Critical update and emerging trends in epidermal growth factor receptor targeting in cancer

Targeting angiogenesis in gynecologic cancers

Gynecologic malignancies carry an estimated incidence of 83,750 cases per year and estimated mortality rate of more than 27,000 women per year. New therapies and therapeutic approaches are needed to improve the outlook for women with gynecologic cancers. Recent insights at the molecular and cellular levels are paving the way for a more directed approach to target mechanisms driving tumorigenesis. This article reviews the roles of new and emerging antiangiogenesis drugs, summarizes the data obtained from clinical trials of antiangiogenic agents, and discusses trials under way to address the role of such strategies in gynecologic cancers.

Cancer therapy and vaccination

Cancer remains one of the leading causes of death worldwide, both in developed and in developing nations. It may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Current therapeutic approaches which include surgery, chemotherapy and radiotherapy are associated with adverse side effects arising from lack of specificity for tumors. The goal of any therapeutic strategy is to impact on the target tumor cells with limited detrimental effect to normal cell function. Immunotherapy is cancer specific and can target the disease with minimal impact on normal tissues. Cancer vaccines are capable of generating an active tumor-specific immune response and serve as an ideal treatment due to their specificity for tumor cells and long lasting immunological memory that may safeguard against recurrences. Cancer vaccines are designed to either prevent (prophylactic) or treat established cancer (therapeutic). Identification of tumor-associated antigens (TAAs) and tumor-specific antigens (TSAs) has led to increased efforts to develop vaccination strategies. Vaccines may be composed of whole cells or cell extracts, genetically modified tumor cells to express costimulatory molecules, dendritic cells (DCs) loaded with TAAs, immunization with soluble proteins or synthetic peptides, recombinant viruses or bacteria encoding tumor-associated antigens, and plasmid DNA encoding TSAs or TAAs in conjunction with appropriate immunomodulators. All of these antitumor vaccination approaches aim to induce specific immunological responses and localized to TAAs, destroying tumor cells alone and leaving the vast majority of other healthy cells of the body untouched.

Phage displayed peptides/antibodies recognizing growth factors and their tyrosine kinase receptors as tools for anti-cancer therapeutics

The basic idea of displaying peptides on a phage, introduced by George P. Smith in 1985, was greatly developed and improved by McCafferty and colleagues at the MRC Laboratory of Molecular Biology and, later, by Barbas and colleagues at the Scripps Research Institute. Their approach was dedicated to building a system for the production of antibodies, similar to a naïve B cell repertoire, in order to by-pass the standard hybridoma technology that requires animal immunization. Both groups merged the phage display technology with an antibody library to obtain a huge number of phage variants, each of them carrying a specific antibody ready to bind its target molecule, allowing, later on, rare phage (one in a million) to be isolated by affinity chromatography. Here, we will briefly review the basis of the technology and the therapeutic application of phage-derived bioactive molecules when addressed against key players in tumor development and progression: growth factors and their tyrosine kinase receptors.

Association between vascular-poor area of primary tumors and epidermal growth factor receptor gene status in advanced lung adenocarcinoma

Mutation of the epidermal growth factor receptor gene (EGFR mutation) is a very important marker in the treatment for non-small cell lung cancer. Since signaling from this receptor induces tumor-associated angiogenesis, we hypothesized that lung cancers with EGFR mutations tend to develop locally with increased angiogenesis. Thus, the association between vascular-poor area of primary tumors and EGFR status was retrospectively investigated in advanced lung adenocarcinomas. To assess vascular-poor area, contrast-enhanced computed tomography scans taken before initial treatment for lung cancer were analyzed, together with primary tumor location (peripheral or central) and size. We analyzed 178 patients with advanced lung adenocarcinoma. EGFR mutations were detected in 95 of the 178 patients (53.4 %). EGFR mutation was found to be significantly related to women (P = 0.0070), never-smokers (P < 0.0001), and tumors without vascular-poor area (P < 0.0001). Based on a multivariate analysis, presence of EGFR mutations was independently associated with never-smokers (P = 0.0046), lack of vascular-poor area (P = 0.0001), and tumor size >30 mm (P = 0.0080). EGFR mutations were found in 41 of 51 never-smokers without vascular-poor area (80.4 %), 19 of 36 never-smokers with vascular-poor area (52.8 %), 19 of 37 current or former-smokers without vascular-poor area (51.4 %), and 16 of 54 current or former-smokers with vascular-poor area (29.6 %). This study showed an association between vascular-poor area of primary tumors and EGFR status. As a consequence, evaluation using a combination of smoking status and vascular-poor area allows us to predict presence of EGFR mutations at a high frequency.

Phosphorylated AKT and MAPK expression in primary tumours and in corresponding metastases and clinical outcome in colorectal cancer patients receiving irinotecan-cetuximab

Background

Clinical observations suggested that a non negligible proportion of patients, ranging from 40% to 70%, does not seem to benefit from the use of anti-EGFR targeted antibodies even in the absence of a mutation of the K- RAS gene. The EGFR pathway activation via the Ras-Raf-MAP-kinase and the protein-serine/threonine kinase AKT could determine resistance to anti-EGFR treatment.

Methods

We tested the interaction between phosphorylated AKT and MAPK expression in colorectal tumours and corresponding metastases and global outcome in K-RAS wild type patients receiving irinotecan-cetuximab.

Results

Seventy-two patients with histologically proven metastatic colorectal cancer, treated with Irinotecan and Cetuximab based chemotherapy, were eligible for our analysis.

In metastases pAKT correlated with RR (9% vs. 58%, p = 0.004), PFS (2.3 months vs.9.2 months p < 0.0001) and OS (6.1 months vs.26.7 months p < 0.0001) and pMAPK correlated with RR (10% vs., 47%, p = 0.002), PFS (2.3 months vs.8.6 months p < 0.0001) and OS (7.8 months vs.26 months p = 0.0004). At multivariate analysis pAKT and pMAPK in metastases were able to independently predict PFS. pAKT in metastases independently correlated with RR as well

Discussion

pAKT and pMAPK expression in metastases may modulate the activity of EGFR-targeted antibodies. We could speculate that in patients with pAKT and pMAPK metastases expression targeting these factors may be crucial.

