Cetuximab shows activity in colorectal cancer patients with tumors that do not express the epidermal growth factor receptor by immunohistochemistry

Cetuximab in the treatment of metastatic colorectal cancer

Cetuximab is a chimeric monoclonal antibody that binds to the epidermal growth factor receptor and thereby inhibits cell proliferation, metastasis and angiogenesis. Preclinical studies indicate that cetuximab induces synergistic antitumor activity when combined with chemotherapy or radiation. This observation is supported by clinical trials demonstrating that cetuximab improves tumor response when used in conjunction with modern chemotherapy in patients with metastatic colorectal cancer. Improved treatment efficacy may help to increase the rate of hepatic metastasis resection after downsizing of initially unresectable lesions. In pretreated patients, cetuximab may restore the sensitivity to irinotecan and, therefore, has been registered in this setting. Ongoing studies are investigating the integration of anti-epidermal growth factor receptor and anti-vascular endothelial growth factor strategies into new treatment regimens. Promising results have already been obtained in a trial combining irinotecan, bevacizumab and cetuximab.

Molecular-based choice of cancer therapy: realities and expectations

Current choice of cancer therapy is usually empirical and relies mainly on the statistical prediction of the treatment success. Molecular research provides some opportunities to personalize antitumor treatment. For example, life-threatening toxic reactions can be avoided by the identification of subjects, who carry susceptible genotypes of drug-metabolizing genes (e.g. TPMT, UGT1A1, MTHFR, DPYD). Tumor sensitivity can be predicted by molecular portraying of targets and other molecules associated with drug response. Tailoring of antiestrogen and trastuzumab therapy based on hormone and HER2 receptor status has already become a classical example of customized medicine. Other predictive markers have been identified both for cytotoxic and for targeted therapies, and include, for example, expression of TS, TP, DPD, OPRT, ERCC1, MGMT, TOP2A, class III beta-tubulin molecules as well as genomic alterations of EGFR, KIT, ABL oncogenes.

Colorectal cancer

Cancers of the colon and rectum will affect 1 in 17 North Americans during their lifetime. The progress witnessed in the treatment of these cancers in recent years has been remarkable. Improvements have been realized in surgical technique, radiation therapy, and systemic therapies, particularly with the addition of oxaliplatin and irinotecan to the previously limited armamentarium of fluorouracil alone. Targeted therapies directed at the vascular endothelial growth factor pathway and the epidermal growth factor pathway are now key players in the treatment of colorectal cancer. With current-day therapies, more than 75% of patients with localized disease are recurrence free at 3 years, and up to 50% of patients with advanced unresectable disease are alive at 2 years. This review focuses on the evidence supporting the current role of chemotherapy and radiation therapy in the adjuvant management of colorectal cancers and the strategy of combining chemotherapy and biological therapy in the treatment of metastatic disease.

A clinically motivated 2-fold framework for quantifying and classifying immunohistochemically stained specimens

Motivated by the current limitations of automated quantitative image analysis in discriminating among intracellular immunohistochemical (IHC) staining patterns, this paper presents a two-fold approach for IHC characterization that utilizes both the protein stain information and the surrounding tissue architecture. Through the use of a color unmixing algorithm, stained tissue sections are automatically decomposed into the IHC stain, which visualizes the target protein, and the counterstain which provides an objective indication of the underlying histologic architecture. Feature measures are subsequently extracted from both staining planes. In order to characterize the IHC expression pattern, this approach exploits the use of a non-traditional feature based on textons. Novel biologically motivated filter banks are introduced in order to derive texture signatures for different IHC staining patterns. Systematic experiments using this approach were used to classify breast cancer tissue microarrays which had been previously prepared using immuno-targeted nuclear, cytoplasmic, and membrane stains.

The Biology of Epidermal Growth Factor Receptor and its Value as a Prognostic/predictive Factor

Receptor tyrosine kinases play a major role in human carcinogenesis. Overexpression of the epidermal growth factor receptor (EGFR) has been associated with poor clinical outcome in several types of cancer. In principle, as with HER2, the EGFR status of a tumor should predict the likelihood of response to EGFR-targeted therapy. However, clinical data have failed to demonstrate a relationship between EGFR expression and response to the EGFR-targeted compounds cetuximab, gefitinib and erlotinib. Recently, patients reported to be EGFR negative have been shown to respond to cetuximab. Possible explanations include methodological failures or most likely heterogeneity and complexity of the mechanisms of EGFR-mediated molecular carcinogenesis. Immunohistochemistry is the most widely used method for measuring EGFR expression; however, its value is limited by lack of methodological standardization. Other approaches to measuring EGFR such as amplification assays are currently being introduced but need further testing before they can enter clinical practice. Mutational analysis seems also fruitful in predicting response to anti-EGFR small molecules. Further work is needed to identify how EGFR contributes to the carcinogenic and metastatic processes.

Cetuximab: appraisal of a novel drug against colorectal cancer

Cetuximab (C225, Erbitux, Merck, Darmstadt, Germany) is a human-mouse chimeric therapeutic monoclonal antibody (mAb) that competitively binds to the extracellular domain of the human epidermal growth-factor receptor (EGFR). It has been developed out of the murine antibody M225 "from bench to bedside" in less than two decades, and is the anti-EGFR mAb furthest ahead in clinical evaluation. In Europe, cetuximab is approved for the treatment of patients with EGFR-expressing, metastatic colorectal cancer after failure of treatment with irinotecan since 2004, and for the treatment of patients with locally advanced squamous cell cancer of the head and neck concomitant to radiotherapy since 2006. We here summarize the current role of cetuximab in the treatment of colorectal cancer, give an overview on the ongoing studies, address the most important controversies, and point out the chances and challenges for the future use of cetuximab in colorectal cancer and other human malignancies.

