Differential responses by pancreatic carcinoma cell lines to prolonged exposure to Erbitux (IMC-C225) anti-EGFR antibody

Establishing and validating an ADCP-related prognostic signature in pancreatic ductal adenocarcinoma

With the progress of precision medicine treatment in pancreatic ductal adenocarcinoma (PDAC), individualized cancer-related examination and prediction is of great importance in this high malignant tumor, and antibody-dependent cell phagocytosis (ADCP) with changed pathways highly enrolled in the carcinogenesis of PDAC. High-throughput data of pancreatic ductal adenocarcinoma were downloaded and 160 differentially expressed ADCP-related genes (ARGs) were obtained. Secondly, GO and KEGG enrichment analyses show that ADCP is a pivotal biologic process in pancreatic carcinogenesis. Next, CALB2, NLGN2, NCAPG and SERTAD2 are identified through multivariate Cox regression. These 4 genes are confirmed with significant prognostic value in PDAC. Then, a risk score formula is constructed and tested in PDAC samples. Finally, the correlation between these 4 genes and M2 macrophage polarization was screened. Some pivotal differentially expressed ADCP-related genes and biologic processes, four pivotal subgroup was among identified in the protein-protein network, and hub genes was found in these sub group. Then, an ADCP-related formula was set: CALB2* 0.355526 + NLGN2* -0.86862 + NCAPG* 0.932348 + SERTAD2* 1.153568. Additionally, the significant correlation between M2 macrophage-infiltration and the expression of each genes in PDAC samples was identified. Finally, the somatic mutation landscape and sensitive chemotherapy drug between high risk group and low risk group was explored. This study provides a potential prognostic signature for predicting prognosis of PDAC patients and molecular insights of ADCP in PDAC, and the formula focusing on the prognosis of PDAC can be effective. These findings will contribute to the precision medicine of pancreatic ductal adenocarcinoma treatment.

Antibody therapy in pancreatic cancer: mAb-ye we're onto something?

Pancreatic cancer remains an extremely deadly disease, with little improvement seen in treatment or outcomes over the last 40 years. Targeted monoclonal antibody therapy is one area that has been explored in attempts to tackle this disease. This review examines antibodies that have undergone clinical evaluation in pancreatic cancer. These antibodies target a wide variety of molecules, including tumour cell surface, stromal, immune and embryonic pathway targets. We discuss the therapeutic utility of these therapies both as monotherapeutics and in combination with other treatments such as chemotherapy. While antibody therapy for pancreatic cancer has yet to yield significant success, lessons learned from research thus far highlights future directions that may help overcome observed hurdles to yield clinically efficacious results.

Repurposing of Cetuximab in antibody-directed chemotherapy-loaded nanoparticles in EGFR therapy-resistant pancreatic tumours

The anti-Epidermal Growth Factor Receptor (EGFR) antibody Cetuximab (CTX) has demonstrated limited anti-cancer efficacy in cells overexpressing EGFR due to activating mutations in RAS in solid tumours, such as pancreatic cancer. The utilisation of antibodies as targeting components of antibody-drug conjugates, such as trastuzumab emtansine (Kadcyla), demonstrates that antibodies may be repurposed to direct therapeutic agents to antibody-resistant cancers. Here we investigated the use of CTX as a targeting agent for camptothecin (CPT)-loaded polymeric nanoparticles (NPs) directed against KRAS mutant CTX-resistant cancer cells. CPT was encapsulated within poly(lactic-co-glycolic acid) (PLGA) NPs using the solvent evaporation method. CTX conjugation improved NP binding and delivery of CPT to CTX-resistant cancer cell lines. CTX successfully targeted CPT-loaded NPs to mutant KRAS PANC-1 tumours in vivo and reduced tumour growth. This study highlights that CTX can be repurposed as a targeting agent against CTX-resistant cancers and that antibody repositioning may be applicable to other antibodies restricted by resistance.

Targeted therapies for pancreatic adenocarcinoma: Where do we stand, how far can we go?

Pancreatic adenocarcinoma (usually referred to as pancreatic cancer) is a highly lethal and aggressive malignancy with a disease-related mortality almost equaling its incidence, and one of the most challenging cancers to treat. The notorious resistance of pancreatic cancer not only to conventional cytotoxic therapies but also to almost all targeted agents developed to date, continues to puzzle the oncological community and represents one of the biggest hurdles to reducing the death toll from this ominous disease. This editorial highlights the most important recent advances in preclinical and clinical research, with regards to targeted therapeutics for pancreatic cancer, outlines current challenges and provides an overview of potential future perspectives in this rapidly evolving field.

In vitro and in vivo antitumor activity of cetuximab in human gastric cancer cell lines in relation to epidermal growth factor receptor (EGFR) expression and mutational phenotype

BACKGROUND

Targeting the epidermal growth factor receptor (EGFR) pathway is an important approach for a variety of tumors. This study assessed the effect of cetuximab, an anti-EGFR monoclonal antibody, on three gastric cancer cell lines with different phenotypes in vitro and in a therapeutic orthotopic murine gastric cancer model.