A phase I dose-escalation study of regorafenib (BAY 73-4506), an inhibitor of oncogenic, angiogenic, and stromal kinases, in patients with advanced solid tumors

PURPOSE

Regorafenib is a novel oral multikinase inhibitor of angiogenic (VEGFR1-3, TIE2), stromal (PDGFR-β, FGFR), and oncogenic kinases (KIT, RET, and RAF). This first-in-man, phase I dose-escalation study assessed the safety, pharmacokinetic, pharmacodynamic, and efficacy profiles of regorafenib in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients aged 18 years or older with advanced solid tumors refractory to standard treatment were recruited. Regorafenib was administered orally for 21 days on/seven days off in repeating cycles, until discontinuation due to toxicity or tumor progression. Adverse events (AE) were assessed using National Cancer Institute Common Terminology Criteria for Adverse Events v3.0. Pharmacokinetic profiles were measured after a single dose and on day 21. Pharmacodynamic and efficacy evaluations included tumor perfusion assessment using dynamic contrast-enhanced MRI, plasma cytokines, and tumor response using RECIST (v1.0).

RESULTS

Fifty-three patients were enrolled into eight cohorts at dose levels from 10 to 220 mg daily. The recommended dose for future studies was determined to be 160 mg daily, with a treatment schedule of 21 days on/seven days off in repeating 28-day cycles. The most common drug-related grade 3 or 4 AEs were dermatologic AEs (hand-foot skin reaction, rash), hypertension, and diarrhea. Pharmacokinetic analysis revealed a similar exposure at steady state for the parent compound and two pharmacologically active metabolites. Tumor perfusion and plasma cytokine analysis showed biologic activity of regorafenib. Three of 47 evaluable patients achieved a partial response (renal cell carcinoma, colorectal carcinoma, and osteosarcoma).

CONCLUSION

Regorafenib showed an acceptable safety profile and preliminary evidence of antitumor activity in patients with solid tumors.

HER2 as therapeutic target for overcoming ATP-binding cassette transporter-mediated chemoresistance in small cell lung cancer

Small cell lung cancer (SCLC) easily acquires multidrug resistance after successful initial therapy. Overexpression of ATP-binding cassette (ABC) transporters is important for the multidrug resistance. Among them, ABCB1 and ABCG2 are known to be upregulated in chemoresistant SCLC cells. We found that human epidermal growth factor receptor 2 (HER2) expressions are also upregulated in chemoresistant SBC-3/ETP, SBC-3/SN-38, and SBC-3/CDDP cells, compared with chemosensitive SBC-3 cells. Lapatinib, a tyrosine kinase inhibitor of HER2, could not suppress proliferation of these HER2-positive SCLC cells alone but successfully restored chemosensitivity to etoposide and SN-38 with a clinically applicable concentration. The reversal effect of lapatinib was thought to be caused by inhibition of drug efflux pump functions of ABC transporters, although lapatinib itself has been reported to be a substrate for them. Moreover, knocking down of HER2 by an short interfering RNA weakened the effect of lapatinib on ABCB1, indicating the involvement of HER2 in the inhibitory mechanisms. Notably, we showed that caveolin-1 and Src play key roles in modulating ABCB1 function via HER2 inactivation. In SBC-3/ETP cells, dephosphorylation of HER2 by lapatinib activates Src and successively leads to increased caveolin-1 phosphorylation. Through this process, caveolin-1 dissociates from HER2 and strengthens association with ABCB1, and finally impairs the pump functions. Furthermore, we showed that treatment by lapatinib in combination with etoposide or irinotecan significantly suppresses the growth of subcutaneous SBC-3/ETP and SBC-3/SN-38 tumors in mice, respectively. Collectively, these results indicate that combination therapy with lapatinib and cytotoxic agents could conquer ABC transporter-mediated chemoresistance especially in HER2-positive SCLC.

Treatment outcome of patients with anaplastic thyroid cancer: a single center experience

PURPOSE

Anaplastic thyroid cancer is known to have a poor prognosis due to its aggressive and rapid metastasis with median survival of less than 6 months. Multimodal treatment involving surgery and chemoradiotherapy has been used to improve the survival of patients. Here, we retrospectively review of treatment outcome of 13 consecutive patients who were treated at a single center.

MATERIALS AND METHODS

We retrospectively reviewed medical records of 13 anaplastic thyroid cancer patients who received multidisciplinary treatment between 2006 and 2010. Kaplan-Meier survival curve was used to analyze progression-free survival and overall survival of patients.

RESULTS

The median patient age at diagnosis was 69 years, and six patients had stage IVc diseases. Eight patients received primary surgery followed by radiotherapy or concurrent chemoradiotherapy (CCRT). Five patients received weekly doxorubicin-based definitive CCRT, but only one patient's condition remained stable, while the rest experienced rapid disease progression. The median progression-free survival was 2.8 months (95% CI, 1.2-4.4 months), and the median overall survival was 3.8 months (95% CI, 3.0-4.6 months).

CONCLUSION

Patients with anaplastic thyroid cancer showed poor prognosis despite multimodality treatment. Therefore, identification of novel therapeutic targets is warranted to take an effective mode of treatment.

Molecular pathology of lung cancer: key to personalized medicine

The majority of lung adenocarcinoma patients with epidermal growth factor receptor- (EGFR) mutated or EML4-ALK rearrangement-positive tumors are sensitive to tyrosine kinase inhibitors. Both primary and acquired resistance in a significant number of those patients to these therapies remains a major clinical problem. The specific molecular mechanisms associated with tyrosine kinase inhibitor resistance are not fully understood. Clinicopathological observations suggest that molecular alterations involving so-called 'driver mutations' could be used as markers that aid in the selection of patients most likely to benefit from targeted therapies. In this review, we summarize recent developments involving the specific molecular mechanisms and markers that have been associated with primary and acquired resistance to EGFR-targeted therapy in lung adenocarcinomas. Understanding these mechanisms may provide new treatment avenues and improve current treatment algorithms.