Recent developments in colorectal cancer treatment by monoclonal antibodies

A growing understanding of the molecular mechanisms involved in cancer biology and continuous refinement of available technologies for drug discovery have prompted the development of new therapeutic tools targeting specific cancer-associated molecular pathways. Among these so-called biological therapies, monoclonal antibodies have now reached the time of clinical application. Besides initial development of the murine antibody edrecolomab, the impact of monoclonal antibodies on cancer therapy has recently been clearly demonstrated in colorectal cancer by targeting two major pathways critical to tumourigenesis: the epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) signalling pathways. These antibodies showed significant clinical activity in advanced colorectal cancer, especially when combined with chemotherapy. This paper reviews the status of the monoclonal chimeric antibody cetuximab (Erbitux) and other anti-EGFR antibodies, and of bevacizumab (Avastin; an anti-VEGF humanised monoclonal antibody), in colorectal cancer treatment.

Lack of usefulness of epidermal growth factor receptor expression determination for cetuximab therapy in patients with colorectal cancer

In patients with metastatic colorectal cancer, the use of cetuximab currently requires a documented tumoral epidermal growth factor receptor positivity. Responses to cetuximab, however, have been described in patients with epidermal growth factor receptor-negative tumors. We have used cetuximab in all eligible patients with metastatic colorectal cancer, whether their tumor expressed epidermal growth factor receptor or not. We assessed the cetuximab efficacy with regard to tumoral epidermal growth factor receptor expression. Twenty patients with metastatic colorectal cancer were treated off study with cetuximab and irinotecan after failure of oxaliplatin- and irinotecan-based regimens. Tumors were analyzed in all patients for epidermal growth factor receptor expression by immunohistochemistry. Tumors were positive for epidermal growth factor receptor in 12 cases and negative in eight cases. An objective response to cetuximab-based therapy was obtained in four patients (20%). Tumors of these four patients were negative for epidermal growth factor receptor expression. These results provide further evidence for the lack of usefulness of epidermal growth factor receptor detection by immunohistochemistry for cetuximab therapy in patients with metastatic colorectal cancer.

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.

Protocol modifications influence the result of EGF receptor immunodetection by EGFR pharmDx™ in paraffin-embedded cancer tissues

EGF receptor (EGFR) became a useful target for several recently introduced therapies of various cancer types including colorectal, lung, head and neck cancers and glioblastoma. The successful clinical application of these novel molecularly targeted therapies requires the expression of their target, EGFR, determined by nucleic acid based or immunohistochemical techniques. However, until now, immunohistochemistry has not become a reliable diagnostic approach for this purpose. The golden standard for the determination of EGFR protein expression in paraffin-embedded cancer tissues is the EGFR pharmDxTM kit. Here we show that the recommended protocol may not be optimal for EGFR immunodetection. Microwave antigen retrieval and extended primary antibody incubation time converted four out of eight EGFR-negative tumors into EGFR-positive in a study of 50 lung adenocarcinoma cases. Accordingly, we recommend retesting cases negative for EGFR with EGFR pharmDxTM using protocol modifications optimizing antigen retrieval and the incubation periods.

A phase II trial of EMD72000 (matuzumab), a humanized anti-EGFR monoclonal antibody, in patients with platinum-resistant ovarian and primary peritoneal malignancies

OBJECTIVE

The primary objective of this study was to determine the rate of response to matuzumab in patients with recurrent, EGFR-positive ovarian, or primary peritoneal cancer. Secondary end points included safety and tolerability, time to tumor progression, duration of response, and overall survival.

METHODS

A multi-institutional single arm phase II trial.

RESULTS

Of 75 women screened for the study, 37 were enrolled and treated. Median age of the treated patient population was 58 years, and most patients had more than four prior lines of chemotherapy. Therapy was well tolerated, the most common toxicities being a constellation of skin toxicities, including rash, acne, dry skin, and paronychia, as well as headache, fatigue, and diarrhea. Serious adverse events were very rare but included a single episode of pancreatitis that may have been drug related. All patients completed therapy, receiving 1 to 30 infusions of matuzumab. There were no formal responses (RR=0%, 95% CI: 0-9.5%), although 7 patients (21%) were on therapy for more than 3 months with stable disease.

CONCLUSIONS

Matuzumab at the dose and schedule selected is well tolerated. In this population of very heavily pretreated patients with epithelial ovarian and primary peritoneal malignancies, there was no evidence of significant clinical activity when matuzumab was administered as monotherapy.

Multicenter phase II and translational study of cetuximab in metastatic colorectal carcinoma refractory to irinotecan, oxaliplatin, and fluoropyrimidines

PURPOSE

This multicenter study evaluated the antitumor activity of cetuximab, an immunoglobulin G1 antibody directed at the epidermal growth factor receptor (EGFR), in metastatic colorectal carcinoma (CRC) refractory to irinotecan, oxaliplatin, and a fluoropyrimidine. It also evaluated the safety, pharmacokinetics, immunokinetics, and biologic determinants of activity.

PATIENTS AND METHODS

Patients with metastatic CRC, whose tumors demonstrated EGFR immunostaining and were refractory to irinotecan, oxaliplatin, and fluoropyrimidines, were treated with cetuximab at a loading dose of 400 mg/m2 followed by 250 mg/m2 weekly. An independent review committee (IRC) reviewed responses. Blood was collected for cetuximab pharmacokinetics and to detect antibodies to cetuximab. EGFR gene sequencing of the tyrosine kinase domain and gene copy number assessments were performed.

