HER1/EGFR targeting: refining the strategy

The Association of the Epidermal Growth Factor Receptor (EGFR) Immunoexpression With Prognostic Parameters in Adenocarcinoma Patients Receiving Neoadjuvant Treatment

The epidermal growth factor receptor (EGFR) expression is considered to play an essential role in the pathogenesis of colorectal adenocarcinoma. This study assessed the expression and predictive/prognostic value of EGFR expression in pre-op biopsy and post-op resection specimens in patients receiving neoadjuvant radiotherapy/neoadjuvant chemoradiotherapy (NRT/NCRT). Thirty-four consecutive patients were included in this study. The association between the prognostic features and EGFR immunohistochemical expression was analyzed in pre- (n=34) and post-treatment (n=22) tissue samples in cases with available tissue blocks. Of 34, 23 (67.6%) were men. The median age was 60.50 ± 10.69 (range, 31-84) years. EGFR expression was detected in 88.2% of biopsy specimens and in 91.2% of surgical specimens. There was only slight agreement between pre-op and post-op EGFR expression scores (kappa value 0.11). There was no significant correlation between pre-op and post-op EGFR expression scores (p>0.05). Although pre-op EGFR positivity and higher pre-op EGFR scores seemed to indicate a worse prognosis, this association between pre-op EGFR expression and overall survival (OS) or disease-specific survival (DSS) did not reach statistical significance (p>0.05). The only case with a post-op EGFR score of three who died of the disease experienced local recurrence and had distant metastasis. In conclusion, EGFR positivity in pre-op biopsy samples seems to be associated with shorter survival, and increased EGFR expression in post-treatment resection specimens predicts aggressive behavior in patients with rectal adenocarcinoma who received NRT/NCRT. However, due to the molecular heterogeneity, EGFR expression status should be evaluated in resection specimens rather than in pre-op biopsy samples for optimal prognosis prediction.

Effect of Smilax spp. and Phellinus linteus combination on cytotoxicity and cell proliferation of breast cancer cells

BACKGROUND

Although the prevalence of breast cancer (BC) has been reduced in recent years, proficient therapeutic regimens should be further investigated with the aim of further reducing the mortality rate. To obtain more effective treatment, the present study aimed to observe the effects of PL synergistically combined with Smilax corbularia and S. glabra extracts (PSS) on BC cell lines, MCF7, T47D, MDA-MB-231, and MDA-MB-468.

METHODS

The half-maximal inhibition (IC₅₀) concentrations of PSS and PL were determined in a dose- and time-dependent manner using MTT assay. The activity of PSS and PL on anti-BC proliferation was evaluated using BrdU assay, and colony formation assay. Moreover, cell cycle analysis and apoptosis induction as a result of PSS and PL exposure were investigated using propidium iodide (PI) staining and co-staining of annexin V DY634 and PI combined flow cytometric analysis, respectively. Finally, changes in the mRNA expression of genes involved in proliferative and apoptotic pathways (MKI67, HER2, EGFR, MDM2, TNFα, PI3KCA, KRAS, BAX, and CASP8) were explored using RT-qPCR following PSS and PL treatment.

RESULTS

The PSS and PL extracts exhibited significant potential in BC cytotoxicity which were in were in dose- and time-dependent response. This inhibition of cell growth was due to the suppression of cell proliferation, the cell cycle arrest, and the induction of apoptosis. Additionally, an investigation of the underlying molecular mechanism revealed that PSS and PL are involved in downregulation of the MKI67, HER2, EGFR, MDM2, TNFα, and PI3KCA expression.

CONCLUSIONS

This present study has suggested that PSS and PL possess anti-BC proliferative activity mediated via the downregulation of genes participating in the relevant pathways. PSS or PL may be combined with other agents to alleviate the adverse side effects resulted from conventional chemotherapeutic drugs.

A review of efficacy and safety of cetuximab and bevacizumab-based monoclonal antibodies in head and neck cancer

A combination of monoclonal antibodies prescribed along with the conventional standard of care has a potential to provide significant improvement in patients suffering from head and neck cancer. This combination has also shown a significant decrease in toxicities and improved overall quality of life. Cetuximab acts by inhibiting the human epidermal growth factors as its overexpression in head and neck tumours that are responsible for treatment failure, resistance, and metastasis. Whereas, bevacizumab acts by inhibiting the vascular endothelial growth factor since its overexpression leads to induction of tumour angiogenesis. Current research has not shown any remarkable beneficial effect in disease outcomes. Thus, the addition of these monoclonal antibodies to the standard regimen for head and neck cancer can be considered a prospect that might be beneficial. Cetuximab has already been included as an option under special recommendations in recurrent/metastatic head and neck cancer by NCCN in a platinum-based regimen as well as in combination with radiation therapy. This review outlines the applicability of cetuximab and bevacizumab in the treatment of head and neck cancer as well as the clinical trials performed that give an idea about the efficacy and safety of these monoclonal antibodies. Based upon the literature reviewed, it can be deduced that immunotherapy is to be adopted and different targets are to be explored in it in order to combat head and neck cancer. Currently, immunotherapeutic drugs of two major targets have been discussed. These agents are even effective in combination with other therapeutic modalities that are not being able to achieve desirable outcomes due to issues such as resistance and toxicities. Thus, newer targets as well as newer agents acting on established targets are to be explored in order to improve disease outcomes.

A novel EGFR inhibitor suppresses survivin expression and tumor growth in human gefitinib-resistant EGFR-wild type and -T790M non-small cell lung cancer

Tyrosine kinase inhibitors of epidermal growth factor receptor (EGFR-TKIs) are currently used therapy for non-small cell lung cancer (NSCLC) patients; however, drug resistance during cancer treatment is a critical problem. Survivin is an anti-apoptosis protein, which promotes cell proliferation and tumor growth that highly expressed in various human cancers. Here, we show a novel synthetic compound derived from gefitinib, do-decyl-4-(4-(3-(4-(3-chloro-4-fluorophenylamino)-7-methoxyquinazolin-6-yloxy)propyl) piper-azin-1-yl)-4-oxobutanoate, which is named as SP101 that inhibits survivin expression and tumor growth in both the EGFR-wild type and -T790M of NSCLC. SP101 blocked EGFR kinase activity and induced apoptosis in the A549 (EGFR-wild type) and H1975 (EGFR-T790M) lung cancer cells. SP101 reduced survivin proteins and increased active caspase 3 for inducing apoptosis. Ectopic expression of survivin by a survivin-expressed vector attenuated the SP101-induced cell death in lung cancer cells. Moreover, SP101 inhibited the gefitinib-resistant tumor growth in the xenograft human H1975 lung tumors of nude mice. SP101 substantially reduced survivin proteins but conversely elicited active caspase 3 proteins in tumor tissues. Besides, SP101 exerted anticancer abilities in the gefitinib resistant cancer cells separated from pleural effusion of a clinical lung cancer patient. Consistently, SP101 decreased the survivin proteins and the patient-derived xenografted lung tumor growth in nude mice. Anti-tumor ability of SP101 was also confirmed in the murine lung cancer model harboring EGFR T790M-L858R. Together, SP101 is a new EGFR inhibitor with inhibiting survivin that can be developed for treating EGFR wild-type and EGFR-mutational gefitinib-resistance in human lung cancers.

