Pancreatic cancer epidermal growth factor receptor (EGFR) intron 1 polymorphism influences postoperative patient survival and in vitro erlotinib response

MiRNA-Mediated Subpathway Identification and Network Module Analysis to Reveal Prognostic Markers in Human Pancreatic Cancer

Background

Pancreatic cancer (PC) remains one of the most lethal cancers. In contrast to the steady increase in survival for most cancers, the 5-year survival remains low for PC patients.

Methods

We describe a new pipeline that can be used to identify prognostic molecular biomarkers by identifying miRNA-mediated subpathways associated with PC. These modules were then further extracted from a comprehensive miRNA-gene network (CMGN). An exhaustive survival analysis was performed to estimate the prognostic value of these modules.

Results

We identified 105 miRNA-mediated subpathways associated with PC. Two subpathways within the MAPK signaling and cell cycle pathways were found to be highly related to PC. Of the miRNA-mRNA modules extracted from CMGN, six modules showed good prognostic performance in both independent validated datasets.

Conclusions

Our study provides novel insight into the mechanisms of PC. We inferred that six miRNA-mRNA modules could serve as potential prognostic molecular biomarkers in PC based on the pipeline we proposed.

Epidermal growth factor receptor intron 1 polymorphism and microsatellite instability in sporadic colorectal cancer

Epidermal growth factor receptor (EGFR) expression is commonly upregulated in sporadic colorectal cancer (CRC) and its high expression is associated with poor prognosis in patients with CRC. CA-SSR1 is a dinucleotide CA repeat of the EGFR gene that can modulate EGFR transcription and is a potential target of the mismatch repair machinery in tumours with microsatellite instability (MSI). In the present study, 160 sporadic colon cancer samples were analysed for EGFR CA-SSR1 polymorphism and MSI status. Additionally, EGFR mRNA and protein expression levels in the tumour centre and in the invasive tumour front, compared with those in adjacent normal tissue samples, were evaluated in 80 tumour samples. An inverse association was identified between EGFR mRNA levels and the sum of repeats in both alleles of the CA-SSR1 polymorphism in normal tissues. Changes in CA-SSR1 were detected in the tumour centre as well as in the invasive tumour front and metastases in all MSI high (MSI-H) tumours. Analysis of EGFR expression at the mRNA and protein levels according to MSI status revealed lower EGFR mRNA and protein expression in MSI-H tumours than microsatellite-stable (MSS) tumours. Furthermore, higher EGFR levels in the invasive tumour front compared with in the tumour centre in MSS tumours were identified, suggesting a role of EGFR in tumour progression and higher invasive potential of MSS than MSI-H tumours.

CA-SSR1 Polymorphism in Intron 1 of the EGFR Gene in Patients with Malignant Tumors Who Develop Acneiform Rash Associated with the Use of Cetuximab

Background and Objective

Epidermal growth factor receptor (EGFR) inhibitors are not equally effective in all cancer patients. One potential clinical factor that could help in selecting patients who may benefit from treatment with cetuximab is acneiform rash, which correlates with the clinical response to EGFR inhibitors. Some previous studies have suggested that the tendency to develop rash may depend on polymorphisms in the EGFR gene. In this investigation, the association of degree of CA dinucleotide polymorphism with skin rash and cetuximab therapy outcome was examined.

Methods

The study included 60 patients treated with cetuximab. For each patient, the severity of acneiform rash was assessed, and the type of polymorphism was determined by genotyping. Associations between genotypes, the acneiform rash, and response to treatment were determined by using the chi-square test and Spearman’s rank correlation. The cutoffs S ≤ 17(CA), L > 17(CA), n(CA) ≤ 35, and n(CA) > 35 were tested, as well as the sum of the two allele repetitions.

Results

A correlation was found between body surface area covered by rash and the sum of the two allele repetitions (p = 0.030). No statistically significant relationship between genotype and response to treatment was observed. However, in patients who have had partial remission, we noticed a higher incidence of polymorphism, with less CA dinucleotide repetitions and early onset of rash.

Conclusion

A correlation between genotype and severity of rash was observed. That is, the severity of rash decreased with an increased number of CA repetitions.

