Cetuximab shows activity in colorectal cancer patients with tumors that do not express the epidermal growth factor receptor by immunohistochemistry

In situ Protein Detection for Companion Diagnostics

The emergence of targeted therapies for cancer has created a need for the development of companion diagnostic tests. Assays developed in recent years are aimed at determining both the effectiveness and safety of specific drugs for a defined group of patients, thus, enabling the more efficient design of clinical trials and also supporting physicians when making treatment-related decisions. Immunohistochemistry (IHC) is a widely accepted method for protein expression analyses in human tissues. Immunohistochemical assays, used to localize and quantitate relative protein expression levels within a morphological context, are frequently used as companion diagnostics during clinical trials and also following drug approval. Herein, we describe established immunochemistry-based methods and their application in routine diagnostics. We also explore the possibility of using IHC to detect specific protein mutations in addition to DNA-based tests. Finally, we review alternative protein binders and proximity ligation assays and discuss their potential to facilitate the development of novel, targeted therapies against cancer.

Concomitant tumor expression of EGFR and TATI/SPINK1 associates with better prognosis in colorectal cancer

Background

Epidermal growth factor receptor (EGFR) activation plays a role in colorectal cancer (CRC) carcinogenesis, and anti-EGFR drugs are used in treatment of advanced CRC. One of the EGFR ligands is tumor-associated trypsinogen inhibitor TATI, also called serine protease inhibitor Kazal type1 (SPINK 1), which we recently showed to be an independent prognostic marker in CRC.

Methods

We studied the prognostic value of immunohistochemical expression of EGFR and concomitant expression of EGFR and TATI/SPINK1 in a series of 619 colorectal cancer patients.

Results

Of the samples, 92% were positive for EGFR. EGFR+/TATI+ was seen in 62.8%, EGFR+/TATI− in 29.5%, EGFR−/TATI+ in 4.9%, and EGFR−/TATI− in 2.7% of patients. EGFR expression correlated with WHO grade (p = 0.040). In univariate analysis, EGFR expression correlated with favourable survival (p = 0.006). EGFR+/TATI+ patients showed better survival than did those with other combinations (p<0.001). In multivariate analysis, EGFR+/TATI+ was an independent prognostic factor of favourable prognosis (p<0.001).

Conclusion

Concomitant positivity of EGFR and TATI/SPINK1 predicts favourable prognosis in CRC.

Imaging of epidermal growth factor receptor expression in head and neck cancer with SPECT/CT and 111In-labeled cetuximab-F(ab')2

Combined treatment of advanced head and neck squamous cell carcinomas (HNSCC) with radiotherapy and the epidermal growth factor receptor (EGFR) inhibitor cetuximab improves clinical outcome in comparison to radiotherapy alone but is effective only in a few cases. To select those patients most likely to benefit from EGFR inhibition, it can be advantageous to quantify the tumor EGFR status before and possibly during therapy. The aim of this study was to develop and characterize the (111)In-cetuximab-F(ab')2 tracer to image EGFR targeting in vivo.

METHODS

The affinity and internalization kinetics of (111)In-cetuximab-F(ab')2 were determined in vitro. The optimal protein-fragment dose for imaging was determined in nude mice with a subcutaneous head and neck carcinoma model (FaDu). Mice with FaDu tumors were imaged using ultra-high-resolution SPECT with (111)In-cetuximab-F(ab')2 or (111)In-cetuximab IgG at 4, 24, 48, and 168 h after injection. Tumor tracer uptake was determined on micro-SPECT and autoradiography images of tumor sections. Immunohistochemical staining was used to analyze EGFR expression in the tumor.

RESULTS

In vitro, more than 50% of (111)In-cetuximab-F(ab')2 was internalized into FaDu cells within 24 h. The half maximal inhibitory concentration (IC50) of (111)In-cetuximab-F(ab')2 and (111)In-cetuximab was similar: 0.42 ± 0.16 nM versus 0.28 ± 0.14 nM, respectively. The protein dose-escalation study showed that the highest uptake of (111)In-cetuximab-F(ab')2 in tumors was obtained at doses of 10 μg/mouse or less (13.5 ± 5.2 percentage injected dose per gram [%ID/g]). Tumor uptake of (111)In-cetuximab was significantly higher (26.9 ± 3.3 %ID/g, P < 0.01). However, because of rapid blood clearance, tumor-to-blood ratios at 24 h after injection were significantly higher for (111)In-cetuximab-F(ab')2 (31.4 ± 3.8 vs. 1.7 ± 0.2, respectively; P < 0.001). The intratumoral distribution of (111)In-cetuximab-F(ab')2 correlated well with the immunohistochemical distribution of EGFR (r = 0.64 ± 0.06, P < 0.0001). micro-SPECT images of (111)In-cetuximab-F(ab')2 clearly showed preferential uptake in the tumor from 4 h onward, with superior tumor-to-background contrast at 24 h, compared with (111)In-cetuximab (107.0 ± 17.0 vs. 69.7 ± 3.9, respectively; P < 0.05).

CONCLUSION

(111)In-cetuximab-F(ab')2 displays higher tumor-to-blood ratios early after injection than (111)In-cetuximab in an HNSCC model, making it more suitable for EGFR visualization and potentially for selecting patients for treatment with EGFR inhibitors.

Pharmacokinetics, clinical indications, and resistance mechanisms in molecular targeted therapies in cancer

The strategy for discovery and development of new cancer drugs has shifted the field from cytotoxic agents to therapies that selectively target oncogenic drivers. In the last decade, a number of targeted cancer therapies have been discovered and proven effective in a variety of hematological and solid malignancies. In this article, we review clinical pharmacokinetic characteristics of the U.S. Food and Drug Administration-approved targeted therapies and provide an overview of key clinical trials that led to approval of these drugs. The major limiting factor of targeted treatment is the development of resistance. We describe general principles of resistance and specific, clinically confirmed mechanisms of resistance to several therapies in different malignancies.

Newly developed strategies for improving sensitivity to radiation by targeting signal pathways in cancer therapy

Inherent and acquired resistance of cancer cells is increasingly recognized as a significant impediment to effective radiation cancer treatment. As important intracellular factors, aberrant tumor transmembrane signal transduction pathways, which include the prosurvival cascades (PI3K/Akt, MAPK/ERK and JAK/STAT) and the proapoptosis pathways (Wnt, p53 and TNF-α/NF-κB), have been proved to be crucial determinants of the probability of cell sensitivity to radiation in malignant lesions. There is increasing evidence that targeting the abnormal pathways that can regulate the activity of the DNA damage response and further influence the response of tumor cells to radiation may be suitable for improving radiation sensitization. Preclinical and clinical evidence suggest that agents targeting aberrant tumor signals can effectively improve the therapeutic effect of ionizing radiation. Therefore, in this review, we discuss the intricate interplay between tumor responses to radiation with the aberrant signal pathways, and the potential druggable targets within the pathways to sensitize tumors without significant collateral damage to normal tissues. The application of novel targeting compounds to manipulate the aberrant signal of tumor cells in clinical treatments is also addressed.