RESULTS

The response rates in 346 patients, as determined by the investigators and IRC, were 12.4% (95% CI, 9.1 to 16.4) and 11.6% (95% CI, 8.4 to 16.4). The median progression-free survival (PFS) and survival times were 1.4 months (95% CI, 1.4 to 2.1) and 6.6 months (95% CI, 5.6 to 7.6), respectively. An acneiform rash occurred in 82.9% of patients; grade 3 rash was observed in 4.9%. Response and survival related strongly to the severity of the rash. In contrast, clinical benefit did not relate to EGFR immunostaining. EGFR tyrosine kinase domain mutations were not identified, and EGFR gene copy number did not relate to response or PFS, but to survival (P = .03).

CONCLUSION

Cetuximab is active and well tolerated in metastatic CRC refractory to irinotecan, oxaliplatin, and fluoropyrimidines. The severity of rash was related to efficacy. Neither EGFR kinase domain mutations nor EGFR gene amplification appear to be essential for response to cetuximab in this setting.

Phase II trial of capecitabine and oxaliplatin (CAPOX) plus cetuximab in patients with metastatic colorectal cancer who progressed after oxaliplatin-based chemotherapy

BACKGROUND

Cetuximab is an IgG1 monoclonal antibody targeting the epidermal growth factor receptor and is able to reverse the resistance to irinotecan in patients with metastatic colorectal cancer (mCRC). This phase II trial evaluates the safety and efficacy of cetuximab combined with capecitabine and oxaliplatin (CAPOX) in the treatment of patients with mCRC progressing under oxaliplatin-based chemotherapy.

PATIENTS AND TREATMENT

Forty patients with mCRC were treated with cetuximab (loading dose 400 mg/m(2) and then 250 mg/m(2) i.v. weekly) in combination with CAPOX (d(1): L-OHP 85 mg/m(2) and d(1-7) capecitabine 2000 mg/m(2) every 2 weeks). Thirty-one (77.5%) and nine (22.5%) patients had oxaliplatin-refractory and -resistant disease, respectively; in addition, 32 (80%) patients had also progressed on prior irinotecan-based chemotherapy.

RESULTS

One hundred and thirty-four cycles were administered (median of four cycles per patient). Main toxic effects included grade 3-4 neutropenia (12.5%), grade 3/4 diarrhea (7.5%), grade 3 fatigue (2.5%), and grade 2-3 neurotoxicity (22.5%). One (2.5%) complete and seven (17.5%) partial responses were achieved [overall objective response rate (ORR): 20%; 95% confidence interval (CI): 9% to 32%)], whereas 11 (27.5%) patients had stable disease [disease control rate (DCR): 47.5%; 95% CI: 30.2% to 64.5%]. The ORR and DCR were 18.7% and 46.8%, respectively, in patients with oxaliplatin-refractory disease. The median time to tumor progression was 3 months, the median survival 10.7 months and the probability of 1-year survival rate 53.4%.

CONCLUSIONS

The combination of cetuximab plus CAPOX is safe and has a promising activity in patients with mCRC refractory or resistant to oxaliplatin.

Integration of EGFR inhibitors with radiochemotherapy

Laboratory studies that led to the development of epidermal growth factor receptor (EGFR) inhibitors indicated that such inhibitors would be effective when given to patients with tumours that are driven by activated EGFR. However, initial clinical studies have shown modest responses to EGFR inhibitors when used alone, and it has not yet been possible to clearly identify which tumours will respond to this therapy. As a result, EGFR inhibitors are now used in combination with radiation therapy, chemotherapy and, more recently, with concurrent radiochemotherapy. In general, these clinical trials have been designed without much preclinical data. What do we need to know to make these combinations successful in the clinic?

Molecular determination of epidermal growth factor receptor in normal and neoplastic colorectal mucosa

The epidermal growth factor receptor (EGFr) is considered a major target for treatment of colorectal cancer (CRC). We found a mean EGFr content significantly lower but more activated in colonic neoplastic tissue than in paired normal mucosa. Phosphorylated (pY1068) EGFr detection in CRC may be a better tool than EGFr detection to select patients for targeted therapies.

Clinicopathologic significance of EGFR and Her-2/neu in colorectal adenocarcinomas

PURPOSE

The purpose of this study was to determine the prognostic impact of epidermal growth factor receptor (EGFR) and Her2/neu protein expression in colorectal cancer.

METHODS

Immunohistochemistry was performed in paraffin-embedded specimens of 106 colorectal carcinomas for the assessment of EGFR and Her-2 expression. The results were correlated with traditional clinicopathologic parameters and patient outcome.

RESULTS

Membranous expression of EGFR was found in 50 cases (47.16%) and cytoplasmic expression in 32 cases (30.19%). Membranous overexpression of Her-2 was identified in six cases (5.66%) whereas cytoplasmic expression was found in 18 cases (16.98%). The correlation with other clinicopathologic parameters demonstrated a statistically significant expression of membranous EGFR in the older age group and a statistically significant expression of membranous Her-2 in patients with negative lymph nodes. None of the other parameters or patient prognosis was associated with EGFR or Her-2 membranous expression. Cytoplasmic expression was not related with any of aforementioned parameters.