Sensitization of Radiation or Gemcitabine-Based Chemoradiation Therapeutic Effect by Nimotuzumab in Pancreatic Cancer Cells

This study was performed to observe the effect of the combination of nimotuzumab with radiation or gemcitabine-based chemoradiation on antipancreatic cancer cell therapy. Pancreatic cancer cells (PANC-1) were treated with nimotuzumab alone or combined with radiation (2, 4, or 8 Gy), which was either with or without gemcitabine chemotherapy. Cell proliferation, cell cycle distribution, and apoptosis were observed. The inhibition rate, the percentage of G2/M phase arrest, and the apoptosis rate of the combined nimotuzumab with radiation group was significantly higher than the group without nimotuzumab (P < .001). The inhibition rate, the percentage of G2/M phase, and the apoptosis rate of the nimotuzumab therapy combined with gemcitabine-based chemoradiation group were obviously higher than that in gemcitabine-based chemoradiation group (P < .001). In conclusion, nimotuzumab could enhance the anticancer effect of radiation and gemcitabine-based chemoradiation in PANC-1 cancer cells because of the enhancement of cell cycle arrest and apoptosis.

CHIP is a novel tumor suppressor in pancreatic cancer through targeting EGFR

Carboxyl terminus of heat shock protein 70-interacting protein (CHIP) is an E3 ubiquitin ligase that is involved in protein quality control and mediates several tumor-related proteins in many cancers, but the function of CHIP in pancreatic cancer is not known. Here we show that CHIP interacts and ubiquitinates epidermal growth factor receptor (EGFR) for proteasome-mediated degradation in pancreatic cancer cells, thereby inhibiting the activation of EGFR downstream pathways. CHIP suppressed cell proliferation, anchor-independent growth, invasion and migration, as well as enhanced apoptosis induced by erlotinib in vitro and in vivo. The expression of CHIP was decreased in pancreatic cancer tissues or sera. Low CHIP expression in tumor tissues was correlated with tumor differentiation and shorter overall survival. These observations indicate that CHIP serves as a novel tumor suppressor by down-regulating EGFR pathway in pancreatic cancer cells, decreased expression of CHIP was associated with poor prognosis in pancreatic cancer.

pERK, pAKT and p53 as tissue biomarkers in erlotinib-treated patients with advanced pancreatic cancer: a translational subgroup analysis from AIO-PK0104

Background

The role of pERK, pAKT and p53 as biomarkers in patients with advanced pancreatic cancer has not yet been defined.

Methods

Within the phase III study AIO-PK0104 281 patients with advanced pancreatic cancer received an erlotinib-based 1^st-line regimen. Archival tissue from 153 patients was available for central immunohistochemistry staining for pERK, pAKT and p53. Within a subgroup analysis, biomarker data were correlated with efficacy endpoints and skin rash using a Cox regression model.

Results

Fifty-five out of 153 patients were classified as pERK^low and 98 patients as pERK^high; median overall survival (OS) was 6.2 months and 5.7 months, respectively (HR 1.29, p = 0.16). When analysing pERK as continuous variable, the pERK score was significantly associated with OS (HR 1.06, 95% CI 1.0-1.12, p = 0.05). Twenty-one of 35 patients were pAKT^low and 14/35 pAKT^high with a corresponding median OS of 6.4 months and 6.8 months, respectively (HR 1.03, p = 0.93). Four out of 50 patients had a complete loss of p53 expression, 20 patients a regular expression and 26 patients had tumors with p53 overexpression. The p53 status had no impact on OS (p = 0.91); however, a significant improvement in progression-free survival (PFS) (6.0 vs 1.8 months, HR 0.24, p = 0.02) and a higher rate of skin rash (84% vs 25%, p = 0.02) was observed for patients with a regular p53 expression compared to patients with a complete loss of p53.

Conclusion

pERK expression may have an impact on OS in erlotinib-treated patients with advanced pancreatic cancer; p53 should be further investigated for its potential role as a predictive marker for PFS and skin rash.

Trial registration

NCT00440167 (registration date: February 22, 2007).