Safety profiles of erlotinib therapy in patients with advanced non-small-cell lung cancer

Erlotinib is an orally available, small-molecule EGF receptor tyrosine kinase inhibitor. It has shown promising activity in chemotherapy-relapsed patients with advanced non-small-cell lung cancer and is now approved in many countries. To date, there have been a number of clinical studies of erlotinib therapy demonstrating its safety as well as its efficacy. This article summarizes clinical study results in advanced non-small-cell lung cancer, so that we can comprehensively understand the toxicities expected with erlotinib in non-small-cell lung cancer patients.

LCH-7749944, a novel and potent p21-activated kinase 4 inhibitor, suppresses proliferation and invasion in human gastric cancer cells

P21-activated kinase 4 (PAK4), a serine/threonine protein kinase, has involved in the regulation of cytoskeletal reorganization, cell proliferation, gene transcription, oncogenic transformation and cell invasion. Moreover, PAK4 overexpression, genetic amplification and mutations were detected in a variety of human tumors, which make it potential therapeutic target. In this paper we found that LCH-7749944, a novel and potent PAK4 inhibitor, effectively suppressed the proliferation of human gastric cancer cells through downregulation of PAK4/c-Src/EGFR/cyclin D1 pathway. In addition, LCH-7749944 significantly inhibited the migration and invasion of human gastric cancer cells in conjunction with concomitant blockage of PAK4/LIMK1/cofilin and PAK4/MEK-1/ERK1/2/MMP2 pathways. Interestingly, LCH-7749944 also inhibited the formation of filopodia and induced cell elongation in SGC7901 cells. Importantly, LCH-7749944 caused successful inhibition of EGFR activity due to its inhibitory effect on PAK4. Taken together, these results provided novel insights into the development of PAK4 inhibitor and potential therapeutic strategies for gastric cancer.

Nimotuzumab, a novel monoclonal antibody to the epidermal growth factor receptor, in the treatment of non-small cell lung cancer

The epidermal growth factor receptor (EGFR) is a promising therapeutic target in non-small cell lung cancer, and several therapeutic agents that target this receptor, including EGFR tyrosine kinase inhibitors and monoclonal antibodies to EGFR, have been developed. Such monoclonal antibodies have shown efficacy in combination with chemotherapy and radiotherapy. Nimotuzumab (h-R3) is a humanized monoclonal antibody to EGFR, and its effects in combination with radiation have been sufficiently promising to warrant further investigation in several types of cancer. Furthermore, the typical severe dermatologic toxicities associated with other monoclonal antibodies to EGFR have not been observed with nimotuzumab. We here summarize the results of preclinical studies as well as of previous and ongoing clinical trials of nimotuzumab for the treatment of non-small cell lung cancer.

Cetuximab induces mitochondrial translocalization of EGFRvIII, but not EGFR: involvement of mitochondria in tumor drug resistance?

Dysregulation of growth factor receptors such as the epidermal growth factor receptor (EGFR) and of its truncated form EGFRvIII is frequently found in human tumors. EGFRvIII is a promising target for selective molecular tumor therapy because it is exclusively expressed by tumor cells. Cetuximab/Erbitux is a monoclonal antibody which targets EGFR and EGFRvIII. The effects of cetuximab on EGFRvIII but still the exact function and mechanism of cetuximab in relation to EGFR and EGFRvIII are incompletely understood. Therefore, we investigated the influence of cetuximab on EGFRvIII signaling and cellular survival. We found that cetuximab leads to increased internalization of EGFRvIII in NR6M cells but is unable to inhibit neither the activation of EGFRvIII nor its downstream signaling pathways. Incubation with cetuximab also did not alter the survival and proliferation of EGFRvIII-expressing cells. However, it caused increased mitochondrial activity and an increase in co-localization of EGFRvIII with mitochondria. These results demonstrate that interaction of EGFRvIII with mitochondria could play a role in survival of cetuximab-treated NR6M cells. Thus, a role of mitochondria in resistance to cetuximab has to be considered.

Design and synthesis of a series of novel bisquinazoline glycosides as epidermal growth factor receptor inhibitors

A new series of potential epidermal growth factor receptor inhibitors possessing bisquinazoline and saccharide moieties were designed and synthesized. The biological results demonstrated that the synthetic derivatives significantly inhibited epidermal growth factor receptor enzymatic activity in vitro. Of them, compound 14b showed the highest inhibitory rate toward epidermal growth factor receptor protein tyrosine kinase (81.36%) at a concentration of 1 μM. Further molecular simulation predicted that 14b offered its saccharide moieties hydrogen bonding to ATP-binding pocket.

Phosphoinositide-3-kinase catalytic alpha and KRAS mutations are important predictors of resistance to therapy with epidermal growth factor receptor tyrosine kinase inhibitors in patients with advanced non-small cell lung cancer

BACKGROUND

Specific mutations of the epidermal growth factor receptor (EGFR) gene are predictive for favorable response to tyrosine kinase inhibitors (TKIs) and are associated with a good prognosis. In contrast, Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation has been shown to predict poor response to such therapy. Nevertheless, tumor that initially responds to EGFR-TKIs almost inevitably becomes resistant later. Other mechanisms of resistance to EGFR inhibitors could involve activating mutations of the other main EGFR effector pathway, i.e., the phosphoinositide-3-kinase/phosphate and tensin homologue deleted from chromosome 10 (PTEN)/alpha serine/threonine protein kinase (AKT) pathway. The aim of this study was to investigate the role of phosphoinositide-3-kinase catalytic alpha (PIK3CA), EGFR, and KRAS gene mutations in predicting response and survival in patients with non-small cell lung cancer (NSCLC) treated with EGFR-TKIs.

PATIENTS AND METHODS

A total of 166 patients with advanced NSCLC treated with EGFR-TKI with available archival tissue specimens were included. PIK3CA, EGFR, and KRAS mutations were analyzed using polymerase chain reaction-based sequencing.