CONCLUSION

Conventional immunohistochemistry was unable to reveal any association between EGFR expression and outcome predicted by the biologic role of EGFR in tumor behavior. Her-2/neu is not a pivotal pathway in colorectal cancer progression because it seems to be expressed in early stages of colorectal cancer.

The new era in the treatment of advanced colorectal cancer patients: the role of monoclonal antibodies

Colorectal cancer (CRC) represents a major health problem in the Western world. Approximately 60% of patients with CRC require systemic therapy for metastatic disease, either at diagnosis or at disease recurrence. Until recently, classic chemotherapeutic agents have been combined in the treatment of advanced CRC. The recent considerable development of novel monoclonal antibodies that target key components of biological pathways has expanded the options to treat advanced CRC patients. These newer agents more specifically target unique features of the cancer cell and its surroundings and so attempt to exploit the progress that has been made in the understanding of basic cell biology. Two targets in particular--the process of new blood vessel development, or angiogenesis, and the EGF receptor and its signalling pathway--are exploited by the newest monoclonal antibodies available for use in this setting. This clinical review focuses on the defining role of the two most clinically advanced novel agents, bevacizumab and cetuximab in metastatic colorectal cancer.

A phase II trial of imatinib mesylate in patients with biochemical relapse of prostate cancer after definitive local therapy

OBJECTIVE

To determine the biological effects of imatinib mesylate (STI-571, Gleevec; Novartis Pharmaceuticals, Inc., East Hanover, NJ, USA), as measured by prostate-specific antigen (PSA) kinetics in men with biochemical relapse of prostate cancer after definitive local therapy.

PATIENTS AND METHODS

Men with prostate cancer, who had had definitive local therapy, with nonmetastatic recurrent disease as manifested by a rising PSA level, were enrolled on this phase II trial. Men received 400 mg of imatinib mesylate orally twice daily and continuously until disease progression or unacceptable toxicity. The PSA level was measured monthly.

RESULTS

In all, 20 men with biochemically relapsed prostate cancer were treated. The median pretreatment PSA level was 5.4 ng/mL. Of the 19 evaluable men, one achieved a >or= 50% reduction in PSA level and two had decreases of <50%. For the 16 men in whom the on-treatment PSA doubling time (PSADT) could be calculated (those with increasing PSA level) the median PSADT did not increase significantly (5.8 vs 7.2 months, P = 0.64). Eleven of 20 men discontinued therapy due to toxicity and the trial was stopped early due to toxicity.

CONCLUSIONS

Based on the lack of PSA modulation and pronounced toxicities leading to early closure of this trial, further study of single-agent imatinib mesylate at this dose (400 mg twice daily) cannot be recommended in this patient population.

Pharmacokinetics of Cetuximab After Administration of Escalating Single Dosing and Weekly Fixed Dosing in Patients with Solid Tumors

PURPOSE

Previous studies of cetuximab pharmacokinetics did not fully characterize its elimination phase. The purpose of this trial was to evaluate the pharmacokinetics of cetuximab given as a single dose followed by weekly fixed repeated dosing in patients with solid tumors.

EXPERIMENTAL DESIGN

Patients were randomly assigned to treatment with a single 2-hour infusion of cetuximab at doses of 50, 100, 250, 400, or 500 mg/m2 followed 3 weeks later by weekly 1-hour infusions of cetuximab at a fixed dose of 250 mg/m2. Extended pharmacokinetic sampling was collected through 504 hours after the first drug administration. Trough samples were obtained before each fixed weekly dose. Single and multidose pharmacokinetic variables were correlated with clinical outcomes.

RESULTS

Forty patients were enrolled. Pharmacokinetic analysis confirmed previous reports of nonlinear pharmacokinetics for cetuximab. Modeling studies predicted a 90% saturation of clearance at a dose of 260 mg/m2. Analyses of weekly trough concentrations indicated a slight accumulation of drug concentrations following repeated weekly dosing. Correlative studies indicated a significant association between cetuximab clearance and both body surface area (P=0.002) and weight (P=0.002). The occurrence of rash was significantly associated with disease stability (P<0.002) but not with cetuximab pharmacokinetic variables.

CONCLUSIONS

Pharmacokinetic results support using body surface area or weight in calculating individual cetuximab doses. A weekly dose of 250 mg/m2 is predicted to nearly fully saturate cetuximab clearance and, by inference, epidermal growth factor receptors. The association between rash and disease stability supports further prospective studies of this relationship.

Clinical implications of the mechanism of epidermal growth factor receptor inhibitors

Novel therapeutic agents that target the epidermal growth factor receptor (EGFR) constitute an important addition to the therapeutic armamentarium for the treatment of metastatic disease. EGFR-targeted agents currently approved by the U.S. Food and Drug Administration include cetuximab, a monoclonal antibody for the treatment of colorectal cancer; and the small-molecule EGFR tyrosine kinase inhibitor (TKI) erlotinib for the treatment of nonsmall cell lung cancer (NSCLC) and pancreatic cancer. Approval of the TKI gefitinib for NSCLC recently was withdrawn. Although both classes of anti-EGFR agents target the same receptor, substantial distinctions regarding their mechanism significantly affect dosing requirements, toxicity profiles, and their use as combination agents.

