. To bridge this gap, prospective clinical trials need to be conducted to evaluate the usefulness of gene expression profiling and candidate markers, such as DNA repair proteins, onset of the methylator phenotype, neo-angiogenetic pathways related to inflammation, matrix metalloproteinases, tumor suppressors and cell signaling pathways (e.g. Akt). In parallel, the unrivalled sensitivity of molecular techniques may be applied to diagnostic parameters, such as cytokeratin 20 mRNA, for the detection of lymph node metastases. This article reviews the current knowledge on prognostic and predictive parameters in order to highlight the close link between tumor biology and tumor pharmacology. The increasing number of candidate markers together with recently introduced therapeutic options offer novel opportunities for a stepwise approach to the ambitious goal of individualized therapy in colorectal cancer.

Biological agents versus chemotherapy in the treatment of colorectal cancer

Biological agents are commonly incorporated as an adjunct to cytotoxic chemotherapy in the treatment of patients with advanced colorectal cancer. In contrast to cytotoxic chemotherapy, biological agents have minimal single agent activity and are largely considered to be cytostatic. Recent data supports the use of either combination regimens with chemotherapy and/or biological therapy. Interest in combining biological agents of co-existing molecular pathways is the most recent strategic approach. However, with the advent of these novel therapies, questions have arisen regarding appropriate clinical indication and potential treatment-related toxicities. The role of biological agents in the treatment of colorectal cancer and their role in contrast to cytotoxic chemotherapy will be explored.

Significance of EGFR protein expression and gene amplification in non-small cell lung carcinoma

We evaluated epidermal growth factor receptor (EGFR) protein expression by immunohistochemical analysis and EGFR gene amplification by fluorescence in situ hybridization in 199 consecutive newly diagnosed and surgically treated patients with primary non-small cell lung carcinoma (NSCLC) and correlated results with clinicopathologic findings. EGFR protein expression was more common in squamous cell carcinoma (SCC; 17 [26.2%]) than in adenocarcinoma (14 [11.1%]; (P = .0076) and more frequently associated with EGFR amplification (8 [14.5%] vs 4 [3.6%] cases; P = .0208). Poor differentiation was associated with a higher average number of EGFR gene copies per cell (mean, 4.18; P = .0322) and a higher EGFR/chromosome 7 ratio (mean, 1.84; P = .0324). N0 disease showed a higher number of EGFR gene copies (mean, 4.196; P = .0163). SCCs demonstrated a higher EGFR/chromosome 7 ratio than adenocarcinomas (mean, 1.95 vs 1.47; P = .0324), particularly T1 tumors (mean, 1.79; P = .0243). Statistical analysis failed to show correlation between outcome and EGFR protein expression and gene amplification in early NSCLC. EGFR protein expression was uncoupled from gene amplification in most cases, although good correlation occurred in a subset of SCCs.

Cetuximab: an epidermal growth factor receptor monoclonal antibody for the treatment of colorectal cancer

BACKGROUND

Cetuximab is a recombinant human/mouse chimeric epidermal growth factor receptor (EGFR) monoclonal antibody. It was approved by the US Food and Drug Administration in February 2004 to be used in combination with irinotecan for the treatment of EGFR-expressing, metastatic colorectal cancer in patients who had failed to improve with irinotecan-based chemotherapy. Cetuximab was also approved for administration as a single agent in the treatment of patients with EGFR-expressing, metastatic colorectal cancer who are intolerant to irinotecan-based chemotherapy.

OBJECTIVE

This article reviews the role of cetuximab, an EGFR monoclonal antibody, in the treatment of colorectal cancer.

METHODS

A MEDLINE search was conducted of articles published from 1976 to the present using the terms cetuximab, C225, IMC-C225, colon cancer, colorectal cancer, monoclonal therapy, and target therapy. Abstracts presented at the American Society of Clinical Oncology annual meetings from 2000 to 2004 and the 2004 Gastrointestinal Cancers Symposium were reviewed and included as applicable.

