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

Clinical experience with anti-EGFR therapy

OBJECTIVES

To review clinical experience and studies with anti-EGFR therapies in metastatic CRC, SCCHN, and NSCLC. Case studies in each tumor type will also be outlined.

DATA SOURCES

Research articles and patient case histories.

CONCLUSION

Several phase II/III trials have shown the activity of anti-EGFR therapy in CRC, SCCHN, and NSCLC. Treatment confers substantial clinical benefit with improved symptoms, particularly in previously treated patients. Toxicity of anti-EGFR therapies is generally manageable and non-overlapping with other treatment options, including chemotherapy and radiotherapy.

IMPLICATIONS FOR NURSING PRACTICE

It is important for nurses to further advance our understanding of anti-EGFR therapies and continue to encourage patient enrollment in ongoing trials of anti-EGFR therapy.

Adjuvant therapy for stage II colorectal cancer: Who and with what?

The role of adjuvant chemotherapy for patients with stage II colon adenocarcinoma remains controversial. The high surgical cure rate for patients with "low-risk" stage II colon cancer, ranging from 75% to 80%, and the available clinical trials and meta-analyses provide conflicting recommendations for or against adjuvant chemotherapy for this group of patients. For fit "high-risk" stage II patients with clinical obstruction or perforation at presentation, in which the 5-year survival rate is 60% to 70%, there is little controversy, as these patients are routinely treated with adjuvant chemotherapy. Other potential high-risk factors, including high histologic grade, microsatellite instability, and loss of 18q, have yet to be validated in prospective trials. Patients with fewer than 12 regional lymph nodes identified in the surgical specimen have a statistically unclear risk of lymph node involvement. These patients may have stage III disease and should receive adjuvant therapy. The decision to use adjuvant chemotherapy to treat low-risk stage II colon cancer patients (no obstruction or perforation) should be an informed decision weighing the magnitude of a net 2% to 5% survival benefit, a 0.5% to 1.0% risk of mortality with chemotherapy in addition to 6 months of chemotherapy-related toxicities, other coexisting patient morbidities, and the anticipated life expectancy of each patient. As adjuvant chemotherapy is therapy addressing local or metastatic microscopic disease, and the effectiveness of systemic and biologically targeted therapy for advanced macroscopic colon cancer continues to improve rapidly, it remains to be determined by clinical trials whether therapies including newer agents such as cetuximab and bevacizumab administered in the adjuvant setting may affect survival for stage II cancer patients.

Prognostic significance of epidermal growth factor receptor expression in colon cancer patients undergoing curative surgery

BACKGROUND

To investigate the role of epidermal growth factor receptor (EGFR) expression as a prognostic marker for prediction of cancer behavior and clinical outcomes in colon cancer patients undergoing potentially curative surgery.

METHODS

EGFR determination using a commercially available immunohistochemistry kit was performed in tissues from 149 colon cancer patients receiving primary surgical treatment and in 25 normal colon mucosa specimens from noncancer patients. EGFR positivity was correlated in univariate and multivariate analyses with disease recurrence and survival. In addition, p27, p53, and vascular endothelial growth factor expression were assessed by immunohistochemistry in 104 patients and correlated with EGFR tumor expression and clinical outcome.

RESULTS

EGFR expression was detected in approximately one third of colon cancer patients (53 of 149; 35.6%). In 126 curatively treated patients, EGFR expression was correlated with disease recurrence and worse survival in both univariate and multivariate analyses. In a multivariate model for predicting recurrence and survival, Dukes' staging, p27, and EGFR expression were the only independent covariates. In particular, in Dukes' A and B patients the 5-year survival probability was 96% for EGFR-negative and high p27 expression cases and was 30.7% for EGFR-positive and low p27 expression cases.

CONCLUSIONS

EGFR expression was an independent prognostic indicator of disease recurrence and poor survival in colon cancer patients undergoing curative surgery. In the context of novel therapeutic options such as molecularly targeted therapies, these findings suggest that anti-EGFR drugs could be evaluated in the adjuvant treatment of EGFR-positive colon cancer patients.

Targeting growth factors and angiogenesis; using small molecules in malignancy

Targeted biologic therapy for cancer has evolved from the laboratory to active clinical protocols and applied clinical practice in selected patients. Major targets include epidermal growth factor, and vascular endothelial growth factor receptors which are commonly expressed in gastro-intestinal cancers head & neck and lung cancers, and to some degree breast and gynecologic malignancy. Down stream signal transduction pathway inhibition of B-raf and N-ras mutations are examined in melanoma. New approaches involving re-packaging of chemotherapeutic agents are being exemplified in the nanoparticle formulation of paclitaxel which provides increased access to endothelial and tumor cells with potential enhanced therapeutic efficacy compared to the conventional version solubilized in a cremophor.

Comparison of two antibodies for immunohistochemical evaluation of epidermal growth factor receptor expression in colorectal carcinomas, adenomas, and normal mucosa

BACKGROUND

Immunohistochemical staining for epidermal growth factor receptor (EGFR) has been used as a criterion for the selection of patients with colon cancer for anti-EGFR therapy. Two antibodies, the PharmDx kit and the 31G7 clone, are used commonly for immunohistochemistry by various laboratories. No comparative studies on the performance of these 2 antibodies are available.

METHODS

EGFR status was evaluated in 744 tissue microarray core samples from primary and metastatic colorectal carcinomas, colorectal adenomas, and normal colorectal mucosa with both the PharmDx kit and the clone 31G7 monoclonal antibodies. The stains were compared for staining intensity by using an automated image-analysis system. The intensity of positive staining (brown color) was measured on a scale from 0 to 255. The staining intensity also was scored manually as 0, 1 +, 2 +, and 3 +.

RESULTS

Statistically, the median staining intensities scored by the automated system between the 2 antibodies did not differ significantly, although, within each category of samples (normal, adenoma, carcinoma, and metastases), the PharmDx antibody staining was slightly more intense than the clone 31G7 antibody staining. There was a linear correlation between automated image-analysis and manual scoring categories. The median automated image-analysis intensity scores for the 4 manual scoring categories with the PharmDx kit were as follows: 0 staining, 67.5; 1 + staining, 75.5; 2 + staining, 89.6; and 3 + staining, 106.0. The median automated image-analysis intensity scores for the 4 manual scoring categories with the clone 31G7 antibody were as follows: 0 staining, 71.3; 1 + staining, 73.6; 2 + staining, 84.6; and 3 + staining, 99.1. The classification of tumors as EGFR-negative (0 staining) or positive (1 +, 2 +, or 3 + staining) was concordant in 151 of 160 carcinomas (94.4%) with 2 antibodies using manual scoring. Five samples (3%) that scored 1 + with the PharmDx kit antibody scored 0 with the clone 31G7 antibody; whereas 4 samples (2.5%) that scored 1 + with the clone 31G7 antibody scored 0 with the PharmDx kit antibody.

CONCLUSIONS

The EGFR expression results obtained by immunohistochemistry using both the EGFR PharmaDx kit and the 31G7 clone were comparable. Either antibody may be used for immunohistochemical detection of EGFR in colorectal carcinomas. In addition, manual scoring had an excellent correlation with automated scoring.

Phase II study of capecitabine, oxaliplatin, and erlotinib in previously treated patients with metastastic colorectal cancer

PURPOSE

To investigate the combination of erlotinib, capecitabine, and oxaliplatin in patients who were previously treated for metastatic colorectal cancer.

PATIENTS AND METHODS

Patients were eligible if they had metastatic colorectal cancer that progressed, were intolerant to first-line chemotherapy, or had disease recurrence within 1 year of adjuvant therapy for early-stage disease. Each 21-day cycle consisted of daily oral erlotinib at 150 mg, oral capecitabine at 1,000 mg/m2 (reduced to 750 mg/m2 after the first 13 patients) twice a day on days 1 to 14, and intravenous oxaliplatin at 130 mg/m2 on day 1.