Metastatic colorectal cancer: Therapeutic options

For the past several decades, the therapy for metastatic colorectal cancer had modest benefits because of the limited therapeutic options. Bolus 5-fluorouracil (5FU) and leucovorin (LV) were the standard of care in the United States until 2002, with a response rate of 25% and a median survival of 10 to 12 months. However, with the advent of new agents, namely oxaliplatin and irinotecan, there has been a dramatic change in the way we treat metastatic colorectal cancer. Based on many well-conducted large randomized trials, we have evidence that combination chemotherapy incorporating oxaliplatin or irinotecan with infusional 5FU/LV is superior to 5FU/LV, with doubling of overall survival (OS) to approximately 20 months. There remains some uncertainty as to the best first-line regimen. This might be irrelevant because studies have shown that OS is dependent on exposure to all the active agents, regardless of the time period of exposure. Bevacizumab, which uses anti-angiogenic strategies, has improved disease-free survival (DFS) and OS when combined with standard chemotherapy and is a vital component of metastatic colorectal cancer therapy. However, there are no data supporting its use past progression. Cetuximab, an epithelial growth factor receptor inhibitor, is mainly used in irinotecan-refractory patients. In spite of all these advances, 5-year OS rates continue to be limited. Patients with curative resection of metastatic disease seem to have longer DFS and better 5-year OS rates. This should be a potential goal for responding patients with upfront unresectable, organ-limited disease.

Challenges in the Use of Epidermal Growth Factor Receptor Inhibitors in Colorectal Cancer

Novel targeted agents increase the therapeutic armamentarium in metastatic colorectal cancer (mCRC). Monoclonal antibodies against the epidermal growth factor receptor (EGFR) are active against EGFR-expressing mCRC that is refractory to irinotecan. EGFR monoclonal antibodies also have promise in less advanced stages of CRC. Cetuximab and panitumumab are clearly active agents. It has been shown that cetuximab is more active when administered in combination with irinotecan. Phase II studies also report promising activity when monoclonal antibodies against the EGFR are combined with classic chemotherapeutic regimens in the first-line treatment of mCRC. However, the best means of scheduling such agents and integrating them with each other and with chemotherapy have yet to be established. The management of toxicity (particularly rash) and finding appropriate means of selecting patients pose additional challenges. While the occurrence of rash is associated with greater likelihood of response, EGFR staining by immunohistochemistry at baseline is not. For reasons that are not yet clear, the tyrosine kinase inhibitors of EGFR seem less effective than their monoclonal antibody counterparts in the therapy of mCRC.

Clinical implications of EGFR expression in the development and progression of solid tumors: focus on non-small cell lung cancer

Dysregulation of the epidermal growth factor receptor (EGFR) signaling pathway is associated with the development and progression of malignancy, and EGFR-targeted therapies offer the promise of better treatment for many types of solid tumors, including non-small cell lung cancer. Anti-EGFR agents include monoclonal antibodies (mAbs) targeting the EGFR extracellular receptor domain and small-molecule tyrosine kinase inhibitors (TKIs) targeting the EGFR intracellular kinase domain. Both mAbs and TKIs have demonstrated encouraging results as monotherapies and in combination with chemotherapy and radiotherapy. This review provides a critical update on the status of these novel therapeutics.

Responses of human colorectal tumor cells to treatment with the anti-epidermal growth factor receptor monoclonal antibody ICR62 used alone and in combination with the EGFR tyrosine kinase inhibitor gefitinib

The anti-epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab has been approved for the treatment of patients with metastatic colorectal cancer. However, there is currently no reliable marker for response to therapy with the EGFR inhibitors. In this study, we investigated the sensitivity of 10 human colorectal tumor cell lines (DiFi, CCL218, CCL221, CCL225, CCL227, CCL228, CCL231, CCL235, CCL244, and HCT-116) to treatment with our anti-EGFR monoclonal antibody, ICR62, and/or the EGFR tyrosine kinase inhibitor, gefitinib. Of the cells examined, only DiFi contained high levels of constitutively active EGFR and were highly sensitive to treatment with both ICR62 (IC(50) = 0.52 nmol/L) and gefitinib (IC(50) = 27.5 nmol/L). In contrast, the growth of other tumor cell lines, which contained low levels of the EGFR, HER-2, and pAkt but comparable or even higher basal levels of phosphorylated mitogen-activated protein kinase (pMAPK), were relatively resistant to treatment with both inhibitors. Both ICR62 and gefitinib induced EGFR down-regulation, reduced the basal levels of pEGFR at five known tyrosine residues, pMAPK, and pAkt, and increased the sub-G(1) population in DiFi cells. However, treatment with a combination of ICR62 and gefitinib neither sensitized colorectal tumor cells that were insensitive to treatment with the single agent nor enhanced the growth-inhibitory effect of the single agent in DiFi cells. These results indicate that basal levels of pMAPK and pAkt are not good indicators of response to the EGFR inhibitors in colorectal cancer cells and dual targeting of the EGFR by a combination of ICR62 and gefitinib is not superior to treatment with a single agent.

Recent advances in targeted therapies for colorectal cancer

BACKGROUND

Recent advances in the molecular biology and genetics of colorectal cancer have led to the identification of potential therapeutic targets such as epidermal growth factor receptor, vascular endothelial growth factor and endothelial receptors.

OBJECTIVE

This review will examine the major therapeutic advances along with the preclinical basis justifying their combination with conventional therapeutic tools. This review will also critically consider current possibilities offered to identify responding patients.

DATA SOURCES

Preclinical and primary clinical trial results published in peer-review journals. The authors examined the relevance and subsequent inclusion of the data.

CONCLUSIONS

Cetuximab and bevacizumab provide new benefits in terms of the response rate and survival. There remain, however, important questions concerning, for instance, optimal combinations between conventional cytotoxic agents and targeted therapies and also between targeted drugs themselves. These new targeted treatments are costly and in this context the question of the identification of the right drug for the right patient is particularly relevant. Adequate tools in predicting the efficacy of targeted treatments are still needed.