From bench to bedside: lessons learned in translating preclinical studies in cancer drug development

The development of targeted agents in oncology has rapidly expanded over the past 2 decades and has led to clinically significant improvements in the treatment of numerous cancers. Unfortunately, not all success at the bench in preclinical experiments has translated to success at the bedside. As preclinical studies shift toward defining proof of mechanism, patient selection, and rational drug combinations, it is critical to understand the lessons learned from prior translational studies to gain an understanding of prior drug development successes and failures. By learning from prior drug development, future translational studies will provide more clinically relevant data, and the underlying hope is that the clinical success rate will improve and the treatment of patients with ineffective targeted therapy will be limited.

Considerations for the successful co-development of targeted cancer therapies and companion diagnostics

As diagnostic tests become increasingly important for optimizing the use of drugs to treat cancers, the co-development of a targeted therapy and its companion diagnostic test is becoming more prevalent and necessary. In July 2011, the US Food and Drug Administration released a draft guidance that gave the agency's formal definition of companion diagnostics and introduced a drug-diagnostic co-development process for gaining regulatory approval. Here, we identify areas of drug-diagnostic co-development that were either not covered by the guidance or that would benefit from increased granularity, including how to determine when clinical studies should be limited to biomarker-positive patients, defining the diagnostically selected patient population in which to use a companion diagnostic, and defining and clinically validating a biomarker signature for assays that use more than one biomarker. We propose potential approaches that sponsors could use to deal with these challenges and provide strategies to help guide the future co-development of drugs and diagnostics.

Markers of resistance to anti-EGFR therapy in colorectal cancer

Epidermal growth factor receptor (EGFR) is a therapeutic target in colorectal cancer (CRC). The benefit from EGFR inhibitors appears to be limited to a subset of patients with CRC. Mechanisms of resistance to EGFR inhibitors are being identified. KRAS codon 12 activating mutation is a predominate mechanism of resistance to EGFR inhibitors in around 40% of patients with advanced CRC. Other potential mechanisms of resistance include ligand expression, increased EGFR number, mutations of BRAF and activation of alternate signaling pathways.

Integrating anti-EGFR therapies in metastatic colorectal cancer

Colorectal cancer remains one of the most common causes of cancer diagnoses and mortality in the United States. The treatment of metastatic colorectal cancer has evolved significantly over the last decade with near-tripling of patient survival rate. A significant contribution to this outcome was the advent of novel targeted agents, such as the epidermal growth factor (EGFR) inhibitors. In an era of emphasis on refining therapy, the presence of KRAS mutation will predict for resistance and limit exposure to patients who are more likely to benefit. In contrast, the presence of BRAF mutations does not seem to have a predictive value. Agents that are thought to reverse resistance to EGFR inhibitors such as those targeting PI3K, c-MET or IGF-1R are currently under study. EGFR inhibitors have exhibited single agent activity, and seem to synergize very well with standard chemotherapy except for cetuximab and 5-fluorouracil, leucovorin, oxaliplatin (FOLFOX). Preliminary data suggests that EGFR inhibitors have similar effectiveness to vascular endothelial growth factor (VEGF) inhibitors in the first line setting. Skin toxicity remains the main limiting factor for the utilization of EGFR inhibitors, but strategies including the use of agents such as minocycline or doxycycline added to topical care seem to limit the severity of the rash.

The status of targeted agents in the setting of neoadjuvant radiation therapy in locally advanced rectal cancers

Radiotherapy has a longstanding and well-defined role in the treatment of resectable rectal cancer to reduce the historically high risk of local recurrence. In more advanced borderline or unresectable cases, where the circumferential resection margin (CRM) is breached or threatened according to magnetic resonance imaging (MRI), despite optimized local multimodality treatment and the gains achieved by modern high quality total mesorectal excision (TME), at least half the patients fail to achieve sufficient downstaging with current schedules. Many do not achieve an R0 resection. In less locally advanced cases, even if local control is achieved, this confers only a small impact on distant metastases and a significant proportion of patients (30-40%) still subsequently develop metastatic disease. In fact, distant metastases have now become the predominant cause of failure in rectal cancer. Therefore, increasing the intensity and efficacy of chemotherapy and chemoradiotherapy by integrating additional cytotoxics and biologically targetted agents seems an appealing strategy to explore-with the aim of enhancing curative resection rates and improving distant control and survival. However, to date, we lack validated biomarkers for these biological agents apart from wild-type KRAS. For cetuximab, the appearance of an acneiform rash is associated with response, but low levels of magnesium appear more controversial. There are no molecular biomarkers for bevacizumab. Although some less invasive clinical markers have been proposed for bevacizumab, such as circulating endothelial cells (CECS), circulating levels of VEGF and the development of overt hypertension, these biomarkers have not been validated and are observed to emerge only after a trial of the agent. We also lack a simple method of ongoing monitoring of 'on target' effects of these biological agents, which could determine and pre-empt the development of resistance, prior to radiological and clinical assessessments or even molecular imaging. These shortcomings probably explain our current relative lack of success in the arena of combining these agents with chemoradiation.

The role of personalized medicine in metastatic colorectal cancer: an evolving landscape

Advances in the treatment of metastatic colorectal cancer have led to an improvement in survival from 12 months with fluorouracil monotherapy to approximately 2 years. This is partly as a result of the addition of irinotecan and oxaliplatin, but is also due to the use of monoclonal antibodies against the epidermal growth factor receptor (EGFR) and antiangiogenic drugs such as bevacizumab. However, there are significant molecular differences between tumours which can affect both prognosis and response to treatment. Personalized medicine aims to tailor treatment according to the characteristics of the individual patient and is now a clinical reality as testing for KRAS mutations to guide treatment with the anti-EGFR monoclonal antibodies cetuximab and panitumumab is now part of routine clinical practice. However, not all patients who are KRAS wild type respond to anti-EGFR therapy and a validated biomarker for antiangiogenic therapy is still lacking. Therefore, other biomarkers are needed to assist with predicting response to both existing drugs as well as to drugs currently under investigation. This review summarizes the molecular biology of colorectal cancer, focusing on the genetic features that are currently most clinically relevant. Current and emerging biomarkers are reviewed along with their roles in selecting patients for targeted treatment with currently licensed therapies and drugs being evaluated in clinical trials. The value of predictive biomarkers of chemosensitivity and potential future treatment strategies are also discussed.

Biomarkers in precision therapy in colorectal cancer

Colorectal cancer (CRC) is the most commonly diagnosed cancer in Europe. Because CRC is also a major cause of cancer-related deaths worldwide, a lot of research has been focused on the discovery and development of biomarkers to improve the diagnostic process and to predict treatment outcomes. Up till now only a few biomarkers are recommended by expert panels. Current TNM criteria, however, cause substantial under- and overtreatment of CRC patients. Consequently, there is a growing need for new and efficient biomarkers to ensure optimal treatment allocation. An ideal biomarker should be easily translated into clinical practice, to identify patients who can be spared from treatment or benefit from therapy, ultimately resulting in precision medicine in the future. In this review we aim to provide an overview of a number of frequently studied biomarkers in CRC and, at the same time, we will emphasize the challenges and controversies that withhold the clinical introduction of these biomarkers. We will discuss both prognostic and predictive markers of chemotherapy, aspirin therapy as well as overall therapy toxicity. Currently, only mutant KRAS, mutant BRAF, MSI and the Oncotype DX® Colon Cancer Assay are used in clinical practice. Other biomarker studies showed insufficient evidence to be introduced into clinical practice. Divergent patient selection criteria, absence of validation studies and a large number of single biomarker studies are possibly responsible. We therefore recommend that future studies focus on combining key markers, rather than analysing single markers, standardizing study protocols, and validate the results in independent study cohorts, followed by prospective clinical trials.