Dermatomyositis following Biosimilar Trastuzumab in a Breast Cancer Patient: A Case Report

Trastuzumab, as a recombinant IgG1 kappa, is a humanized monoclonal antibody against human epidermal growth factor receptor 2. Accordingly, it is widely used in breast cancers at early and advanced stages. Dermatomyositis is a rare adverse event of trastuzumab therapy, which is not well documented yet. In this study, a patient was treated for invasive ductal carcinoma with some symptoms of rash and generalized fatigue. These symptoms started after the fifth cycle of trastuzumab, which were gradually deteriorating. This patient's medical and family histories were unremarkable. The progression of the disease was ruled out as a possible cause of dermatomyositis, and the laboratory evaluation revealed a moderate increase in serum muscle protein (CPK). So, trastuzumab treatment was discontinued, and by passing 1 month from the start of prednisolone and hydroxychloroquine, the patient had no symptoms.

Predictors of Acquired T790M Mutation in Patients Failing First- or Second-Generation Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors

BACKGROUND

This study aims to determine the predictors of acquired exon 20 T790M mutation in advanced non-small cell lung cancer (NSCLC) patients harbouring sensitizing epidermal growth factor receptor (EGFR) mutation following the failure of first- or second-generation EGFR-tyrosine kinase inhibitor (TKI).

METHODS

This is a retrospective observational study of NSCLC patients with sensitising EGFR mutation experiencing disease progression (PD) whilst on first- or second-generation EGFR-TKIs with subsequent investigations to detect acquired T790M mutation at the University of Malaya Medical Centre from 1st January 2015 to 31st December 2017.

RESULTS

A total of 87 patients were included. Upon PD, acquired T790M mutation was found in 55 (63.2%) patients and was significantly more common in patients who achieved partial response (PR) whilst on the EGFR-TKIs (p = 0.008) or had new lung metastasis upon PD (p = 0.048). It was less frequent in patients who developed new symptomatic brain lesions (p = 0.021). Patients with exon 19 deletion were more likely to acquire T790M mutation compared to those with exon 21 L858R point mutation (p = 0.077). Multivariate analysis revealed PR whilst on EGFR-TKI treatment was an independent predictor of acquiring T790M mutation (p = 0.021), whereas development of new symptomatic brain lesions (p = 0.034) or new lymph node metastases (p = 0.038) upon PD was independently against acquiring T790M mutation. Patients with exon 19 deletion were more likely to acquire T790M mutation compared to those with exon 21 L858R point mutation (odds ratio: 2.3, 95% confidence interval: 0.84-6.25, p = 0.104).

CONCLUSION

The best tumour response of PR to first- or second-generation EGFR-TKI treatment independently predicts acquired T790M mutation. Patients with exon 19 deletion are likely to acquire T790M mutation. This would prove useful for clinicians to prognosticate and plan subsequent treatments for patients with advanced NSCLC harbouring EGFR mutations.

Varlitinib Mediates Its Activity Through Down Regulating MAPK/EGFR Pathway in Oral Cancer

Background:

Oral Squamous Cell Carcinoma (OSCC) is a major sub-type of oral cancer that shares 90% proportion of oral cavity cancers. It is declared as the sixth most frequent cancer among all cancer types throughout the world. Higher morbidity in Asian countries is reported due to frequent use of Smokeless Tobacco (SLT) products besides exposure to other risk factors. Hyperactivation of epidermal growth factor receptors is a molecular event in many solid tumors including oral cancer making them potential therapeutic targets.

Objective:

Current study was designed to explore the effect of varlitinib, a pan-HER inhibitor, on oral cancer cell line. We investigated key regulatory genes in downstream pathway in response to drug treatment. Furthermore, we also examined expression profile of these genes in malignant and healthy oral tissue.

Method:

Gene expression pattern in drug treated and untreated cancer cell line along with OSCC tumor samples (n=45) and adjacent normal tissues was studied using real time PCR.

Results:

In response to varlitinib treatment, significant suppression of oncogenes (IGF1R, MAPK1, SFN and CDK2) was observed. Interestingly, mRNA expression level of CDKN1A and Akt1 was found to be the opposite of what was expected. In case of malignant tissue, over expression of oncogenes (IGF1R, Akt1, MAPK1, SFN and CDK2) with simultaneous down expression of tumor suppressor genes (Tp53 and CDKN1A) was noted. STRING analysis indicated a strong association among differentially expressed genes suggesting their combined role in carcinogenesis.

Conclusion:

In summary, our results indicate that varlitinib can be considered as a potential therapeutic agent in oral cancer due to its antitumor potential.

Gynecologic Cancers: Molecular Updates 2018

Ovarian carcinoma continues to be a concern for woman and maintains significant morbidity and mortality. Emerging molecular markers are providing additional opportunities for effective diagnosis and prognosis of disease. An integrated clinicopathologic and molecular classification of gynecologic malignancies has the potential to refine the clinical risk prediction of patients with cancer and to provide more tailored treatment recommendations.

Human Glioma Migration and Infiltration Properties as a Target for Personalized Radiation Medicine

Gliomas are primary brain tumors that present the majority of malignant adult brain tumors. Gliomas are subdivided into low- and high-grade tumors. Despite extensive research in recent years, the prognosis of malignant glioma patients remains poor. This is caused by naturally highly infiltrative capacities as well as high levels of radio- and chemoresistance. Additionally, it was shown that low linear energy transfer (LET) irradiation enhances migration and invasion of several glioma entities which might counteract today’s treatment concepts. However, this finding is discussed controversially. In the era of personalized medicine, this controversial data might be attributed to the patient-specific heterogeneity that ultimately could be used for treatment. Thus, current developments in glioma therapy should be seen in the context of intrinsic and radiation-enhanced migration and invasion. Due to the natural heterogeneity of glioma cells and different radiation responses, a personalized radiation treatment concept is suggested and alternative radiation concepts are discussed.