METHODS

Three human gastric cancer cell lines (AGS, MKN-45, NCI-N87) were evaluated for cell surface EGFR expression, and K-ras and BRAF mutations. In vitro, the effects of cetuximab, carboplatin, irinotecan, and docetaxel were investigated. Orthotopic tumors derived from MKN-45 and NCI-N87 were established in nude mice. After 4 weeks, the animals received cetuximab (1 mg/kg, weekly i.p.) or carboplatin (20 mg/kg, weekly i.p.), or both agents. The volume of the primary tumor and local and systemic tumor spread were determined at autopsy at 14 weeks. Tumor sections were immunostained for EGFR, as well as stained for CD31 to analyze microvessel density.

RESULTS

Cell surface expression of EGFR was found only in AGS and NCI-N87 cells. AGS cells displayed a codon 12 K-ras mutation, and all three cell lines were BRAF wild-type. In vitro, cetuximab significantly reduced cell viability and proliferation only in EGFR-positive/K-ras wild-type NCI-N87 cells (-48%). In vivo, cetuximab in combination with carboplatin synergistically reduced tumor volume (-75%), dissemination (-63%), and vascularization (-47%) in NCI-N87 xenografts. Tumors derived from EGFR-negative MKN-45 cells were unaffected by cetuximab.

CONCLUSIONS

Cetuximab is effective in K-ras wild-type, EGFR-expressing gastric cancer cell lines and xenografts. In vivo, the combination of cetuximab with carboplatin displayed synergistic antitumor activity.

Growth and metastasis suppression of glioma xenografts expressing exon 4-deletion variant of epidermal growth factor receptor by monoclonal antibody CH12-mediated receptor degradation

We recently isolated an exon-4-deleted epidermal growth factor receptor (EGFR) variant, termed de4 EGFR. Because the extracellular domain alteration of receptors often influences the antitumor effect of therapeutic antibodies, it is essential to test the sensitivity of de4 EGFR(+) tumors to anti-EGFR antibodies. Therefore, in this study, the antitumor activities of mAb CH12, an anti-EGFRvIII antibody developed in our laboratory, as well as a U.S. Food and Drug Administration-approved anti-EGFR antibody, cetuximab (C225), were characterized on de4 EGFR(+) models. The results of FACS assays showed that CH12 bound to de4 EGFR with a higher avidity than did C225. Interestingly, CH12, but not C225, significantly inhibited the metastasis and growth of U87MG-de4 EGFR xenografts, with a growth-inhibition ratio of 46.48% in vivo, and prolonged the survival of the tumor-bearing mice by 37.2%. Treatment with CH12 significantly suppressed tumor proliferation and angiogenesis with increased tumor apoptosis. Mechanistically, de4 EGFR protein expression was virtually undetectable in the U87MG-de4 EGFR xenografts treated with CH12. This may account for the observed reduction of Akt and Erk phosphorylation, cyclin D1, Bcl-2, and Bcl-x(L) expression and the increase of p27 and E-cadherin expression. Intriguingly, LAMP-1, a major component of the lysosome, was significantly up-regulated in the CH12-treated group but not in the C225-treated group, suggesting its contribution to the degradation of de4 EGFR. Taken together, our data demonstrated that mAb CH12 is a promising therapeutic agent for treating de4 EGFR(+) gliomas.

Efficient blockade of Akt signaling is a determinant factor to overcome resistance to matuzumab

BACKGROUND

Clinical studies have shown antineoplastic effectiveness of monoclonal antibodies (MAbs) against EGFR for different indications. Several MAbs directed to EGFR were developed recently, such as matuzumab, but there is still lack of information on preclinical data on its combination with chemo-radiation. Thus, the present study intended to examine the molecular pathways triggered by matuzumab alone or associated to chemo-radiotherapy in gynecological cell lines and its impact on cell growth and signaling.

RESULTS

Combination of matuzumab with radiation and cisplatin did not enhance its cytostatic effects on A431, Caski and C33A cells (high, intermediate and low EGFR expression, respectively) in clonogenic assays, when compared to controls. The lack of effect was mediated by persistent signaling through EGFR due to its impaired degradation. In spite of the fact that matuzumab inhibited phosphorylation of EGFR, it had no effect upon cell viability. To analyze which downstream molecules would be involved in the EGFR signaling in the presence of matuzumab, we have tested it in combination with either PD98059 (MAPK inhibitor), or LY294002 (PI3K inhibitor). Matuzumab exhibited a synergic effect with LY294002, leading to a reduction of Akt phosphorylation that was followed by a decrease in A431 and Caski cells survival. The combination of PD98059 and matuzumab did not show the same effect suggesting that PI3K is an important effector of EGFR signaling in matuzumab-treated cells. Nonetheless, matuzumab induced ADCC in Caski cells, but not in the C33A cell line, suggesting that its potential therapeutic effects in vitro are indeed dependent on EGFR expression.

