Epidermal Growth Factor Tyrosine Kinase Research Articles

Abstract 3361: EGFR signaling regulates aerobic glycolysis in EGFR-mutated lung adenocarcinoma

Abstract Recent accumulating evidences suggest that genetic mutations in tumor cells cause several unique metabolic phenotypes that are critical for cancerous cell proliferation. Mutations in the tyrosine kinase epidermal growth factor receptor (EGFR) induce oncogenic addiction in lung adenocarcinoma (LAD). However, the linkage between oncogenic mutated EGFR and cancer metabolism has not yet been clearly elucidated. In this study, we measured extracellular lactate production, glucose consumption and the glucose-induced extracellular acidification rate (ECAR) after the inhibition of EGFR signaling in LAD cell culture. Using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS)-based metabolomic techniques, the major intracellular metabolites in EGFR-mutated LAD cells were quantified in the absence or presence of the tyrosine kinase inhibitor (TKIs) erlotinib. The molecular profile regulating the metabolic enzymes at the transcriptional and post-translational levels was characterized by RT-PCR, Western blotting and flow cytometry. We demonstrated that EGFR signaling was required for lactate production, glucose consumption and glucose-induced ECAR, indicating that EGFR signaling promoted the Warburg effect in LAD cells. Moreover, comprehensive metabolomic analysis revealed that the levels of key intermediate metabolites in glycolysis and the pentose phosphate pathway (PPP) were decreased after treatment with EGFR inhibitors. The glucose transport carried out by GLUT1 and GLUT3 was the most rapid and critically regulated function of glucose metabolism linked to EGFR signaling, although the expression of MYC-dependent glycolytic genes and the phosphorylation of pyruvate kinase muscle (PKM2) were down-regulated by EGFR inhibition at a later time point. A modest down-regulation of both total and membrane-bound GLUT3 was also observed after EGFR inhibition. Despite an equivalent total amount of GLUT1 in LAD cells, the levels of membrane-bound GLUT1 was decreased by EGFR-TKI treatment, suggesting that EGFR signaling controlled GLUT1 function through post-translational modification. We concluded that EGFR signaling regulated aerobic glycolysis in EGFR-mutated LAD cells. Our data suggests that the glycolytic pathway plays a central role in the pathogenesis of EGFR-mutated lung cancer. This regulatory pathway could be an attractive target for the development of targeted therapies to better treat patients with EGFR-mutated LAD. Citation Format: Hideki Makinoshima, Masahiro Takita, Shingo Matsumoto, Atsushi Yagishita, Satoshi Owada, Hiroyasu Esumi, Katsuya Tsuchihara. EGFR signaling regulates aerobic glycolysis in EGFR-mutated lung adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3361. doi:10.1158/1538-7445.AM2014-3361

Transmembrane Domain Targeting Peptide Antagonizing ErbB2/Neu Inhibits Breast Tumor Growth and Metastasis

Breast cancer is still a deadly disease despite major achievements in targeted therapies designed to block ligands or ligand-binding subunits of major tyrosine kinase receptors. Relapse is significant and metastases deleterious, which demands novel strategies for fighting this disease. Here, we report a proof-of-concept experiment demonstrating that small peptides interfering with the transmembrane domain of the tyrosine kinase epidermal growth factor receptor ErbB2 exhibit anticancer properties when used at micromolar dosages in a genetically engineered mouse model of breast cancer. Different assays demonstrate the specificity of the ErbB2-targeting peptide, which induces long-term reduction of ErbB2 phosphorylation and Akt signaling consistent with reduced tumor cell proliferation and increased survival. Microcomputed tomography analysis established the antimetastatic activity of the peptide and its impact on primary tumor growth. This reveals the interior of the cell membrane as an unexplored dimension for drug design.