Epidermal growth factor receptor – targeted molecular therapeutics for head and neck squamous cell carcinoma

Several molecular-targeted therapeutics have been tested in clinical trials for the treatment of head and neck squamous cell carcinoma (HNSCC). Of these, therapeutics targeting the epidermal growth factor receptor (EGFR) have been studied most extensively and some agents have demonstrated measurable clinical effectiveness. However, molecular studies designed to define HNSCC patient subcohorts of likely responders to EGFR-targeted therapy have not identified molecular signatures that correlate with clinical response. Here, the authors summarise the relevant clinical findings and highlight reported molecular correlative studies for EGFR-targeted therapeutics for HNSCC. The authors focus especially on molecular markers evaluated for association with clinical response and include data from EGFR-targeted clinical studies in other cancer sites that they anticipate will be of interest to the head and neck cancer research and treatment communities.

Phase I trial of cetuximab in combination with capecitabine, weekly irinotecan, and radiotherapy as neoadjuvant therapy for rectal cancer

PURPOSE

To establish the feasibility and efficacy of chemotherapy with capecitabine, weekly irinotecan, cetuximab, and pelvic radiotherapy for patients with locally advanced rectal cancer.

METHODS AND MATERIALS

Twenty patients with rectal cancer (clinical Stage uT3-T4 or N+) received a standard dosing regimen of cetuximab (400 mg/m(2) on Day 1 and 250 mg/m(2) on Days 8, 15, 22, and 29) and escalating doses of irinotecan and capecitabine according to phase I methods: dose level I, irinotecan 40 mg/m(2) on Days 1, 8, 15, 22, and 29 and capecitabine 800 mg/m(2) on Days 1-38; dose level II, irinotecan 40 mg/m(2) and capecitabine 1000 mg/m(2); and dose level III, irinotecan 50 mg/m(2) and capecitabine 1000 mg/m(2). Radiotherapy was given to a dose of 50.4 Gy (45 Gy plus 5.4 Gy). Resection was scheduled 4-5 weeks after termination of chemoradiotherapy.

RESULTS

On dose level I, no dose-limiting toxicities occurred; however, Grade 3 diarrhea affected 1 of 6 patients on dose level II. Of 5 patients treated at dose level III, 2 exhibited dose-limiting toxicity (diarrhea in 2 and nausea/vomiting in 1). Therefore, dose level II was determined as the recommended dose for future studies. A total of 10 patients were treated on dose level II and received a mean relative dose intensity of 100% of cetuximab, 94% of irinotecan, and 95% of capecitabine. All patients underwent surgery. Five patients had a pathologically complete remission and six had microfoci of residual tumor only.

CONCLUSION

Preoperative chemoradiotherapy with cetuximab, capecitabine, and weekly irinotecan is feasible and well tolerated. The preliminary efficacy is very promising. Larger phase II trials are ongoing.

Comparing antibody and small-molecule therapies for cancer

The 'magic bullet' concept of specifically targeting cancer cells at the same time as sparing normal tissues is now proven, as several monoclonal antibodies and targeted small-molecule compounds have been approved for cancer treatment. Both antibodies and small-molecule compounds are therefore promising tools for target-protein-based cancer therapy. We discuss and compare the distinctive properties of these two therapeutic strategies so as to provide a better view for the development of new drugs and the future direction of cancer therapy.

Expression and genomic status of EGFR and ErbB-2 in alveolar and embryonal rhabdomyosarcoma

Both epidermal growth factor receptor (EGFR) and ErbB-2 play an important role in cancer biology and constitute promising molecular targets of therapy. EGFR and ErbB-2 expression has been observed in rhabdomyosarcoma cell lines but not analyzed systematically in rhabdomyosarcoma tumors. Tissue microarray sections representing 66 rhabdomyosarcoma tumors (34 embryonal rhabdomyosarcoma, 32 alveolar rhabdomyosarcoma) were surveyed by immunohistochemistry using antibodies specific for EGFR and ErbB-2. Immunostains were assessed for intensity (0: no immunostaining; 1: weak; 2: moderate; 3: strong) and percentage of at least 500 neoplastic cells exhibiting membranous or membranous and cytoplasmic immunostaining. EGFR and ErbB-2 expression was considered positive if the product of intensity and percentage was greater than 10. Patients had a median age of 5.7 years (range 8 months-19.1 years), and of 65/66 patients, 38 were males and 27 were females. Expression of ErbB-2 was identified in 22/66 (33%) cases and tended to be more frequent in the alveolar subtype (13/32, 41%, vs 9/34, 26%, P=0.30). Expression of EGFR was identified in 31/66 (47%) cases and correlated with the embryonal subtype (26/34, 76%, vs 5/32, 16%, P<0.0001) independent of stage, age, and gender. Coexpression of EGFR and ErbB-2 was identified in eight tumors, of which six were embryonal rhabdomyosarcoma. None of the cases exhibited EGFR or ErbB-2 gene amplification, as assessed using fluorescence in situ hybridization. Furthermore, analysis of 11 additional rhabdomyosarcoma tumors (six alveolar; five embryonal) revealed no evidence of mutations in EGFR exons 18, 19, 20, and 21. In summary, expression of EGFR and/or ErbB-2 is detected in a sizeable subset of rhabdomyosarcoma tumors without evidence of EGFR or ErbB-2 amplification or mutations in the EGFR tyrosine kinase domain. Notably, expression of EGFR correlates with the embryonal subtype, which is also more likely to coexpress EGFR and ErbB-2.