111In-cetuximab-F(ab')2 SPECT imaging for quantification of accessible epidermal growth factor receptors (EGFR) in HNSCC xenografts

BACKGROUND AND PURPOSE

Immunohistochemical epidermal growth factor receptor (EGFR) expression does not correlate with treatment response in head and neck squamous cell carcinomas (HNSCC). Aim was to apply the tracer (111)In-cetuximab-F(ab')2 for EGFR microSPECT imaging and to investigate if tracer uptake correlated with response to EGFR-inhibition by cetuximab in HNSCC xenografts. Usage of F(ab)2 fragments allows for shorter interval between tracer injection and imaging.

MATERIALS AND METHODS

Mice with HNSCC xenografts, SCCNij202, 153, 185 and 167 were imaged with microSPECT using (111)In-cetuximab-F(ab')2. Subsequently, tumors were analyzed by autoradiography and immunohistochemistry and tracer concentration was determined. Tumor uptake was correlated with previously assessed response to cetuximab treatment.

RESULTS

MicroSPECT imaging showed preferential uptake in HNSCC xenografts. Tumor-to-liver ratios were 3.1 ± 0.2 (SCCNij202), 2.8 ± 0.4 (SCCNij153), 2.0 ± 0.8 (SCCNij185), 2.0 ± 0.4 (SCCNij167). Immunohistochemical EGFR fractions (fEGFR) differed significantly between xenografts; 0.77 ± 0.07 (SCCNij202), 0.66 ± 0.11 (SCCNij153), 0.57 ± 0.19 (SCCNij185), 0.16 ± 0.10 (SCCNij167) (p < 0.001). Tumor fEGFR correlated with (111)In-cetuximab-F(ab')2 tumor uptake (r = 0.6, p < 0.01) and tracer autoradiography (r = 0.7, p < 0.0001). Tumor uptake of (111)In-cetuximab-F(ab')2 was proportionally associated with cetuximab treatment response in three out of four xenograft models.

CONCLUSION

(111)In-cetuximab-F(ab')2 showed good tumor-to-background contrast on microSPECT imaging, allowing noninvasive assessment of EGFR expression in vivo, and possibly evaluation of treatment response to EGFR-inhibition.

Ligand-dependent activation of EGFR in follicular dendritic cells sarcoma is sustained by local production of cognate ligands

PURPOSE

The aim of this study was to investigate the biological and clinical significance of epidermal growth factor receptor (EGFR) signaling pathway in follicular dendritic cell sarcoma (FDC-S).

EXPERIMENTAL DESIGN

Expression of EGFR and cognate ligands as well as activation of EGFR signaling components was assessed in clinical samples and in a primary FDC-S short-term culture (referred as FDC-AM09). Biological effects of the EGFR antagonists cetuximab and panitumumab and the MEK inhibitor UO126 on FDC-S cells were determined in vitro on FDC-AM09. Direct sequencing of KRAS, BRAF, and PI3KCA was conducted on tumor DNA.

RESULTS

We found a strong EGFR expression on dysplastic and neoplastic FDCs. On FDC-AM09, we could show that engagement of surface EGFR by cognate ligands drives the survival and proliferation of FDC-S cells, by signaling to the nucleus mainly via MAPK and STAT pathways. Among EGFR ligands, heparin-binding EGF-like growth factor, TGF-α and Betacellulin (BTC) are produced in the tumor microenvironment of FDC-S at RNA level. By extending this finding at protein level we found that BTC is abundantly produced by FDC-S cells and surrounding stromal cells. Finally, direct sequencing of tumor-derived genomic DNA showed that mutations in KRAS, NRAS, BRAF, and PI3KCA, which predicts resistance to anti-EGFR MoAb in other cancer models, are not observed in FDC-S.

CONCLUSION

Activation of EGFR by cognate ligands produced in the tumor microenvironment sustain viability and proliferation of FDC-S indicating that the receptor blockade might be clinically relevant in this neoplasm.

Overexpression of epidermal growth factor receptor as a prognostic factor in colorectal cancer on the basis of the Allred scoring system

BACKGROUND

Overexpression of epidermal growth factor receptor (EGFR) is found in many types of neoplasms. The aim of the study was to evaluate EGFR expression in colorectal cancer (CRC) specimens and to determine whether EGFR expression correlates with clinicopathological data and overall survival.

PATIENTS AND METHODS

Tissue specimens from 181 consecutive CRC patients treated at the Military Institute of Medicine in 2006-2010 were collected and examined for EGFR expression, by immunohistochemistry staining. The staining intensity and percentage of cells with membranous EGFR expression were scored and then grouped according to the parameters of the Allred Scoring system. Cutoff values were subjected to further statistical analysis. Univariate tests and a multivariate Cox proportional hazards model were used in data analysis.

RESULTS

EGFR was overexpressed in 96 of 181 CRC specimens (53%). EGFR expression was not correlated with other clinicopathological variables. On univariate analysis, overexpression of EGFR, determined by PS (percentage score) (>3) and total score (sum of PS and intensity score) (>4), was associated with poor overall survival. On multivariate analysis, EGFR overexpression (PS > 3) was an independent adverse prognostic factor (hazard ratio [HR] 1.62; 95% confidence interval [CI]: 1.03-2.53). Elevated carcinoembryonic antigen (CEA) serum concentration before treatment, performance status (Word Health Organization [WHO]-2), and tumor localized in colon and liver metastases were also independent unfavorable prognostic factors.

CONCLUSION

EGFR overexpression (PS > 3) in a CRC patient population was an independent adverse prognostic factor. Implementation of the Allred Scoring system criteria into clinical practice might facilitate treatment decisions in CRC patients.

Individualized therapy for metastatic colorectal cancer

Systemic therapeutic efficacy is central to determining the outcome of patients with metastatic colorectal cancer (CRC). In these patients, there is a critical need for predictive biomarkers to optimize efficacy whilst minimizing toxicity. The integration of a new generation of molecularly targeted drugs into the treatment of CRC, coupled with the development of sophisticated technologies for individual tumours as well as patient molecular profiling, underlines the potential for personalized medicine. In this review, we focus on the latest progress made within the genomic and proteomic fields, concerning predictive biomarkers for individualized therapy in metastatic CRC.

FOLFOX4 plus cetuximab administered weekly or every second week in the first-line treatment of patients with KRAS wild-type metastatic colorectal cancer: a randomized phase II CECOG study

BACKGROUND

This randomized phase II study investigated first-line chemotherapy plus cetuximab administered every second week in KRAS wild-type metastatic colorectal cancer.