Clinical utility of erlotinib for the treatment of non-small-cell lung cancer in Japanese patients: current evidence

Gefitinib, an epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI), has been approved in Japan for the treatment of patients with advanced non-small-cell lung cancer (NSCLC) based on Phase II clinical trials since 2002. Erlotinib, another EGFR-TKI, was also approved a few years thereafter. In 2004, activating mutations in the EGFR gene were discovered to be a predictive biomarker for EGFR-TKI treatment, and gefitinib, which is not effective for patients with EGFR wild-type NSCLC, has since been used only in patients with EGFR-mutated NSCLC. In contrast, erlotinib is potentially effective for the treatment of EGFR wild-type NSCLC. Similar to gefitinib, erlotinib is also effective for EGFR-mutated NSCLC and has been used as an initial treatment for patients with advanced EGFR-mutated NSCLC. Both gefitinib and erlotinib can be used in a Japanese clinical setting. The approved daily dose of erlotinib (150 mg) is equal to the maximum tolerated dose of erlotinib. In contrast, the daily dose of gefitinib has been set at 250 mg, which is approximately one-third of the maximum tolerated dose of gefitinib. Accordingly, a higher serum concentration can be achieved using erlotinib, compared with gefitinib. This advantage can be applied to the treatment of central nervous system metastases (brain metastasis and carcinomatous meningitis), the treatment of which is complicated by the difficulty drugs have penetrating the blood–brain barrier. Although patients with EGFR-mutated NSCLC respond dramatically to EGFR-TKIs, some patients have a poor response and the majority eventually undergo disease progression. To overcome such resistance, several novel treatment strategies, such as combination therapy and next-generation EGFR-TKIs, have been attempted.

Epidermal Growth Factor Receptor (EGFR) Signaling Regulates Global Metabolic Pathways in EGFR-mutated Lung Adenocarcinoma

Genetic mutations in tumor cells cause several unique metabolic phenotypes that are critical for cancer cell proliferation. Mutations in the tyrosine kinase epidermal growth factor receptor (EGFR) induce oncogenic addiction in lung adenocarcinoma (LAD). However, the linkage between oncogenic mutated EGFR and cancer cell metabolism has not yet been clearly elucidated. Here we show that EGFR signaling plays an important role in aerobic glycolysis in EGFR-mutated LAD cells. EGFR-tyrosine kinase inhibitors (TKIs) decreased lactate production, glucose consumption, and the glucose-induced extracellular acidification rate (ECAR), indicating that EGFR signaling maintained aerobic glycolysis in LAD cells. Metabolomic analysis revealed that metabolites in the glycolysis, pentose phosphate pathway (PPP), pyrimidine biosynthesis, and redox metabolism were significantly decreased after treatment of LAD cells with EGFRTKI. On a molecular basis, the glucose transport carried out by glucose transporter 3 (GLUT3) was downregulated in TKI-sensitive LAD cells. Moreover, EGFR signaling activated carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase (CAD), which catalyzes the first step in de novo pyrimidine synthesis. We conclude that EGFR signaling regulates the global metabolic pathway in EGFR-mutated LAD cells. Our data provide evidence that may link therapeutic response to the regulation of metabolism, which is an attractive target for the development of more effective targeted therapies to treat patients with EGFR-mutated LAD.

In silico molecular docking study of natural compounds on wild and mutated epidermal growth factor receptor

The role played by overexpression of tyrosine kinase epidermal growth factor receptor (EGFR), the transmembrane receptor central to numerous cellular processes comprising cell migration, adhesion, apoptosis, and cell proliferation, has been highlighted in various cancers such as prostate, breast, lung, and ovarian cancers as well as in mutations in the EGFR kinase domain. Although many therapeutic approaches have targetted EGFR, the mutations occurring in the EGFR kinase domain including L858 EGFR and T790/L858R had led to the amplification of EGFR signals, consequently leading to increased cell proliferation and cell growth. The strategies involving the inhibition of EGFR L858 and T790M have been accredited with limited achievement in addition to being associated with unwanted adverse effects as a result of crosstalk of wild-type EGFR. All current EGFR tyrosine kinase inhibitors have been identified as ATP competitive inhibitors of wild-type EGFR possessing aniline and quinazoline moiety on the ligands skeleton. Our results obtained by performing molecular docking study on Maestro 9.3 molecular docking suite indicated that CID5280343 possesses better energy conformation against wild-type EGFR as well as two mutated EGFR. Moreover, it was discovered in this study that the natural compounds CID72276, CID5280445, CID441794, and CID72277 and InterBioScreen’s library STOCK1N-78657, STOCK1N-78976, and STOCK1N-78847 have better binding conformation against gatekeeper T790M mutated EGFR concluded to be brought about by means of flexible ligands/receptor-based molecular docking protocol. Miraculous features of these compounds are their various pharmacokinetic and pharmacodynamic parameters which were found to be satisfactory as drug-like molecules. This molecular docking study also summarizes docking free energy, protein–ligands interaction profile, and pharmacokinetic and pharmacodynamic parameter of lead molecules which were tremendously helpful in enhancing the activity of these natural compounds against EGFR.