CONCLUSIONS

Matuzumab combined with chemoradiation did not induce cytotoxic effects on gynecological cancer cell lines in vitro, most likely due to impaired EGFR degradation. However, a combination of matuzumab and PI3K inhibitor synergistically inhibited pAkt and cell survival, suggesting that the use of PI3K/Akt inhibitors could overcome intrinsic resistance to matuzumab in vitro. Altogether, data presented here can pave the way to a rational design of clinical strategies in patients with resistant profile to anti-EGFR inhibitors based on combination therapy.

Molecular targeted approaches for treatment of pancreatic cancer

Human pancreatic cancer remains a highly malignant disease with almost similar incidence and mortality despite extensive research. Many targeted therapies are under development. However, clinical investigation showed that single targeted therapies and most combined therapies were not able to improve the prognosis of this disease, even though some of these therapies had excellent anti-tumor effects in pre-clinical models. Cross-talk between cell proliferation signaling pathways may be an important phenomenon in pancreatic cancer, which may result in cancer cell survival even though some pathways are blocked by targeted therapy. Pancreatic cancer may possess different characteristics and targets in different stages of pathogenesis, maintenance and metastasis. Sensitivity to therapy may also vary for cancer cells at different stages. The unique pancreatic cancer structure with abundant stroma creates a tumor microenvironment with hypoxia and low blood perfusion rate, which prevents drug delivery to cancer cells. In this review, the most commonly investigated targeted therapies in pancreatic cancer treatment are discussed. However, how to combine these targeted therapies and/or combine them with chemotherapy to improve the survival rate of pancreatic cancer is still a challenge. Genomic and proteomic studies using pancreatic cancer samples obtained from either biopsy or surgery are recommended to individualize tumor characters and to perform drug sensitivity study in order to design a tailored therapy with minimal side effects. These studies may help to further investigate tumor pathogenesis, maintenance and metastasis to create cellular expression profiles at different stages. Integration of the information obtained needs to be performed from multiple levels and dimensions in order to develop a successful targeted therapy.

Epithelial-to-mesenchymal transition and c-myc expression are the determinants of cetuximab-induced enhancement of squamous cell carcinoma radioresponse

PURPOSE

Radiation therapy cures malignant tumors of the head and neck region more effectively when it is combined with application of the anti-EGFR monoclonal antibody cetuximab. Despite the successes achieved, we still do not know how to select patients who will respond to this combination of anti-EGFR monoclonal antibody and radiation. This study was conducted to elucidate possible mechanisms which cause the combined treatment with cetuximab and irradiation to fail in some cases of squamous cell carcinomas.

METHODS AND MATERIALS

Mice bearing FaDu and A431 squamous cell carcinoma xenograft tumors were treated with cetuximab (total dose 3 mg, intraperitoneally), irradiation (10 Gy) or their combination at the same doses. Treatment was applied when tumors reached 8mm in size. To collect samples for further protein analysis (two-dimensional differential gel electrophoresis (2-D DIGE), mass spectrometry MALDI-TOF/TOF, Western blot analysis, and ELISA), mice from each group were sacrificed on the 8th day after the first injection of cetuximab. Other mice were subjected to tumor growth delay assay.

RESULTS

In FaDu xenografts, treatment with cetuximab alone was nearly as effective as cetuximab combined with ionizing radiation, whereas A431 tumors responded to the combined treatment with significantly enhanced delay in tumor growth. Tumors extracted from the untreated FaDu and A431 xenografts were analysed for protein expression, and 34 proteins that were differently expressed in the two tumor types were identified. The majority of these proteins are closely related to intratumoral angiogenesis, cell adhesion, motility, differentiation, epithelial-to-mesenchymal transition (EMT), c-myc signaling and DNA repair.

CONCLUSIONS

The failure of cetuximab to enhance radiation response in FaDu xenografts was associated with the initiation of the program of EMT and with c-myc up-regulation in the carcinoma cells. For this reason, c-myc and EMT-related proteins (E-cadherin, vimentin) may be considered as potential biomarkers to predict squamous cell carcinoma response after treatment with cetuximab in combination with radiation.

A review of kinases implicated in pancreatic cancer

The current 5-year survival rate of pancreatic cancer is about 3% and the median survival less than 6 months because the chemotherapy and radiation therapy presently available provide only marginal benefit. Clearly, pancreatic cancer requires new therapeutic concepts. Recently, the kinase inhibitors imatinib and gefitinib, developed to treat chronic myelogenous leukaemia and breast cancer, respectively, gave very good results. Kinases are deregulated in many diseases, including cancer. Given that phosphorylation controls cell survival signalling, strategies targeting kinases should obviously improve cancer treatment. The purpose of this review is to summarize the present knowledge on kinases potentially usable as therapeutic targets in the treatment of pancreatic cancer. All clinical trials using available kinase inhibitors in monotherapy or in combination with chemotherapeutic drugs failed to improve survival of patients with pancreatic cancer. To detect kinases relevant to this disease, we undertook a systematic screening of the human kinome to define a 'survival kinase' catalogue for pancreatic cells. We selected 56 kinases that are potential therapeutic targets in pancreatic cancer. Preclinical studies using combined inhibition of PAK7, MAP3K7 and CK2 survival kinases in vitro and in vivo showed a cumulative effect on apoptosis induction. We also observed that these three kinases are rather specific of pancreatic cancer cells. In conclusion, if kinase inhibitors presently available are unfortunately not efficient for treating pancreatic cancer, recent data suggest that inhibitors of other kinases, involved more specifically in pancreatic cancer development, might, in the future, become interesting therapeutic targets.