RESULTS

Thirty-two patients were enrolled onto this phase II study. By intention-to-treat analyses, eight patients (25%) experienced a partial response and 14 patients (44%) had stable disease for at least 12 weeks. The median progression-free survival was 5.4 months and the median overall survival was 14.7 months. These results were essentially unchanged when limited to the cohort of patients (78%) who received prior irinotecan for metastatic colorectal cancer. Most common grade 3 to 4 toxicities included diarrhea (38%), nausea/emesis (19%), fatigue (16%), dehydration (16%), and dermatitis (13%); grade 3 or 4 toxicities were reduced with a lower starting dose of capecitabine.

CONCLUSION

The combination of capecitabine, oxaliplatin, and erlotinib seems to have promising activity against metastatic colorectal cancer in patients who received prior chemotherapy, with a relatively higher response rate and progression-free survival compared with previous reports of either infusional FU, leucovorin, and oxaliplatin or capecitabine and oxaliplatin in similar patient populations.

Interaction of the epidermal growth factor receptor and the DNA-dependent protein kinase pathway following gefitinib treatment

The epidermal growth factor receptor (EGFR) is an important target for cancer therapy. We previously showed that the EGFR inhibitor gefitinib modulated repair of DNA damage following exposure to cisplatin and etoposide involving the DNA-dependent protein kinase (DNA-PK) pathway. In this study, we specifically investigated the effect of EGFR inhibition by gefitinib on functional activity of DNA-PK in cancer cell lines and the interaction between EGFR and DNA-PK. The effects of DNA-PK inhibition by wortmannin and small interfering RNA to the catalytic subunit of DNA-PK (DNA-PK(CS)) on cell proliferation and DNA interstrand cross-link repair were investigated in the human MCF-7 breast cancer cell line and compared with the effects of gefitinib. DNA-PK activity was quantitated and expression measured by immunoblotting following gefitinib treatment. Immunoprecipitation experiments were done with and without gefitinib in MCF-7 cells, the AR42J pancreas cell line with high EGFR, and the human MDA-453 breast cancer cell line expressing low EGFR. Nuclear and cytoplasmic extracts were immunoblotted with antibody to DNA-PK(CS) to determine if gefitinib treatment altered cellular expression. Reduction of DNA-PK activity by wortmannin and expression by small interfering RNA to DNA-PK(CS) sensitized cells to cisplatin and inhibited repair of cisplatin-induced interstrand cross-links. Gefitinib treatment reduced DNA-PK activity in MCF-7 and AR42J but not MDA-453 cells. Immunoprecipitation experiments showed interaction between EGFR and DNA-PK(CS) in a dose-dependent and time-dependent manner following gefitinib treatment in MCF-7 and AR42J but not MDA-453 cells. Gefitinib treatment reduced nuclear expression and increased cytosolic expression of DNA-PK(CS) in MCF-7 and AR42J but not MDA-453 cells. Treatment with gefitinib modulates association of EGFR and DNA-PK(CS). This is correlated with decreased function of DNA-PK(CS). Inhibition of DNA-PK(CS) may be an important factor in sensitization to chemotherapy and radiation following treatment with inhibitors of the EGFR pathway.

From pathogen to medicine: HIV-1-derived lentiviral vectors as vehicles for dendritic cell based cancer immunotherapy

Over the years, the unique capacity of dendritic cells (DC) for efficient activation of naive T cells has led to their extensive use in cancer immunotherapy protocols. In order to be able to fulfil their role as antigen-presenting cells, the antigen of interest needs to be efficiently introduced and subsequently correctly processed and presented by the DC. For this purpose, a variety of both viral and non-viral antigen-delivery systems have been evaluated. Amongst those, HIV-1-derived lentiviral vectors have been used successfully to transduce DC. This review considers the use of HIV-1-derived lentiviral vectors to transduce human and murine DC for cancer immunotherapy. Lentivirally transduced DC have been shown to present antigenic peptides, prime transgene-specific T cells in vitro and elicit a protective cytotoxic T-lymphocyte (CTL) response in animal models. Different parameters determining the efficacy of transduction are considered. The influence of lentiviral transduction on the DC phenotype and function is described and the induction of immune responses by lentivirally transduced DC in vitro and in vivo is discussed in detail. In addition, direct in vivo administration of lentiviral vectors aiming at the induction of antigen-specific immunity is reviewed. This strategy might overcome the need for ex vivo generation and antigen loading of DC. Finally, future perspectives towards the use of lentiviral vectors in cancer immunotherapy are presented.

Efficacy of Cetuximab After Treatment with Oral Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor—Based Chemotherapy in Metastatic Colorectal Cancer

PURPOSE

We studied the efficacy of cetuximab therapy in patients with metastatic colorectal cancer (mCRC) previously treated with an oral inhibitor of the tyrosine kinase domain of the epidermal growth factor receptor.

PATIENTS AND METHODS

We reviewed the posttrial records of 73 patients with mCRC who participated in 1 of 3 clinical trials that examined a combination of gefitinib or erlotinib with standard cytotoxic chemotherapy. Medical and pharmacy records were used to identify patients who were subsequently treated with cetuximab-based therapy. Computed tomography scans during cetuximab-based therapy were reviewed, and the clinical activity of cetuximab was assessed by response rate using Response Evaluation Criteria in Solid Tumors and progression-free survival.

RESULTS

Twenty-four patients with mCRC previously treated with gefitinib or erlotinib and combination cytotoxic chemotherapy who subsequently received cetuximab-based therapy were identified. While receiving cetuximab-based therapy, no patient experienced a partial or complete response; however, 3 patients (16% of patients with available scans for formal measurements) had a minor response, defined as a 15%-29.9% decrease in the sum of longest dimensions of target lesions, and 72% had stable disease. The progression-free survival was 5.1 months for all patients and 6 months for patients who had documented progression of disease while previously receiving gefitinib- or erlotinib-based therapy.

CONCLUSION

Cetuximab appears to have clinical benefit in patients with mCRC previously treated with a chemotherapy regimen that included an oral tyrosine kinase inhibitor of epidermal growth factor receptor. Whether these results apply to other cancer types is unknown but worthy of further study.

Individualizing chemotherapeutic treatment of colorectal cancer

PURPOSE

Patient-specific factors that enter into decisions about the chemotherapy used to treat colorectal cancer are illustrated in several case studies.

SUMMARY

Genetic polymorphisms in genes that encode drug-metabolizing enzymes may affect the disposition and the risk for toxicity from chemotherapy agents used to treat colorectal cancer. Severe toxicity from 5-fluorouracil has been attributed to a deficiency in dihydropyrimidine dehydrogenase (DPD), but currently there is no widely used genetic test for DPD deficiency. An assay is available for genotypic testing of the enzyme UGT1A1, which is predictive of toxicity from irinotecan. Advanced age, prior pelvic or abdominal radiotherapy, a poor performance status, and increased pretreatment total bilirubin concentration also are associated with irinotecan-related toxicity. A reduction in irinotecan dosage or use of an alternative agent may be warranted in patients with risk factors for toxicity. Positive epidermal growth factor receptor (EGFR) expression by immunohistochemical (IHC) staining does not necessarily predict the response to cetuximab, a monoclonal antibody that binds EGFR, possibly because of the low sensitivity of the test. Carcinoembryonic antigen (CEA) is the tumor marker of choice for monitoring for progression of colorectal cancer.

CONCLUSION

Individualizing chemotherapy based on disease stage, pharmacogenetics, prior therapy, patient age, performance status, and CEA level may help to optimize outcomes from chemotherapy for patients with colorectal cancer.