PATIENTS AND METHODS

Patients received FOLFOX4 plus either standard weekly cetuximab (arm 1) or cetuximab (500 mg/m(2)) every second week (arm 2), until disease progression or unacceptable toxicity. Primary end point was the objective response rate (ORR). Progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and safety were also investigated. The study was not powered to establish non-inferiority, but aimed at the estimation of treatment differences.

RESULTS

Of 152 randomized eligible patients, 75 were treated in arm 1 and 77 in arm 2; ORRs [53% versus 62%, odds ratio 1.40, 95% confidence interval (CI) 0.74-2.66], PFS [median 9.5 versus 9.2 months, hazard ratio (HR) 0.92, 95% CI 0.63-1.34], OS (median 25.8 versus 23.0 months, HR 0.86, 95% CI 0.56-1.30) and DCR (87%) were comparable. HRs adjusted for baseline factors were 1.01 and 0.99 for PFS and OS, respectively. Frequencies of grade 3/4 adverse events in arms 1 versus 2 were similar: most common were neutropenia (28% versus 34%) and rash (15% versus 17%).

CONCLUSIONS

Activity and safety of FOLFOX4 plus either cetuximab administered weekly or every second week were similar.

Molecular biomarkers of resistance to anti-EGFR treatment in metastatic colorectal cancer, from classical to innovation

BACKGROUND

Systematic dissection of the EGFR pathway was considered as the best way to identify putative markers of resistance to anti-EGFR therapies. This kind of approach leaves other, less known but by no means less important, putative mechanisms of resistance. We tried to shed some light on these mechanisms of resistance.

MATERIALS AND METHODS

We performed a research through Pubmed database of all published articles highlighting mechanisms of resistance to Cetuximab and Panitumumab based therapies, published in 2000-2012 period.

CONCLUSIONS

We reviewed the "classical" molecular factors, extensively analyzed as predictive factors for efficacy to anti-EGFR therapy, such as K-ras, B-raf, and PI3K-mTOR-Akt, focusing on their predictive or prognostic value and on the controversial aspects of the biomarker analysis for clinical practice. On the second part we will then move on to other less known molecular markers, for the future understanding of biological mechanisms underlying anti-EGFR therapy resistance, such as non-canonical heterodimer candidates, microRNA, IGF1-IGF1R, HGF-cMET and secondary mutations of EGFR.

Expression of Epidermal Growth Factor Receptor Detected by Cetuximab Indicates Its Efficacy to Inhibit In Vitro and In Vivo Proliferation of Colorectal Cancer Cells

Cetuximab is a chimeric mouse–human monoclonal antibody that targets the human epidermal growth factor receptor (EGFR). However, EGFR expression determined by immunohistochemistry does not predict clinical outcomes of colorectal cancer (CRC) patients treated with cetuximab. Therefore, we evaluated the correlation between EGFR levels detected by cetuximab and drug sensitivities of CRC cell lines (Caco-2, WiDR, SW480, and HCT116) and the A431 epidermoid carcinoma cell line. We used flow cytometry (FCM) to detect EGFR-binding of biotinylated cetuximab on the cell surface. Subcloned cell lines showing the highest and lowest EGFR expression levels were chosen for further study. Cytotoxic assays were used to determine differential responses to cetuximab. Xenograft models treated with cetuximab intraperitoneally to assess sensitivity to cetuximab. Strong responses to cetuximab were specifically exhibited by subcloned cells with high EGFR expression levels. Furthermore, cetuximab inhibited the growth of tumors in xenograft models with high or low EGFR expression levels by 35% and 10%–20%, respectively. We conclude that detection of EGFR expression by cetuximab promises to provide a novel, sensitive, and specific method for predicting the sensitivity of CRC to cetuximab.

ANALYSIS OF BREAST CANCER PROFILES USING BAYESIAN NETWORK MODELING

Breast cancer is the leading cause of cancer-related death for women in Tunisia and the prognosis of its metastasis remains a major problem for oncologists despite advances in treatment. In this work we use Bayesian networks to develop a decision support system that is based on the modeling of relationships between key signaling proteins and clinical and pathological characteristics of breast tumors and patients. Motivated by the lack of prior information on the parameters of the problem, we use the Implicit inference for the structure and parameter learning. A dataset of 84 Tunisian breast cancer patients was used and new prognosis factors were identified. The system predicts a metastasis risk for different patients by computing a score that is the joint probability of the Bayesian network using parameters estimated on the learning database. Based on the results of the developed system we identified that overexpression of ErbB2, ErbB3, bcl2 as well as of oestrogen and progesterone receptors associated with a low level of ErbB4 was the predominant profile associated with high risk of metastasis.

Lapatinib inhibits the growth of esophageal squamous cell carcinoma and synergistically interacts with 5-fluorouracil in patient-derived xenograft models

Lapatinib is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and human EGFR-2 (HER2) tyrosine kinase domains. To explore the potential utility of lapatinib for the treatment of esophageal squamous cell carcinoma (ESCC), we examined the expression profiles of EGFR and HER2 in tumor tissues and in paired adjacent non-neoplastic tissues from patients with ESCC. We evaluated the antitumor effects of lapatinib alone or in combination with oxaliplatin or 5-fluorouracil (5-FU) on a panel of primary ESCC cells in vitro with various levels of EGFR and HER2 expression. The in vivo effect of lapatinib alone or in combination with oxaliplatin or 5-FU was evaluated using a primary ESCC xenograft model. EGFR was overexpressed in 80.9% (76/94) of the ESCC samples, while 24.5% (23/94) of the samples overexpressed HER2. EGFR and HER2 co-overexpression was detected in 22.3% of samples (21/94). In vitro, the primary ESCC cells were more sensitive to lapatinib combined with 5-FU or oxaliplatin than to lapatinib alone. Lapatinib in combination with 5-FU had more potent antitumor effects in the primary ESCC xenograft model, and markedly reduced the phosphorylation of EGFR and HER2, compared with lapatinib alone or in combination with oxaliplatin. These data indicate that lapatinib has activity in EGFR- and/or HER2-expressing ESCC primary cells, and that lapatinib in combination with 5-FU may be a promising treatment strategy for patients with ESCC.

Companion biomarkers: paving the pathway to personalized treatment for cancer

BACKGROUND

Companion biomarkers are biomarkers that are used in combination with specific therapies and that prospectively help predict likely response or severe toxicity. In this article we review the role of companion biomarkers in guiding treatment in patients with cancer.

CONTENT

In addition to the established companion biomarkers such as estrogen receptors and HER2 (human epidermal growth factor receptor 2) in breast cancer, several new companion biomarkers have become available in recent years. These include v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations for the selection of patients with advanced colorectal cancer who are unlikely to benefit from anti-epidermal growth factor receptor antibodies (cetuximab or panitumumab), epidermal growth factor receptor (EGFR) mutations for selecting patients with advanced non-small cell lung cancer (NSCLC) for treatment with tyrosine kinase inhibitors (gefitinib or erlotinib), v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations for selecting patients with advanced melanoma for treatment with anti-BRAF agents (vemurafenib and dabrafenib), and anaplastic lymphoma receptor tyrosine kinase (ALK) translocations for identifying patients with NSCLC likely to benefit from crizotinib.