Immunohistochemical expression of HER-2/NEU-CERBB-2 in patients with adenocarcinoma of the stomach

OBJECTIVES: To determine the prevalence of Her-2/Neu-cerbb-2 in the gastric mucosa of patients with gastric adenocarcinoma in a brazilian patient group. METHODS: The immunohistochemical expression of Her-2/Neu was studied in 37 formalin-fixed paraffin-embedded tissue sections. RESULTS: The immunohistochemical reaction produced by the anti-HER-2/Neu antibody was positive in two cases (5.4%). CONCLUSION: The low prevalence of Her-2/Neu observed in these southern brazilian cases is probably due to the great number of poorly differentiated cancers in this serie.

Monoclonal antibodies in the treatment of pancreatic cancer

Human pancreatic cancer is a malignant disease with almost equal incidence and mortality. Effective diagnostic and therapeutic strategies are still urgently needed to improve its survival rate. With advances in structural and functional genomics, recent work has focused on targeted molecular therapy using monoclonal antibodies. This review summarizes the target molecules on the tumor cell surface and normal tissue stroma, which are related to pancreatic cancer oncogenesis, tumor growth or resistance to chemotherapy, as well as molecules involved in regulating inflammation and host immunoresponses. Targeted molecules include cell-surface receptors, such as the EGF receptor, HER2, death receptor 5 and IGF-1 receptor. Effects of monoclonal antibodies against these target molecules alone or in combination with chemotherapy, small-molecule signal transduction inhibitors, or radiation therapy are also discussed. Also discussed are the use of toxin or radioisotope conjugates, and information relating to the use of these targeting agents in pancreatic cancer clinical trials. Although targeted molecular therapy with monoclonal antibodies has made some progress in pancreatic cancer treatment, especially in preclinical studies, its clinical application to improve the survival rate of pancreatic cancer patients requires further investigation.

Pancreatic cancer: from molecular pathogenesis to targeted therapy

Pancreatic cancer is a deadly malignancy with still high mortality and poor survival despite the significant advances in understanding, diagnosis, and access to conventional and novel treatments. Though cytotoxic chemotherapy based on the purine analogue gemcitabine remains the standard approach in adjuvant and palliative setting the need for novel agents aiming at the main pathophysiological abnormalities and molecular pathways involved remains soaring. So far, evidence of clinical benefit, though small, exists only from the addition of the targeted agent erlotinib on the standard gemcitabine chemotherapy. Apart from the popular monoclonal antibodies and small molecules tyrosine kinase inhibitors, other novel compounds being tested in preclinical and clinical studies target mTOR, NF-kappaB, proteasome and histone deacetylase. These new drugs along with gene therapy and immunotherapy, which are also under clinical evaluation, may alter the unfavorable natural course of this disease. In this review we present the main pathophysiological alterations met in pancreatic cancer and the results of the florid preclinical and clinical research with regards to the targeted therapy associated to these abnormalities.

The combination of epidermal growth factor receptor inhibitors with gemcitabine and radiation in pancreatic cancer

PURPOSE

Gemcitabine-radiotherapy is a standard treatment for locally advanced pancreatic cancer. Clinical data have shown that gemcitabine plus erlotinib is superior to gemcitabine alone for advanced pancreatic cancer. Therefore, we investigated the effects of the combination of epidermal growth factor receptor inhibitors with gemcitabine and radiation on a pancreatic cancer model.

EXPERIMENTAL DESIGN

EGFR signaling was analyzed by measuring phosphorylated EGFR (pEGFR(Y845, (Y1173)) and AKT (pAKT(S473)) protein levels in pancreatic cancer cell lines and tumors. The effects of scheduling on gemcitabine-mediated cytotoxicity and radiosensitization combined with erlotinib were determined by clonogenic survival. In vivo, the effects of cetuximab or erlotinib in combination with gemcitabine-radiation on the growth of BxPC-3 tumor xenografts were measured.