N-O Reduction and ROS-Mediated AKT/FOXO1 and AKT/P53 Pathways Are Involved in Growth Promotion and Cytotoxicity of Cyadox

Cyadox is a novel derivative of quinoxaline-1,4-dioxides (QdNOs) with the potential to be developed as a feed additive. However, the pharmacological and toxicological bioactive molecules of cyadox and the molecular mechanism of its pharmacological and toxic actions remain unclear. In the present study, cyadox and its main metabolites of cy1, cy4, cy6, and cy12 were selected; the growth promotion characteristic was indicated by the mRNA level of EGF; and the cytotoxicity of cyadox was determined by methylthiazol tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release, and Annexin V-FITC/PI apoptosis detection kit with flow cytometry. The intracellular ROS, cyclin D1, and Akt/P53/FOXO1 signaling pathway were also investigated. Our data suggested that cyadox showed relatively higher activity than its metabolites, and the ROS was generated from N-O reduction of cyadox. Moreover, cyadox (2 μM) activated the Akt and increased the EGF, cyclin D1, and FOXO1 expression levels. Cyadox (100 μM) induced cytotoxicity in L02 cells in a concentration- and time-dependent manner. Additionally, the activated P53 pathway, hyperactivated Akt, and apoptosis were found in L02 cells after incubation with 100 μM cyadox. Our data demonstrated that Akt promoted cell survival when it was mildly activated by cyadox at 2 μM, and Akt leads to apoptosis when it was severely activated by cyadox at 100 μM. Thus, the present study revealed that N-O reduction of cyadox and ROS-mediated AKT/FOXO1 and AKT/P53 pathways were involved in growth promotion and cytotoxicity of cyadox.

Potential anti-proliferative activity of AgNPs synthesized using M. longifolia in 4T1 cell line through ROS generation and cell membrane damage

To overcome the problem of breast cancer, silver nanoparticles (AgNPs) synthesized using Indian medicinal plant Madhuca longifolia could be explored as an alternative anticancer medicine. Synthesized AgNPs were studied their characteristics and their anti-proliferative property was investigated in breast cancer cell line (4T1). Based on zeta sizer analysis, the size of the AgNPs was 103.5 nm and potential -9.57 eV. Fe-SEM results showed particle size of 69.4-99.4 nm while TEM images indicated the particle size of 18-24 nm. In dose-dependent study, AgNPs showed 93% of anti-proliferative activity at 50 μg/ml whereas the methanolic extract of M. longifolia showed 80% activity only at 10-fold increased concentration (500 μg/ml). AgNPs exhibited higher level of cytotoxicity in breast cancer cell line than extract through cell wall degradation and ROS generation. Such effective AgNPs could be investigated further through in vivo models with a view to develop anticancer drug.

The evolution into personalized therapies in pancreatic ductal adenocarcinoma: challenges and opportunities

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is projected to be the second leading cause of cancer related mortality in the United States in 2030, with a 5-year overall survival of less than 10% despite decades of extensive research. Pancreatic cancer is marked by the accumulation of complex molecular changes, complex tumor-stroma interaction, and an immunosuppressive tumor microenvironment. PDAC has proven to be resistant to many cytotoxic, targeted and immunologic treatment approaches. Areas covered: In this paper, we review the major areas of research in PDAC, with highlights on the challenges and areas of opportunity for personalized treatment approaches. Expert commentary: The focus of research in pancreatic cancer has moved away from developing conventional cytotoxic combinations. The marked advances in understanding the molecular biology of this disease especially in the areas of the microenvironment, metabolism, and DNA repair have opened new opportunities for developing novel treatment strategies. Improved understanding of molecular abnormalities allows the development of personalized treatment approaches.

HDAC inhibitors enhance neratinib activity and when combined enhance the actions of an anti-PD-1 immunomodulatory antibody in vivo

Patients whose NSCLC tumors become afatinib resistant presently have few effective therapeutic options to extend their survival. Afatinib resistant NSCLC cells were sensitive to clinically relevant concentrations of the irreversible pan-HER inhibitor neratinib, but not by the first generation ERBB1/2/4 inhibitor lapatinib. In multiple afatinib resistant NSCLC clones, HDAC inhibitors reduced the expression of ERBB1/3/4, but activated c-SRC, which resulted in higher total levels of ERBB1/3 phosphorylation. Neratinib also rapidly reduced the expression of ERBB1/2/3/4, c-MET and of mutant K-/N-RAS; K-RAS co-localized with phosphorylated ATG13 and with cathepsin B in vesicles. Combined exposure of cells to [neratinib + HDAC inhibitors] caused inactivation of mTORC1 and mTORC2, enhanced autophagosome and subsequently autolysosome formation, and caused an additive to greater than additive induction of cell death. Knock down of Beclin1 or ATG5 prevented HDAC inhibitors or neratinib from reducing ERBB1/3/4 and K-/N-RAS expression and reduced [neratinib + HDAC inhibitor] lethality. Neratinib and HDAC inhibitors reduced the expression of multiple HDAC proteins via autophagy that was causal in the reduced expression of PD-L1, PD-L2 and ornithine decarboxylase, and increased expression of Class I MHCA. In vivo, neratinib and HDAC inhibitors interacted to suppress the growth of 4T1 mammary tumors, an effect that was enhanced by an anti-PD-1 antibody. Our data support the premises that neratinib lethality can be enhanced by HDAC inhibitors, that neratinib may be a useful therapeutic tool in afatinib resistant NSCLC, and that [neratinib + HDAC inhibitor] exposure facilitates anti-tumor immune responses.

Anti-EGFR-iRGD recombinant protein conjugated silk fibroin nanoparticles for enhanced tumor targeting and antitumor efficiency

In this study, we report a novel kind of targeting with paclitaxel (PTX)-loaded silk fibroin nanoparticles conjugated with iRGD–EGFR nanobody recombinant protein (anti-EGFR-iRGD). The new nanoparticles (called A-PTX-SF-NPs) were prepared using the carbodiimide-mediated coupling procedure and their characteristics were evaluated. The cellular cytotoxicity and cellular uptake of A-PTX-SF-NPs were also investigated. The results in vivo suggested that NPs conjugated with the recombinant protein exhibited more targeting and anti-neoplastic property in cells with high EGFR expression. In the in vivo antitumor efficacy assay, the A-PTX-SF-NPs group showed slower tumor growth and smaller tumor volumes than PTX-SF-NPs in a HeLa xenograft mouse model. A real-time near-infrared fluorescence imaging study showed that A-PTX-SF-NPs could target the tumor more effectively. These results suggest that the anticancer activity and tumor targeting of A-PTX-SF-NPs were superior to those of PTX-SF-NPs and may have the potential to be used for targeted delivery for tumor therapies.

Pharmacogenomics of cetuximab in metastatic colorectal carcinoma

Cetuximab is a chimeric monoclonal antibody that has revolutionized the treatment of metastatic colorectal cancer. Knowledge of the mechanisms that underlie its effectiveness, as well as the primary and secondary resistance mechanisms, have led to important developments in the understanding of cetuximab biology. In light of knowledge gained from recent trials, the efficacy of cetuximab has been clearly demonstrated to depend upon RAS mutational status, moreover cetuximab should only be used in a subset of patients who may benefit. In this article, we critically review clinical and pharmacogenetic issues of cetuximab, focusing on the cost-effectiveness involved with the use of the drug.