Cooperation of tyrosine kinase receptor TrkB and epidermal growth factor receptor signaling enhances migration and dispersal of lung tumor cells.

TrkB mediates the effects of brain-derived neurotrophic factor (BDNF) in neuronal and nonnneuronal cells. Based on recent reports that TrkB can also be transactivated through epidermal growth-factor receptor (EGFR) signaling and thus regulates migration of early neurons, we investigated the role of TrkB in migration of lung tumor cells. Early metastasis remains a major challenge in the clinical management of non-small cell lung cancer (NSCLC). TrkB receptor signaling is associated with metastasis and poor patient prognosis in NSCLC. Expression of this receptor in A549 cells and in another adenocarcinoma cell line, NCI-H441, promoted enhanced migratory capacity in wound healing assays in the presence of the TrkB ligand BDNF. Furthermore, TrkB expression in A549 cells potentiated the stimulatory effect of EGF in wound healing and in Boyden chamber migration experiments. Consistent with a potential loss of cell polarity upon TrkB expression, cell dispersal and de-clustering was induced in A549 cells independently of exogeneous BDNF. Morphological transformation involved extensive cytoskeletal changes, reduced E-cadherin expression and suppression of E-cadherin expression on the cell surface in TrkB expressing tumor cells. This function depended on MEK and Akt kinase activity but was independent of Src. These data indicate that TrkB expression in lung adenoma cells is an early step in tumor cell dissemination, and thus could represent a target for therapy development.

FRI0340 Inhibition of Collagen-Induced Arthritis in Rats by Intra-Articular Injection with an Inhibitor of the Tyrosine Kinase Epidermal Growth Factor Receptor

BackgroundEpidermal growth factor receptors (EGFR) can trigger intracellular signal cascades such as PI3K-Akt pathway, and participate in the regulation of cell proliferation. Synovium of rheumatoid arthritis (RA) has high expressions...

Epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of central nerve system metastases from non-small cell lung cancer

Brain metastases (BM) are common and disastrous occurrence in patients with non-small cell lung cancer (NSCLC). Currently increasing studies suggest remarkable efficacy and mild toxicity of the epidermal growth factor tyrosine kinase inhibitor (EGFR TKI) in these patients, making targeted therapy an attractive option to BM from NSCLC. We here present a review about the use of EGFR-TKIs in this context and the following questions would be discussed: Are TKIs capable of permeating across brain–blood barrier (BBB)? How to boost exposure of EGFR TKI in cerebrospinal fluid to overcome the resistance of refractory metastases? Would the combination with other treatment like radiotherapy bring about advanced effect? And which patients with BM is the fittest population to EGFR-TKI treatment? In fact, though the administration of EGFR TKI only could achieve certain effect with limited penetration across BBB, increasing dose and combined radiotherapy would carry out better outcome. Unsurprisingly EGFR mutations were still the most important predictor of the sensitivity.

A phase 2 study of defactinib (VS-6063), a cancer stem cell inhibitor that acts through inhibition of focal adhesion kinase (FAK), in patients with KRAS-mutant non-small cell lung cancer.

TPS8126 Background: KRAS mutations have been associated with poor prognosis in NSCLC and resistance to epidermal growth factor (EGFR) tyrosine kinase inhibitors. FAK represents a therapeutic target...

Abstract IA10: Molecular testing to personalized EGFR and ALK inhibitor therapies in lung cancer.