RESULTS

We found in vitro that gemcitabine induced phosphorylation of EGFR at Y845 and Y1173 that was blocked by erlotinib. Treatment of BxPC-3 cells with gemcitabine before erlotinib enhanced gemcitabine-mediated cytotoxicity without abrogating radiosensitization. In vivo, cetuximab or erlotinib in combination with gemcitabine-radiation inhibited growth compared with gemcitabine-radiation (time to tumor doubling: gemcitabine + radiation, 19 +/- 3 days; cetuximab + gemcitabine + radiation, 30 +/- 3 days; P < 0.05, erlotinib + gemcitabine + radiation 28 +/- 3 days; P < 0.1). Cetuximab or erlotinib in combination with gemcitabine-radiation resulted in significant inhibition of pEGFR(Y1173) and pAKT(S473) early in treatment, and pEGFR(Y845), pEGFR(Y1173), and pAKT(S473) by the end of treatment. This study shows a novel difference pEGFR(Y845) and pEGFR(Y1173) in response to EGFR inhibition.

CONCLUSIONS

These results show that the EGFR inhibitors cetuximab and erlotinib increase the efficacy of gemcitabine-radiation. This work supports the integration of EGFR inhibitors with gemcitabine-radiation in clinical trials for pancreatic cancer.

Erlotinib: the first biologic in the management of pancreatic cancer

BACKGROUND

Pancreatic cancer remains a major therapeutic challenge largely characterized by chemotherapy-refractory disease and poor responses to currently available treatments. Pivotal studies of combination chemotherapeutic agents with gemcitabine showed that responses may exceed single-agent gemcitabine, but with added toxicities. The EGFR is known to be overexpressed in pancreatic cancer and data suggest that the presence of EGFR is associated with a poor prognosis.

OBJECTIVE

To analyze the current data on erlotinib and compare against other agents targeting against the EGFR pathway in pancreatic cancer.

METHODS

PubMed, Ovid, Cochran and the American Society of Clinical Oncology abstract database were searched using the terms 'erlotinib', 'EGFR', 'cetuximab', 'gemcitabine', 'fluorouracil', 'capecitabine' and 'pancreatic cancer' to identify relevant studies. Only studies using erlotinib in pancreatic cancer patients were reviewed and analyzed.

CONCLUSIONS

The combination of gemcitabine and erlotinib is the first combination therapy to demonstrate survival benefits in pancreatic cancer in a Phase III study albeit a modest one. Increased understanding of the EGFR pathway may permit the use of other targeted agents to either augment therapeutic efficacy or circumvent resistance. It is warranted to develop strategies to truly target our therapy with the EGFR agents by identifying those patients who are most likely to derive benefit and achieve meaningful responses.

Administration of cetuximab every 2 weeks in the treatment of metastatic colorectal cancer: an effective, more convenient alternative to weekly administration?

The primary purpose of this paper is to present the available evidence for the administration of cetuximab on an every-2-weeks basis in combination with irinotecan in metastatic colorectal cancer (mCRC). Cetuximab is an epidermal growth factor receptor-targeted IgG(1) monoclonal antibody that is approved for use in combination with irinotecan or as monotherapy in the treatment of mCRC. The currently approved dosing regimen for cetuximab is a 400-mg/m(2) initial dose followed by 250 mg/m(2) weekly. Many commonly used chemotherapy agents for mCRC (including irinotecan alone or in combination with 5-fluorouracil [5-FU]/folinic acid [FA] and oxaliplatin plus 5-FU/FA) are administered on an every-2-weeks basis. The ability to synchronize the administration of cetuximab and concomitant chemotherapy is desirable for both patients and health care workers. A cetuximab dose of 500 mg/m(2) every 2 weeks exhibited predictable pharmacokinetics, which were similar to those of the approved weekly dosing regimen. Active serum concentrations of cetuximab were maintained throughout the 2-week dosing period with this regimen. There was no difference between the dosing regimens on pharmacodynamic parameters in skin. The efficacy and safety of the every-2-weeks dosing regimen were similar to those reported for the approved weekly dosing regimen. The indication from these preliminary findings is that every-2-weeks administration of cetuximab (500 mg/m(2)) may be a potentially convenient alternative to the approved weekly dosing regimen of 250 mg/m(2) (following an initial dose of 400 mg/m(2)) in the treatment of mCRC.

Complete remission of a metastatic pancreatic carcinoma after modified G-FLIP therapy

This is a report about a patient who had a complete remission of a metastatic pancreatic adenocarcinoma after a modified G-FLIP therapy administered in an outpatient setting. The patient underwent surgery and the complete remission could be proven histologically. The administered chemotherapy was very effective and is even more attractive since it could be administered without admission to hospital.

Emerging drugs for the treatment of pancreatic cancer

Treatment of pancreatic cancer remains challenging today and mostly palliative. Despite many efforts to understand the underlying mechanisms of this aggressive tumoral phenotype and to develop new therapeutic agents, advances in its management and survival benefit are poor. Although gemcitabine remains the backbone of routine therapy in advanced disease, newer drugs, mainly constituted by (multi)targeted agents, represent promising therapeutic areas. In this setting, anti-EGF receptor, antiangiogenic or both therapies combined appear to have valuable potential, providing their optimal and comprehensive development and use in pancreatic cancer. Multitargeted agents, such as receptor tyrosine kinase inhibitor small molecules, combining different therapeutic interventions, also deserve new preclinical and clinical development, supported and paralleled by a translational approach. Over the next few years, we need to identify new target mechanisms in pancreatic carcinogenesis, to rapidly test selected drugs against these targets and imperatively to understand and determine which patients respond and who will benefit from such therapies. Significant advances should be immediately evaluated in the perioperative setting in order to improve the curative approach of this devastating disease.