RESULTS

In a Phase III trial, cetuximab was administered to 329 patients with colorectal cancer who were irinotecan refractory and/or had failed to respond to oxaliplatin treatment. Partial response was achieved in 10.8% of patients who received cetuximab monotherapy and 22.9% of patients who received cetuximab plus irinotecan therapy (P = 0.007). The overall response rate in 2 Phase II trials using the conventional dosing regimen of cetuximab to treat EGFR-expressing, metastatic colorectal cancer that was refractory to irinotecan therapy ranged from 9% to 12%. The drug was well tolerated with proper administration precautions. The most common adverse events reported included acnelike rash and hypersensitivity reaction. The positive correlation of the incidence of skin reactions to response rates and median survival is one aspect that warrants further investigation in terms of its use as a response predictor. Unfortunately, the role of immunohistochemistry for EGFR expression continues to be a poor predictor of patients who may benefit from cetuximab. Clinical studies are ongoing of cetuximab in combination with radiation therapy and/or platinum in patients with squamous cell head and neck cancer, as well as cetuximab in combination with various antineoplastic agents in the treatment of non-small cell lung cancer and pancreatic cancer.

CONCLUSIONS

Cetuximab has shown considerable activity-both as monotherapy and in combination with chemotherapy-in the treatment of metastatic colorectal cancer that is resistant to chemotherapy. The future of cetuximab lies in its use in combination with antineoplastic agents and/or radiation therapy in the treatment of colorectal cancer, head and neck cancer, non-small cell lung cancer, and pancreatic cancer. The lack of a predictive marker that would allow clinicians to select patients who are most likely to benefit from cetuximab therapy, especially taking into consideration the high costs of this medication, remains a challenge.

Treatment of hepatic metastases from colorectal cancer: Many doubts, some certainties

About 50% of patients with colorectal cancer (CCR) are destined to develop hepatic metastases during the course of the disease. Surgery is currently the only potentially curative treatment with a five year survival rate after hepatectomy from 26% to 49%. The criteria for resectability are now less rigid than in the past and the tendency to adopt a more aggressive treatment of metastatic lesions is the rule. Systemic infusion chemotherapies based on 5-fluorouracil (5-FU), oxaliplatin (OHP) and irinotecan (CPT-11) are well tolerated and have been shown to be effective in non-operable patients. These regimens allow surgery for patients who are initially not suitable for resection, giving them a probability of survival at five years similar to that of patients operated on at diagnosis. Intra-arterial infusion chemotherapy (HAI) is very effective in inducing objective responses, but is costly, difficult to manage and encumbered by major side effects, so that its application is necessarily limited to centres with specific experience. However, despite the broader criteria and recent advances of chemotherapy, surgery is not possible in most patients. The role of other local therapeutic techniques like cryosurgery (CS) and radiofrequency ablation (RF), alone or combined with surgery or chemotherapy, is not yet established in a multidisciplinary therapeutic approach. Roughly two thirds of patients relapse during the first two years after surgery suggesting appropriate post-operative chemotherapy treatment after hepatic resection may be indicated, but no randomised studies have been published to date. In case of relapse, another hepatectomy should be considered. The role of novel targeted therapies in pre-operative, post-operative and palliative management has yet to be evaluated.

Strategies and methodologies for identifying molecular targets in sarcomas and other tumors

Sarcomas are a heterogeneous group of tumors that respond poorly to conventional cytotoxic chemotherapy. Sarcomas possess specific molecular characteristics that exist because of unique somatic mutations, vital growth factor or growth factor receptor overexpression, or are critically dependent on host pathways. Currently these tumors are classified on the basis of their tissue of origin and histologic appearance. Gene expression and proteomic analysis of sarcomas may enable reclassification of these tumors and help predict their biologic behavior and devise common therapeutic strategies within a class. It may not be long before cDNA/protein expression profiling and karyotyping complement the current standard pathological evaluation of a newly diagnosed sarcoma, thereby helping the clinician pick targeted agent(s) relevant to the expression profile. The spectacular success of imatinib in patients with gastrointestinal stromal tumor demonstrates how molecular targeting can fulfill the promise of low toxicity and high response rates. Finding new targets, and learning how to use the current generation of targeting drugs in sarcoma, are urgent challenges. Therapeutic clinical trials with a host of new molecular-targeting agents are underway that will drive new paradigms in sarcoma therapeutics. Patients with refractory disease who currently have no viable therapeutic options may have options that open up with the advent of newer targeted approaches, converting their disease from an acute short-lived one to a chronic process with preservation of quality of life while receiving therapy.