ADVANCES IN THE ADJUVANT TREATMENT OF COLORECTAL CANCER

BACKGROUND

There have been numerous advances in the adjuvant therapy of colon cancer in the last two decades.

METHODS

This review outlines the historical perspectives of adjuvant treatment as well as current and emerging standards of care.

RESULTS

Although previous regimens included a variety of equivalent schedules of 5-fluorouracil and folinic acid, integration of newer drugs such as oxaliplatin are offering significant improvements in disease-free survival. The use of targeted agents such as bevacuzimab creates the potential to further increase cure rates in the adjuvant setting. The current low rate of referral of eligible patients for chemotherapy in Australia is also discussed.

CONCLUSION

Adjuvant therapy for colon cancer is making major strides as we attempt to cure more patients.

Cetuximab and irinotecan as third-line therapy in advanced colorectal cancer patients: a single centre phase II trial

The epidermal growth factor receptor (EGFR), which participates in signalling pathways that are deregulated in cancer cells, is frequently mutated in colorectal-cancer cells. Cetuximab is a monoclonal antibody that specifically blocks the EGFR. We evaluated the efficacy of cetuximab in weekly combination with irinotecan in metastatic colorectal cancer patients refractory to previous treatments based on oxaliplatin or irinotecan. We included 55 heavily pretreated patients (colon/rectum: 34/11, M/F: 16/29, median age 63 years, range: 27–79) whose disease had progressed during or within an oxaliplatin-based first-line chemotherapy and a irinotecan-based second-line regimen. Patients were followed for tumour response and were also evaluated for the time to tumour progression, and safety of treatment. Cetuximab was given at an initial dose of 400 mg m⁻², followed by weekly infusions of 250 mg m⁻². Irinotecan was administered weekly at the dose of 90 mg m⁻². All patients were assessable for treatment efficacy and safety response rate was 25.4% (95% CI: 21.7–39.6%); 38.2% (95 CI: 18.6–39.8%) of patients showed a disease stability as the best response. As a consequence, the overall tumour control rate was 63.6% (95% CI: 46.4–70.6%). The median time to progression was 4.7 months (95% CI: 2.5–7.1 months) and the median survival time was 9.8 months (95% CI: 3.9–10.1 months). The most common G3-4 noncutaneous side toxicities were: diarrhoea (16.4%), fatigue (12.7%) and stomatitis (7.3%). 89.1% of patients developed skin toxicity and 32.6% of cases was of grade 3–4. No allergic reactions were identified at any courses in any patients. Fever was documented in 27.3% of patients and was most commonly recorded after the first administration. Cetuximab has clinically significant activity even in heavily pretreated colorectal cancer patients progressed after both oxaliplatin and irinotecan-based chemotherapy regimens.

Synergy between an IGF-1R antibody and Raf/MEK/ERK and PI3K/Akt/mTOR pathway inhibitors in suppressing IGF-1R-mediated growth in hematopoietic cells

The Insulin-like growth factor-1 receptor (IGF-1R) is overexpressed in a variety of tumors including breast, prostate and myeloma. Thus, IGF-1R and its downstream signaling effectors are good candidates for molecular-based targeted antitumor therapies. Indeed, protein inhibitors of IGF-1R signaling and IGF-1R blocking antibodies are undergoing clinical trials. Herein, the molecular basis for antibody-mediated IGF-1R signal inhibition has been investigated in a hematopoietic cell line model, FDC-P1, that has been rendered interleukin-3 independent in a ligand-dependent manner through retroviral-mediated expression of IGF-1R (FD/IGF-1R). Furthermore, the ability of an anti-IGF-1R antibody to synergize with signal-transduction pathway inhibitors and induce apoptosis was determined. The alphaIGF-1R antibody, A12, was capable of arresting IGF-1 or insulin-induced FD/IGF-1R cell proliferation in the G1 phase of the cell cycle and resulted in apoptotic induction. A12 effectiveness could be potentiated through combination treatment with small molecule inhibitors of the Ras/Raf/MEK/ERK or PI3K/Akt/mTOR pathways. These results validate the use of the FD/IGF-1R cells to evaluate the effectiveness and mechanisms of targeted IGF-1R therapeutic strategies.

Multicenter phase II study of gemcitabine and oxaliplatin (GEMOX) as second-line chemotherapy in colorectal cancer patients pretreated with 5-fluorouracil plus irinotecan

PURPOSE

To evaluate the efficacy and tolerance of the gemcitabine/oxaliplatin (GEMOX) combination as second-line chemotherapy for patients with advanced colorectal cancer (CRC) pretreated with an irinotecan (CPT-11)/5-fluorouracil (5-FU)/leucovorin (LV) regimen.

PATIENTS AND METHODS

Patients with documented disease progression during or after first-line treatment with CPT-11 and 5-FU/LV were enrolled. Gemcitabine (1,000 mg/m(2) days 1 and 8) and oxaliplatin (100 mg/m(2) day 1) were administered every 3 weeks.

RESULTS

Partial responses were observed in 6 of the 34 (17.7%) patients enrolled (intention-to-treat analysis; overall response rate: 17.7%; 95% confidence interval 4.8-30.5%). Eight (23.5%) patients experienced disease stabilization and 20 (59%) disease progression (tumor growth control rate = 41.2%). The median duration of response was 5.5 months, and the median time to tumor progression 2.7 months. The median overall survival was 9.1 months (1-year survival rate: 44.0%). Grade 3 neutropenia and thrombocytopenia occurred in 18 and 15% of the patients, respectively. Other severe non-hematologic toxicities were rare.

CONCLUSION

The interesting tumor growth control rate and the favorable toxicity profile of the GEMOX regimen in pretreated patients with advanced CRC strongly suggest that this regimen may provide an alternative therapeutic option for this group of patients.

KRAS Mutation Status Is Predictive of Response to Cetuximab Therapy in Colorectal Cancer

The anti-epidermal growth factor receptor (anti-EGFR) cetuximab has been proven to be efficient in metastatic colorectal cancer. The molecular mechanisms underlying the clinical response to this drug remain unknown. Genetic alterations of the intracellular effectors involved in EGFR-related signaling pathways may have an effect on response to this targeted therapy. In this study, tumors from 30 metastatic colorectal cancer patients treated by cetuximab were screened for KRAS, BRAF, and PIK3CA mutation by direct sequencing and for EGFR copy number by chromogenic in situ hybridization. Eleven of the 30 patients (37%) responded to cetuximab. A KRAS mutation was found in 13 tumors (43%) and was significantly associated with the absence of response to cetuximab (KRAS mutation in 0% of the 11 responder patients versus 68.4% of the 19 nonresponder patients; P = 0.0003). The overall survival of patients without KRAS mutation in their tumor was significantly higher compared with those patients with a mutated tumor (P = 0.016; median, 16.3 versus 6.9 months). An increased EGFR copy number was found in 3 patients (10%) and was significantly associated with an objective tumor response to cetuximab (P = 0.04). In conclusion, in this study, KRAS mutations are a predictor of resistance to cetuximab therapy and are associated with a worse prognosis. The EGFR amplification, which is not as frequent as initially reported, is also associated with response to this treatment.

Beyond 5-fluorouracil: new horizons in systemic therapy for advanced colorectal cancer

Worldwide, colorectal cancer is a common cancer and a major cause of morbidity and mortality. Patients frequently present with, or later develop, metastatic disease. Median survival with supportive care alone is approximately 6 - 8 months. However, a number of recent developments have greatly increased the range of therapeutic options, improving median survival to > 20 months. Cytotoxic agents such as capecitabine, irinotecan and oxaliplatin are now established treatment strategies. In parallel, an improved understanding of tumour biology has led to the development of non-cytotoxic targeted therapies. Examples include bevacizumab (targeting tumour angiogenesis) and cetuximab (targeting the epidermal growth factor receptor). These agents have recently been incorporated into standard management. This paper reviews these and other advances in the care of patients with advanced colorectal cancer and discusses a number of agents that are currently under development.