Novel therapeutic approaches in the treatment of advanced pancreatic carcinoma

Pancreatic cancer is still a malignant disease of grim prognosis despite all therapeutic efforts. Because clinical symptoms in the early stage are usually absent or aspecific, it is frequently discovered at advanced or metastatic stage, only around 15-20% of tumors are resectable. In the majority of patients only the chemotherapy offers a prolongation of life, but even the first-line chemotherapeutic agent, the gemcitabine has a modest survival benefit, and objective tumor response is rarely achieved. Combination of various cytostatics did not produce a significant improvement either. For that reason, continuous search for other agents is mandatory. Nowadays, in the era of molecular-targeted oncotherapeutic approaches, pancreatic cancer is also a subject such trials: epidermal growth factor receptor blockade, inhibition of angiogenesis, modulation of tumor response through the extracellular matrix, inhibition of cyclooxygenase-2, farnesyl transferase inhibitors, signal transduction inhibitors, ablation of the hormonal influence and some other aspects have all been studies, but to date, no breakthrough in the treatment of pancreatic carcinoma is proven. In several Phase II-III studies these compounds given alone displayed marginal effects, but when combined with the standard cytostatics, some beneficial effects were observed, however, some of them displayed a severe (sometimes fatal) toxicity. To date, the role of the molecular targeted therapy in pancreatic carcinoma is promising, but the results are not convincingly superior to the standard chemotherapeutic treatments. Pancreatic adenocarcinoma remains a great challenge for the oncologists, and continuous search for better molecules and/or combinations is inevitable.

Differential effects of cetuximab and AEE 788 on epidermal growth factor receptor (EGF-R) and vascular endothelial growth factor receptor (VEGF-R) in thyroid cancer cell lines

This study evaluated the role of EGF and the effects of EGF-targeting drugs (Cetuximab, AEE 788) on growth, apoptosis, and autocrine VEGF-secretion of thyroid cancer (TC) cells. Autocrine activation of the epidermal growth factor receptor (EGF-R) is commonly regarded to contribute to the malignant phenotype of TC cells and may therefore represent a rational therapeutic target. Out of a number of TC cell lines two anaplastic (Hth74, C643), one follicular (FTC133), and one papillary thyroid cancer cell line (TPC1) were analyzed in depth for VEGF-R-and EGF-R-expression, basal and EGF-stimulated (1-100 ng/ml) VEGF protein secretion and proliferation. Subsequently the antiprolifereative and antiangiogenic effect of cetuximab (Erbitux), a monoclonal antibody that blocks the EGF-R and AEE 788, a novel dual-kinase inhibitor of EGF-R and VEGF-R were assessed, and the downstream EGF-R signal transduction was analyzed by means of detecting phosphorylated pEGF-R, pVEGF-R, pAkt, and p-MAPK. EGF stimulated VEGF-mRNA expression and protein secretion in all TC cell lines. The EGF-R antagonist Cetuximab consistently decreased VEGF secretion in all TC cell lines (min. 15%, n.s. in C643 cells and max. 90% in Hth74 cells, P < 0.05), but did not affect tumor cell proliferation in vitro. In contrast, the EGF-R- and VEGF-R-kinase inhibitor AEE 788 not only reduced VEGF secretion (min. 55%, P < 0.05 in C643 and max. 75%, P < 0.05, in FTC133), but also exhibited a dose-dependent inhibition of tumor cell proliferation (min. 75%, P < 0.05 in C643 and max. 95%, P < 0.05 in Hth74) and was a potent inductor of apoptosis in two of four TC cell lines. These effects were always accompanied by reduced levels of pEGF-R, pVEGF-R, pAkt, and pMAPK. Although inhibition of the EGF-receptor by Cetuximab potently disrupts autocrine secretion of VEGF, only the concurrent inhibition of the VEGF- and EGF receptor, e.g., by AEE 788 induces reduced proliferation and apoptosis in vitro. This suggests a particular rationale for the use of tyrosine kinase inhibitors with dual modes of action such as AEE 788 in thyroid cancer.

HER family inhibitors in pancreatic cancer: current status and future directions

Pancreatic cancer is characterized by multiple genetic abnormalities that can be used as targets for specific therapeutics. The HER family consists of four transmembrane growth factor receptors. Targeting HER1 with the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib demonstrated a survival advantage for patients with advanced pancreatic cancer. Multiple other agents that target members of the HER family are under investigation. These include reversible and irreversible, single and pan HER tyrosine kinase inhibitors. Chimeric, humanized and fully human monoclonal antibodies that target specific HER receptors are also being studied. These agents are also radiation sensitizers. This article reviews clinical trials of HER family inhibitors in pancreatic cancer, discusses the role of these agents in the management of patients and outlines future directions for pancreatic cancer management.