RESULTS

EGFR mutation was detected in 25.3% of patients, PIK3CA mutation in 4.1%, and KRAS mutation in 6.7%. PIK3CA mutation correlated with shorter median time to progression (TTP) (p = 0.01) and worse overall survival (OS) (p < 0.001). EGFR mutation (p < 0.0001) correlated with favorable response to TKIs treatment and longer TTP (p < 0.0001). KRAS mutation correlated with progressive disease (p = 0.05) and shorter median TTP (p = 0.003) but not with OS. Cox multivariate analysis including histology and performance status showed that PIK3CA mutation was an independent factor to predict worse OS (p = 0.0001) and shorter TTP (p = 0.03), while KRAS mutation to predict shorter TTP (p = 0.01).

CONCLUSION

PIK3CA and KRAS mutations seem to be indicators of resistance and poor survival in patients with NSCLC treated with EGFR-TKIs.

Differential action of small molecule HER kinase inhibitors on receptor heterodimerization: therapeutic implications

Deregulation of ErbB/HER receptor tyrosine kinases has been linked to several types of cancer. The mechanism of activation of these receptors includes establishment of receptor dimers. Here, we have analyzed the action of different small molecule HER tyrosine kinase inhibitors (TKIs) on HER receptor dimerization. Breast cancer cell lines were treated with distinct TKIs and the formation of HER2-HER3 dimers was analyzed by coimmunoprecipitation and western blot or by Förster resonance energy transfer assays. Antibody-dependent cellular cytotoxicity was analyzed by measuring the release of lactate dehydrogenase and cell viability. Lapatinib and neratinib interfered with ligand-induced dimerization of HER receptors; while pelitinib, gefitinib, canertinib or erlotinib did not. Moreover, lapatinib and neratinib were able to disrupt previously formed receptor dimers. Structural analyses allowed the elucidation of the mechanism by which some TKIs prevent the formation of HER receptor dimers, while others do not. Experiments aimed at defining the functional importance of dimerization indicated that TKIs that impeded dimerization prevented down-regulation of HER2 receptors, and favored the action of trastuzumab. We postulate that TKIs that prevent dimerization and down-regulation of HER2 may augment the antitumoral action of trastuzumab, and this mechanism of action should be considered in the treatment of HER2 positive tumors which combine TKIs with antireceptor antibodies.

Preparation of cystamine core dendrimer and antibody-dendrimer conjugates for MRI angiography

Herein we report the preparation along with the in vivo and in vitro MRI characterization of two generation four and five cystamine core dendrimers loaded with thirty and fifty-eight derivatized Gd-DOTA (G4SS30, G5SS58) respectively. Likewise the development and characterization of two half-dendrimers conjugated to the F(ab')(2) fragment of the monoclonal antibody (mAb) panitumumab functionalized with a maleimide conjugation functional group site (Ab-(G4S15)(4), Ab-(G5S29)(4)) are also described. The in vitro molar relaxivity of the Ab-(G4S15)(4) conjugate, measured at pH 7.4, 22 °C, and 3T showed a moderate increase in relaxivity as compared to Magnevist (6.7 vs 4.0 mM(-1) s(-1)) while the Ab-(G5S29)(4) conjugate was 2-fold higher (9.1 vs 4.0 mM(-1) s(-1)). The data showed that only a high injection dose (0.050 mmol Gd(3+)/kg) produced a detectable contrast enhanced contrast for the Ab-(G4S15)(4) conjugate while a lower dose (0.035 mmol Gd(3+)/kg) was sufficient for the Ab-(G5S29)(4) conjugate. The antibody-SMCC conjugate was purified by a Sephadex G-100 column, and the antibody-dendrimer-based agents were purified by spin filtration using a Centricon filter (50,000 MCO). The protein assay coupled with cysteine and Ellman's assay indicated an antibody to dendrimer ratio of 1:4. The in vivo blood clearance half-lives of the four agents measured at the jugular vein were ~12-22 min.

Blockade of the HER family of receptors in the treatment of HER2-positive metastatic breast cancer

Breast cancer is the most common type of cancer among women and the second leading cause of cancer death in the United States. Metastatic breast cancer is considered incurable, and treatment is aimed at palliating symptoms, achieving remission, and prolonging survival. Treatment options for metastatic disease vary based on tumor surface markers and clinical factors in an individual patient and include cytotoxic chemotherapy, hormonal therapy, biological therapy, or some combination of these. An important molecular determinant of therapy is the human epidermal growth factor receptor 2 (HER2) positivity of the tumor, which affects response to HER2-targeted treatment. HER2 is a member of the human epidermal growth factor receptor family of receptor tyrosine kinases, also known as the HER family, which activates signaling that promotes tumorigenic cellular processes such as proliferation and evasion of apoptosis. Several targeted agents, including monoclonal antibodies and tyrosine kinase inhibitors that inhibit one or more HER family receptors have been developed that affect signaling through this pathway. Some of these, such as trastuzumab and lapatinib, have been approved for breast cancer treatment. Resistance to therapy is a challenge that limits the duration of benefit achieved with these agents. Therefore, combinations of HER family-targeted agents with other therapies such as cytotoxic agents, hormonal therapy, or inhibitors of other cellular pathways, are being developed to exploit synergy and overcome resistance mechanisms. Here we review the HER family-targeted agents currently approved or in development for HER2-positive metastatic breast cancer with a focus on strategies to overcome tumor resistance.

Defining new paradigms for the treatment of pancreatic cancer

Pancreatic cancer (PC) is the fourth leading cause of cancer death in the United States. Despite significant improvement in understanding disease biology, the 5-year survival rates remain less than 5%. Targeted agents failed to add any meaningful survival benefit in this patient population despite very promising pre-clinical data. The new paradigm for the treatment of PC must emphasize validation of targeted agents in the appropriate pre-clinical models, identification of predictive markers for disease response, and extending range of targets into cancer stem cells and tumor microenvironment. It is also necessary to perform studies that are designed to address the various stages of disease with respect to study endpoints and application of a multimodality approach in management. Phase III trials should only be considered when a strong efficacy signal is demonstrated in phase II studies that is based on a survival endpoint. This review will focus on the development of novel treatments in pancreas cancer and the proposed design of future clinical trials.