Surgical treatment of liver metastases of colorectal cancer: Strategies and controversies in 2006

AIMS

To review the latest strategies and controversies in the surgical treatment of liver metastases of colorectal cancer systemically and comprehensively.

METHODS

A medline based literature search on relevant topics was performed in PubMed for key articles concerning the novel strategies and controversies in the management of liver metastases of colorectal cancer. Some information was obtained from 'Proc Am Soc Clin Oncol' published recently. The findings and discussions were related to our own experiences.

RESULTS

Although for well-indicated patients, a consensus has been reached that hepatic resection is the only management that could provide the patients curability, there still exist many controversies, such as the prognostic evaluation, contraindications to hepatic resection, treatment for synchronous liver metastases, the place of laparoscopic surgery, etc. Meanwhile, various strategies to improve the respectabilities are available, including neoadjuvant chemotherapy, portal vein embolization, two stage hepatectomy, and some locally ablative approaches. The current condition is difficult and sometimes confusing for a relevant surgeon when designing treatment protocols for more complex diseases.

CONCLUSION

As the advancing of the management of liver metastases of colorectal cancer, more patients will become candidates for and benefit from potentially curative surgical resections. Optimal effect could only be achieved when used in a manner tailored to the individual patient.

Targeted therapies for esophageal cancer

Esophageal cancer is a highly aggressive neoplasm. In 2005, 14,520 Americans will be diagnosed with esophageal cancer, and more than 90% will die of their disease. On a global basis, cancer of the esophagus is the sixth leading cause of cancer death worldwide. In fact, gastric and esophageal cancers together accounted for nearly 1.3 million new cases and 980,000 deaths worldwide in 2000-more than lung, breast, or colorectal cancer. Although esophageal squamous cell carcinoma cases have steadily declined, the incidence of gastroesophageal junction adenocarcinoma has increased 4%-10% per year among U.S. men since 1976, more rapidly than for any other cancer type, and parallels rises in population trends in obesity and reflux disease. With advances in surgical techniques and treatment, the prognosis of esophageal cancer has slowly improved over the past three decades. However, the 5-year overall survival rate (14%) remains poor, even in comparison with the dismal survival rates (4%) from the 1970s. The underlying reasons for this disappointingly low survival rate are multifold: (a) ineffective screening tools and guidelines; (b) cancer detection at an advanced stage, with over 50% of patients with unresectable disease or distant metastasis at presentation; (c) high risk for recurrent disease after esophagectomy or definitive chemoradiotherapy; (d) unreliable noninvasive tools to measure complete response to chemoradiotherapy; and (e) limited survival achieved with palliative chemotherapy alone for patients with metastatic or unresectable disease. Clearly, additional strategies are needed to detect esophageal cancer earlier and to improve our systemic treatment options. Over the past decade, the field of drug development has been transformed with the identification of and ability to direct treatment at specific molecular targets. This review focuses on novel targeted treatments in development for esophageal squamous cell carcinoma and distal esophageal and gastroesophageal junction adenocarcinoma.

EGFR in colorectal cancer: more than a simple receptor

BACKGROUND

Advances in the understanding of tumor biology have led to the development of targeted therapies allowing progress in colorectal cancer treatment. One of the most promising targets is the epidermal growth factor receptor (EGFR).

METHOD

The presence and distribution of high- and low-affinity EGFR was investigated retrospectively in a group of 82 colorectal cancer samples (43 normal colon-colon cancer paired samples) using a specific ligand binding assay (Scatchard Analysis).

FINDINGS

A large majority of tumor samples exhibited one class of high-affinity binding sites (78%). Eighteen cases (22%) exhibited both high- and low-affinity binding sites. A wide interpatient variability was observed for the site number, with physiologically-relevant high-affinity sites ranging from 7 to 310 fmol/mg protein in tumors and from 6 to 313 fmol/mg protein in normal mucosa. A significant positive correlation was demonstrated between tumor and normal mucosa for the high-affinity Kd values and for the number of high-affinity sites, suggesting a common regulation for both tumor and normal tissue.

INTERPRETATION

These observations (i) could explain recently-reported clinically-active EGFR targeting in colorectal tumors apparently negative for EGFR, and (ii) may offer a plausible explanation for the link observed between toxicity in normal tissue (cutaneous rash) and clinical outcome of patients treated with anti-EGFR drugs. Present data extends our understanding of EGFR identity in colorectal cancer which could be useful in reconsidering the predictive tools for the identification of tumors putatively responsive to EGFR targeted therapy.

Epidermal Growth Factor Receptor (EGFR) Inhibitors in Gastrointestinal Cancer

Gastrointestinal (GI) cancer continues to be a leading cause of cancer morbidity and mortality worldwide. Over the past decade the treatment options for patients with GI cancers have increased with the advent of newer combination chemotherapy regimes. Despite these clinical advances, new strategies are warranted in order to improve the efficacy as well as the safety. New molecular targets have provided novel opportunities in the treatment of GI cancer. One of the most advanced new approaches to date is the use of targeted inhibitors of the epidermal growth factor receptor (EGFR). In this review we describe the current status of therapeutic strategies based on EGFR inhibitors in the treatment of GI cancer.

Simultaneous targeting of the epidermal growth factor receptor and cyclooxygenase-2 pathways for pancreatic cancer therapy

The aims of this study were to determine the effects of (a) combining the epidermal growth factor receptor (EGFR) blocker (erlotinib) and the cyclooxygenase-2 inhibitor (celecoxib) on cell growth and apoptosis in human pancreatic cancer cell lines, (b) baseline EGFR expression on the potentiation of erlotinib-induced apoptosis by celecoxib, and (c) the effects of the combination on the expression of the COX-2, EGFR, HER-2/neu, and nuclear factor-kappaB (NF-kappaB). Baseline expression of EGFR was determined by Western blot analysis in five human pancreatic cancer cell lines. BxPC-3, PANC-1, and HPAC had high EGFR and MIAPaCa had low EGFR. Cells were grown in culture and treated with erlotinib (1 and 10 micromol/L), celecoxib (1 and 10 micromol/L), and the combination. Growth inhibition was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was assayed by ELISA. Reverse transcriptase-PCR was used to evaluate COX-2 and EGFR mRNA. EGFR, COX-2, and HER-2/neu expression was determined by Western immunoblotting. Electrophoretic mobility shift assay was used to evaluate NF-kappaB activation. Growth inhibition and apoptosis were significantly (P < 0.05) higher in BxPC-3, HPAC, and PANC-1 cells treated with celecoxib and erlotinib than cells treated with either celecoxib or erlotinib. However, no potentiation in growth inhibition or apoptosis was observed in the MIAPaCa cell line with low expression of the EGFR. Significant down-regulation of COX-2 and EGFR expression was observed in the BxPC-3 and HPAC cells treated with the combination of erlotinib (1 micromol/L) and celecoxib (10 micromol/L) compared with celecoxib- or erlotinib-treated cells. Celecoxib significantly down-regulated HER-2/neu expression in BxPC-3 and HPAC cell lines. Significant inhibition of NF-kappaB activation was observed in BxPC-3 and HPAC cell lines treated with erlotinib and celecoxib. (a) Celecoxib can potentiate erlotinib-induced growth inhibition and apoptosis in pancreatic cell lines, (b) high baseline EGFR expression is a predictor of this potentiation, and (c) the down-regulation of EGFR, COX-2, and HER-2/neu expression and NF-kappaB inactivation contributes to the potentiation of erlotinib by celecoxib.