Abstract The concept of “oncogene addiction” led to the realization that not all patients respond equally to each targeted therapy, and best therapeutic results are obtained when the therapy is given to patients whose tumor harbors the “driver mutation” that is sensitive to the drug. In lung cancer, two currently approved new therapies require patient selection based on the presence of sensitizing epidermal growth factor (EGFR) tyrosine kinase domain (TKD) mutation or the anaplastic lymphoma kinase (ALK) gene rearrangement. EGFR mutations occur almost always in lung cancer of adenocarcinoma histology, and uncommonly in other histologies except when they also contain adenocarcinoma component. They are more common in East Asian (~45%) compared to Caucasian (~15-25%) patients, in never/light smokers and in female patients. Ninety percent of EGFR sensitizing mutations involve the 3-5 amino acid deletions on exon 19 and the L858R mutation on exon 21. Although ALK rearrangement also occurs mainly in lung adenocarcinoma and never/light smokers, it is not associated with sex or ethnicity. A great majority of the ALK gene rearrangements that occur in lung cancer involve a fusion between the C-terminal of ALK containing the kinase domain and the N-terminal of echinoderm microtubule-associated protein-like 4 (EML4), which results from an inversion on the short arm of chromosome 2. While EGFR mutations are detected by mainly by sequencing or PCR-based techniques, ALK rearrangement is best detected by the fluorescent in situ hybridization (FISH). However, recent data suggest that the oncogenic ALK fusion proteins can be detected with close to 100% sensitivity and specificity in lung cancer by immunohistochemistry using commercially available ALK specific antibodies, while the native ALK protein is not expressed in normal lung cells. Based on a systematic review of the published literatures, experts representing the International Association for the Study of Lung Cancer (IASLC), in collaboration with the College of American Pathologists (CAP) and the Association of Molecular Pathologists (AMP) recently issued a guideline on Molecular Testing of EGFR and ALK in Lung Cancer. The testing algorithm reported in this guideline will be discussed. Citation Format: Ming Sound Tsao. Molecular testing to personalized EGFR and ALK inhibitor therapies in lung cancer. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr IA10.

Translational Traits of Non-Small-Cell Lung Carcinoma with Drug Resistances by Dual mRNA and Protein Quantification at the Single Cell Level

Translation in eukaryotic cells is a fundamental biological process that has been investigated widely for understanding gene expression. To comprehensively understand gene expression, single cell level observation of both transcript and protein is desirable for translational analysis. The simultaneous observation of both transcript and protein, however, remains challenging due to the requirements of a highly sensitive and multi-modal platform. Here, we report a robust microdevice enabling both transcript and protein quantification from a single cell with a large number of cells per assay. Using 25600 microwells, we quarantined single cells for observing protein expression through immunostaining and sequentially mRNA expression via single cell reverse transcription polymerase chain reaction. Based on this correlation between transcript and protein, 2-dimensional cytometric representation from single cells is possible. The relationship between transcript and proteome of three NSCLC cell lines (HCC827, H1650 and H1975) with different levels of drug resistances to epidermal growth factor tyrosine kinase inhibitors clearly indicates unique translational traits of each cell line. Our data demonstrated that the most drug resistant cell line, H1975, showed least translational efficiency in cMET whereas the least drug resistant cell line, HCC827, showed most translational efficiency. Cytometric platforms, like the one introduced here, may ultimately allow researchers to quantify the evolution of cancerous tissues enabling detailed monitoring of tumor progression.

Recurrent response to advanced lung adenocarcinoma with erlotinib developing leptomeningeal metastases during gefitinib therapy and two case reports.

Epidermal growth factor-tyrosine kinase inhibitors (EGFR-TKIs) are one of the effective medicines in advanced lung adenocarcinoma leptomeningeal metastasis (LM) treatment in recent years. This paper reports two cases of advanced lung adenocarcinoma with exon-EGFR19 mutation. LM occurred during gefitinib treatment with an extracranial condition under control. Later, erlotinib was adopted with a recurrent response. The progression free survival of both patients was over six months and their LM was under control for six and a half and nine months, respectively. LM may be sensitive on different levels to different EGFR-TKIs. Erlotinib can be used to replace gefitinib if intracranial tumor progress occurs during gefitinib treatment. However, our conclusion still needs to be proven by further clinical research.