Novel curcumin analogs to overcome EGFR-TKI lung adenocarcinoma drug resistance and reduce EGFR-TKI-induced GI adverse effects

Curcumin (1) down-regulates the expression as well as phosphorylation of epidermal growth factor receptor (EGFR) in lung adenocarcinoma cells expressing gefitinib-resistant EGFR. Thirty-seven newly synthesized curcumin analogues including dimethoxycurcumin (2, DMC) were evaluated for their effects on EGFR expression as well as phosphorylation in two gefitinib-resistant lung adenocarcinoma cell lines, CL1-5 (EGFR(wt)) and H1975 (EGFR(L858R+T790M)). Based on the identified structure-activity relationships, methoxy substitution at C-3', C-4', or both positions favored inhibitory activity (compounds 1, 2, 5, 8-15, 17, 36), while compounds with more polar substituents were generally less active in both cell lines. Compound 36 with a fluorine substituent at C-6' and its protonated counterpart 2 did not lose activity, suggesting halogen tolerance. In addition, a conjugated linker was essential for activity. Among all evaluated curcumin derivatives, compound 2 showed the best inhibitory effects on both wild-type and mutant EGFR by efficiently inducing gefitinib-insensitive EGFR degradation. Compound 23 also reduced gefitinib-induced gastrointestinal damage in the non-transformed intestinal epithelial cell line IEC-18.

Hepassocin activates the EGFR/ERK cascade and induces proliferation of L02 cells through the Src-dependent pathway

Hepassocin (HPS) is a secreted protein with mitogenic activity on primary hepatocytes and protects hepatocytes from chemically-induced injury. Our previous studies showed that HPS stimulates proliferation of hepatocytes in an ERK pathway-dependent manner. However, the molecular mechanism of HPS-induced activation of the ERK pathway remains unclear. In this study, we found that HPS induced the phosphorylation of the epidermal growth factor receptor (EGFR) in the human L02 hepatocyte cell line, and this event was concomitant with the activation of the non-receptor tyrosine kinase Src. Specific inhibition of EGFR kinase activity by gefitinib or down-regulation of EGFR by specific EGFR siRNAs prevented HPS-induced activation of the ERK pathway and proliferation of L02 cells. Furthermore, inhibition of Src activity significantly blocked HPS-induced activation of the EGFR, which was suggestive of a ligand-independent transactivation mechanism of EGFR itself as well as ERK phosphorylation and proliferation of L02 cells. These results indicate that EGFR plays an important role in the mitogenic signaling induced by HPS in L02 cell lines and may further stimulate research on the role of HPS in hepatocytes within biological processes in human health and disease.

Combination epidermal growth factor receptor inhibition and radical radiotherapy for NSCLC

Non-small cell lung cancer (NSCLC) remains the most common cause of cancer-related death in the developed world. Despite advances in therapy with conventional modalities, over 85% of patients will die from their disease within 5 years of diagnosis. For patients with inoperable lung cancer, the addition of chemotherapy to radical radiotherapy yields a small but significant 10% survival benefit at 3 years. However, the systemic toxicity of chemotherapy is common and may be severe. Over the past 20 years, dramatic improvements in our understanding of the molecular etiology of cancer have enabled the development of novel targeted therapies. Overexpression of the epidermal growth factor receptor (EGFR) in lung cancer correlates with an aggressive disease course and poor tumor response to radiotherapy. Strategies to inhibit this molecular switch have become a focus for drug development. Preclinical efficacy has been repeatedly demonstrated with anti-EGFR monoclonal antibodies and small molecule tyrosine kinase inhibitors, and responses have been documented in the clinic with acceptable toxicity. Phase III trials combining EGFR tyrosine kinase inhibitors with radical chemoradiation are recruiting at present. This review addresses the current challenges of discovering how best to use these new anticancer therapies, with particular emphasis on the enhancement of existing therapeutic strategies such as radical radiotherapy, factors relating to patient selection and prediction of clinical response.

Changes in epidermal growth factor receptor expression during chemotherapy in non-small cell lung cancer

BACKGROUND

Antibodies targeting epidermal growth factor receptor (EGFR), such as cetuximab, may potentially improve outcome in non-small cell lung cancer (NSCLC) patients with high EGFR expression. The EGFR expression may be heterogeneously distributed within tumors, and small biopsies may thus not accurately reveal the EGFR expression. In addition, EGFR expression may also change during chemotherapy. The current study investigates the magnitude of these two issues.

MATERIALS AND METHODS

EGFR expression in diagnostic biopsies and resection specimen was compared in 53 NSCLC patients stage T1-4N0-1M0 treated with surgery without preceding chemotherapy (OP group), and 65 NSCLC patients stage T1-3N0-2M0 (NAC group) treated with preoperative carboplatin and paclitaxel in order to evaluate the discordance of EGFR expression between samples.

RESULTS

Discordance between tumors dichotomized according to EGFR expression (high: H-score ≥200; low: H-score <200) in diagnostic biopsies and immediate resection specimens was 25 % in the OP group and 33 % in the NAC group (p = 0.628). Five (9 %) of primary tumors in the OP group and 4 (13 %) in the NAC group had increased EGFR expression in the resection specimens as compared to the diagnostic biopsies (p = 0.583). A decrease in EGFR expression was observed in 6 (11 %) in the OP group and 7 (23 %) in the NAC group (p = 0.148).

CONCLUSION

EGFR expression in 25 % of diagnostic biopsies may potentially not be accurate compared to the prevailing pattern in the whole tumor based on the larger resection specimens. This may potentially be an obstacle for proper use of antibodies targeting the EGFR in NSCLC. EGFR expression does, however, not change significantly during paclitaxel and carboplatin and rebiopsies in order to decide on anti-EGFR antibody therapy following chemotherapy do not seem warranted.

Gynecologic cancers: molecular updates

This article reviews the molecular features and pathogenesis of gynecologic malignancies. Understanding the molecular basis of endometrial carcinoma helps to provide an explanation for the prognosis of these tumors and opens up avenues for research into novel therapies that may prove beneficial.

Down-regulation of epidermal growth factor receptor by curcumin-induced UBE1L in human bronchial epithelial cells

UBE1L, ubiquitin-activating enzyme E1-like, is the activating enzyme of ISG15ylation (ISG15, interferon stimulated gene 15). Loss of UBE1L and activation of epidermal growth factor receptor (EGFR) signaling are common events in lung carcinogenesis. Curcumin, a well-studied chemopreventive agent, is known to down-regulate EGFR. The present study demonstrated that curcumin decreased EGFR expression in human bronchial epithelial (HBE) Beas-2B cells and lung cancer A549 cells. For the first time, UBE1L was found to be induced by curcumin in HBE cells. Interestingly, overexpression of UBE1L reduced EGFR at posttranslational level in HBE cells. UBE1L triggered EGFR membrane internalization and promoted complex formation between ISG15 and EGFR. Curcumin decreased EGFR downstream signaling pAKT and nuclear factor κB (NF-κB). Overexpression or knockdown of UBE1L also resulted in down-regulation or up-regulation of phosphoinositide 3-kinase/AKT/NF-κB correspondently. In human samples, there was an inverse relationship between UBE1L and EGFR/AKT/NF-κB in non-small cell lung cancer tissues and adjacent tissues. These results uncover a novel chemopreventive mechanism of curcumin in inducing UBE1L and down-regulating EGFR signaling in HBE cells.