Cetuximab and irinotecan/5-fluorouracil/folinic acid is a safe combination for the first-line treatment of patients with epidermal growth factor receptor expressing metastatic colorectal carcinoma

BACKGROUND

To investigate the safety/tolerability of the EGFR-antibody cetuximab when added to irinotecan/5-fluorouracil (5-FU)/folinic acid (FA) for first-line treatment in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Twenty-one patients with untreated, metastatic, EGFR-expressing CRC received cetuximab 400 mg/m(2) as an initial dose, and thereafter 250 mg/m(2) weekly. In addition, patients received infusional 5-FU (24 h) in two dose levels (1500 mg/m(2), low 5-FU group, n = 6 or 2000 mg/m(2), high 5-FU group, n = 15), plus FA at 500 mg/m(2) and irinotecan at 80 mg/m(2), weekly x6 q50d.

RESULTS

Twenty patients were assessable for tolerability after the first cycle. There were no dose limiting toxicities (DLTs) in the low 5-FU group and three DLTs (20%) in the high 5-FU group (two patients with diarrhea grade 3 and one patient with diarrhea grade 4). In the low 5-FU group all six patients received >80% of the planned dose. In the high 5-FU group, seven of 14 patients (50%) received < or =80% of the planned chemotherapy dose during the first cycle due to dosage reductions whilst treatment delays occurred in 10/14 patients. During the whole study period, the common grade 3/4 adverse events were acne-like rash (38%) and diarrhea (29%). Chemotherapy did not affect the pharmacokinetics of cetuximab determined at weeks 1 and 4. Fourteen patients (67%, 95% CI 47% to 87%) had a confirmed response, and six (29%) had stable disease. Median time to progression was 9.9 months [lower 95% confidence limit (CL) 7.9, upper 95% CL not reached]. Median survival time was 33 months (lower CL 20, upper CL not reached). Four patients received secondary surgery with curative intent, and a fifth was potentially eligible for surgery but declined.

CONCLUSIONS

Addition of cetuximab to weekly infusional 5-FU/FA plus irinotecan is safe and first data suggest a promising activity. The 5-FU dose of 1500 mg/m(2) is recommended for further studies.

Efficacy and safety of cetuximab/irinotecan in chemotherapy-refractory metastatic colorectal adenocarcinomas: a clinical practice setting, multicenter experience

BACKGROUND

This study was designed to evaluate the efficacy and safety of irinotecan/cetuximab administered as third- or fourth-line therapy in a retrospective series of patients with metastatic colorectal cancer refractory to oxaliplatin and irinotecan.

PATIENTS AND METHODS

Most patients (90%) had been previously treated with adjuvant 5-fluorouracil/leucovorin, and all had received oxaliplatin-based regimens before receiving irinotecan-based second-line treatment. Sixty patients with irinotecan-refractory colorectal cancer received a regimen comprising weekly irinotecan 120 mg/m2 as a 1-hour intravenous infusion and cetuximab 400 mg/m2 infused over 2 hours as the initial dose and 250 mg/m2 infused over 1 hour for the subsequent administrations. A single treatment cycle comprised 4 weekly infusions followed by 2 weeks of rest.

RESULTS

According to an intent-to-treat analysis, a partial response was exhibited in 12 of 60 enrolled patients (20%; 95% confidence interval, 11%-32%) with a median duration of 5.1 months (range, 3-7.4 months). The tumor growth control rate was 50% (95% confidence interval, 37%-63%). Objective responses did not correlate with performance status, number of sites of disease, and pretreatments or epidermal growth factor receptor status. The median progression-free survival was 3.1 months (range, 1.2-9 months), whereas median overall survival was 6 months (range, 2-13 months). Both survival parameters correlated with performance status at the beginning of treatment. The main grade 3/4 toxicities were nausea (33%), diarrhea (27%), leukopenia (18%), asthenia (13%), and acne-like reaction (13%).

CONCLUSION

Our data suggest that the weekly irinotecan/cetuximab regimen is feasible in an outpatient setting and tolerated by most patients. At present, combinations of chemotherapy with cetuximab are being evaluated in patients with earlier-stage disease in a number of ongoing studies.

Prognostic Value of an Activation State Marker for Epidermal Growth Factor Receptor in Tissue Microarrays of Head and Neck Cancer

Overexpression and mutation of epidermal growth factor receptors (EGFR) have been shown to be important in the prognosis of several cancers, including head and neck cancers. However, our inability to define the activation status of these and other receptors limits our ability to assess the importance of these pathways and to exploit effectively new molecularly targeted treatments directed at their catalytic activities. Here we describe the use of automated, high-throughput fluorescence lifetime imaging microscopy to measure EGFR autophosphorylation status by fluorescence resonance energy transfer (FRET) in head and neck tumors. We have correlated FRET efficiency with the clinical and survival data. The results from head and neck arrays show that high FRET efficiency is correlated with worsening disease-free survival but not with overall survival. This powerful tool could be exploited as a new independent quantitative prognostic factor in clinical decisions and cancer management.

Cetuximab and irinotecan interact synergistically to inhibit the growth of orthotopic anaplastic thyroid carcinoma xenografts in nude mice

PURPOSE

Anaplastic thyroid carcinoma (ATC) remains one of the most lethal known human cancers. Targeted molecular therapy with cetuximab, a monoclonal antibody against epidermal growth factor receptor, offers new treatment potentials for patient with ATC. Cetuximab has also been reported to have synergistic effects when combined with irinotecan, a topoisomerase inhibitor. Therefore, we hypothesized that cetuximab and irinotecan would be effective in inhibiting the growth and progression of ATC in a murine orthotopic model.

EXPERIMENTAL DESIGN

The in vitro antiproliferative effects of cetuximab and irinotecan on ATC cell line ARO were examined. We also studied the in vivo effects of cetuximab and irinotecan on the growth, invasion, and metastasis of orthotopic ATC tumors in nude mice. The in vivo antitumor efficacy of cetuximab/irinotecan combination was also compared with that of doxorubicin.

RESULTS

Cetuximab alone did not show any antiproliferative or proapoptotic effect on this cell line. However, when combined with irinotecan, cetuximab potentiated the in vitro antiproliferative and proapoptotic effect of irinotecan. Cetuximab, irinotecan, and cetuximab/irinotecan combination resulted in 77%, 79%, and 93% in vivo inhibition of tumor growth, respectively. Incidences of lymph node metastasis, laryngeal invasion, and tumor microvessel density were also significantly decreased in these treatment groups. Furthermore, the cetuximab/irinotecan combination was significantly more effective than doxorubicin in inhibiting the growth of orthotopic ATC xenografts.

CONCLUSIONS

Combination therapy with cetuximab/irinotecan inhibits the growth and progression of orthotopic ATC xenografts in nude mice. Given the lack of curative options for patients with ATC, combination therapy with cetuximab and irinotecan treatment warrants further study.

Gefitinib in patients with chemo-sensitive and chemo-refractory relapsed small cell cancers: a Hoosier Oncology Group phase II trial

BACKGROUND

Gefitinib has demonstrated activity in patients with non-small cell lung cancer (NSCLC). Clinical trials have not demonstrated a relationship between response to gefitinib and over-expression of the epidermal growth factor receptor (EGFR). Although, EGFR is not over-expressed in small cell lung cancer (SCLC), we postulated that gefitinib might affect tumor growth through other mechanisms. Agents that are active in NSCLC usually are also effective in SCLC.

METHODS

The primary objective was to assess the clinical control rate: complete response (CR) partial response (PR) and stable disease (SD > 90 days), of gefitinib in patients with chemo-resistant and chemo-sensitive small cell cancers. Eligibility criteria included pathologic proof of a neuroendocrine tumor, especially small cell cancer, Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2, prior treatment with one or two prior chemotherapy regimens and adequate end-organ function. Patients received gefitinib, 250 mg p.o. daily until disease progression or intolerable side effects.