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-624) contains supplementary material, which is available to authorized users.

Genetic variants of EGF and VEGF predict prognosis of patients with advanced esophageal squamous cell carcinoma

PURPOSE

To investigate the association between genetic polymorphisms of growth factor-related genes and prognosis in patients with advanced esophageal squamous cell carcinoma (ESCC).

PATIENTS AND METHODS

A total of 334 ESCC patients with advanced tumor stages (stages IIB, III and IV) were enrolled in the study. The genotypes of 14 candidate single nucleotide polymorphisms (SNPs) involved in growth factor-related functions were analyzed using iPLEX Gold technology from the genomic DNA of peripheral leukocytes, and were correlated with the clinical outcome of patients. Serum levels of growth factors were examined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The genetic polymorphisms of EGF:rs4444903, EGF:rs2237051 and VEGF:rs2010963 showed significant associations with overall survival (OS) of advanced ESCC patients (A/A+ A/G vs. GG, [HR = 0.77, 95% CI = 0.60-0.99, P = 0.039 for rs4444903; A/G+ G/G vs. A/A, [HR = 0.74, 95% CI = 0.58-0.95, P = 0.019 for rs2237051; G/G+G/C vs. C/C, [HR] inves = 0.69, 95% CI = 0.50-0.95, P = 0.023 for rs2010963). EGFR:rs2227983 and 3 SNPs of PIK3CA also showed borderline significant correlation with OS of advanced ESCC patients (P = 0.058 for rs2227983; P = 0.069, 0.091 and 0.067 for rs6443624, rs7651265 and rs7621329 of PIK3CA respectively). According to cumulative effect analysis of multiple SNPs, patients carrying 4 unfavorable genotypes exhibited more than a 3-fold increased risk of mortality. Finally, both EGF and VEGF expression levels significantly associated with patient mortality.

CONCLUSION

The genetic variants and expression levels of EGF and VEGF can serve as prognostic predictors in patients with advanced ESCC, and thus provide more information for optimizing personalized therapies for patients with ESCC.

KRAS mutation status is not predictive for objective response to anti-EGFR treatment with erlotinib in patients with advanced pancreatic cancer

BACKGROUND

It has not yet been defined if KRAS has a prognostic value or is a predictive biomarker for the efficacy of erlotinib in advanced pancreatic cancer (PC).

METHODS

AIO-PK0104 was a phase III trial comparing gemcitabine/erlotinib followed by capecitabine with capecitabine/erlotinib followed by gemcitabine in advanced PC. For this post hoc subgroup analysis, biomarker data on the KRAS exon 2 mutation status were correlated with objective response to 1st-line therapy and with overall survival after start of 2nd-line chemotherapy (OSc).

RESULTS

KRAS codon 12 was mutated in 121 of 173 (70 %) patients. The KRAS status showed no association with objective response (p = 0.40), but KRAS wildtype patients had an improved OS (HR 1.68, p = 0.005). A trend for a survival benefit was also observed during (non-erlotinib containing) 2nd-line chemotherapy, with a HR of 1.47 (p = 0.10) for the OSc.

CONCLUSION

This post hoc analysis of AIO-PK0104 supports the assumption that KRAS is rather a prognostic than a predictive biomarker in PC.

EGFR intron-1 CA repeat polymorphism is a predictor of relapse and survival in complete resected only surgically treated esophageal cancer

Basal transcription regulation of the epidermal growth factor receptor is dependent upon a CA simple sequence repeat polymorphism in the intron-1 (CA-SSR-1). Here, we evaluate the role of CA-SSR-1 in complete resected esophageal cancer (EC) patients without neoadjuvant or adjuvant treatment. Genomic DNA was extracted from peripheral blood leukocytes of 241 patients. To determine the number of the CA repeats in the CA-SSR-1, DNA was amplified by polymerase chain reaction and sequenced. The results were correlated with clinicopathological parameters and clinical outcome. Three genotypes were defined based on cut-off points for short allele (S) with ≤18 and long allele (L) >18 CA repeats. A steadily increasing risk was evident between LL, SL, and SS genotype for larger tumor size, presence of lymph node metastases, and disseminated tumor cells in bone marrow as well as tumor recurrence (P < 0.001, chi-square test). A gradual decrease in disease-free and overall survival (OS) was present among LL, SL, and SS patients (P < 0.001, log-rank test). The different outcomes were also evident in nodal status and histological type adjusted subgroup analyses. CA-SSR-1 was identified as the strongest independent prognosticator of tumor recurrence and OS (P < 0.001, Cox regression analysis). CA-SSR-1 is a strong predictive factor for tumor recurrence and overall survival in patients with complete resected esophageal cancer without neoadjuvant or adjuvant therapy.