Metastatic colorectal cancer

Metastatic colorectal cancer remains a public-health issue on a global scale. With development of a new generation of cytotoxic agents, survival has improved for patients with metastatic disease. How to maximize the benefit of chemotherapy with acceptable toxicity remains incompletely answered. Hepatic resection can provide a significant hope for long term survival, and a subset of patients might benefit from perioperative approaches. More recently, specific molecular processes have been targeted for therapeutic interventions, and encouraging results have been achieved using inhibitors of the Epidermal Growth Factor Receptor and the Vascular Endothelial Growth Factor.

Matching patients with drugs: triumphs and challenges

The foundations of personalized medicine are built on the premise that laboratory tests can accurately predict the response of individual patients to a particular treatment. Herceptin® and the HercepTest®, which is used to select patients with human epidermal growth factor receptor (HER2)-positive breast cancer, are rightfully the jewels in the crown of this new treatment paradigm. Although over 8 years have past since their joint approval, there remain ongoing concerns about the quality of HER2 testing in community pathology laboratories. The development of predictive epidermal growth factor receptor (EGFR) tests for treatment with Tarceva®, Iressa® and Erbitux® has proven more difficult due to the complex biology of the target. It has also exposed some of the business challenges of co-developing both a drug and a companion diagnostic test. This article describes Genentech’s experience of developing predictive tests for HER2 and EGFR and highlights the need for close collaboration between all parties involved in incorporating predictive diagnostic tests into clinical trials and clinical practice.

A Phase I Study of Cetuximab/Paclitaxel in Patients with Advanced-Stage Breast Cancer

BACKGROUND

The epidermal growth factor receptor (EGFR) is part of the ErbB family of receptor tyrosine kinases and is known to be variably expressed in breast cancers. Cetuximab is a humanized monoclonal antibody directed against the EGFR that works by blocking the downstream signaling function of this protein and thereby interfering with cancer cell proliferation. Preclinical studies have indicated a synergistic effect for the combination of anti-EGFR therapy plus paclitaxel in breast cancer models.

PATIENTS AND METHODS

Hence, we conducted a dose-escalation phase I trial using cetuximab/paclitaxel in patients with metastatic breast cancer to evaluate the feasibility of this combination. Patients with EGFR-positive metastatic breast cancer treated with <or= 1 previous therapy, excluding taxanes, were eligible. Treatment consisted of weekly cetuximab therapy and every-3-week paclitaxel, with dose escalation of cetuximab until the maximum tolerated dose was reached.

RESULTS

Twelve patients were enrolled to 3 treatment cohorts. Two of 6 patients on the second cohort (cetuximab 100 mg/m2) developed dose-limiting toxicities, presenting as grade 3 rash. The third cohort was amended to allow the same cetuximab dose but to modify the paclitaxel to a weekly schedule. Despite this, 1 of 3 patients in this group also developed grade 3 skin toxicity as a dose-limiting toxicity; thus, the trial was stopped. Ten of the 12 patients were evaluable for response, and of these, 2 patients experienced stable disease, and 8 patients experienced disease progression.

CONCLUSION

Because of prohibitive dermatologic toxicity and disappointing preliminary efficacy, the combination of paclitaxel/cetuximab was not considered promising in this population, although further study of this regimen might be warranted.

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.

Targeting receptor tyrosine kinases and their signal transduction routes in head and neck cancer

Squamous cell carcinoma of the head and neck (SCCHN) is the sixth most common cancer in the world. At present several therapeutic approaches, including surgical removal, chemotherapy and radiotherapy, are used. Yet a significant number of patients relapse, often with metastases. In an attempt to improve treatment of SCCHN new targeted therapies are emerging. Among them special interest has been devoted to agents that act on the epidermal growth factor receptor (EGFR) and other receptor tyrosine kinases, or the signal transduction routes used by these receptors to induce tumour cell proliferation. Such treatments include monoclonal antibodies and small molecule inhibitors of either the intracellular tyrosine kinase activity of these receptors or relevant signalling intermediates. Here we review the biological bases of these new targeted treatments, with special emphasis on the clinical results that point to an implementation of these drugs into the therapeutic armamentarium against SCCHN.

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.

Protein therapeutics: new applications for pharmacogenetics

Pharmacogenetic studies have traditionally focused on genes involved in processes that affect the pharmacokinetics of small-molecule drugs, such as drug metabolism. However, attention is shifting to the effects of genetic variations in drug targets and associated pathway components on drug responses. We describe how these variations are important for understanding differences in responses to the growing number of protein therapeutics that are entering clinical practice. Pharmacogenetic studies of these drugs are surveyed, and issues important to the success of such endeavours are discussed. As novel protein therapeutics are introduced, we anticipate that the use of pharmacogenetics will assume a key role in their development and clinical application.

Gemcitabine in combination with EGF-Receptor antibody (Cetuximab) as a treatment of cholangiocarcinoma: a case report

Background

Extensive disease of cholangiocarcinoma (CC) determines the overall outcome and limits curative resection. Despite chemotherapy, which has been introduced to improve the outcome of biliary tract malignancies, the benefit in survival is still marginal.