Anti-EGFR strategies as an incremental step for the treatment of colorectal cancer patients: moving from scientific evidence to clinical practice

The epidermal growth factor receptor (EGFR) is a 170,000 Da transmembrane glycoprotein involved in signalling pathways affecting cellular growth, differentiation and proliferation. An abnormal overexpression of the EGFR has been described in many human tumours and implicated in the development and prognosis of malignancies, thus representing not only a possible prognostic marker, but primarily a rational molecular target for a new class of anticancer agents. Several clinical trials have been reported with the use of EGFR-targeted monoclonal antibodies and tyrosine kinase inhibitors, mainly in combination with chemotherapy for advanced colorectal cancer patients. Taken together, results available so far suggest that anti-EGFR treatment strategies represent an incremental step for the the treatment of colorectal cencer patients with a manageable and acceptable toxicity profile. Nevertheless, many critical issues are yet unresolved, such as the optimal chemotherapy regimen to combine with anti-EGFR treatment and the most adequate patients setting. Moreover, the biological selection of colorectal tumours most likely to benefit from this treatment approach is still to be defined.

Epidermal growth factor receptor inhibition for the treatment of glioblastoma multiforme and other malignant brain tumours

Gliomas are the most common primary central nervous system tumours and about 55% are glioblastoma multiforme (GBM). Between 40% and 50% of GBM have dysregulated epidermal growth factor receptor (HER1/EGFR), and almost half of these co-express the mutant receptor subtype EGFRvIII, which may contribute to the aggressive and refractory course of GBM. Limited therapeutic options exist for GBM, and recurrence is common. Standard therapy is surgical resection, where possible, and radiotherapy. Adjuvant chemotherapy provides a modest survival benefit. New therapies are essential, and HER1/EGFR-targeted agents may provide a viable strategy. The HER1/EGFR tyrosine kinase inhibitors erlotinib and gefitinib are in advanced clinical development for glioma, and a number of trials are in progress, or have recently been completed. Preliminary results with gefitinib show no objective responses, but do provide evidence of disease control. In contrast, preliminary data with erlotinib appear more encouraging. Erlotinib inhibits wild-type HER1/EGFR and EGFRvIII, which may underlie its promising clinical activity. Other HER1/EGFR-targeted agents are also being investigated for glioma, including monoclonal antibodies, radio-immuno conjugates, ligand-toxin conjugates, antisense oligonucleotides and ribozymes. Further studies will define their clinical potential and hopefully provide new, effective treatments for GBM and other malignant brain tumours.

Current Status of Small-Molecule Tyrosine Kinase Inhibitors Targeting Epidermal Growth Factor Receptor in Colorectal Cancer

The epidermal growth factor receptor (EGFR) is expressed in the majority of colorectal cancers (CRCs) and is associated with poor clinical outcome. Ample evidence suggests that inhibition of this pathway by monoclonal antibodies directed against EGFR leads to antitumor activity in CRC. Small-molecule tyrosine kinase inhibitors (TKIs) provide distinct advantages over monoclonal antibodies by virtue of lower production costs, ease of oral administration, and ability to target multiple cellular survival pathways. Despite theoretical advantages, multiple early-phase trials of EGFR TKIs fail to demonstrate single-agent activity in CRC. However, the unusually high response rates observed when gefitinib, an EGFR TKI, is combined with chemotherapy for patients with metastatic CRC suggest a possible synergistic effect. This effect is not seen in non-small-cell lung cancer (NSCLC), for which larger phase III trials have been conducted. The differences between NSCLC and CRC with respect to EGFR expression and mutation status do not completely explain this dichotomy, and further investigation into the pharmacogenomics of EGFR tyrosine kinase inhibition in CRC is under way. Significant effort is directed toward newer strategies targeted at the EGFR in CRC. A new generation of small-molecule TKIs is emerging in which multiple receptor pathways, including ErbB2 and vascular endothelial growth factor receptor, can be simultaneously targeted with EGFR. These agents are still in early-phase clinical trials, and specific data for patients with CRC are forthcoming.