Preclinical pharmacokinetic/pharmacodynamic models to predict schedule-dependent interaction between erlotinib and gemcitabine

PURPOSE

To investigate the pharmacological effects of different erlotinib (ER) and gemcitabine (GM) combination schedules by in vitro and in vivo experiments and PK/PD models in non-small cell lung cancer cells.

METHODS

H1299 cells were exposed to different ER combined with GM schedules. Cell growth inhibition was analyzed to evaluate these schedules. A preclinical in vivo study was then conducted to compare tumor suppression effects of different schedules in H1299 xenografts. PK/PD models were developed to quantify the anti-tumor interaction of ER and GM.

RESULTS

Synergism was observed when ER preceded GM, but other sequences showed antagonism. The optimal in vitro schedule, or interval schedule, was applied to the animal study, which showed greater anti-tumor effect than simultaneous group. PK/PD models implied that interaction of the two drugs was additive in simultaneous treatment but synergistic in interval schedule. The simulation results showed that interval schedule can delay tumor growth for a longer time, and demonstrated more evident anti-tumor effect compared with simultaneous group if the treatment duration was longer.

CONCLUSIONS

Interval schedule of the two drugs can achieve synergistic anti-tumor effect, and is superior to simultaneous treatment.

Investigational therapies targeting the ErbB (EGFR, HER2, HER3, HER4) family in GI cancers

INTRODUCTION

Gastrointestinal (GI) malignancies account for nearly one-fourth of all cancer-related deaths in the United States and approximately 30% of all cancer-related deaths worldwide. Use of combination cytotoxic therapy offers a modest improvement in survival, but the prognosis and long-term survival of most patients with GI cancer remains poor. In certain GI malignancies, therapies that target members of the HER family of receptors have positively impacted patient care.

AREAS COVERED

In this review, we discuss the significance of the HER family of receptors in esophagogastric, hepatobiliary, pancreatic, and colorectal cancers and explain the rationale supporting the use of monoclonal antibodies (mAbs) and small molecule tyrosine kinase inhibitors (TKIs) to inhibit HER activation and downstream events that contribute to tumor proliferation, migration, and survival.

EXPERT OPINION

Despite recent advances, the treatment of GI cancers remains challenging. Therapies targeting the HER family of receptors have been extensively studied in these malignancies with inconsistent results. The rationale behind varied tumor responses with these agents remains uncertain. We believe that additional studies are needed to identify biomarkers that could help identify a population of patients who would be more responsive to a given therapy.

Role of erlotinib in the treatment of non-small cell lung cancer: clinical outcomes in wild-type epidermal growth factor receptor patients

Erlotinib is an orally administered small molecule inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase. Erlotinib at the standard oral daily dose of 150 mg is approved for the treatment of unselected chemorefractory advanced non-small cell lung cancer patients as well as maintenance therapy after first-line chemotherapy. The European Medicines Agency has recently also approved erlotinib as the first-line therapy in patients with EGFR mutations. Although recent studies have identified higher response rates and improved survival with erlotinib in a subset of patients with EGFR mutations, the survival benefit from single agent erlotinib in chemorefractory patients and in the maintenance setting is well observed in EGFR wild-type patients. The role of single agent erlotinib in the first-line setting in special subsets of EGFR wild-type patients (elderly, poor performance status, non-smokers) needs to be further determined. The combination of erlotinib with other targeted therapies has shown promising results and warrants further studies in EGFR wild-type patients.

Research progress on criteria for discontinuation of EGFR inhibitor therapy

The clinical success of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) as therapeutic agents has prompted great interest in their further development and clinical testing for a wide variety of malignancies. However, most studies have focused on the efficacy of TKI, and few studies have been done on the criteria for their discontinuation. The current standard for drug discontinuation is “until progression”, based on change in tumor size. However, tumor size is not related to the gene expression which determines the efficacy of TKI in the final analysis, and it is also difficult to make a thorough and correct prediction based on tumor size when the TKI is discontinued. Nevertheless, clinical evaluation of the criteria for TKI discontinuation is still in its early days. Some promising findings have started to emerge. With the improving knowledge of EGFR and its inhibitors, it is expected that the criteria for discontinuation of EGFR inhibitor therapy will become clearer.

Pre-targeting and direct immunotargeting of liposomal drug carriers to ovarian carcinoma

Background

Epidermal growth factor receptor (EGFR) is overexpressed in many solid tumor types, such as ovarian carcinoma. Immunoliposome based drug targeting has shown promising results in drug delivery to the tumors. However, the ratio of tumor-to-normal tissue concentrations should be increased to minimize the adverse effects of cytostatic drugs.

Methodology/Principal Findings

We studied the EGFR-targeted doxorubicin immunoliposomes using pre-targeting and local intraperitoneal (i.p.) administration of the liposomes. This approach was used to increase drug delivery to tumors as compared to direct intravenous (i.v.) administration of liposomes. EGFR antibodies were attached on the surface of PEG coated liposomes using biotin-neutravidin binding. Receptor mediated cellular uptake and cytotoxic efficacy of EGFR-targeted liposomes were investigated in human ovarian adenocarcinoma (SKOV-3 and SKOV3.ip1) cells. In vivo distribution of the liposomes in mice was explored using direct and pre-targeting approaches and SPECT/CT imaging. Targeted liposomes showed efficient and specific receptor-mediated binding to ovarian carcinoma cells in vitro, but the difference in cytotoxicity between targeted and non-targeted liposomes remained small. The relatively low cytotoxic efficacy is probably due to insufficient doxorubicin release from the liposomes rather than lack of target binding. Tumor uptake of targeted liposomes in vivo was comparable to that of non-targeted liposomes after both direct and pre-targeting administration. For both EGFR-targeted and non-targeted liposomes, the i.p. administration increased liposome accumulation to the tumors compared to i.v. injections.

Conclusions/Significance

Intraperitoneal administration of liposomes may be a beneficial approach to treat the tumors in the abdominal cavity. The i.p. pre-targeting method warrants further studies as a potential approach in cancer therapy.

Phthalocyanine-peptide conjugates for epidermal growth factor receptor targeting

Four phthalocyanine (Pc)-peptide conjugates designed to target the epidermal growth factor receptor (EGFR) were synthesized and evaluated in vitro using four cell lines: human carcinoma A431 and HEp2, human colorectal HT-29, and kidney Vero (negative control) cells. Two peptide ligands for EGFR were investigated: EGFR-L1 and -L2, bearing 6 and 13 amino acid residues, respectively. The peptides and Pc-conjugates were shown to bind to EGFR using both theoretical (Autodock) and experimental (SPR) investigations. The Pc-EGFR-L1 conjugates 5a and 5b efficiently targeted EGFR and were internalized, in part due to their cationic charge, whereas the uncharged Pc-EGFR-L2 conjugates 4b and 6a poorly targeted EGFR maybe due to their low aqueous solubility. All conjugates were nontoxic (IC(50) > 100 μM) to HT-29 cells, both in the dark and upon light activation (1 J/cm(2)). Intravenous (iv) administration of conjugate 5b into nude mice bearing A431 and HT-29 human tumor xenografts resulted in a near-IR fluorescence signal at ca. 700 nm, 24 h after administration. Our studies show that Pc-EGFR-L1 conjugates are promising near-IR fluorescent contrast agents for CRC and potentially other EGFR overexpressing cancers.