EGF receptor-targeted therapy in non-small-cell lung cancer: role of germline polymorphisms in outcome and toxicity

Conventional chemotherapeutic regimens have limited impact against most solid tumors and deal with significant toxicity. Over the last 10 years, novel anticancer treatments targeting specific molecules or genes involved in cancer progression have been developed to improve outcome and reduce side effects. In particular, the tyrosine kinase inhibitors gefitinib and erlotinib have been approved for the treatment of non-small-cell lung cancer. Their clinical activity has been related to different clinical and biological parameters, such as EGFR-activating mutations. However, not all clinical outcomes, including tolerability, are explained, and the identification/validation of novel biomarkers is a viable area of research. Germline polymorphisms can be easily assessed in blood samples, and candidate polymorphisms in EGFR and ABCG2 have been correlated with outcome and toxicity in non-small-cell lung cancer patients treated with gefitinib or erlotinib. However, differences in study population and design resulted in several controversial findings, while the prognostic versus predictive role of the polymorphisms still needs to be validated within larger prospective studies. More studies on the relationship of the genotype with drug pharmacokinetics and mechanism of action are also warranted. These future studies, as well as further development and application of novel technologies to decipher genetic alterations, might contribute to the validation of selected polymorphisms as molecular markers predictive of drug activity and help in the selection of tyrosine kinase inhibitors best suited to the individual patient.

EGFR pathway biomarkers in erlotinib-treated patients with advanced pancreatic cancer: translational results from the randomised, crossover phase 3 trial AIO-PK0104

Background:

We aimed to identify molecular epidermal growth factor receptor (EGFR) tissue biomarkers in pancreatic cancer (PC) patients treated with the anti-EGFR agent erlotinib within the phase 3 randomised AIO-PK0104 study.

Methods:

AIO-PK0104 was a multicenter trial comparing gemcitabine/erlotinib followed by capecitabine with capecitabine/erlotinib followed by gemcitabine in advanced PC; primary study end point was the time-to-treatment failure after first- and second-line therapy (TTF2). Translational analyses were performed for KRAS exon 2 mutations, EGFR expression, PTEN expression, the EGFR intron 1 and exon 13 R497K polymorphism (PM). Biomarker data were correlated with TTF, overall survival (OS) and skin rash.

Results:

Archival tumour tissue was available from 208 (74%) of the randomised patients. The KRAS mutations were found in 70% (121 out of 173) of patients and exclusively occurred in codon 12. The EGFR overexpression was detected in 89 out of 181 patients (49%) by immunohistochemistry (IHC), and 77 out of 166 patients (46%) had an EGFR gene amplification by fluorescence in-situ hybridisation (FISH); 30 out of 171 patients (18%) had a loss of PTEN expression, which was associated with an inferior TTF1 (first-line therapy; HR 0.61, P=0.02) and TTF2 (HR 0.66, P=0.04). The KRAS wild-type status was associated with improved OS (HR 1.68, P=0.005); no significant OS correlation was found for EGFR–IHC (HR 0.96), EGFR–FISH (HR 1.22), PTEN–IHC (HR 0.77), intron 1 (HR 0.91) or exon 13 R497K PM (HR 0.83). None of the six biomarkers correlated with the occurrence of skin rash.