99mTc-Hydrazinonicotinamide epidermal growth factor-polyethylene glycol-quantum dot imaging allows quantification of breast cancer epidermal growth factor receptor expression and monitors receptor downregulation in response to cetuximab therapy

Therapy of cancer, including basallike breast tumors, that targets the epidermal growth factor receptor (EGFR) would greatly benefit from noninvasive methods that can quantitatively monitor receptor status and treatment response.

METHODS

Here, we investigated the potential of a novel technique based on streptavidin cadmium selenide/zinc sulfide quantum dots (Qdots) multiplexed with polyethylene glycol (PEG), epidermal growth factor (EGF), and (99m)Tc-hydrazinonicotinamide. In vitro binding affinity and specificity were evaluated in cultured cells. Biodistribution studies and in vivo imaging were performed in murine breast tumor xenografts of basallike phenotype MDA-MB-468 cells and EGFR-negative cells.

RESULTS

(99m)Tc-hydrazinonicotinamide EGF-PEG-Qdot showed specific and high-affinity EGFR targeting on confocal microscopy, immunoblotting, and binding assays. When intravenously injected, MDA-MB-468 tumors were visualized with high contrast by both optical and scintigraphic imaging. Scintigraphic image-based quantification correctly discriminated high-EGFR-expressing MDA-MB-468 tumors from other tumors, and image-based tumor uptake closely correlated to EGFR content. Importantly, serial imaging of MDA-MB-468 tumors responding to cetuximab therapy could detect a significant reduction of tumor uptake that was paralleled by downregulation of EGFR expression. Furthermore, high baseline uptake predicted good response to cetuximab therapy.

CONCLUSION

(99m)Tc-hydrazinonicotinamide EGF-PEG-Qdot provides EGFR-targeted imaging of breast tumors and may allow noninvasive monitoring of EGFR status in living subjects before and after targeted therapies.

Overall and KRAS-specific results of combined cetuximab treatment and chemotherapy for metastatic colorectal cancer: a meta-analysis

PURPOSE

This study compared the efficacy and toxicities of cetuximab combined with chemotherapy versus chemotherapy for patients with metastatic colorectal cancer (mCRC). The influence of KRAS mutation status on the outcomes was also investigated.

METHODS

Literature retrieval, trials selection and assessment, data collection, and statistical analysis were performed according to the Cochrane Handbook 5.0.2. The outcome measures were tumor response rate, progression-free survival, overall survival, and adverse effects.

RESULTS

Four randomized controlled trials, comprising totally 2,912 patients, were included. Meta-analysis showed higher response rate (RR 1.93; 95% CI, 1.14-3.26) and significant improvement in progression-free survival (PFS; HR 0.80; 95% CI, 0.67-0.95) in cetuximab-chemotherapy groups versus chemotherapy groups. There was no significant difference between the two treatment groups regarding overall survival (OS; HR 0.95; 95% CI, 0.87-1.05). In wild-type KRAS patients, treatment with cetuximab plus chemotherapy significantly increased response rate (RR 1.44; 95% CI, 1.20-1.73) and improved PFS (HR 0.64; 95% CI, 0.50-0.84), as compared with chemotherapy groups, but not for OS (HR 0.84; 95% CI, 0.64-1.11). In mutant KRAS patients, there was no significant difference between those treated with cetuximab plus chemotherapy and those with chemotherapy alone regarding response rate (RR 0.81; 95% CI, 0.61-1.08), PFS (HR 1.37; 95% CI, 0.81-2.31), and OS (HR 1.03; 95% CI, 0.74-1.44). The risk of grade 3/4 rash, diarrhea, neutropenia, and fatigue was significantly increased in cetuximab combination groups as compared with chemotherapy groups.

CONCLUSIONS

The use of cetuximab in addition to chemotherapy was a valid alternative for patients with mCRC. Benefit of cetuximab was only limited to patients with wild-type KRAS tumors.

Targeting tumor cell motility to prevent metastasis

Mortality and morbidity in patients with solid tumors invariably result from the disruption of normal biological function caused by disseminating tumor cells. Tumor cell migration is under intense investigation as the underlying cause of cancer metastasis. The need for tumor cell motility in the progression of metastasis has been established experimentally and is supported empirically by basic and clinical research implicating a large collection of migration-related genes. However, there are few clinical interventions designed to specifically target the motility of tumor cells and adjuvant therapy to specifically prevent cancer cell dissemination is severely limited. In an attempt to define motility targets suitable for treating metastasis, we have parsed the molecular determinants of tumor cell motility into five underlying principles including cell autonomous ability, soluble communication, cell-cell adhesion, cell-matrix adhesion, and integrating these determinants of migration on molecular scaffolds. The current challenge is to implement meaningful and sustainable inhibition of metastasis by developing clinically viable disruption of molecular targets that control these fundamental capabilities.

EGFR gene amplification is related to adverse clinical outcomes in cervical squamous cell carcinoma, making the EGFR pathway a novel therapeutic target

Background:

The aim of this study was to investigate the patterns of epidermal growth factor receptor (EGFR) overexpression, EGFR gene amplification, and the presence of activating mutations in the tyrosine kinase domain of this gene in squamous cell carcinomas and adenocarcinomas/adenosquamous carcinomas of the uterine cervix.

Methods:

The EGFR expression, amplification, and mutation in cervical carcinomas were assessed by immunohistochemistry, fluorescence in situ hybridisation, and PCR–SSCP, respectively, and correlated with clinical data collected by a retrospective chart review. A functional assessment was performed by inactivating EGFR in cervical cancer cells with the potent inhibitor AG1478.