RESULTS

From April 2003 to March 2004, 19 patients were enrolled. Small cell lung cancer accounted for 18 of the 19 patients and one patient had metastatic Merkel cell carcinoma. Twelve patients (63%) had chemo-sensitive disease, defined as progression greater than three months from completion of prior chemotherapy; 7 (37%) had chemo-refractory disease; 13 (68%) had one prior chemotherapy regimen. Other patient characteristics: mean age 64 years (range 52-79 years); ECOG PS 0/1/2 = 7/9/3, M:F = 9:10. Grade 3 toxicities included: fatigue in three patients (15.8%), pulmonary toxicities in three (15.8%) and one patient (5.3%) each with hyperglycemia or pain. Four patients had grade four toxicities: one patient (5.3%) with fatigue and three patients (15.8%) with dyspnea. There were no patients with grade 3 or 4 rash or diarrhea. Two patients had stable disease (<90 days) and 17 had progressive disease as their best response. This study was a two-stage design and because the continuing criterion for stage one was not met, stage 2 was not performed. Median time to progression (TTP) was 50 days (95% CI = 21-58 days). One year overall survival (OS) was 21% (95% CI = 6-45.6%).

CONCLUSION

Although gefitinib has activity in select patients with NSCLC, this study failed to demonstrate benefit in patients with small cell lung cancer.

Tumor Endothelial Cells Express Epidermal Growth Factor Receptor (EGFR) but not ErbB3 and Are Responsive to EGF and to EGFR Kinase Inhibitors

Epidermal growth factor (EGF) receptor family members are expressed by tumor cells and contribute to tumor progression. The expression and activity of EGF receptors in endothelial cells are less well characterized. Analysis of tumor-derived endothelial cells showed that they express EGFR, ErbB2, and ErbB4, whereas their normal counterparts express ErbB2, ErbB3, and ErbB4. The gain in expression of EGFR and the loss of ErbB3 expression in tumor vasculature was also observed in vivo. As a consequence of their expressing EGFR, tumor endothelial cells responded to EGF and other EGF family members by activating both EGFR and ErbB2, by activating the downstream mitogen-activated protein kinase pathway, and by enhanced proliferation. On the other hand, normal endothelial cells did not respond to EGF but instead were responsive to neuregulin (NRG), a ligand for ErbB3 and ErbB4. NRG activated ErbB3 in normal endothelial cells and inhibited growth of these cells. In contrast, tumor endothelial cells, which do not express ErbB3, were not growth inhibited by NRG. Furthermore, due to their expression of EGFR, tumor endothelial cells, unlike normal endothelial cells, are direct targets for EGFR kinase inhibitors. These low-molecular-weight compounds block EGF-induced EGFR activation and proliferation of tumor endothelial cells. These results suggest that a gain of EGF-induced endothelial cell proliferation, and loss of NRG-induced growth inhibition in tumor endothelial cells constitutes a switch that promotes tumor angiogenesis. In addition, these results suggest that EGFR kinase inhibitors may be effective for antiangiogenesis therapy by specifically targeting the tumor, but not the normal, vasculature.

Anti-CD3 x anti-epidermal growth factor receptor (EGFR) bispecific antibody redirects T-cell cytolytic activity to EGFR-positive cancers in vitro and in an animal model

PURPOSE

Targeting epidermal growth factor receptor (EGFR) overexpressed by many epithelial-derived cancer cells with anti-EGFR monoclonal antibodies (mAb) inhibits their growth. A limited number of clinical responses in patients treated with the anti-EGFR mAb, (cetuximab), may reflect variability in EGFR type or signaling in neoplastic cells. This study combines EGFR-targeting with the non-MHC-restricted cytotoxicity of anti-CD3 activated T cells (ATC) to enhance receptor-directed cytotoxicity.

EXPERIMENTAL DESIGN

ATC from normal and patient donors were expanded ex vivo. Specific cytolytic activity of ATC armed with anti-CD3 x anti-EGFR (EGFRBi) against EGFR-expressing cancer cells derived from lung, pancreas, colon, prostate, brain, skin, or EGFR-negative breast cancer cells was evaluated in (51)Cr release assays. In vivo studies comparing tumor growth delay induced by EGFRBi-armed ATCs or cetuximab were done in severe combined immunodeficient/Beige mice (SCID-Beige) bearing COLO 356/FG pancreatic and LS174T colorectal tumors.

RESULTS

At effector/target ratios from 3.125 to 50, both EGFRBi-armed normal and patient ATC were significantly more cytotoxic, by 23% to 79%, against EGFR-positive cells over ATC, cetuximab, anti-CD3 alone, or ATC armed with irrelevant BiAb directed at CD20. EGFRBi-armed ATC also secreted significantly higher levels of some T(H1)/T(H2) cytokines compared with ATC alone. In mice, i.v. infusions of EGFRBi-armed ATC (0.001 mg equivalent/infusion) were equally effective as cetuximab (1 mg/infusion) alone for significantly delaying growth of established COLO 356/FG but not LS174T tumors compared with mice that received ATC alone or vehicle (P < 0.001).

CONCLUSIONS

Combining EGFR antibody targeting with T cell-mediated cytotoxicity may overcome some limitations associated with EGFR-targeting when using cetuximab alone.

Cetuximab preclinical antitumor activity (monotherapy and combination based) is not predicted by relative total or activated epidermal growth factor receptor tumor expression levels

Although Erbitux (cetuximab) has proven therapeutic benefit in the clinical setting, the molecular determinants predicting responsiveness to this agent are still not very well understood. Here, we assessed the relationship between basal total and activated (pY1068) epidermal growth factor receptor (EGFR) levels in a tumor and the responsiveness to cetuximab monotherapy or combination-based treatment using human xenograft models. Cetuximab treatment alone (0.25-1 mg/mouse/injection, q3d, i.p.) effectively delayed the growth of GEO and L2987 tumors by a minimum of 10 days corresponding to log cell kill values of >or=1.0. Borderline activity was seen in the A549 and WiDr xenografts. However, cetuximab failed to show any significant antitumor activity in the HT29, HCT116, LOVO, Colo205, LX-1, HCC70, and N87 models. All of the studied tumors had detectable yet variable levels of EGFR. For combination regimens, cetuximab (1 mg/mouse/injection, q3dx5, i.p.) and cisplatin (4.5 mg/kg/injection, q3dx5, i.v.) proved to be significantly more efficacious than individual monotherapies in the cisplatin-refractory yet cetuximab-responsive GEO tumor model (P < 0.001). However, no therapeutic enhancement was observed in the cisplatin and cetuximab weakly responsive A549 xenograft. Similarly, combinations of CPT-11 (48 mg/kg/injection, q3dx5, i.v.) with cetuximab (1 mg/mouse/injection, q3dx5, i.p.) failed to show any improvements over individual monotherapies in the cetuximab resistant/weakly responsive HT29, A549, and WiDr models. We conclude that preclinical activity associated with cetuximab monotherapy does not correlate directly with relative basal levels of total or activated (pY1068) EGFR in a tumor. Moreover, robust single-agent activity by cetuximab may be the best predictor for this agent to potentiate chemotherapy-mediated antitumor activities.

Epidermal growth factor receptor-negative colorectal cancer: is there truly such an entity?

The epidermal growth factor receptor (EGFR) has been identified as a targer for anticancer therapies. Cetuximab is a chimeric murin-human monoclonal antibody that targets the extracellular domain of the EGFR. Based on the (un proven) assumption that the presence of this receptor would quantitatively correlate with activity of cetuximab, early clinical trials with cetuximab required demonstration of the receptor by immunohistochemical (IHC) techniques. However, assumptions were made regarding the stability of EGFR expression and the reproducibility of this IHC expression that , in retrospect, were almost certainly unrealistic and are incorrect. Current techniques lack the sensitivity and predictability to inform decisions as to the usefulness of cetuximab or other anti-EGFR therapies in the treatment of colorectal or other cancers. As such, the IHC staining for EGFR that is currently in use lacks any meaningful clinical predictive value and has no use in the management of patients with cancer. Current data do not support the use of the EGFR IHC stain for making any clinical decisions regarding patient management. No patient should be refused treatment with an EGFR-targeting agent solely on the basis of a negative EGFR IHC test and no patient should be given anti-EGFR therapy simply on the basis of a positive or strongly positive EGFR test result.