Conclusion:

The KRAS wild-type was associated with an improved OS in erlotinib-treated PC patients in this phase 3 study; it remains to be defined whether this association is prognostic or predictive.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

Role of epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of esophageal carcinoma and the suggested mechanisms of action

Cumulative evidence indicates that epidermal growth factor receptor (EGFR) is one of the most commonly altered genes in human cancer, via overexpression, amplification and mutation. Targeted inhibition of EGFR activity suppresses signal transduction pathways which control tumor cell growth, proliferation and resistance to apoptosis. Small molecule tyrosine kinase inhibitors (TKIs) are among the most common EGFR-targeting agents and have been used clinically to treat various malignancies. This review discusses the mechanism of action and clinical data that are relevant to the use of EGFR-TKIs in the treatment of esophageal carcinoma. The clinical and basic scientific experience of these agents thus far have implications for the future of therapeutic targeting of EGFR.

Targeting ErbB3-mediated stromal-epithelial interactions in pancreatic ductal adenocarcinoma

Background:

We sought to investigate the role of ErbB3-mediated signalling on the interaction between pancreatic cancer-associated fibroblasts (CAF) and carcinoma cells in an effort to disrupt tumourigenic pancreatic ductal adenocarcinoma (PDAC) stromal–epithelial cross-communication.

Methods:

Primary CAF cultures were established from human PDAC surgical specimens. AsPC-1 pancreatic cancer cell murine subcutaneous xenografts were developed in the presence and absence of CAF and were subsequently treated with epidermal growth factor receptor (EGFR) inhibitors (erlotinib) and ErbB3 inhibitors (MM-121, monoclonal ErbB3 antibody).

Results:

Cancer-associated fibroblasts were found to secrete neuregulin-1 (NRG-1), which promoted proliferation via phosphorylation of ErbB3 and AKT in AsPC-1 PDAC cells. This signalling cascade was effectively inhibited both in vitro and in vivo by specific ErbB3 blockade with MM-121, with greater degree of tumourigenesis inhibition when combined with erlotinib. The CAF–AsPC-1 pancreatic cancer xenografts reached significantly greater tumour volume than those xenografts lacking CAF and were resistant to the anti-tumour effects of EGFR inhibition with erlotinib.

Conclusion:

Cancer-associated fibroblasts-derived NRG-1 promote PDAC tumourigenesis via ErbB3-AKT signalling and overcomes single-agent EGFR inhibition. Disruption of this stromally mediated tumourigenic mechanism is best obtained through combined EGFR-ErbB3 inhibition with both erlotinib and MM-121. We have identified the NRG-1/ErbB3 axis as an attractive molecular target for the interruption of tumourigenic stromal–epithelial interactions within the PDAC microenvironment.

Epidermal growth factor receptor in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer related death. The difficulty in detecting pancreatic cancer at an early stage, aggressiveness and the lack of effective therapy all contribute to the high mortality. Epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein, which is expressed in normal human tissues. It is a member of the tyrosine kinase family of growth factors receptors and is encoded by proto-oncogenes. Several studies have demonstrated that EGFR is over-expressed in pancreatic cancer. Over-expression correlates with more advanced disease, poor survival and the presence of metastases. Therefore, inhibition of the EGFR signaling pathway is an attractive therapeutic target. Although several combinations of EGFR inhibitors with chemotherapy demonstrate inhibition of tumor-induced angiogenesis, tumor cell apoptosis and regression in xenograft models, these benefits remain to be confirmed. Multimodality treatment incorporating EGFR-inhibition is emerging as a novel strategy in the treatment of pancreatic cancer.