Polycystic Kidney Disease: A Case of Suppressed Autophagy?

Autosomal-dominant polycystic kidney disease is the most common form of polycystic kidney disease in adults and is caused by a mutation in the polycystic kidney disease 1 or 2 genes, which encode, respectively, polycystin-1 and polycystin-2. Autophagy is present in polycystic kidneys in rat and mouse models of polycystic kidney disease. Autophagy has yet to be shown in human polycystic kidney disease kidneys. The mechanism of cyst growth has been studied extensively in vitro and in vivo. Multiple molecules and signaling pathways have been implicated in cyst growth including mammalian target of rapamycin, the renin-angiotensin-aldosterone system, vasopressin and cyclic adenosine monophosphate, epidermal growth factor and insulin-like growth factor tyrosine kinases, vascular endothelial growth factor, extracellular signal-related kinase, tumor necrosis factor-α, cyclin-dependent kinases, caspases and apoptosis, and cyclic adenosine monophosphate-activated protein kinases. Many of the agents that inhibit these signaling pathways and slow cyst growth are also autophagy inducers such as mammalian target of rapamycin inhibitors, cyclin-dependent kinase inhibitors, caspase inhibitors, tyrosine kinase inhibitors, metformin, curcumin, and triptolide. There are reasons to believe that suppression of autophagy may play a role in cyst formation and growth. This review presents the hypothesis that suppression of autophagy may play a role in cyst formation and growth, based on the following: (1) many of the agents that protect against polycystic kidney disease also induce autophagy, (2) suppression of autophagy in polycystic kidney disease 1 knockout cells, (3) a defect in autophagy in congenital polycystic kidney mice with polycystic kidney disease, (4) how suppressed autophagy may relate to apoptosis in polycystic kidney disease, and (5) conditions with defective cilia, the ciliopathies, are associated with decreased autophagy.

Challenges to Implementation of an Epidermal Growth Factor Receptor Testing Strategy for Non–Small-Cell Lung Cancer in a Publicly Funded Health Care System

Data from seven recent randomized clinical trials have demonstrated that epidermal growth factor (EGFR) mutation status is predictive of improved progression-free survival and quality of life from first-line EGFR tyrosine kinase inhibitor therapy compared with platinum-based chemotherapy. We examined barriers to the initial implementation of a national EGFR testing policy in Canada. Five laboratories across Canada underwent a validation and quality-control exercise for EGFR mutation testing using reverse transcriptase-polymerase chain reaction with financial support from the pharmaceutical industry for the initial 12 months. Oncologists registered patients with nonquamous histology for EGFR mutation testing using a Web-based platform. Basic demographics were collected including age, histology, sex, smoking status, and ethnicity. The decision to prescribe gefitinib was subsequently registered on the system. Between March and December 2010, 2104 requests were received for EGFR mutation testing. Demographic details are as follows: adenocarcinoma (91.6%); Asian ethnicity (13.9%); female (58%); light/never smoker (41.3%); stage IV disease (87.1%). The number of tests requested each month ranged from 200 to 250. Mutation testing was conducted in 1771 of 2104 requests (84%). The median turnaround time for EGFR testing was 18 days (standard deviation 9.7). Gefitinib was prescribed in 302 patients (17.1%). The number of test requests dropped to 50 to 100 per month at the end of the initial 12 months. There was rapid uptake of EGFR mutation testing into routine clinical practice in Canada. Uptake of EGFR mutation testing dropped substantially once funding from pharmaceutical industry was discontinued. There is a need for a national strategy to ensure resources are in place to implement molecular testing for new molecularly targeted agents.