SUMMARY

The availability of companion biomarkers should improve drug efficacy, decrease toxicity, and lead to a more individualized approach to cancer treatment.

Predictive tests for individualization of pharmacological cancer treatment

BACKGROUND

The selection of cancer drugs for an individual patient is still based mostly on cancer type and stage. Predictive tests are needed to make individualized and more efficient pharmacological cancer treatment possible.

OBJECTIVE

To provide an overview of available, possible future development and principles for development of predictive tests for individualized selection of cancer drugs.

METHODS

Overview of published data.

RESULTS/CONCLUSION

Despite increased knowledge in cancer biology, only limited progress has been made in the development and use of predictive tests. However, rapid progress in this field will be possible using already available and emerging technologies, but requires a paradigm shift in principles for the development and use of cancer drugs. Assessment of drug activity in intact tumor cells and tumor cell gene expression signatures are considered to have greatest potential for the development of versatile predictive tests.

Wild-Type KRAS and BRAF Could Predict Response to Cetuximab in Chinese Colorectal Cancer Patients

OBJECTIVE

To analyze the relationship between KRAS, BRAF mutations and the response toCetuximab in Chinese colorectal cancer patients.

METHODS

A total of273 Chinese colorectal cancer patients were evaluated for KRAS and BRAF mutations by Sanger sequencing. Among them, 59 patients with metastatic colorectal cancer (mCRC) were treated with Cetuximab in combination with chemotherapy from August 2005 to July 2009. Statistical analysis was conducted to assess the relationship between KRAS, BRAF mutations and the response or survival of 59 mCRC patients.

RESULTS

KRAS and BRAF mutation rates were 38.5% (105/273) and 5.1% (14/273), respectively, and KRAS/BRAF mutations were mutually exclusive. Among 59 patients treated with Cetuximab plus chemotherapy, KRAS and BRAF mutations were identified in 11and 5 patients, respectively. The response rates and median progression-free survivals (PFS) in KRAS wild-type and mutant patients were 35.4% (17/48) vs. 9.1% (1/11) (P=0.054) and 153 days vs. 99 days (P=0.01), respectively.Also, the response rates and median PFS in BRAF wild-type and mutant patients were 37.2% (16/43) vs. 20% (1/5) (P=0.016) and 138 days vs. 90 days (P=0.036), respectively.

CONCLUSION

Besides KRAS, assessing BRAF mutation should also be required to select patients eligible for Cetuximab. Further prospective evaluation in large samples should be performed to confirm these preliminary findings.

Recommendations from the EGAPP Working Group: can testing of tumor tissue for mutations in EGFR pathway downstream effector genes in patients with metastatic colorectal cancer improve health outcomes by guiding decisions regarding anti-EGFR therapy?

SUMMARY OF RECOMMENDATIONS

The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group (EWG) found that, for patients with metastatic colorectal cancer (mCRC) who are being considered for treatment with cetuximab or panitumumab, there is convincing evidence to recommend clinical use of KRAS mutation analysis to determine which patients are KRAS mutation positive and therefore unlikely to benefit from these agents before initiation of therapy. The level of certainty of the evidence was deemed high, and the magnitude of net health benefit from avoiding potentially ineffective and harmful treatment, along with promoting more immediate access to what could be the next most effective treatment, is at least moderate.The EWG found insufficient evidence to recommend for or against BRAF V600E testing for the same clinical scenario. The level of certainty for BRAF V600E testing to guide antiepidermal growth factor receptor (EGFR) therapy was deemed low. The EWG encourages further studies of the potential value of testing in patients with mCRC who were found to have tumors that are wild type (mutation negative) for KRAS to predict responsiveness to therapy.The EWG found insufficient evidence to recommend for or against testing for mutations in NRAS, or PIK3CA, and/or loss of expression of PTEN or AKT proteins. The level of certainty for this evidence was low. In the absence of supporting evidence, and with consideration of other contextual issues, the EWG discourages the use of these tests in guiding decisions on initiating anti-EGFR therapy with cetuximab or panitumumab unless further evidence supports improved clinical outcomes.

RATIONALE

It has been suggested that patients with mCRC whose tumors harbor certain mutations affecting EGFR pathway signaling are typically unresponsive to therapy with anti-EGFR antibodies (cetuximab and panitumumab). The EWG identified recent evidence reviews that have addressed this topic, and this recommendation statement is based on results of these reviews. In developing these recommendations the EWG considered evidence in the areas described below.

ANALYTIC VALIDITY

Although no research syntheses that have formally evaluated analytic validity of these tests were found, the EWG was able to draw the following conclusions from assessments included in the evidence reviews under consideration. There is adequate evidence that KRAS mutation analysis reliably and accurately detects common mutations (codons 12 and 13), whereas evidence was inadequate for less frequent KRAS mutations (e.g., codon 61). There is also adequate evidence that testing for BRAF V600E accurately and reliably detects the mutation. For common mutations in NRAS, PIK3CA, and expression of PTEN AKT, there is adequate evidence of accurate and reliable detection. However, much less data exist in support. Furthermore, in the specific context of mCRC, no evidence was found on the analytic validity of immunohistochemistry (IHC) assays for PTEN or AKT expression.

CLINICAL VALIDITY

For KRAS mutation analysis, the EWG found convincing evidence for association with treatment response to anti-EGFR therapy, independent of prognostic association. For BRAF V600E mutation testing, the EWG found insufficient evidence for association with treatment response to anti-EGFR therapy independent of prognostic association. The EWG found insufficient evidence for association of results of testing for mutations in NRAS or PIK3CA, and loss of expression of PTEN or ATK proteins, with treatment response to anti-EGFR therapy.

CLINICAL UTILITY

For KRAS mutation analysis, the EWG found adequate evidence that improved health outcomes are achieved by avoiding ineffective chemotherapy and potential side effects and expediting access to the next most effective treatment. Inadequate evidence was found regarding association of BRAF V600E mutation testing or loss of PTEN expression with improved health outcomes among patients with mCRC undergoing anti-EGFR therapy as compared with patients with tumors bearing wild-type BRAF sequence and PTEN expression levels, respectively. No evidence was found to support improved health outcomes associated with testing results for NRAS or PIK3CA variants, or AKT protein expression levels in this clinical scenario.

CONTEXTUAL ISSUES

CRC is an important and highly prevalent health problem. Improvements in mCRC outcomes associated with pharmacogenetic testing could have important clinical, and potentially public health, impacts. Adverse events related to cancer chemotherapy can be common and severe. Therefore, successfully optimizing treatment to maximize efficacy and minimize side effects is important for reducing mCRC-related morbidity and mortality.

Amphiregulin enhances regulatory T cell-suppressive function via the epidermal growth factor receptor

Epidermal growth factor receptor (EGFR) is known to be critically involved in tissue development and homeostasis as well as in the pathogenesis of cancer. Here we showed that Foxp3(+) regulatory T (Treg) cells express EGFR under inflammatory conditions. Stimulation with the EGF-like growth factor Amphiregulin (AREG) markedly enhanced Treg cell function in vitro, and in a colitis and tumor vaccination model we showed that AREG was critical for efficient Treg cell function in vivo. In addition, mast cell-derived AREG fully restored optimal Treg cell function. These findings reveal EGFR as a component in the regulation of local immune responses and establish a link between mast cells and Treg cells. Targeting of this immune regulatory mechanism may contribute to the therapeutic successes of EGFR-targeting treatments in cancer patients.