Targeted therapy for colorectal cancer: mapping the way

In spite of the significant advances in conventional therapeutic approaches to colorectal cancer (CRC), most patients ultimately die of their disease. Dissecting the molecular mechanisms underlying CRC progression will not only accelerate the development of novel cancer-selective drugs but will also enable the therapeutic regimen to be personalized according to the molecular features of individual patients and tumors. Here, we report on the novel insights into CRC biology that are paving the way to the development of molecular therapies and summarize the results from recent clinical trials demonstrating that agents targeting tumor-specific molecular derangements can significantly improve the therapeutic efficacy of conventional chemotherapy. Only a broader clinical implementation of these concepts will provide patients with CRC the best chance of a cure.

Promises and pitfalls in the prediction of antiepidermal growth factor receptor activity

There is a constant examination of the features that may anticipate or predict the likelihood of the clinical benefit that a patient may experience from a given therapy. This is especially true in the case of novel targeted therapies, as proof-of-principle experimental or pilot analyses are increasingly being embedded into clinical protocols. An unprecedented number of significant developments in the field of epidermal growth factor receptor-targeted therapy have occurred in recent months. This is exemplified by the discovery of activating mutations in the catalytic domain of the epidermal growth factor receptor that increase sensitivity to antiepidermal growth factor receptor small-molecule inhibitors. This review discusses the recent advances and controversies of the different approaches to predict the efficacy of antiepidermal growth factor receptor agents and the effectiveness of the tools that we are using to evaluate and predict the efficacy of epidermal growth factor receptor-targeted drugs and their potential pitfalls.

Assessing epidermal growth factor receptor expression in tumours: What is the value of current test methods?

Over-expression of the epidermal growth factor receptor (EGFR) in tumours is associated with aggressive disease and poor clinical prognosis. In theory, the EGFR status of a tumour provides an indication of the likelihood of response to EGFR-targeted therapy. However, the clinical data do not support a relationship between EGFR expression and response to EGFR-targeted therapies cetuximab, gefitinib and erlotinib. Recently, patients who appear to lack EGFR expression have been shown to respond to cetuximab. Possible causes for this paradox include false negative results due to a lack of sensitivity in the detection system, heterogeneity of EGFR expression within the tumour and specific mutations that mediate response to the tyrosine kinase inhibitors. Immunohistochemistry is the most reliable assay for EGFR expression but its interpretation is confounded by the lack of non-standard techniques. Other approaches for measuring EGFR expression can be considered at best exploratory at this point. Further work is needed to identify how EGFR contributes to carcinogenic and metastatic processes. As tumours that appear to be EGFR negative can respond to cetuximab, there is some doubt as to the usefulness of immunohistochemistry as a screen to select patients for treatment. Histopathology will continue to be essential for unravelling the role of this enigmatic molecule and refining its status as a legitimate target in cancer therapy.

Epidermal growth factor receptor (EGFR) status in primary colorectal tumors correlates with EGFR expression in related metastatic sites: biological and clinical implications

BACKGROUND

Epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of colorectal cancer (CRC). There are several potential strategies to target EGFR. However, monoclonal antibodies and low molecular weight tyrosine kinase inhibitors are the most advanced in clinical development. The majority of studies so far have merely required EGFRs to be expressed by CRC cells. The detection of EGFR expression is usually performed by immunohistochemistry (IHC) in the primary tumor. There are few data regarding the EGFR status in the corresponding distant metastases.

PATIENTS AND METHODS

EGFR status was analyzed by IHC in 80 patients (31 male, 49 female) with CRC (70 colon, 10 rectum) and at least one distant metastatic lesion. Metastatic sites analyzed (n=80) were liver (79 patients) and lung (one patient).

RESULTS

EGFR reactivity was similar in the primary tumor and the related metastases. Among the 80 paired primary/metastatic tumors, only five (6.3%) showed discordance in EGFR status: two cases with EGFR expression in the primary tumor but not in the metastasis, and three samples with EGFR expression in the metastasis but not in the primary tumor.

CONCLUSIONS

Between the paired primary tumors and distant metastatic lesions, 94% of samples had concordant EGFR status when analyzed by IHC.