EGFR mutation in malignant pleural effusion of non-small cell lung cancer

EGFR testing has become the consensus before epidermal growth factor-tyrosine kinase inhibitorrs (EGFR-TKIs) treatment in non-small cell lung cancer(NSCLC) patients.Malignant pleural effusion is the common clinical manifestation in NSCLC patients,and EGFR testing by using different methods in pleural effusion cells and free nucleic acids has good prospect for predicting the efficacy of EGFR-TKIs. Key words: Carcinoma, non-small cell lung; Receptor, epidermal growth factor; Mutation; Malignant pleural effusion

Dermatologic toxicities to targeted cancer therapy: shared clinical and histologic adverse skin reactions

Dermatologic toxicities (DT) to targeted cancer therapy may present as inflammatory dermatoses, keratoses, and as benign and malignant squamous proliferations. Published reports of DT with cancer therapy with epidermal growth factor receptor (EGFR), tyrosine kinase (TK), MEK, PI3K, AKT, and BRAF inhibitors were reviewed. DT associated with targeted cancer therapy demonstrated similar reactions and may be grouped as (i) DT as cutaneous inflammation, and (ii) DT as cutaneous epithelial proliferation. EGFR inhibitor, cetuximab, and MEK inhibitors, selumetinib and trametinib, demonstrated papulopustular rash with a suppurative folliculitis in 83%, 93%, and 80% of the patients on therapy, respectively. Common DT with EGFR inhibitors erlotinib and tyrosine kinase inhibitor sorafenib were hand-foot skin reactions in 30-60% of patients on therapy. PI3K inhibitor BKM-120 and AKT inhibitor MK2206 produced maculopapular eruptions seen as dermal hypersensitivity reaction on the skin biopsy. RAF inhibitors vemurafenib and sorafenib were associated with a variety of cutaneous epithelial proliferations (keratosis pilaris, seborrheic keratosis, verruca vulgaris, actinic keratosis, keratoacanthoma, and squamous cell carcinoma. Various anticancer agents may target similar cellular compounds and/or cell signaling pathways thus share similar clinical and histologic features of DT. The knowledge of the overlap of DT with different types of targeted cancer therapy will assist in evaluation of cutaneous reactions.

Impact of erlotinib activity on overall survival in non small cell lung cancer patients: Is the post progression survival a new paradigm?

e19086 Background: In the last few years, the treatment of non-small cell lung cancer (NSCLC) has been dramatically changed with the introduction of EGFR TK (Epidermal Growth Factor Tyrosine Kinase) inhibitors. Given its objectivity and the benefits derived by patients, overall survival (OS) has been historically considered the most important therapeutic objective in advanced NSCLC. However, little is known about postprogression survival (PPS) in NSCLC. This study evaluates the correlation between response to erlotinib and post progression survival (i.e. the time between disease progression and death) to estimate the impact of this drug on overall survival. Methods: We retrospectively analyzed 68 NSCLC unselected patients consecutively treated with second or third line erlotinib at our institution from 2007 to 2010, including in the responder group patients who progressed after stable disease on erlotinib for at least six months (n=20). The relationship between OS and PPS was evaluated by standard statistical tests. P-values <0.05 were considered statistically significant. Results: Survival was significantly prolonged in responders patients (18.6 vs 11.3) suggesting the important role of EGFR TK inhibitors in NSCLC management. In addition a significant increase of PPS was recorded in these patients (9.1 vs 4.6 p=0.02), allowing to perform further therapy lines to better control cancer evolution. Conclusions: These data underline the key role of EGFR in NSCLC growth and progression and the impact of erlotinib in cancer control evolution. Post progression therapy influence the effect on overall survival. This analysis suggests that a treatment strategy incorporating all active agents over the course of disease optimizes OS. Further investigations will be needed in selected patients harboring EGFR-activating mutations to better define the role of PPS as new indicator of erlotinib efficacy.

EGFR Tyrosine Kinase Inhibitors: Difference in Efficacy and Resistance

Lung cancer will be diagnosed in 230,000 patients in the U.S. in 2013. Adenocarcinoma will be the most common histology, and 10% of lung cancers will be diagnosed in never or former light smokers. These patients will be those most likely to harbor targetable mutations, in particular, mutations in epidermal growth factor (EGFR). Preclinical work beginning in the 1980s led to the development of EGFR-targeted therapy in lung cancer patients. Analysis of the responders to gefitinib and erlotinib led to the discovery of activating mutations underlying sensitivity to EGFR-directed treatment. Although EGFR-mutant patients have higher response rates, better quality of life, and longer progression free survival, all patients eventually develop resistance. Mutations in the tyrosine kinase domain that render tumors resistant to erlotinib and gefitinib are the most common mechanism of resistance. A second generation of EGFR inhibitors are now making their way to the clinic, with hopes of thwarting these resistance mechanisms or providing more durable responses via irreversible inhibition, as well as targeting of additional HER receptors. Here we review the evolution of EGFR as a target in lung cancer, and the second generation of EGFR inhibitors in development.