Recent data with anti-epidermal growth factor receptor antibodies and irinotecan in colon cancer

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of colorectal cancers. It is the target for a class of agents at the forefront of development for the treatment of colorectal cancer, ie, the anti-EGFR monoclonal antibodies, which include cetuximab, panitumumab, and matuzumab. At present, cetuximab is the furthest along in terms of established efficacy in the treatment of metastatic or inoperable disease and is licensed for the treatment of patients with irinotecan-refractory colorectal cancer. This article reviews the recent evidence supporting the combination of these anti-EGFR agents with the cytotoxic chemotherapeutic agent irinotecan.

Overview of monoclonal antibodies and small molecules targeting the epidermal growth factor receptor pathway in colorectal cancer

The epidermal growth factor receptor (EGFR) provides survival signals and is overexpressed in the majority of colorectal cancers. As more is learned about the molecular details of EGFR signaling, antibodies can be designed to interfere with specific domains of the EGFR molecule. In this review, we analyze preclinical and current clinical data on EGFR-targeting molecules and their potential role in the treatment of colorectal cancer. Cetuximab binds to domain III of EGFR and hinders ligand binding. It is now approved by the US Food and Drug Administration for metastatic colorectal cancer treatment. Panitumumab is another widely studied anti-EGFR antibody with similar properties. Bispecific antibodies are modified immunoglobulin molecules containing 2 different binding specificities. These antibodies can redirect the immune response against tumor cells by tethering effector cells such as CD3e-expressing T cells or CD16-expressing natural killer cells and granulocytes to the surface of cancer cells. Tyrosine kinase inhibitors are quinazoline-derived, low molecular weight synthetic molecules that can block the intracellular tyrosine kinase domain of several receptors, including EGFR, Erb2, and vascular endothelial growth factor receptor, and thereby inhibit ligand-induced receptor phosphorylation and abrogate the biologic effect of EGFR signaling. The presence of skin rash and EGFR gene amplification have been advanced as possible predictors of clinical effectiveness of targeted anti-EGFR therapies.

Antibody-based therapies for colorectal cancer

The recent successful development of novel monoclonal antibodies that target key components of biologic pathways has expanded the armamentarium of treatment options for patients with colorectal cancer. Two targets in particular--the process of new blood vessel development, or angiogenesis, and the epidermal growth factor receptor and its signaling pathway--are exploited by the newest monoclonal antibodies that are available for use in colorectal cancer patients. This clinical review focuses on the defining role of the two most clinically advanced novel agents, bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA, http://www.gene.com) and cetuximab (Erbitux; ImClone Systems, Inc., New York, http://www.imclone.com), in colorectal cancer.

Novel approaches to treatment of advanced colorectal cancer with anti-EGFR monoclonal antibodies

The standard treatment of metastatic colorectal cancer (mCRC) is combination of 5- fluorouracil/folinic acid with irinotecan or oxaliplatin-based chemotherapy. Epidermal growth factor receptor (EGFR) is overexpressed in 70%-80% of colorectal cancers (CRC). EGFR overexpression is known to be involved in carcinogenic processes, such as cell proliferation, apoptosis, angiogenesis and metastasis. Monoclonal antibodies targeting EGFR have shown antitumor activity and improved the efficacy of chemotherapy. Cetuximab is a chimeric immunoglobulin (Ig) G1 anti-EGFR monoclonal antibody (MoAb). Several clinical studies have shown cetuximab, either as a single agent or in combination with irinotecan, having promising efficacy in patients with metastatic CRC. Cetuximab with 5-fluorouracil/LV (leucovorin) plus irinotecan or oxaliplatin-based chemotherapy has shown higher response rate and longer time to progression as first-line treatment of mCRC. Currently, there are no data showing that addition of cetuximab would prolong overall survival in randomized studies. Panitumumab, a fully human IgG2 monoclonal antibody, has also shown antitumor activity against EGFR-expressing mCRC with less allergic reaction. Anti-EGFR MoAbs are well tolerated and have limited overlapping toxicities in combination with other cytotoxic drugs. The most common side effect of anti-EGFR MoAb is an acneform skin rash, which is a surrogate marker of efficacy of treatment with MoAbs. In this review, we will discuss the use of anti-EGFR MoAbs in the treatment of mCRC, with focus on cetuximab and panitumumab.

Quantitative determination of nuclear and cytoplasmic epidermal growth factor receptor expression in oropharyngeal squamous cell cancer by using automated quantitative analysis

BACKGROUND

Several lines of evidence support the epidermal growth factor receptor (EGFR) as a molecular target for therapy in head and neck squamous cell carcinomas (HNSCC). Determination of tumor EGFR levels by conventional immunohistochemistry has not always predicted antitumor efficacy. Quantitative assays may provide more accurate assessment of the level of EGFR receptor in the tumor, which may thus provide more reliable prognostic and predictive information. We studied the prognostic value of quantitative assessment of EGFR in oropharyngeal squamous cell cancers treated with radiotherapy.

EXPERIMENTAL DESIGN

We studied EGFR protein expression on a tissue microarray composed of 95 oropharyngeal cancer cases using an in situ molecular-based method of quantitative assessment of protein expression (AQUA) and correlated those with clinical and pathologic data. Automated, quantitative analysis uses cytokeratin to define pixels as cancer (tumor mask) within the array spot and measures intensity of EGFR expression using a Cy5-conjugated antibody within the mask. A continuous index score is generated, which is directly proportional to the number of molecules per unit area, and cases were defined as high expressing if they were above the median expression level.

RESULTS

The mean follow-up time for survivors was 44.9 months, and for the entire cohort was 34.8 months. Patients with high tumor EGFR expression levels had a local recurrence rate of 58% compared with 17% for patients with low EGFR tumor expression (P < 0.01). Similarly, patients with high nuclear EGFR expression had a local recurrence rate of 54% compared with 21% for patients with low EGFR nuclear expression (P < 0.05). Additionally, patients with high tumor and nuclear EGFR levels had inferior disease-free survival compared with low expressors (19% versus 43% and 19% versus 45%, respectively. P < 0.05 for each). In multivariate analysis adjusting for well-characterized prognostic variables, high tumor and nuclear EGFR expression levels retained their prognostic significance.

CONCLUSION

The AQUA system provides a continuous measurement of EGFR on paraffin-embedded tissue and was able to reveal the association between EGFR expression and outcome expected from the biological role of EGFR. In the future, EGFR AQUA score may be useful in predicting response to EGFR-targeted therapies.

Effect of Epidermal Growth Factor Receptor Expression Level on Survival in Patients with Epithelial Ovarian Cancer

BACKGROUND

Several lines of laboratory evidence support the epidermal growth factor receptor (EGFR) as an adverse prognostic indicator in ovarian cancers. However, different methods of immunohistochemical assessment have yielded conflicting results. Here, we sought to determine the prognostic value of EGFR in ovarian cancer using a novel method of compartmentalized in situ protein analysis.

METHODS

A tissue array composed of 150 advanced-stage ovarian cancers uniformly treated, with surgical debulking followed by platinum-paclitaxel combination chemotherapy, was constructed. For evaluation of EGFR protein expression, we used an immunofluorescence-based method of automated in situ quantitative measurement of protein analysis (AQUA).