Amphiregulin enhances regulatory T cell-suppressive function via the epidermal growth factor receptor

Epidermal growth factor receptor (EGFR) is known to be critically involved in tissue development and homeostasis as well as in the pathogenesis of cancer. Here we showed that Foxp3(+) regulatory T (Treg) cells express EGFR under inflammatory conditions. Stimulation with the EGF-like growth factor Amphiregulin (AREG) markedly enhanced Treg cell function in vitro, and in a colitis and tumor vaccination model we showed that AREG was critical for efficient Treg cell function in vivo. In addition, mast cell-derived AREG fully restored optimal Treg cell function. These findings reveal EGFR as a component in the regulation of local immune responses and establish a link between mast cells and Treg cells. Targeting of this immune regulatory mechanism may contribute to the therapeutic successes of EGFR-targeting treatments in cancer patients.

EGFR gene copy number as a prognostic marker in colorectal cancer patients treated with cetuximab or panitumumab: a systematic review and meta analysis

Background

The epidermal growth factor receptor (EGFR) gene copy number (GCN) has been previously demonstrated to correlate with the clinical outcome of colorectal cancer (CRC) treated with anti-EGFR monoclonal antibodies (mAbs), although it remains controversial. We conducted a systematic review and meta-analysis to assess EGFR GCN as a potential biomarker of survival for patients with advanced CRC receiving treatment with anti-EGFR mAbs.

Methods

We systematically identified articles investigating EGFR GCN by fluorescent or chromogenic in situ hybridization or other detection techniques in patients with metastatic CRC treated with panitumumab or cetuximab, (last search: 10 August 2012). Eligible studies had to report on overall survival (OS), progression-free survival (PFS) or time-toprogression (TTP), stratified by EGFR GCN. Summary hazard ratios (HRs) were calculated using random-effects models.

Results

Among 13 identified studies, 10 (776 patients, 302 with increased GCN), 8 (893 patients, 282 with increased GCN) and 3 (149 patients, 66 with increased GCN) were eligible for the OS, PFS and TTP meta-analyses, respectively. Increased EGFR GCN was associated with increased OS (HR = 0.62; 95% CI 0.50–0.77; P<0.001), PFS (HR = 0.65; 95% CI 0.47–0.89; P = 0.008) but not TTP (HR = 0.71; 95% CI 0.44–1.14; P = 0.157). It was also shown that EGFR GCN is independent of other factors such as KRAS status. Among those populations received second-line or higher treatment, increased EGFR GCN was strongly associated with improved survival (for OS, HR = 0.60; 95% CI 0.47–0.75; P<0.001; for PFS, HR = 0.59; 95% CI 0.47–0.75; P<0.001), whereas it did not influence survival in patients that received first-line therapy.

Conclusion

Among the anti-EGFR-treated patients, increased EGFR GCN appears to be associated with improved survival outcomes. The effect on survival appears to be related to patients receiving the line of treatment.

Molecular characterization of mucinous ovarian tumours supports a stratified treatment approach with HER2 targeting in 19% of carcinomas

Mucinous ovarian carcinomas (MCs) typically do not respond to current conventional therapy. We have previously demonstrated amplification of HER2 in 6 of 33 (18.2%) mucinous ovarian carcinomas (MCs) and presented anecdotal evidence of response with HER2-targeted treatment in a small series of women with recurrent HER2-amplified (HER2+) MC. Here, we explore HER2 amplification and KRAS mutation status in an independent cohort of 189 MCs and 199 mucinous borderline ovarian tumours (MBOTs) and their association to clinicopathological features. HER2 status was assessed by immunohistochemistry (IHC), FISH, and CISH, and interpreted per ASCO/CAP guidelines, with intratumoural heterogeneity assessment on full sections, where available. KRAS mutation testing was performed with Sanger sequencing. Stage and grade were associated with recurrence on both univariate and multivariate analysis (p < 0.001). Assessment of HER2 status revealed overexpression/amplification of HER2 in 29/154 (18.8%) MCs and 11/176 (6.2%) MBOTs. There was excellent agreement between IHC, FISH, and CISH assessment of HER2 status (perfect concordance of HER2 0 or 1+ IHC with non-amplified status, and 3+ IHC with amplified status). KRAS mutations were seen in 31/71 (43.6%) MCs and 26/33 (78.8%) MBOTs, and were near mutually exclusive of HER2 amplification. In the 189 MC cases, a total of 54 recurrences and 59 deaths (53 of progressive disease) were observed. Within MCs, either HER2 amplification/overexpression or KRAS mutation was associated with decreased likelihood of disease recurrence (p = 0.019) or death (p = 0.0041) when compared to cases with neither feature. Intratumoural heterogeneity was noted in 26% of HER2-overexpressing cases. These data support the stratification of MCs for the testing of new treatments, with HER2-targeted therapy as a viable option for HER2+ advanced or recurrent disease. Further research is required to delineate the molecular and clinical features of the ∼34% of MC cases with neither HER2 amplification nor KRAS mutations.

Expression of E-cadherin and KRAS mutation may serve as biomarkers of cetuximab-based therapy in metastatic colorectal cancer

Cetuximab (Cmab), a chimeric monoclonal antibody for targeting the epidermal growth factor receptor, has become one of the standard treatments for metastatic colorectal cancer (mCRC). However, only a small proportion of patients respond to Cmab, and it has been reported that KRAS mutation is a negative biomarker of response to Cmab therapy. The aim of this study was to detect additional biomarkers of response to Cmab therapy in patients with mCRC. We evaluated the effects of Cmab therapy in 36 patients with mCRC according to the Response Evaluation Criteria in Solid Tumors, and classified patients who achieved complete response, partial response or stable disease as responders, and patients who achieved progressive disease as non-responders. We retrospectively examined the difference between the two groups using KRAS analysis and immunohistochemistry to determine the expression of E-cadherin, p53 and Ki67. Nineteen patients were responders, while 17 patients were non-responders. KRAS status and expression of E-cadherin were significantly correlated with the effect of Cmab therapy. Moreover, the expression of E-cadherin was significantly correlated with the effect of Cmab therapy in KRAS wild-type patients. In KRAS mutant-type patients, the expression of E-cadherin did not significantly correlate with the effect of Cmab therapy, but all responders with KRAS mutant-type tumors expressed E-cadherin. Our results indicate that the expression of E-cadherin detected by immunohistochemistry may be a positive predictor of Cmab-based therapy in mCRC, and that a combination of E-cadherin immunohistochemistry and KRAS analysis may be a more sensitive biomarker than KRAS analysis alone.