Targeting the HER2 pathway for the therapy of lower esophageal and gastric adenocarcinoma

INTRODUCTION

The mysteries of complex molecular pathways of tumorigenesis are only beginning to be unraveled. Overexpression of HER2 receptors has been associated with adverse outcomes in certain malignant solid tumors.

AREAS COVERED

The authors give a focused review of the HER2 pathway and its importance for cancer cell survival. Similar to the situation in breast cancer, HER2 overexpression is seen in up to one-quarter of all gastric and gastroesophageal junction adenocarcinomas. The audience will also be familiarized with the existing HER2 targeted agents (both at the bench and at the bedside) for the therapy of gastric and gastroesophageal cancers.

EXPERT OPINION

Despite recent advances, treatment of upper gastrointestinal malignancies remains a significant challenge. Trastuzumab in combination with chemotherapy is the current standard of therapy for patients with metastatic HER2-overexpressing esophageal and gastric cancers. The activity of lapatinib, an active agent in advanced HER2-positive breast cancer, is now being tested in HER2-overexpressing esophageal and gastric adenocarcinomas. A variety of monoclonal antibodies and tyrosine kinase inhibitors with affinity for HER2 are in development and may improve further the outcomes of these malignancies.

Recent advancements in multimodality treatment of gliomas

Gliomas account for the vast majority of malignant adult brain tumors. Even though tremendous effort has been made to optimize treatment of patients with high-grade glioma, the prognosis remains poor, especially for patients with glioblastoma. The dismal prognosis conferred by these tumors is in part caused by the tendency to diffusely infiltrate into neighboring brain tissue, but also by the inherent resistance of these tumors to both chemotherapy and radiation. This article reviews the recent advancements in multimodality treatment of patients with gliomas, both in the primary and recurrent setting, with an emphasis on the emerging targeted therapies. Moreover, the external beam radiotherapy options, including intensity modulated radiotherapy and particle (proton and carbon ion) radiotherapy are reviewed.

EGFR-targeted magnetic nanoparticle heaters kill cancer cells without a perceptible temperature rise

It is currently believed that magnetic nanoparticle heaters (MNHs) can kill cancer cells only when the temperature is raised above 43 °C due to energy dissipation in an alternating magnetic field. On the other hand, simple heat conduction arguments indicate that in small tumors or single cells the relative rates of energy dissipation and heat conduction result in a negligible temperature rise, thus limiting the potential of MNHs in treating small tumors and metastatic cancer. Here we demonstrate that internalized MNHs conjugated to epidermal growth factor (EGF) and which target the epidermal growth factor receptor (EGFR) do result in a significant (up to 99.9%) reduction in cell viability and clonogenic survival in a thermal heat dose dependent manner, without the need for a perceptible temperature rise. The effect appears to be cell type specific and indicates that magnetic nanoparticles in alternating magnetic fields may effectively kill cancer cells under conditions previously considered as not possible.

Curcumin induces EGFR degradation in lung adenocarcinoma and modulates p38 activation in intestine: the versatile adjuvant for gefitinib therapy

Background

Non-small cell lung cancer (NSCLC) patients with L858R or exon 19 deletion mutations in epidermal growth factor receptor (EGFR) have good responses to the tyrosine kinase inhibitor (TKI), gefitinib. However, patients with wild-type EGFR and acquired mutation in EGFR T790M are resistant to gefitinib treatment. Here, we showed that curcumin can improve the efficiency of gefitinib in the resistant NSCLC cells both in vitro and in vivo models.

Methods/Principal Findings

After screening 598 herbal and natural compounds, we found curcumin could inhibit cell proliferation in different gefitinib-resistant NSCLC cell lines; concentration-dependently down-regulate EGFR phosphorylation through promoting EGFR degradation in NSCLC cell lines with wild-type EGFR or T790M EGFR. In addition, the anti-tumor activity of gefitinib was potentiated via curcumin through blocking EGFR activation and inducing apoptosis in gefitinib-resistant NSCLC cell lines; also the combined treatment with curcumin and gefitinib exhibited significant inhibition in the CL1-5, A549 and H1975 xenografts tumor growth in SCID mice through reducing EGFR, c-MET, cyclin D1 expression, and inducing apoptosis activation through caspases-8, 9 and PARP. Interestingly, we observed that the combined treatment group represented better survival rate and less intestinal mucosal damage compare to gefitinib-alone therapy. We showed that curcumin attenuated the gefitinib-induced cell proliferation inhibition and apoptosis through altering p38 mitogen-activated protein kinase (MAPK) activation in intestinal epithelia cell.

Conclusions/Significance

Curcumin potentiates antitumor activity of gefitinib in cell lines and xenograft mice model of NSCLC through inhibition of proliferation, EGFR phosphorylation, and induction EGFR ubiquitination and apoptosis. In addition, curcumin attenuates gefitinib-induced gastrointestinal adverse effects via altering p38 activation. These findings provide a novel treatment strategy that curcumin as an adjuvant to increase the spectrum of the usage of gefitinib and overcome the gefitinib inefficiency in NSCLC patients.

Trastuzumab (herceptin)

Herceptin (trastuzumab) is a human monoclonal antibody that interferes with the HER2 receptor. It is currently the only FDA-approved therapeutic antibody for HER2-positive breast cancer. This article will present the mechanism at action as well as the clinical role at this monoclonal antibody.

Assessment of ERBB2 and EGFR gene amplification and protein expression in gastric carcinoma by immunohistochemistry and fluorescence in situ hybridization

Background

The goal of this study was to investigate ERBB2(HER2) and EGFR gene amplification and protein expression in gastric cancer. Fluorescence in situ hybridization (FISH) and immunohistochemistry were used to analyze ERBB2 and EGFR gene amplification and protein expression in 69 cases of gastric cancer.

Results

FISH analysis revealed that 20.3% of the cases exhibited ERBB2 gene amplification. Increases in ERBB2 copy number and gene amplification were present in 52.2% of the samples. Expression of the ERBB2 protein was observed in 42.0% of cases. FISH analysis detected EGFR gene amplification in 29.0% of samples. Increases in EGFR copy number and gene amplification occurred in 57.9% of samples, and EGFR protein expression was present in 52.2% of samples. Both ERBB2 and EGFR gene amplification were 3 cases (4.3%), but abnormalities in both ERBB2 and EGFR gene copy number were present 36.2% of samples. ERBB2 and EGFR gene amplification were significantly associated with the depth of tumor invasion (P < 0.05) and lymph node metastasis (P < 0.05), but not with sex, age, or histological type (P > 0.05).