Results:

Immunohistochemical analysis revealed that 6 out of 59 (10.2%) cervical squamous cell carcinomas showed significant amplification of the EGFR locus, whereas none of the 52 adeno/adenosquamous cell carcinomas had detectable EGFR amplification (P<0.05). The EGFR amplification significantly correlated with shorter overall survival (P=0.001) in cervical squamous cell carcinomas. Multivariate analysis showed that EGFR gene amplification was an independent prognostic factor for overall survival (P=0.011). None of the squamous cell carcinomas (0%: 0 out of 32) had detectable oncogenic mutations in EGFR exons 18 through 21. The frequencies of KRAS and BRAF mutations were very low in both squamous and adeno/adenosquamous cell carcinomas. Sensitivity of cervical cancer cells to AG1478 depended on the presence of EGFR overexpression. AG1478-induced EGFR inactivation in cell lines with EGFR overexpression significantly suppressed tumour development and progression in a mouse xenograft model.

Conclusion:

Our data suggest that EGFR signalling is important in a subset of cervical squamous cell carcinomas and that anti-EGFR therapy may benefit patients who carry the 7p11.2 amplicon in their tumours.

Selective targeting of antibody conjugated multifunctional nanoclusters (nanoroses) to epidermal growth factor receptors in cancer cells

The ability of smaller than 100 nm antibody (Ab) nanoparticle conjugates to target and modulate the biology of specific cell types may enable major advancements in cellular imaging and therapy in cancer. A key challenge is to load a high degree of targeting, imaging, and therapeutic functionality into small, yet stable particles. A versatile method called thin autocatalytic growth on substrate (TAGs) has been developed in our previous study to form ultrathin and asymmetric gold coatings on iron oxide nanocluster cores producing exceptional near-infrared (NIR) absorbance. AlexaFluor 488 labeled Abs were used to correlate the number of Abs conjugated to iron oxide/gold nanoclusters (nanoroses) with the hydrodynamic size. A transition from submonolayer to multilayer aggregates of Abs on the nanorose surface was observed for 54 Abs and an overall particle diameter of ∼60-65 nm. The hydrodynamic diameter indicated coverage of a monolayer of 54 Abs, in agreement with the prediction of a geometric model, by assuming a circular footprint of 16.9 nm diameter per Ab molecule. The targeting efficacy of nanoclusters conjugated with monoclonal Abs specific for epidermal growth factor receptor (EGFR) was evaluated in A431 cancer cells using dark field microscopy and atomic absorbance spectrometry (AAS) analysis. Intense NIR scattering was achieved from both high uptake of nanoclusters in cells and high intrinsic NIR absorbance of individual nanoclusters. Dual mode imaging with dark field reflectance microscopy and fluorescence microscopy indicates the Abs remained attached to the Au surfaces upon the uptake by the cancer cells. The ability to load intense multifunctionality, specifically strong NIR absorbance, conjugation of an Ab monolayer in addition to a strong r2 MRI contrast that was previously demonstrated in a total particle size of only 63 nm, is an important step forward in development of theranostic agents for combined molecular specific imaging and therapy.

Dual blockade of EGFR and c-Met abrogates redundant signaling and proliferation in head and neck carcinoma cells

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) is usually fatal, and innovative approaches targeting growth pathways are necessary to effectively treat this disease. Both the epidermal growth factor receptor (EGFR) and the hepatocyte growth factor (HGF)/c-Met pathways are overexpressed in HNSCC and initiate similar downstream signaling pathways. c-Met may act in consort with EGFR and/or be activated as a compensatory pathway in the presence of EGFR blockade.

EXPERIMENTAL DESIGN

Expression levels of EGFR and c-Met were determined by Western analysis in HNSCC cell lines and correlated with antitumor responses to inhibitors of these pathways.

RESULTS

Combining the c-Met inhibitor PF2341066 with the EGFR inhibitor gefitinib abrogated HNSCC cell proliferation, invasion, and wound healing significantly more than inhibition of each pathway alone in HNSCC cell lines. When both HGF and the EGFR ligand, TGF-α, were present in vitro, P-AKT and P-MAPK expression were maximally inhibited by targeting both EGFR and c-Met pathways, suggesting that c-Met or EGFR can compensate when phosphorylation of the other receptor is inhibited. We also showed that TGF-α can induce phosphorylation of c-Met over sixfold by 8 hours in the absence of HGF, supporting a ligand-independent mechanism. Combined targeting of c-Met and EGFR resulted in an enhanced inhibition of tumor volumes accompanied by a decreased number of proliferating cells and increased apoptosis compared with single agent treatment in vivo.

CONCLUSIONS

Together, these results suggest that dual blockade of c-Met and EGFR may be a promising clinical therapeutic strategy for treating HNSCC.

Combination treatment with HER-2 and VEGF peptide mimics induces potent anti-tumor and anti-angiogenic responses in vitro and in vivo

HER-2 is a member of the EGF receptor family and is overexpressed in 20-30% of breast cancers. HER-2 overexpression causes increased expression of VEGF at both the RNA and protein levels. HER-2 and VEGF are therefore considered good targets for cancer treatment, which has led to the development of two humanized monoclonal antibodies (mAb) pertuzumab and bevacizumab. Although passive immunotherapy with these Abs are approved for treatment of advanced breast cancer, a number of concerns exist. Treatment is expensive, has a limited duration of action, and is usually accompanied by serious side effects. We hypothesized that therapy with conformational peptide mimics aimed at blocking receptor-ligand interaction is potentially safer with little toxicity, cheaper with a longer half-life, and has greater penetrating abilities than mAbs. We designed and synthesized peptides based on the binding of HER-2 with pertuzumab and VEGF with VEGFR2. We show that treatment with the peptide mimics induces potent anti-tumor responses in vitro as determined by cell viability, proliferation, and HER2 phosphorylation assays. We also demonstrate in a transplantable BALB/c mouse tumor model that treatment with the peptide mimics resulted in a greater delay in tumor growth and development. Similarly, treatment with the peptide mimics inhibited angiogenesis in vivo as assessed by a Matrigel plug assay. To address the problem of degradability of L-amino acid peptides in vivo, we synthesized the retro-inverso D-peptide mimics that resulted in higher efficacy in treatment. Our study shows that combination treatment with HER-2 and VEGF peptide mimics provides greater efficacy than individual treatments.