KRAS p.G13D mutations are associated with sensitivity to anti-EGFR antibody treatment in colorectal cancer cell lines

PURPOSE

Targeted therapies using the anti-EGFR antibodies panitumumab (Pmab) or cetuximab (Cmab) are currently restricted to patients with metastatic colorectal adenocarcinoma whose tumours do not show a mutation in KRAS. However, recent retrospective studies indicated that patients with tumours mutated in codon 13 of KRAS may benefit from treatment with Cmab in contrast to patients with tumours mutated in KRAS codon 12.

METHODS

To study the functional impact of the subtype of KRAS mutations on the efficiency of EGFR-targeted therapies, we correlated the KRAS mutation status of 15 colorectal carcinoma cell lines with the in vitro sensitivity of these cells to Cmab/Pmab. Mutations in the potential predictive biomarkers BRAF and PIK3CA as well as protein expression of EGFR and PTEN were also determined.

RESULTS

Four out of seven KRAS-mutated cell lines were characterised by the p.G13D mutation. Treatment of these cells using Cmab/Pmab induced a significant growth inhibition in contrast to cell lines showing a KRAS mutation at codon 12 or 61. Out of the eight KRAS wild-type cell lines, five were insensitive to Cmab/Pmab. These cell lines were characterised either by BRAF mutation or by absence of EGFR or PTEN protein expression.

CONCLUSIONS

Since KRAS p.G13D-mutated tumour cells may respond to EGFR-targeted therapy, we suggest including subtype analysis of KRAS mutations in prospective clinical trials. In KRAS wild-type tumour cells, BRAF mutations and loss of EGFR or PTEN expression may lead to resistance to EGFR-targeted therapy and should be considered as additional negative predictive biomarkers.

Targeted therapies in colorectal cancer-an integrative view by PPPM

In developed countries, colorectal cancer (CRC) is the third most common malignancy, but it is the second most frequent cause of cancer-related death. Clinicians are still faced with numerous challenges in the treatment of this disease, and future approaches which target the molecular features of the disorder will be critical for success in this disease setting. Genetic analyses of many solid tumours have shown that up to 100 protein-encoding genes are mutated. Within CRC, numerous genetic alterations have been identified in a number of pathways. Therefore, understanding the molecular pathology of CRC may present information on potential routes for treatment and may also provide valuable prognostic information. This will be particularly pertinent for molecularly targeted treatments, such as anti-vascular endothelial growth factor therapies and anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapy. KRAS and BRAF mutations have been shown to predict response to anti-EGFR therapy. As EGFR can also signal via the phosphatidylinositol 3-kinase (PI3K) kinase pathway, there is considerable interest in the potential roles of members of this pathway (such as PI3K and PTEN) in predicting treatment response. Therefore, a combined approach of new techniques that allow identification of these biomarkers alongside interdisciplinary approaches to the treatment of advanced CRC will aid in the treatment decision-making process and may also serve to guide future therapeutic approaches.

Mechanisms of resistance to EGFR targeted therapies

EGFR is a validated therapeutic target in many human cancers. EGFR targeted therapies are in widespread clinical use in patients with non-small cell lung cancer and other tumor types. Despite the clinical success of EGFR targeted therapy, resistance to treatment is a significant barrier to the optimized use of EGFR inhibitors to cure patients with lung and other cancers. Here, we review established and emerging mechanisms of resistance to EGFR targeted therapy and highlight strategies that could overcome treatment resistance and therefore enhance clinical outcomes.

Panitumumab following disease progression on cetuximab in patients with metastatic colorectal cancer: A retrospective review

Despite advances in treatment options for metastatic colorectal cancer over the past decade, the number of chemotherapy agents available remains limited. We report here a retrospective review of 11 patients who were treated with panitumumab following documented disease progression on cetuximab. Two patients demonstrated minor radiographic responses, albeit only for a short period of time. We conclude that the use of one epidermal growth factor receptor inhibitor following failure on the other may be of benefit to patients who would otherwise have no other treatment options. However, studies to help identify the subset of patients who might benefit from this strategy are needed.

Role of immunoglobulin G fragment C receptor polymorphism-mediated antibody-dependant cellular cytotoxicity in colorectal cancer treated with cetuximab therapy

Antibody-dependent cellular cytotoxicity (ADCC), which is activated by effector cells via immunoglobulin G (IgG) fragment C receptors (FcRs), was proposed as a mechanism of cetuximab efficacy. Peripheral blood mononuclear cells (PBMCs) from 23 healthy donors and 13 patients with metastatic colorectal cancer (mCRC) treated with cetuximab were tested for FcγR polymorphisms and cetuximab-mediated ADCC. ADCC was measured by chromium-51 release on a epidermal growth factor receptor (EGFR)-positive human colon cancer cell line. Overall, 86 mCRC patients were genotyped for study purposes. PBMCs harbouring the FcγRIIIa 158 V/V genotype had a significantly higher cetuximab-mediated ADCC. No correlation was found between FcγR polymorphisms and response rate or time to progression after cetuximab-based therapy. Despite the in vitro analysis showing that the FcγRIIIa 158 V/V genotype is associated with higher ADCC, clinical data do not support a predictive role of FcγRIIIa polymorphisms in mCRC treated with cetuximab.

Detection of the epidermal growth factor receptor, amphiregulin and epiregulin in formalin-fixed paraffin-embedded human placenta tissue by matrix-assisted laser desorption/ionization mass spectrometry imaging

The study of the expression and the tissue distribution of the tyrosine kinase drug-target epidermal growth factor receptor (EGFR) is of interest in oncology as a marker of potential efficacy of treatment. It has been reported, however, that the response rates to anti-EGFR drugs are poorly linked to its expression. Clinical studies have also revealed a patient response correlation with the expression levels of two EGFR ligands; amphiregulin and epiregulin. Here, we report the development of a matrix-assisted laser desorption/ionisation mass spectrometry imaging methodology for the study of EGFR, epiregulin and amphiregulin distribution in formalin fixed paraffin embedded human placental tissue and a comparison to expression patterns obtained by immunohiostochemistry. Using on-tissue digests and imaging of specific peptides, the tissue distribution of these proteins has been obtained down to 30 microm spatial resolution.

In vivo molecular imaging of epidermal growth factor receptor in patients with colorectal neoplasia using confocal laser endomicroscopy

Epidermal growth factor receptor (EGFR) plays an important role in tumorigenesis of colorectal cancer (CRC), and its in vivo molecular imaging in rodent models has become the subject of an increased number of studies using novel imaging techniques for gastrointestinal endoscopy. Current study aimed to evaluate the use of confocal endomicroscopy (CLE) for in vivo molecular imaging of EGFR in patients with colorectal neoplasia. Molecular imaging of colorectal neoplasia in patients was performed by CLE after topical application of a fluorescent-labeled molecular probe against EGFR. Representative images of CLE were chosen to calculate EGFR-specific fluorescence intensity. Targeted biopsy specimens were taken from each examined site during in vivo imaging for histology and immunohistochemistry (IHC). During in vivo molecular imaging in 37 patients, an EGFR-specific fluorescence signal was present in 18/19 CRC, and 12/18 colorectal adenomas. No or only weak fluorescence signal was observed in vivo in 10 cases of normal mucosa. CLE is a novel tool that could be used in molecular imaging with specific targeting of EGFR in patients with colorectal neoplasia. This technique demonstrates a promising imaging approach for targeted therapies of colorectal neoplasia.