Conclusions

Our data indicated that ERBB2 and EGFR genetic abnormalities were associated with the prognosis of gastric cancer. Clinical assessment of ERBB2 and EGFR amplification may represent an important factor for the development of personalized treatment programs for gastic cancer.

A conformationally constrained peptidomimetic binds to the extracellular region of HER2 protein

Human epidermal growth factor receptor 2 (HER2) is a member of the human epidermal growth factor receptor kinases (other members include EGFR or HER1, HER3, and HER4) that are involved in signaling cascades for cell growth and differentiation. It is well established that HER2-mediated heterodimerization has important implications in cancer. Deregulation of signaling pathways and overexpression of HER2 is known to occur in cancer cells, indicating a role of HER2 in tumorigenesis. Therefore, blocking HER2-mediated signaling has potential therapeutic value. We have designed several peptidomimetics to inhibit HER2-mediated signaling for cell growth. One of the compounds (HERP5, Arg-beta Naph-Phe) exhibited antiproliferative activity with IC(50) values in the micromolar-to-nanomolar range in breast cancer cell lines. Binding of fluorescently labeled HERP5 to HER2 protein was evaluated by fluorescence assay, microscopy, and circular dichroism spectroscopy. Results indicated that HERP5 binds to the extracellular region of the HER2 protein. Structure of the peptidomimetic HERP5 was studied by NMR and molecular dynamics simulations. Based on these results a model was proposed for HER2-EGFR dimerization and possible blocking by HERP5 peptidomimetic using a protein-protein docking method.

Structure-activity relationship of conformationally constrained peptidomimetics for antiproliferative activity in HER2-overexpressing breast cancer cell lines

Human epidermal growth factor receptor 2 (HER2) is a member of the human epidermal growth factor receptor kinases and is involved in a signaling cascade for cell growth and differentiation. It is well established that HER2-mediated heterodimerization has important implications in cancer. Deregulation of signaling pathways and overexpression of HER2 is known to occur in cancer cells, indicating the role of HER2 in tumorigenesis. Therefore, blocking HER2-mediated signaling has potential therapeutic value. We have designed several peptidomimetics to inhibit HER2-mediated signaling for cell growth. One of the compounds (compound 5, Arg-[3-amino-3(1-napthyl)-propionic acid]-Phe) exhibited antiproliferative activity with IC(50) values in the nanomolar to micromolar range in breast cancer cell lines. To further investigate the structure-activity relationship of the compounds, various analogs of compound 5 were designed. Conformational constraints were initiated in the peptidomimetic with introduction of a Pro residue in the peptidomimetic sequence. Results of antiproliferative activity indicated that analogs of compound 5 with C-and N-terminal ends capped (compound 16) and compound 9 with Asp at the C-terminal exhibited antiproliferative activity in the lower micromolar range against breast cancer cell lines. Introduction of conformational constraints such as Pro residue in the sequence or cyclization did not enhance the activity of the peptidomimetic. Competitive binding studies were carried out to evaluate the binding of potent peptidomimetics to HER2-overexpressing cancer cell lines. Results indicated that compounds exhibiting antiproliferative activity in breast cancer cell lines bind to the cells that overexpress HER2 protein.

Correlation of HER2 and EGFR abnormalities with clinicopathological parameters in gastric cancer

AIM: To investigate the clinical significance of human epidermal growth factor receptor type 2 (HER2) and epidermal growth factor receptor (EGFR) abnormalities in gastric cancer.

METHODS: The gene amplification and protein expression of HER2 and EGFR in 52 cases of gastric cancer were detected by fluorescence in situ hybridization (FISH) and immunohistochemistry, respectively.

RESULTS: The rate of HER2 gene amplification in gastric cancer patients was 17.3% (9/52). Of 43 patients without HER2 gene amplification, 3 had HER2 trisomy, 7 had HER2 tetrasomy, and 6 had HER2 polysomy. Approximately 48.1% (25/52) of the patients showed increased HER2 gene copy number or gene amplification. The positive rate of HER2 protein expression in gastric cancer patients was 42.3% (22/52). The ratio of HER2 gene amplification was significantly higher in patients with high (+++) and moderate (++) HER2 expression than in those with low (+) HER2 expression (2/3 and 4/7 vs 3/12, both P < 0.05). The rate of EGFR gene amplification rate in gastric cancer patients was 26.9% (14/52). Of 38 patients without EGFR gene amplification, 2 had EGFR trisomy, 9 had EGFR tetrasomy, and 10 had EGFR polysomy. Approximately 67.3% (35/52) of the patients showed increased EGFR gene copy number or gene amplification. The ratio of EGFR gene amplification was significantly higher in patients with high (+++) and moderate (++) EGFR expression than in those with low (+) EGFR expression (4/5 and 6/8 vs 4/16, both P < 0.05). Approximately 36.5% (19/52) of patients showed both HER2 and EGFR gene abnormalities (gene amplification and increased copy number). The rates of HER2 and EGFR gene amplification were significantly correlated with the depth of tumor invasion and lymph node metastasis (both P < 0.05), but not with histological type, age at onset, and sex (all P > 0.05).

CONCLUSION: There is a significant correlation between HER2 and EGFR gene abnormalities in gastric cancer patients. Detection of HER2 and EGFR gene abnormalities can be used as an important parameter for diagnosis and prognostic evaluation of gastric cancer and for development of individualized treatment plan.

Cetuximab (erbitux)

Cetuximab, a recombinant chimeric monoclonal antibody, has been successfully used in the treatment of the head and neck and colorectal cancers. We present a review of its mechanism of action, indications, side effects and economic issues, accompanied by a clinical example from our institution.

Erlotinib treatment in pretreated patients with non-small cell lung cancer: A Phase II study

Erlotinib is an oral, small-molecule targeting therapy that inhibits epidermal growth factor tyrosine kinase receptors. Erlotinib has been administered for the treatment of advanced pancreatic cancer and non-small cell lung cancer. In the present trial, erlotinib was administered as second-line monotherapy in pretreated patients with advanced non-small cell lung cancer. Our objectives were to determine response, survival and toxicity. Fifty-four patients pretreated with cisplatin or its analogue-based combinations were evaluated. The disease stage of the patients was IIIB and IV. Thirty-eight patients were male, 16 were female, the median age was 65 years, and the WHO performance status was 0-2. Twenty-five cases were adenocarcinomas, 19 squamous cell carcinomas and 10 were undifferentiated. Erlotinib was administered at a dose of 150 mg daily. In case of intolerable adverse reactions, the dose was either reduced to 100 mg daily or treatment was interrupted for a maximum of two weeks. A partial response was observed in 10 (18.52%) and stable disease in 40 (74.07%) patients. The median time to disease progression was 3 months (95% CI 1.7-10.3), and the median survival was 6 months. Concerning toxicity, 53 patients (98.15%) developed a grade 1-2 skin rash, and 1 (1.85%) grade 3. Diarrhea occurred in 9 (16.67%) patients, nausea and vomiting in 4 (7.41%) and gastritis in 2 (3.70%). The majority of patients tolerated the erlotinib treatment. Of note were the 18.52% response rate and 74.07% stable disease.