Prolonged exposure of colon cancer cells to the epidermal growth factor receptor inhibitor gefitinib (Iressa™) and to the antiangiogenic agent ZD6474: Cytotoxic and biomolecular effects

AIM: To analyze the biological effects of prolonged in vitro exposure of HT-29 and LoVo colon cancer cell lines to gefitinib (Iressa™), an inhibitor of epidermal growth factor receptor (EGFR) activity, and ZD6474, an inhibitor of both KDR and EGFR activities.

METHODS: Cells were treated with each drug for up to 2 wk using either a continuous or an intermittent (4 d of drug exposure followed by 3 d of washout each week) schedule.

RESULTS: In both cell types, prolonged exposure (up to 14 d) to gefitinib or ZD6474 produced a similar inhibition of cell growth that was persistent and independent of the treatment schedule. The effects on cell growth were associated with a pronounced inhibition of p-EGFR and/or p-KDR expression. Treatment with gefitinib or ZD6474 also inhibited the expression of EGFR downstream signal molecules, p-Erk1/2 and p-Akt, although the magnitude of these effects varied between treatments and cell lines. Furthermore, expression of the drug resistance-related protein ABCG2 was shown to significantly increase after 14 d of continuous exposure to the two drugs.

CONCLUSION: We conclude that long-term exposure of colon cancer cells to gefitinib and ZD6474 does not modify their cytotoxic effects but it might have an effect on sensitivity to classical cytotoxic drugs.

Pancreatic cancer: from bench to 5-year survival

Pancreatic ductal adenocarcinoma is one of the most aggressive human malignancies, with an overall 5-year survival rate of less than 4%. On the molecular level, an increasing number of genetic and epigenetic alterations have been discovered, with a particular focus on growth factors and related pathways. Small-molecule tyrosine kinase inhibitors, antibodies, and other approaches have been developed in recent years to target these signal transduction pathways, and first clinical trials show encouraging results. In addition, molecular alterations have been identified that enable the cancer cells to invade the perineurium and the retroperitoneal space, thus explaining at least in part the high rate of local recurrence and the severe pain syndrome. Technically, pancreatic surgery has advanced, with acceptable morbidity and mortality rates in high-volume centers. Randomized controlled trials are increasingly carried out to define the best palliative and adjuvant therapy for this disease. Translational research combined with clinical trials will hopefully lead to improved survival and better quality of life for pancreatic cancer patients in the future.

Recent advances on the molecular mechanisms involved in pancreatic cancer progression and therapies

This review describes the recent advances in the molecular events involved in pancreatic cancer initiation, progression, and metastasis. Additionally, the importance of deregulated cellular signaling elements as potential targets for developing novel therapeutic strategies against incurable forms of pancreatic cancer is reported. The emphasis is on the critical functions gained by numerous growth factors and their receptors, such as epidermal growth factor receptor, hedgehog signaling, and proangiogenic agents such as vascular endothelial factor and interleukin-8 for the sustained growth, survival, and metastasis of pancreatic cancer cells. The molecular mechanisms associated with antitumoral properties and the clinical benefits of gemcitabine alone or in combination with other cytotoxic agents for the treatment of pancreatic cancer are discussed.

The Evolution of Antibodies into Versatile Tumor-Targeting Agents

In recent years, monoclonal antibodies have become important weapons in the arsenal of anticancer drugs, and in select cases are now the drugs of choice due to their favorable toxicity profiles. Originally developed to confer passive immunity against tumor-specific antigens, clinical uses of monoclonal antibodies are expanding to include growth factor sequestration, signal transduction modulation, and tumor-specific drug delivery. In this review, we shall present the origins of antibody therapeutics within the field of immunotherapy and their evolution into effective anticancer agents, then discuss their multiple mechanisms of action, the basis of their tumor selectivity, and their therapeutic properties compared with traditional therapies. Antibodies are complex molecules whose efficacy and toxicity depend on the antigen, the antibody, any conjugated groups, and even the patient. Finally, we shall present new technologies being developed to increase the efficacy and selectivity of antibody-based therapeutics. Interestingly, many of the new approaches straddle the middle ground between immunotherapy and the traditional modalities of chemotherapy and radiotherapy, and can be seen as ways of combining the selectivity of the former with the efficacy of the latter.