A Comprehensive, Multi-Scale Dynamical Model of ErbB Receptor Signal Transduction in Human Mammary Epithelial Cells

The non-receptor tyrosine kinase Src and receptor tyrosine kinase epidermal growth factor receptor (EGFR/ErbB1) have been established as collaborators in cellular signaling and their combined dysregulation plays key roles in human cancers, including breast cancer. In part due to the complexity of the biochemical network associated with the regulation of these proteins as well as their cellular functions, the role of Src in EGFR regulation remains unclear. Herein we present a new comprehensive, multi-scale dynamical model of ErbB receptor signal transduction in human mammary epithelial cells. This model, constructed manually from published biochemical literature, consists of 245 nodes representing proteins and their post-translational modifications sites, and over 1,000 biochemical interactions. Using computer simulations of the model, we find it is able to reproduce a number of cellular phenomena. Furthermore, the model predicts that overexpression of Src results in increased endocytosis of EGFR in the absence/low amount of the epidermal growth factor (EGF). Our subsequent laboratory experiments also suggest increased internalization of EGFR upon Src overexpression under EGF-deprived conditions, further supporting this model-generated hypothesis.

Abstract 1323: Identification of conditions of lapatinib effectiveness in prostate cancer.

Abstract ABSTRACT Lapatinib has been used in multiple clinical trials of either hormone-naïve men with prostate cancer (PCa) or in patients who have progressed to castration resistant prostate cancer (CRPC) following androgen deprivation therapy (ADT). Although lapatinib as a single-agent showed no overall positive effect in hormone-naive PCa, a small subset of unselected CRPC patients experienced PSA decline ∼50% with lapatinib treatment, with one patient remaining on this drug >45 months (Whang, Y.E. et al, 2011. Urol Oncol). The current investigation had been undertaken to determine whether lapatinib may benefit any select group of patients with PCa. Studies in vitro and in animal models supported the observation that lapatinib was ineffective in the presence of androgens; however, in low-androgen conditions, only androgen-dependent LNCaP PCa cells, but not CRPC cells, responded to lapatinib. Since lapatinib is a dual inhibitor of the receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) and a closely related member, ErbB2, hence we investigated the effect of this drug on the EGFR family. Comparison of the various cell lines that did or did not respond to lapatinib demonstrated that those that did not respond to lapatinib had very high inherent EGFR and ErbB3 activity, whereas LNCaP cells did not. More importantly, unlike its CRPC sublines C4-2 and LNCaP-AI, which were less responsive to lapatinib compared to LNCaP, the parental line experienced an increase in ErbB3 during androgen deprivation. Overexpression of ErbB3 induced resistance to lapatinib even in LNCaP cells, indicating an increase in the levels of RTKs as a potential cause for lapatinib resistance. Indeed, lapatinib treatment resulted in an overall increase in the levels of EGFR and/or ErbB2 in all the cell lines tested, even in LNCaP cells that do respond to lapatinib. Thus, our data demonstrate that (i) lapatinib is ineffective in PCa expressing high ErbB3 and (ii) among those with low intrinsic ErbB3, lapatinib is effective only in tumors where ErbB3 levels increase upon androgen withdrawal. Our results show that the critical window of opportunity for employing lapatinib and other dual EGFR/ErbB2 inhibitors is when ErbB3 levels are rising, but not once they have already increased. Since ErbB3 can be detected in the serum of patients with PCa, the increase of this RTK during ADT should be tested in future studies as a predictive marker of lapatinib response. Citation Format: Maitreyee K. Jathal, Benjamin A. Mooso, Leandro S. D'Abronzo, Salma Siddiqui, Liqun Chen, Elyse van Spyck, Anisha Madhav, Paramita M. Ghosh. Identification of conditions of lapatinib effectiveness in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1323. doi:10.1158/1538-7445.AM2013-1323