Direct and immune mediated antibody targeting of ERBB receptors in a colorectal cancer cell-line panel

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erb-b) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs). We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. There was a significant correlation between the direct effects of cetuximab and lapatinib. Both agents were associated (P = 0.0004) with "triple' wild-type status in KRAS, BRAF, and PIK3CA exon 20. Most cell lines were resistant to the direct effects of anti-ERBB2 Mabs, suggesting that the effects of lapatinib might mainly be through ERBB1. Microarray mRNA expression profiles of sensitive and resistant cell lines showed that although ERBB1 receptor or ligand levels did not associate with cetuximab sensitivity, high levels of ERBB2 (P = 0.036) and amphiregulin (P = 0.026) predicted sensitivity to lapatinib. However, higher ERBB1 expression predicted susceptibility to cetuximab-induced antibody-dependent cellular cytotoxicity and occurred independently of KRAS/BRAF/PIK3CA mutations (P = 0.69). Lapatinib may be an effective alternative therapy to cetuximab in triple wild-type tumors. Microarray analysis provides suggestive biomarkers for resistance. ERBB1 levels, independent of mutation status, predict immune killing. Therefore, anti-ERBB1 antibodies may be considered in CRC tumors with higher ERBB1 expression and favorable FcγR polymorphisms.

Mechanisms of acquired resistance to anti-EGF receptor treatment in colorectal cancer

SUMMARY The anti-EGFR monoclonal antibodies, cetuximab and panitumumab, are effective in a subset of colorectal cancer patients. However, acquisition of resistance to these drugs invariably develops. Elucidation of the molecular mechanisms underlying resistance is a crucial first step to develop therapeutic strategies to bypass secondary resistance. Three mechanisms of resistance have been characterized in patients so far: a mutation in the extracellular domain of EGFR preventing cetuximab-EGFR binding – interestingly, this mutation does not affect panitumumab effectiveness; activation of EGFR-related receptor HER2 by amplification or ligand overexpression; emergence of KRAS mutations or amplification. Importantly, already approved drugs can be used to bypass known mechanisms of resistance. Large-scale studies including biopsy at progression and prospective clinical trials are warranted.

Variant 1 of KIAA0101, overexpressed in hepatocellular carcinoma, prevents doxorubicin-induced apoptosis by inhibiting p53 activation

KIAA0101 overexpression was detected in numerous malignant solid tumors and involved in tumor progression; however, the correlation between KIAA0101 expression level and human hepatocellular carcinoma (HCC) was controversial. Our data revealed abnormal expression of the KIAA0101 transcript variant 1 (KIAA0101 tv1) at both messenger RNA and protein levels in HCC tissues and cell lines assessed by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR), virtual northern blot, western blot, and immunohistochemical analysis, especially in stage 3-4 HCCs. NIH3T3 cells transfected with KIAA0101 tv1 induced colony formation in vitro and tumor xenorafts in vivo, implying the oncogenic potential of KIAA0101 tv1. Semiquantitative RT-PCR, real-time quantitative RT-PCR, and western blot analysis demonstrated that doxorubicin (Adriamycin, ADR) treatment down-regulated expression of the KIAA0101 tv1, whereas it increased the acetylation of the p53 protein. Additionally, KIAA0101 tv1 prevented cells from apoptosis caused by ADR through suppressing the acetylation of p53 at Lys382. Immunoprecipitation analysis and mammalian two-hybrid assay indicated that KIAA0101 tv1 bound to the transactivation region (1-42 amino acids) of p53 and strongly inhibits its transcriptional activity. Taken together, our data suggest that KIAA0101 tv1 played an important role in the late stage of metastatic HCC and prevented apoptosis after chemotherapeutic drug treatment through inhibiting the transcriptional activity of the p53 gene.

CONCLUSION

KIAA0101 tv1 may function as a regulator, promoting cell survival in HCC through regulating the function of p53. Suppression of the KIAA0101 tv1 function is likely to be a promising strategy to develop novel cancer therapeutic drugs.

Impact of epidermal growth factor receptor (EGFR) cell surface expression levels on effector mechanisms of EGFR antibodies

The epidermal growth factor receptor (EGFR) is a widely expressed Ag that is successfully targeted in tumor patients by mAbs or tyrosine kinase inhibitors. A clinical study in non-small cell lung cancer patients demonstrated a positive correlation between EGFR expression levels and the therapeutic efficacy of the EGFR mAb cetuximab. However, the impact of EGFR expression on the different mechanisms of action (MoAs) triggered by the EGFR mAb has not been defined. In this study, BHK-21 cells were stably transfected to express different EGFR levels, which were quantified by immunofluorescence and immunohistochemistry and compared with EGFR levels of clinical non-small cell lung cancer samples. These cells were used to systematically investigate the impact of target Ag expression levels on Fab- or Fc-mediated MoAs of EGFR mAb. A negative correlation between EGFR levels and potency of Fab-mediated MoA was observed. Interestingly, Ab-dependent cell-mediated cytotoxicity (ADCC) by NK cells, monocytes, or polymorphonuclear cells as well as complement-dependent cytotoxicity positively correlated with the number of EGFR molecules. In comparison with ADCC by mononuclear cells, polymorphonuclear cell-mediated ADCC and complement-dependent cytotoxicity required higher EGFR expression levels and higher mAb concentrations to trigger significant tumor cell killing. This correlation between EGFR expression levels and Fc-mediated MoA was confirmed in an independent panel of human tumor cell lines carrying diverse genetic alterations. Furthermore, RNA interference-induced knockdown experiments reinforced the impact of EGFR expression on tumor cell killing by EGFR mAb. In conclusion, these results suggest that EGFR expression levels may determine distinct patterns of MoAs that contribute to the therapeutic efficacy of EGFR mAb.

Therapeutic antibodies against cancer

Antibody-based therapeutics against cancer are highly successful and currently enjoy unprecedented recognition of their potential; 13 monoclonal antibodies (mAbs) have been approved for clinical use in the European Union and in the United States. Bevacizumab, rituximab, and trastuzumab had sales in 2010 of more than $5 billion each. Hundreds of mAbs, including bispecific mAbs and multispecific fusion proteins, mAbs conjugated with small-molecule drugs, and mAbs with optimized pharmacokinetics, are in clinical trials. However, deeper understanding of mechanisms is needed to overcome major problems including resistance to therapy, access to targets, complexity of biological systems, and individual variations.

Concordant KRAS mutations in primary and metastatic colorectal cancer tissue specimens: a meta-analysis and systematic review

A meta-analysis was performed to compare KRAS gene mutations in colorectal cancer tissue samples with primary and metastatic colorectal cancers. A total of 19 publications with 986 paired primary and distant metastases and 171 paired primary and lymph node metastases showed that KRAS genotype was highly concordant in primary and distant metastatic tumors, indicating that either type of tumor tissue could be useful as a source to detect KRAS mutations for selection of anti-EGFR therapy. However, lymph-node-metastatic tumors might not be suitable for diagnostic analysis of KRAS mutations due to an obvious discordant rate between primary and lymph-node-metastatic tumors.