Mechanisms of resistance to Erbitux (anti-epidermal growth factor receptor) combination therapy in pancreatic adenocarcinoma cells

We previously demonstrated that pancreatic adenocarcinoma BxPC-3 xenografts display resistance to treatment with Erbitux, gemcitabine, and radiation, whereas MIA PaCa-2 xenografts are highly sensitive to the same therapy. Here, we elucidate in vitro mechanisms that may explain the observed differential response of epidermal growth factor receptor (EGFR) expressing pancreatic adenocarcinoma xenografts to Erbitux-based combination therapy in vivo. MIA PaCa-2 and BxPC-3 protein lysates were probed with antibodies to EGFR, ErbB2, ErbB3, and ErbB4. Constitutive ErbB3 activity was visualized by immunoblot analysis using anti-phosphotyrosine antibodies and receptor-specific immunoprecipitates. erbB2 and erbB3 gene expression in both cell lines was quantified with real-time polymerase chain reaction. Erbitux-induced internalization of EGFR was determined by flow cytometry following Erbitux treatment for different incubation times at 0 degrees C and 37 degrees C. MIA PaCa-2 and BxPC-3 protein extracts were also probed with anti-phospho-mitogen-activated protein kinase antibody after stimulation with EGF and in the presence of Erbitux. Although both cell lines expressed EGFR and ErbB2 protein, ErbB3 protein was selectively expressed by BxPC-3 cells, where it also showed evidence of constitutive phosphorylation. There was a 10-fold increase of erbB3 transcript levels in BxPC-3 cells compared with MIA PaCa-2. ErbB4 protein was not detectable in either cell line. Erbitux mediated EGFR internalization in MIA PaCa-2 cells after 2 hours of incubation, whereas it did not promote EGFR internalization in BxPC-3 cells. Likewise, EGF-dependent phosphorylation of MAPK p44/42 was blocked by Erbitux treatment in MIA PaCa-2 but not BxPC-3 cells. Erbitux selectively interfered with EGF-induced MAPK activation in MIA PaCa-2 but not BxPC-3 cells. Persistent MAPK activation and impaired in vitro internalization of EGFR by BxPC-3 pancreatic cancer cells may be due to constitutive ErbB3 signaling, facilitated by heterodimerization with EGFR, which may explain resistance to Erbitux-based combination therapy in vivo.

Bax deficiency rescues resection-induced enterocyte apoptosis in mice with perturbed EGF receptor function

BACKGROUND

Adaptation after massive smallbowel resection (SBR) is associated with increased cell turnover, increased rates of enterocyte proliferation, and apoptosis. Epidermal growth factor receptor (EGFR) inhibition attenuates adaptation and increases apoptosis. Intestinal levels of bax appear to correlate with EGFR signaling. This study tested the hypothesis that bax is required for the exaggerated postresection apoptosis induced by perturbed EGFR signaling.

METHODS

Waved-2 mice with impaired EGFR signaling were crossbred with bax-null mice. Offspring were subjected to either 50% proximal SBR or sham operation (bowel transection and reanastomosis). After 7 days, parameters of adaptation (villus height, wet weight), proliferation (% Ki-67 immunostaining of crypt cells), and apoptosis (# apoptotic bodies per crypt) were recorded in the remnant ileum.

RESULTS

Enterocyte apoptosis was increased in waved-2 mice and prevented in bax-null mice after SBR. The accelerated apoptosis in the waved-2 mice was rescued in the context of deficient bax expression. Other parameters of adaptation were restored in the bax-null/waved-2 mice.

CONCLUSION

Bax is required for the induction of postresection enterocyte apoptosis. Defective EGFR signaling augments resection-induced enterocyte apoptosis via a mechanism that also requires bax expression. These data implicate a link between EGFR signaling and bax in the genesis of postresection apoptosis and adaptation.

Inflammatory mechanisms contributing to pancreatic cancer development

OBJECTIVE

Pancreatic cancer is the most deadly of all gastrointestinal (GI) malignancies, yet relatively little is known regarding mechanisms of tumor development including the role of inflammation.

SUMMARY BACKGROUND DATA

Chronic pancreatitis (CP) increases the risk of developing cancer by 10- to 20-fold; mediators of the chronic inflammatory process and the surrounding fibrotic stroma likely support a transformation to malignancy, yet the exact mechanisms remain undefined. The purpose of our present study was to determine potential inflammatory components in epithelial and stromal cells that may contribute to both CP and pancreatic cancers.

METHODS

Specimens of normal pancreas, CP, and pancreatic cancer were examined using laser-capture microdissection (LCM), gene array, and immunohistochemistry.

RESULTS

Gene array analysis from LCM-dissected tissues demonstrated: (i) increased expression of interleukin-8 (IL-8), an activator of the inflammatory factor nuclear factor-kappaB (NF-kappaB), and (ii) decreased expression of IkappaB (an inhibitor of NF-kappaB) in CP ductal cells compared with normal ducts. Compared with CP, cancers demonstrated: (i) increased expression of tumor related genes including S100A4, cyclin E1, and epidermal growth factor (EGF) receptor, and (ii) expression of matrix metalloproteinase 2, a pro-invasive factor for tumor cells, which was not present in the CP stroma. Increased staining of both the p50 NF-kappaB subunit and IKKalpha kinase (a protein that allows activation of NF-kappaB) was noted in CP and cancers.

CONCLUSIONS

Our results demonstrate that similar inflammatory components and downstream effectors are present in CP and pancreatic cancers. Importantly, these findings suggest that a common pathway for pancreatic cancer development may be through a chronic inflammatory process including stroma formation. These findings may lead to novel strategies for pancreatic cancer prophylaxis based on inhibition of inflammatory mediators.