Case presentation

We report a 69-year-old patient with non-resectable CC showing hepatic metastasis and peritoneal carcinomatosis. Diagnosis was based on computed tomography, mini-laparoscopy and bioptic specimens. Histology revealed an adenocarcinoma of the biliary tract with expression of epithelial growth factor receptor. After informed consent the patient received experimental gemcitabine (1000 mg/m²) every other week and cetuximab (250 mg/m²) weekly for palliative chemotherapy. During the reported follow up (since time of first presentation) 20 cycles of chemotherapy were administered. Relevant chemotherapy-related toxicity was limited on gemcitabine-associated side effects. Predominantly, haematological toxicity (CTC, grade 3) and neutropenic fever (CTC, grade 3) promoted by catheter-related sepsis were observed. Cetuximab caused only mild skin toxicity (CTC, grade 1).

Chemotherapy led to a partial response (> 30% reduction, according to RECIST) of the target lesions and disappearance of the peritoneal carcinomatosis as shown by computed tomography. Partial response occurred after 17 weeks of treatment and remained stable during the entire course of chemotherapy for 9.7 months. In parallel, Ca 19-9 serum levels, which were elevated 5-fold at time of diagnosis, returned to normal after 16 weeks of treatment. The performance status stabilized and intravenous alimentation could be discontinued.

Conclusion

Our experience from one patient with CC suggests, that a combination of cytotoxic chemotherapy together with cetuximab may show promising efficacy in respect to survival and quality of life. Therefore cetuximab, as a component of palliative chemotherapy in biliary tract cancer, needs further evaluation in prospective randomized trials.

Expression of epidermal growth factor receptor in squamous cell carcinomas of the anal canal is independent of gene amplification

Immunohistochemical detection of expression of the epidermal growth factor receptor (EGFR) has been utilized to identify eligible patients with solid malignant tumors, including colorectal adenocarcinoma, for monoclonal antibody therapy (eg, cetuximab). The EGFR status in squamous cell carcinoma of the anal canal, an uncommon malignancy traditionally treated with chemoradiation, has not been well investigated. In this study, 38 primary squamous cell carcinomas of the anal canal were immunohistochemically examined for EGFR expression and analyzed by fluorescence in situ hybridization (FISH) for EGFR gene copy numbers. The results showed a variable degree of EGFR expression in 21 (55%) tumors, among which 13 (62%) cases exhibited a 2+ to 3+ staining pattern according to the Dako EGFR phamDx interpretation guide. There were no significant differences among tumors stratified by stage, degree of keratinization, or tissue block storage times. FISH analysis showed that none of the 34 cases with interpretable results had EGFR gene amplification. Increased gene copy numbers due to polysomy 7 were seen in seven of 18 (39%) cases that expressed EGFR protein and four of 16 (25%) cases that did not (P=0.3876). Ten (56%) tumors with positive EGFR staining showed a balanced disomy 7 pattern and one case with monosomy 7 exhibited strong EGFR expression (3+). These results demonstrate that EGFR is overexpressed in more than one-half of the squamous cell carcinomas of the anal canal through mechanisms other than gene amplification. These observations may have important therapeutic implications since EGFR-based targeted therapies have shown promise for other malignant neoplasms.

Advances in chemotherapy for colorectal cancer

Gastroenterologists have a primary role in the management of colorectal cancer patients in that they frequently establish the diagnosis, direct or perform tumor staging evaluations, and initiate referrals for oncologic treatment. Several important advances have been made in the adjuvant treatment of colon and rectal cancers and in therapy of metastatic disease. These advances include the development of more effective combination chemotherapy regimens and molecularly targeted antibodies. These antibodies are directed against regulators of angiogenesis (vascular endothelial growth factor) and tumor cell growth (epidermal growth factor receptor) and have been shown to enhance the efficacy of cytotoxic chemotherapy. In the treatment of localized rectal cancer, the integration of chemotherapy and radiation with surgery has resulted in neoadjuvant approaches that achieve improved tumor control, sphincter preservation, and reduce treatment-related toxicities. This review presents an update of the current approach to colon and rectal cancer treatment, highlighting recent chemotherapeutic advances in the management of these highly prevalent malignancies.

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.

Cetuximab in advanced non-small cell lung cancer

Non-small cell lung cancer (NSCLC) remains a major problem in the western civilization and developing countries. Since most patients with NSCLC have advanced disease at diagnosis, to date, chemotherapy, with third-generation platinum-based doublets, represents the standard of care. Advances in the knowledge of tumour biology and mechanisms of oncogenesis has granted the singling out of several molecular targets for NSCLC treatment. Epidermal growth factor receptor (EGFR), a member of ErbB family, is one of the most studied target. Cetuximab is a chimeric (human-murine) monoclonal antibody directed against the extracellular domain of the EGFR that blocks ligand (TGF-alpha, EGF) access to the receptor. In the present paper we discuss about the activity, tolerability and efficacy of cetuximab, the EGFR monoclonal blocking antibody with the largest amount of clinical data being available on the treatment of advanced NSCLC.

First- and second-line therapy of metastatic colorectal cancer

In the USA, colorectal cancer is the fourth most prevalent cancer and is the second leading cause of cancer death after lung cancer. In 2006, 148,610 colorectal cancer cases are expected in the USA, with 55,170 deaths expected from this disease. After years of stagnation, the treatment of metastatic colorectal cancer has recently made dramatic advances. The previous standard of care, 5-fluorouracil, is the now the backbone of combination regimens with oxaliplatin or irinotecan. The addition of biological agents, such as the vascular endothelial growth factor inhibitor, bevacizumab, and the epidermal growth factor receptor inhibitors, cetuximab and panitumumab, have further enhanced the activity of conventional chemotherapy. These advances have increased the overall survival of advanced colorectal cancer patients, which was once 6 months with best supportive care, to over 2 years if all active agents are used in the course of the disease.