RESULTS

Mean follow-up time for the entire cohort was 34.4 months. Eighty-one of 150 cases had sufficient tissue for AQUA analysis. High tumor EGFR expression was associated with poor outcome for overall survival (P=0.0001) and disease-free survival (P=0.0005) at 3 years. In multivariable analysis, adjusting for well-characterized prognostic variables, EGFR expression status was the most significant prognostic factor for disease-free and overall survival.

CONCLUSION

The conflicting results in the literature regarding the prognostic value of EGFR may be due to the technical difficulties inherent in assessing EGFR with immunocytochemistry. In the present study, we show that measurement of EGFR protein levels in ovarian cancer using AQUA is feasible and can give important prognostic information.

Enhancing oxaliplatin-based regimens in colorectal cancer by inhibiting the epidermal growth factor receptor pathway

In the past several years, significant advances in the treatment of colorectal cancer (CRC) have been made. With the introduction of irinotecan and oxaliplatin combined with infusional 5-fluororuracil, survival times for patients with metastatic CRC have nearly doubled. With the incorporation of biologic agents that target the vascular endothelial growth factor and epidermal growth factor (EGF) pathways, additional improvements in response, progression-free survival, and overall survival have been seen in patients with advanced, metastatic disease. This article reviews the impact of EGF receptor inhibitors on improving survival in CRC when combined with oxaliplatin-containing regimens.

Treatment for multiple bilobar liver metastases of colorectal cancer

BACKGROUND

Recent advances have extended indications for hepatectomy to include multiple bilobar colorectal liver metastases (CLM). Staging systems based on the biological malignancy of primary and metastatic tumors provide appropriate indications for hepatectomy in CLM. However, suitability for resection in patients with complex and extensive hepatic metastases is controversial.

METHODS

A medline search was performed to identify papers reporting the resection for CLM. Techniques, indication, and results were reviewed.

RESULTS

If the anticipated remnant liver volume is small (25-40% of total), suggesting a high risk of postoperative liver failure, portal vein embolization (PVE) is recommended prior to hepatectomy. However, curative resections are not always possible. Specifically in synchronous multiple bilobar CLM, two-stage hepatectomy, comprising bilateral hepatectomy and primary resection with or without PVE, can prevent growth of ipsilateral metastatic nodules in the remnant liver and reduce surgical risk. Several local ablation techniques can complement surgery if hepatic resection alone increases the risk of postoperative liver failure or is not curative. Chemotherapy combined with targeted treatment can suppress recurrence and extend indications for hepatectomy by reducing the size and number of primary irresectable tumors.

CONCLUSION

PVE or staged procedure combining with local ablation or neoadjuvant, downstaging or adjuvant therapies extends indications for hepatectomy to include multiple bilobar CLM. The 5-year survival rate for multiple bilobar CLM treated with alternating hepatectomy and chemotherapy is comparable to the values reported for single and hemilateral CLM.

Molecular alterations in tumors and response to combination chemotherapy with gefitinib for advanced colorectal cancer

PURPOSE

Recently, activating mutations of the epidermal growth factor receptor (EGFR) gene were discovered in non-small cell lung cancers sensitive to gefitinib (ZD1839, an EGFR tyrosine kinase inhibitor) but not in gefitinib-resistant cancers. Abnormalities of EGFR and related pathways may have an effect on responsiveness of advanced colorectal cancer to combination chemotherapy with gefitinib.

EXPERIMENTAL DESIGN

We examined patients with previously untreated metastatic colorectal cancer, who were enrolled into two phase I/II trials of combination chemotherapy (irinotecan, leucovorin, and 5-fluorouracil) and daily oral gefitinib. We obtained paraffin tissue blocks of primary tumors from 31 patients, sequenced the EGFR, KRAS, and BRAF genes, and did immunohistochemistry for EGFR, phosphorylated AKT1, p53, p21, and p27.

RESULTS

Twelve (39%) of the 31 patients experienced a partial objective response to the therapy. A novel EGFR mutation in exon 18 (c.2170G>A, p.Gly724Ser) was identified in only one patient who did not experience an objective tumor response. EGFR immunohistochemistry was not predictive of responsiveness. In contrast, loss of p21 was associated with a higher response rate to therapy (P = 0.05). Moreover, the response rate among patients whose tumors maintained p21 expression and possessed a mutation in p53 was only 9% (1 of 11, P = 0.005). Overexpression of phosphorylated AKT1 also seemed to predict a trend towards resistance to the therapy.

CONCLUSIONS

p21 expression in colorectal cancer, especially in combination with p53 mutation, is a predictor of resistance to the combination chemotherapy with gefitinib. Activating EGFR mutations are rare in colorectal cancer and do not seem to confer sensitivity to gefitinib and chemotherapy.

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.

Epidermal growth factor receptor expression and gene amplification in colorectal carcinoma: an immunohistochemical and chromogenic in situ hybridization study

Recent data suggest that detection of epidermal growth factor receptor protein by immunohistochemistry (IHC) does not predict response to the antiepidermal growth factor receptor drug, cetuximab, in patients with colorectal carcinoma. In searching for foundation for further investigation to optimize patient selection for cetuximab therapy, this study sought to exploit the tissue microarray and chromogenic in situ hybridization techniques to evaluate the status of epidermal growth factor receptor gene amplification in colorectal cancer and its relationship with protein expression by IHC. The study included 158 primary or metastatic colorectal adenocarcinomas. Immunohistochemical results were scored as 0-3+ based on the intensity of membrane staining. The in situ hybridization signals were counted in 30 nuclei per tissue core. Overall, the rate of tissue loss was 7%, yielding 147 analyzable cases: 123 primary, 24 metastatic. Positive immunohistochemical staining of any intensity was detected in 85% (105/123) of primary and 79% (19/24) of metastatic tumors, whereas gene amplification (>5 gene copies/nucleus) was only seen in 12% (15/123) of primary and 8% (2/24) of metastatic tumors. Only 2/15 primary and 1/2 metastatic tumors that showed gene amplification were amplified at a high level (>10 gene copies/nucleus). Although a positive correlation was detected between the intensity of protein expression and the likelihood of gene amplification in both the primary (P = 0.01) and the metastatic (P = 0.05) tumors, IHC had a low specificity (17% in primary, 23% in metastatic) in predicting gene amplification. Conversely, all tumors that did not express the protein by IHC lacked gene amplification. Thus, this study shows that only a small fraction of epidermal growth factor receptor- positive colorectal carcinomas detected by IHC are associated with gene amplification. Additional studies are needed to determine whether epidermal growth factor receptor gene amplification bears any informative value in predicting response to cetuximab-based therapy.

Resistance to epidermal growth factor receptor-targeted therapy

The epidermal growth factor receptor (EGFR) has been a major target of molecular anticancer therapy. Two approaches have been developed, involving monoclonal antibodies and receptor tyrosine kinase inhibitors, and both have demonstrated benefit in clinical trials. However, evidence of resistance to these drugs has been described. Cellular levels of EGFR do not always correlate with response to the EGFR tyrosine kinase inhibitors, indicating acquired resistance to these drugs. Since EGFR antagonists interfere with the activation of several intracellular pathways that control cell proliferation, survival, apoptosis, angiogenesis, invasion and metastasis, acquired resistance can occur as a result of several different molecular mechanisms: autocrine/paracrine production of ligand, receptor mutation, constitutive activation of the downstream pathway and activation of alternative pathways. We will describe here potential mechanisms that can cause resistance to EGFR-targeted drugs. Combinations of EGFR antagonists with inhibitors targeting different signaling mechanism(s) - such as insulin-like growth factor receptor and vascular endothelial growth factor receptor - that share the same downstream mediator (e.g., phosphatidylinositol 3-kinase/Akt, mitogen-activated protein kinase), may circumvent or delay the development of resistance to EGFR antagonists resulting in enhanced antitumor activities.