ErbB3 expression promotes tumorigenesis in pancreatic adenocarcinoma

Historically, ErbB3 has been overlooked within the ErbB receptor family due to its perceived lack of tyrosine kinase activity. We have previously demonstrated that in pancreatic cancer ErbB3 is the preferred dimerization partner of EGFR, ErbB3 protein expression level directly correlates with the anti-proliferative effect of erlotinib (an EGFR-specific tyrosine kinase inhibitor), and transient knockdown of ErbB3 expression results in acquired resistance to EGFR-targeted therapy. In this study, we develop a stable isogenic model of ErbB3 expression in an attempt to decipher ErbB3's true contribution to pancreatic cancer tumorigenesis and to examine how this receptor affects cellular sensitivity to EGFR-targeted therapy. Analysis of the EGFR-ErbB3 heterodimer demonstrates that ligand-induced PI3K-AKT signaling is limited to ErbB3-expressing cells and that this signaling cascade can be partially abrogated by inhibiting EGFR function with erlotinib. Using our model of exogenous ErbB3 expression we showed a direct relationship between ErbB3 protein levels and increased pancreatic cancer cell proliferation in vitro. In vivo, ErbB3(+)PANC-1 xenografts had a significantly larger tumor volume than PANC-1 control xenografts (ErbB3-PANC-1) and displayed increased sensitivity to EGFR-targeted therapy. In pancreatic cancer, ErbB3 appears to be critically involved in EGFR signaling as evidenced by its profound effect on cellular proliferation and its ability to influence response to EGFR-targeted therapy.

Epidermal growth factor receptor (EGFR) intron 1 polymorphism and clinical outcome in pancreatic adenocarcinoma

BACKGROUND

Epidermal growth factor receptor (EGFR) intron 1 has a polymorphic region of CA repeats that is believed to be associated with increased EGFR expression, tumor aggressiveness, and worse survival in cancer patients.

METHODS

A large population of pancreatic adenocarcinoma patients was investigated to evaluate this polymorphism as a potential prognostic marker of clinical outcome. Deoxyribonucleic acid obtained from 50 resected pancreatic adenocarcinomas and from 85 diagnostic endoscopic ultrasound-guided fine-needle aspiration procedures corresponding to patients with unresectable tumors was included. The correlation between CA repeat length and EGFR messenger ribonucleic acid levels was also examined.

RESULTS

Analysis of the 135 patients revealed no correlation between EGFR intron 1 CA repeat length and tumor stage. There was no difference in overall patient survival when stratified by allele length. A correlation between EGFR intron 1 length and EGFR transcript and protein levels could not be established.

CONCLUSIONS

The length of the EGFR intron 1 CA repeats does not correlate with levels of EGFR expression and cannot be used as marker of clinical prognosis in pancreatic cancer patients.

Epidermal growth factor receptor intron 1 CA dinucleotide repeat polymorphism and survival of advanced gastric cancer patients treated with cetuximab plus modified FOLFOX6

Cetuximab is a monoclonal antibody targeting epidermal growth factor receptor (EGFR). The present study investigated the association between germline genetic polymorphisms and the treatment outcome of cetuximab plus modified leucovovin, fluorouracil, and oxaliplatin (FOLFOX)6 chemotherapy in advanced gastric cancer (AGC). DNA from peripheral blood mononuclear cells of 38 patients enrolled in a phase II study of cetuximab plus modified FOLFOX6 were analyzed for 16 polymorphisms in eight genes (EGFR, epidermal growth factor, transforming growth factor-alpha (TGFA), thymidylate synthase, excision repair cross-complementation group 1, Xeroderma pigmentosum group D, and fragment c gamma receptors (FCGR)2A and 3A). The EGFR intron 1 CA repeat polymorphism was associated with survival. Twenty-one patients had low repeats (sum of both alleles or=38). Patients with low CA repeats had longer progression-free survival (adjusted hazard ratio [HR] 0.42 [95% confidence interval [CI] 0.19-0.96], P = 0.040) and overall survival (adjusted HR 0.40 [95% CI 0.16-0.99], P = 0.048) compared with patients with high CA repeats. In addition, the tumor EGFR expression was higher in patients with a lower number of CA repeats. The association between the CA repeat status and survival was not found in a separate cohort of AGC patients (n = 68) treated only with modified FOLFOX6. These results suggest that the EGFR intron 1 CA repeat polymorphism could be a useful, predictive biomarker of cetuximab efficacy in AGC and merits further investigation in randomized studies.

Basic principles and technologies for deciphering the genetic map of cancer

The progress achieved in the field of genomics in recent years is leading medicine to adopt a personalized model in which the knowledge of individual DNA alterations will allow a targeted approach to cancer. Using pancreatic cancer as a model, we discuss herein the fundamentals that need to be considered for the high throughput and global identification of mutations. These include patient-related issues, sample collection, DNA isolation, gene selection, primer design, and sequencing techniques. We also describe the possible applications of the discovery of DNA changes to the approach of this disease and cite preliminary efforts where the knowledge has been translated into the clinical or preclinical setting.