Pharmacokinetic and pharmacodynamic perspectives on the clinical drug development of panitumumab

Panitumumab is a recombinant, fully human IgG2 monoclonal antibody directed against the epidermal growth factor receptor (EGFR). It is indicated for use as monotherapy in the treatment of patients with EGFR-expressing metastatic colorectal cancer after disease progression with standard chemotherapy. The currently indicated dose is 6 mg/kg given every 2 weeks. Panitumumab is mainly distributed into the vascular space and exhibits nonlinear pharmacokinetics that are consistent with target-mediated drug disposition, involving saturable binding to EGFR and subsequent internalization and degradation inside the cells. Panitumumab is also cleared in a linear fashion by the reticuloendothelial system, similarly to other endogenous immunoglobulins. After single-dose administration of panitumumab as a 1-hour intravenous infusion, the area under the serum concentration-time curve increases in a greater-than-dose-proportional manner as the dose increases from 0.75 to 5 mg/kg; however, at doses above 2 mg/kg, the exposure to panitumumab increases in a dose-proportional manner. Panitumumab pharmacokinetics are not meaningfully affected by the tumour type, EGFR membrane expression, tumour KRAS mutation, sex, age, race or renal or hepatic dysfunction. In addition, irinotecan-containing and paclitaxel/carboplatin-containing chemotherapeutic regimens do not appear to affect panitumumab pharmacokinetics. The results of population pharmacokinetic analyses have shown that bodyweight is the most influential covariate on panitumumab exposure, supporting the current use of bodyweight-adjusted doses (mg/kg). The relationship between the weekly dose of panitumumab and skin rash, an on-target pharmacodynamic effect of EGFR inhibition, reaches a plateau at 2.5 mg/kg, indicating that this is the optimal weekly dose. Two less-frequent dosing regimens (6 mg/kg given every 2 weeks and 9 mg/kg given every 3 weeks) achieve steady-state serum trough concentrations similar to those achieved by 2.5 mg/kg given every week, ensuring maximal EGFR coverage. Anti-panitumumab antibody production is uncommon and does not appear to have an impact on the pharmacokinetics of panitumumab.

Antitumor activity of HM781-36B, an irreversible Pan-HER inhibitor, alone or in combination with cytotoxic chemotherapeutic agents in gastric cancer

Trastuzumab, a HER2 directed treatment has shown clinical benefit in HER2 amplified gastric cancer. This study demonstrated the potent antitumor activity of HM781-36B, a quinazoline-based irreversible pan-HER inhibitor, in HER2 amplified gastric cancer cells (SNU216 and N87) in vitro and in vivo. HM781-36B inhibited phosphorylation of HER family and downstream signaling molecules, and induced apoptosis and G1 arrest. Furthermore, HM781-36B exerted synergistic effects with chemotherapeutic agents in both HER2 amplified and HER2 non-amplified gastric cancer cells. Therefore, HM781-36B may be useful for the treatment of HER2 amplified gastric cancer alone or in combination with chemotherapeutic agents.

Synergistic effect between erlotinib and MEK inhibitors in KRAS wild-type human pancreatic cancer cells

PURPOSE

The combination of erlotinib and gemcitabine has shown a small but statistically significant survival advantage when compared with gemcitabine alone in patients with advanced pancreatic cancer. However, the overall survival rate with the erlotinib and gemcitabine combination is still low. In this study, we sought to identify gene targets that, when inhibited, would enhance the activity of epidermal growth factor receptor (EGFR)-targeted therapies in pancreatic cancer cells.

EXPERIMENTAL DESIGN

A high-throughput RNA interference (RNAi) screen was carried out to identify candidate genes. Selected gene hits were further confirmed and mechanisms of action were further investigated using various assays.

RESULTS

Six gene hits from siRNA screening were confirmed to significantly sensitize BxPC-3 pancreatic cancer cells to erlotinib. One of the hits, mitogen-activated protein kinase (MAPK) 1, was selected for further mechanistic studies. Combination treatments of erlotinib and two MAP kinase kinase (MEK) inhibitors, RDEA119 and AZD6244, showed significant synergistic effect for both combinations (RDEA119-erlotinib and AZD6244-erlotinib) compared with the corresponding single drug treatments in pancreatic cancer cell lines with wild-type KRAS (BxPC-3 and Hs 700T) but not in cell lines with mutant KRAS (MIA PaCa-2 and PANC-1). The enhanced antitumor activity of the combination treatment was further verified in the BxPC-3 and MIA PaCa-2 mouse xenograft model. Examination of the MAPK signaling pathway by Western blotting indicated effective inhibition of the EGFR signaling by the drug combination in KRAS wild-type cells but not in KRAS mutant cells.

CONCLUSIONS

Overall, our results suggest that combination therapy of an EGFR and MEK inhibitors may have enhanced efficacy in patients with pancreatic cancer.

EGFR and COX-2 protein expression in non-small cell lung cancer and the correlation with clinical features

Background

To evaluate the expression of EGFR and COX-2 and their correlation with prognosis in NSCLC

Methods

The paraffin embedded tumor samples of 50 NSCLC patients receiving radical resection were analyzed immunohistochemically for EGFR and COX-2 expression and their prognostic values were explored.

Results

The positive rate of EGFR protein in NSCLC tumor cells was 46%, which was significantly higher than its expression in normal lung (p = 0.0234) and paracancerous tissues (p = 0.020). EGFR expression was significantly higher in nodal positive than in nodal negative patients (p = 0.04). The mean survival time for EGFR positive patients (31 months) was significantly lower than that for patients with EGFR negative expression (48 months) (p = 0.008,). In patients receiving post-operation thoracic irradiation, the mean survival time for EGFR positive patients was significantly lower than that for patients without EGFR positive expression (25 vs. 48 months, P = 0.004). The positive rate of COX-2 protein expression in NSCLC tumor cells was 90%, which was significantly higher than that in normal tissue(p = 0.00) and paracancerous tissue (p = 0.00). There was no correlation between COX-2 expression and patient survival, and no correlation between COX-2 and EGFR protein expression (P = 0.555).