Design, synthesis, and docking studies of peptidomimetics based on HER2-herceptin binding site with potential antiproliferative activity against breast cancer cell lines

Epidermal growth factor receptor kinase and the related human epidermal growth factor receptor-2 (HER2, ErbB2) are two growth factor receptors that have implications in cancer. The overexpression or activation of HER2 occurs frequently in breast, ovarian, and lung cancers, making it an important therapeutic target in the treatment of cancer. Blocking HER2-mediated signaling with antibodies or small molecules has been shown to be effective in inhibiting cell growth. After analyzing the crystal structure of the HER2-herceptin complex, several peptidomimetics (HERP5, 6, and 7) were designed to inhibit HER2-mediated signaling for cell growth. We have used an in silico screening method to investigate the chemical diversity of the designed compounds. autodock software was used to dock the different analogs of HERP5 and HERP7 with HER2 protein extracellular domain. A total of 53 compounds were docked to HER2 protein, and their binding modes were analyzed in terms of docking energy, hydrogen bonding, and hydrophobic interactions. Compounds that exhibited low-energy docked structures were chosen for chemical synthesis and biological activity. Two of the compounds (HERP5 and HERP7) exhibited antiproliferative activity, with IC(50) values of 0.396 microm and 0.143 microm, respectively, against SKBR-3 cell lines (breast cancer cell lines) that overexpress HER2 protein.

Theme: Oncology - Molecular mechanisms determining the efficacy of EGF receptor-specific tyrosine kinase inhibitors help to identify biomarker candidates

Non-small-cell lung cancer is a major subtype of lung cancer, which is the most common and fatal cancer in the world. Gefitinib (Iressa™) and later erlotinib (Tarceva™), specific tyrosine kinase inhibitors for EGF receptors (EGFRs), have been demonstrated to be effective for some non-small-cell lung cancer patients and used in clinics as pioneers of molecule-based targeted drugs for cancer. There has been an urgent need to develop biomarkers and to select appropriate patients who should benefit from treatment with these drugs because of the high sensitivity of target cancer cells. However, problems of acquired resistance after long-term treatment with these drugs have been recognized. Emerging evidence indicates that the efficacy of these drugs is partly dependent on somatic mutations in the EGFR. In this review, we summarize recent understandings of the molecular mechanisms that determine the efficacy of EGFR–tyrosine kinase inhibitors. Towards the end of this article, we discuss recent ongoing projects validating potential biomarkers and future prospects.

Status of HER1 and HER2 in peritoneal, ovarian and colorectal endometriosis and ovarian endometrioid adenocarcinoma

A role for the EGF system, in particular HER1 and 2, in growth of the endometrium has been suggested but HER1 and 2 have not been studied in all locations of endometriosis and in ovarian endometrioid adenocarcinoma (OEC) which is a rare form of malignant transformation of endometriosis. Immunohistochemistry (IHC) was used for studying HER1 and HER2 in ovarian (n = 10), peritoneal (n = 10), colorectal endometriosis (n = 20) and OEC (n = 10). Fluorescent in situ hybridisation (FISH) was used for analysing the status of HER2 gene in colorectal endometriosis and OEC. All samples were negative for HER2 in both glandular and stromal cells and in glandular cells for HER1 by IHC. In 15 out of 20 colorectal endometriosis, there was a weak expression in stromal cells. Following FISH, two colorectal samples had a partial 17 aneusomy and three OEC, a 17 polysomy. The other samples were 17 disomic without HER2 amplification; HER1 and 2 do not seem to have a role in endometriosis physiopathology.

Dose-dependent increases in circulating TGF-alpha and other EGFR ligands act as pharmacodynamic markers for optimal biological dosing of cetuximab and are tumor independent

PURPOSE

The objective of this study was to characterize treatment-induced circulating ligand changes during therapy with epidermal growth factor receptor (EGFR) inhibitors and evaluate their potential as surrogate indicators of the optimal biological dose.

EXPERIMENTAL DESIGN

Conditioned medium from human tumor cell lines, ascites fluid from tumor xenografts, and plasma samples from normal mice, as well as colorectal cancer patients, were assessed for ligand elevations using ELISA, following treatment with cetuximab (Erbitux), an anti-mouse EGFR neutralizing antibody, or a small-molecule EGFR tyrosine kinase inhibitor.

RESULTS

A rapid elevation in human transforming growth factor alpha (TGF-alpha) was observed in all cell lines after treatment with cetuximab, but not with small-molecule inhibitors. The elevation showed a dose-response effect and plateau that corresponded to the maximal decrease in A431 proliferation in vitro and HT29 tumor growth in vivo. The TGF-alpha increase was exacerbated by ongoing ligand production and cleavage from the plasma membrane but did not involve transcriptional up-regulation of TGF-alpha or the matrix metalloproteinase tumor necrosis factor-alpha-converting enzyme/ADAM17. Elevations in plasma TGF-alpha, amphiregulin, and epiregulin were also detected in normal mice treated with an anti-mouse EGFR monoclonal antibody, illustrating a host tissue-dependent component of this effect in vivo. Finally, circulating TGF-alpha increased in the plasma of six patients with EGFR-negative colorectal tumors during cetuximab treatment.

CONCLUSIONS

Treatment-induced increases in circulating ligands, particularly TGF-alpha, should be serially assessed in clinical trials of anti-EGFR therapeutic antibodies as potential biomarkers to aid in determination of the optimal biological dose.

Matrix metalloproteinase 9 is a mediator of epidermal growth factor-dependent e-cadherin loss in ovarian carcinoma cells

Epidermal growth factor (EGF) receptor (EGFR) is frequently elevated in epithelial ovarian cancer, and E-cadherin expression is often reduced in advanced disease. In this study, we investigated a mechanism by which EGFR activation promotes disruption of adherens junctions through induction of matrix metalloproteinase 9 (MMP-9). We show that EGFR activation down-modulates E-cadherin, and broad spectrum MMP inhibition ameliorates EGF-stimulated junctional disruption and loss of E-cadherin protein. MMP-9 involvement in EGF-dependent down-regulation of E-cadherin was determined by siRNA specifically directed against MMP-9. Furthermore, treatment with recombinant MMP-9 or transient expression of MMP-9 is sufficient to reduce E-cadherin levels in differentiated ovarian tumor cells. Stable overexpression of MMP-9 led to a loss of E-cadherin and junctional integrity, and promoted a migratory and invasive phenotype. Thus, elevated MMP-9 protein expression is sufficient for junctional disruption and loss of E-cadherin in these cells. The associations between EGFR activation, MMP-9 expression, and E-cadherin were investigated in human ovarian tumors and paired peritoneal metastases wherein immunohistochemical staining for activated (phospho) EGFR and MMP-9 colocalized with regions of reduced E-cadherin. These data suggest that regulation of MMP-9 by EGFR may represent a novel mechanism for down-modulation of E-cadherin in ovarian cancer.