Markers involved in resistance to cytotoxics and targeted therapeutics in pancreatic cancer

Pancreatic cancer retains a poor prognosis among the gastrointestinal cancers and remains a challenge in oncology. In 1997, gemcitabine became the standard of care in metastatic setting. In the last decades, despite a number of clinical trials assessing novel cytotoxic agents and cell signaling inhibitors, overall survival has reached a plateau that remains difficult to improve. Development of mechanisms implicated in intrinsic and acquired resistance to chemotherapy are considered to play a key role that could explain the limited benefit of most treatment in pancreatic cancers. Key molecular factors implicated in this process include: deficiencies in drugs uptake, activations of DNA repair pathways, resistance to apoptosis, and tumor microenvironment. Moreover, for cell signaling inhibitors, mutations in kinase domains, activation of alternative pathways, mutations of genes downstream of the target, activation of autocrine/paracrine pathways and/or feed-back amplification of the target represent the most important mechanisms achieving resistance of pancreatic cancer cells.

Erlotinib in the treatment of advanced pancreatic cancer

Single agent gemcitabine has been the mainstay of therapy for advanced pancreatic cancer over the past decade. Multiple trials of newer chemotherapeutic agents both alone and in combination have yielded disappointing results, spurring the ongoing search for new agents and combinations in this aggressive malignancy. Inhibitors of the epidermal growth factor receptor (EGFR) have shown promising activity in multiple solid tumors types, and preclinical data support a role for EGFR inhibition in pancreatic cancer. A recent phase III study by the National Cancer Institute of Canada Clinical Trials Group (NCIC-CTG) demonstrated a significant survival benefit with the addition of the EGFR tyrosine kinase inhibitor, erlotinib, to gemcitabine chemotherapy for the first-line treatment of patients with advanced pancreatic cancer, becoming the first phase III study to demonstrate a survival benefit of combination therapy as well as targeted therapy in this disease. This article reviews the evidence supporting EGFR inhibition and the use of erlotinib in advanced pancreatic cancer as well as future implications of targeted therapy in this challenging malignancy.

Relationship of EGFR mutations, expression, amplification, and polymorphisms to epidermal growth factor receptor inhibitors in the NCI60 cell lines

PURPOSE

The mechanism of sensitivity and resistance to epidermal growth factor receptor (EGFR) inhibitors is incompletely understood, particularly in cancers other than non-small-cell lung cancer (NSCLC). To understand the variable response to this class of drugs, we used the NCI60 cancer cell lines. We aimed to determine if there are interactions between EGFR expression, mutations, polymorphisms, and gene amplification, and whether these factors are associated with variability in response to EGFR inhibitors.

EXPERIMENTAL DESIGN

The EGFRVIII and tyrosine kinase (TK) domain mutations were examined in the NCI60 cancer cell lines. Five polymorphisms, -216G/T, -191C/A, intron 1 (CA)n, R497K, and 2607A/G, were genotyped. EGFR amplification was also assessed with high-density single-nucleotide polymorphism chip and real-time PCR, respectively. The results were correlated with cytotoxicity data for erlotinib and other 11 EGFR inhibitors, as well as other publicly available data for these lines.

RESULTS

All 12 inhibitors behaved similarly. No EGFRVIII but putative TK mutations in two cell lines were found. Both mutant cell lines were insensitive to all inhibitors. Meanwhile, response did not correlate with EGFR amplification but with EGFR gene expression, especially in the cell lines with relatively normal gene status. In addition, EGFR expression was associated with the -216G/T polymorphism but not with the intron 1 (CA)n polymorphism. A combination of -216G/T and R497K polymorphisms was weakly associated with drug response.

CONCLUSIONS

These observations suggest that in addition to TK mutations, germ-line variability may also contribute to the pharmacodynamics of EGFR inhibitors, particularly when EGFR is genetically normal.