Conclusions

COX-2 and EGFR are over-expressed in NSCLC. EGFR is an independent prognostic factor and a predictive factor for radiotherapy response in NSCLC.

Differences in adverse events between 250 mg daily gefitinib and 150 mg daily erlotinib in Japanese patients with non-small cell lung cancer

PURPOSE

The maximum tolerated dose (MTD) of erlotinib (150 mg) is the approved daily dose. In contrast, the approved daily dose of gefitinib (250 mg) is only one-third of its MTD. Significantly different adverse events have been associated with gefitinib and erlotinib.

EXPERIMENTAL DESIGN

A retrospective investigation examining the adverse events and tolerances of 250 mg daily gefitinib and 150 mg daily erlotinib in Japanese patients with non-small cell lung cancer (NSCLC) was performed. Adverse events were assessed according to Common Terminology Criteria for Adverse Events version 3.0. To determine tolerance for each agent, failure was defined as dose reduction or discontinuation of the drug due to adverse events, and early failure as dose reduction or discontinuation due to adverse events before the first evaluation of response.

RESULTS

More adverse events including skin disorders, diarrhea, oral mucositis, asthenic conditions, anorexia, nausea, vomiting, and gastrointestinal bleeding were observed in the erlotinib group. Liver function test abnormalities and pneumonitis did not differ between the two groups. Based on multivariate analysis, failure, early failure, and discontinuation due to adverse events were independently associated with erlotinib use.

CONCLUSION

Our data show that 150 mg daily erlotinib was associated with more toxicity and less tolerability than 250 mg daily gefitinib.

Duration of prior gefitinib treatment predicts survival potential in patients with lung adenocarcinoma receiving subsequent erlotinib

PURPOSE

We investigated survival potential in patients receiving erlotinib after failure of gefitinib, focusing on response and time to progression (TTP) with gefitinib.

METHODS

We retrospectively reviewed lung adenocarcinoma patients who received erlotinib after experiencing progression with gefitinib. Our primary objective was to evaluate the prognostic significance of erlotinib therapy.

RESULTS

A total 42 lung adenocarcinoma patients were included in this study. Overall disease control rate was 59.5% (partial response [PR], 2.4%; stable disease [SD], 57.1%). Median overall survival was 7.1 months, and median progression-free survival was 3.4 months. The number of patients who achieved PR and non-PR (SD+ progressive disease [PD]) with gefitinib were 22 (52%) and 20 (48%), respectively. Patients with PR for gefitinib showed significantly longer survival times than those with non-PR (9.2 vs. 4.7 months; p=0.014). In particular, among PR patients, those with TTP <12 months on gefitinib showed significantly longer survival times than those with TTP ≥12 months (10.3 vs. 6.4 months; p=0.04).

CONCLUSIONS

Erlotinib may exert survival benefit for lung adenocarcinoma patients with less than 12 months of TTP of prior gefitinib who achieved PR for gefitinib.

EpCAM- and EGFR-targeted selective gene therapy for biliary cancers using Z33-fiber-modified adenovirus

A critical issue in adenovirus (Ad)-based cancer gene therapy is to improve the specificity of gene delivery to cancer cells for better efficacy and safety. We explored methods of retargeting Ad vectors for selective gene therapy of human biliary cancers using the Ad incorporating an IgG Fc-binding motif (Z33) from the Staphylococcus protein A (Ad-FZ33) combined with tumor-specific antibodies. Flow cytometry analysis revealed high-expression levels of epithelial cell adhesion molecule (EpCAM) and epidermal growth factor receptor (EGFR) on human biliary cancer cells. Ad-FZ33 expressing LacZ combined with antibodies against EpCAM or EGFR, followed by β-gal assay, demonstrated highly efficient gene transduction in these biliary cancer cells, compared to the treatment with control antibody or without antibody. Ad-FZ33 expressing uracil phosphoribosyl transferase (UPRT), an enzyme which greatly enhances the toxicity of 5-fluorouracil (FU), combined with antibodies against EpCAM or EGFR, remarkably enhanced the sensitivity of biliary cancer cells to 5-FU. By contrast, the treatment did not affect the 5-FU sensitivity of the cells not expressing EpCAM or EGFR including normal hepatocytes. Finally, treatments with the UPRT-expressing Ad-FZ33 with antibodies against EpCAM or EGFR, followed by 5-FU administration, significantly suppressed the growth of biliary cancer xenografts in nude mice. These results indicate that the gene therapy mediated by the Z33 fiber modified Ad with anti-EpCAM or anti-EGFR antibodies offers a potentially effective therapeutic modality against biliary cancers.

Tumour gene expression predicts response to cetuximab in patients with KRAS wild-type metastatic colorectal cancer

BACKGROUND

Although it is accepted that metastatic colorectal cancers (mCRCs) that carry activating mutations in KRAS are unresponsive to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies, a significant fraction of KRAS wild-type (wt) mCRCs are also unresponsive to anti-EGFR therapy. Genes encoding EGFR ligands amphiregulin (AREG) and epiregulin (EREG) are promising gene expression-based markers but have not been incorporated into a test to dichotomise KRAS wt mCRC patients with respect to sensitivity to anti-EGFR treatment.

METHODS

We used RT-PCR to test 110 candidate gene expression markers in primary tumours from 144 KRAS wt mCRC patients who received monotherapy with the anti-EGFR antibody cetuximab. Results were correlated with multiple clinical endpoints: disease control, objective response, and progression-free survival (PFS).

RESULTS

Expression of many of the tested candidate genes, including EREG and AREG, strongly associate with all clinical endpoints. Using multivariate analysis with two-layer five-fold cross-validation, we constructed a four-gene predictive classifier. Strikingly, patients below the classifier cutpoint had PFS and disease control rates similar to those of patients with KRAS mutant mCRC.

CONCLUSION

Gene expression appears to identify KRAS wt mCRC patients who receive little benefit from cetuximab. It will be important to test this model in an independent validation study.