Epidermal growth factor receptor-targeted treatment for advanced colorectal carcinoma

New insight into the role of the ADAM protease family in breast carcinoma progression

Protease and adhesion molecules play a very emphasized role in the occurrence or progression of metastasis in many types of cancers. In this context, a molecule that contains both protease and adhesion functions play a crucial role in metastasis. ADAMs (a disintegrin and metalloprotease) are molecules with this special characteristic. Recently, a lot of attention has been attracted to various ADAM molecules and researchers have tried to elucidate the role of ADAMs in breast cancer occurrence and progression. Disrupting ADAMs protease and adhesion capabilities can lead to the discovery of worthy therapeutic targets in breast cancer treatment. In this review, we intend to discuss the mechanism of action of various ADAM molecules, their relation to pathogenic processes of breast cancer, and their potential as possible targets for breast cancer treatment.

Zinc finger protein 277 is an intestinal transit-amplifying cell marker and colon cancer oncogene

Sustained proliferative signaling and resisting cell death are hallmarks of cancer. Zinc finger protein 277 (ZNF277; murine Zfp277), a transcription factor regulating cellular senescence, is overexpressed in colon cancer, but its actions in intestinal homeostasis and neoplasia are unclear. Using human and murine intestine, human colon cancer cells, and Apc^Min/+ mice with dysregulated β-catenin signaling and exuberant intestinal neoplasia, we explored the actions of ZNF277/Zfp277 and defined the underlying mechanisms. In normal human and murine intestine, ZNF277/Zfp277 was expressed uniquely in early stem cell progenitors, undifferentiated transit-amplifying cells (TACs). Zfp277 was overexpressed in the Apc^Min/+ mouse colon, implicating ZNF277/Zfp277 as a transcriptional target of β-catenin signaling. We confirmed this by showing β-catenin knockdown reduced ZNF277 expression and, using chromatin IP, identified 2 β-catenin binding sites in the ZNF277 promoter. Zfp277 deficiency attenuated intestinal epithelial cell proliferation and tumor formation, and it strikingly prolonged Apc^Min/+ mouse survival. RNA-Seq and PCR analyses revealed that Zfp277 modulates expression of genes in key cancer pathways, including β-catenin signaling, the HOXD family that regulates development, and p21^WAF1, a cell cycle inhibitor and tumor suppressor. In both human colon cancer cells and the murine colon, ZNF277/Zfp277 deficiency induced p21^WAF1 expression and promoted senescence. Our findings identify ZNF277/Zfp277 as both a TAC marker and colon cancer oncogene that regulates cellular proliferation and senescence, in part by repressing p21^WAF1 expression.

Regulation of signal transduction pathways in colorectal cancer: implications for therapeutic resistance

Resistance to anti-cancer treatments is a critical and widespread health issue that has brought serious impacts on lives, the economy and public policies. Mounting research has suggested that a selected spectrum of patients with advanced colorectal cancer (CRC) tend to respond poorly to both chemotherapeutic and targeted therapeutic regimens. Drug resistance in tumours can occur in an intrinsic or acquired manner, rendering cancer cells insensitive to the treatment of anti-cancer therapies. Multiple factors have been associated with drug resistance. The most well-established factors are the emergence of cancer stem cell-like properties and overexpression of ABC transporters that mediate drug efflux. Besides, there is emerging evidence that signalling pathways that modulate cell survival and drug metabolism play major roles in the maintenance of multidrug resistance in CRC. This article reviews drug resistance in CRC as a result of alterations in the MAPK, PI3K/PKB, Wnt/β-catenin and Notch pathways.

Analysis of the EGFR Amplification and CDKN2A Deletion Regulated Transcriptomic Signatures Reveals the Prognostic Significance of SPATS2L in Patients With Glioma

Purpose: This study was conducted in order to analyze the prognostic effects of epidermal growth factor receptor (EGFR) and CDKN2A alterations and determine the prognostic significance of EGFR and CDKN2A alterations on regulated genes in patients with glioblastoma (GBM) or lower grade glioma (LGG).

Methods: The alteration frequencies of EGFR and CDKN2A across 32 tumor types were derived from cBioPortal based on The Cancer Genome Atlas (TCGA) datasets. The Kaplan–Meier analysis was used to determine the prognostic significance of EGFR and CDKN2A alterations. EGFR and CDKN2A alterations on regulated expression signatures were identified from RNA-seq data in the TCGA GBM datasets. The prognostic significance of EGFR and CDKN2A alterations on regulated genes in patients with glioma was determined using the TCGA and the Chinese Glioma Genome Atlas (CGGA) datasets.

Results: Compared with the other 31 tumor types, EGFR amplification and CDKN2A deletion particularly occurred in patients with GBM. GBM patients with EGFR amplification or CDKN2A deletion demonstrated poor prognosis. Statistical analysis showed the coexistence of EGFR alteration and CDKN2A deletion in GBM patients. We identified 864 genes which were commonly regulated by EGFR amplification and CDKN2A deletion, and those genes were highly expressed in brain tissues and associated with the cell cycle, EBRR2, and MAPK signaling pathways. Spermatogenesis-associated serine-rich 2-like gene (SPATS2L) was upregulated in GBM patients with EGFR amplification or CDKN2A alteration. Higher expression levels of SPATS2L were associated with worse prognosis in patients with GBM in both TCGA and CGGA datasets. Moreover, the expression levels of SPATS2L were higher in patients with a mesenchymal subtype of GBM. Statistical analysis also showed that the coexistence of EGFR alteration and CDKN2A deletion was significant in patients with LGG. SPATS2L was upregulated in LGG patients with EGFR amplification or CDKN2A alteration. Furthermore, higher expression levels of SPATS2L were associated with worse prognosis in patients with LGG in both TCGA and CGGA datasets. The expression levels of SPATS2L were higher in patients with an astrocytoma subtype of LGG. Finally, the coexistence and unfavorable prognostic effects of EGFR amplification and CDKN2A alteration were validated using the Memorial Sloan Kettering Cancer Center (MSKCC) glioma datasets.

Conclusions: EGFR amplification and CDKN2A deletion of the regulated gene SPATS2L have significant prognostic effects in patients with GBM or LGG.

Effect of KRAS and NRAS mutations on the prognosis of patients with synchronous metastatic colorectal cancer presenting with liver-only and lung-only metastases

It has been reported that 20–25% of patients with colorectal cancer (CRC) have metastases at the time of diagnosis. Liver and lung are the most common metastatic sites. The aim of the present study was to investigate the association of KRAS and NRAS mutations with clinicopathological features and prognosis of patients with initial liver-metastasis only (LiM-only) or lung-metastasis only (LuM-only) metastatic CRC (mCRC). Overall, 166 patients with CRC with initial LiM-only (n=124) and LuM-only (n=42) were retrospectively analyzed from January 2014 to December 2017. The median follow-up time was 19.2 months (1.0–57.1 months). Patient characteristics at diagnosis were collected. Genomic DNA was isolated from frozen primary CRC tissues for targeting KRAS and NRAS. Patients with LuM-only were significantly older compared with those with LiM-only (65.5 vs. 61.5 years; P=0.05). There was no significant differences between the LiM-only and LuM-only groups in terms of sex, location of the primary tumor, serum carcinoembryonic antigen level, histological grade and RAS mutation status. KRAS mutations were detected in 43 (41.0%) patients with LiM-only and 13 (35.1%) patients with LuM-only. The overall survival time (OS) of LuM-only was more favorable compared with that of patients with LiM-only (44.5 vs. 24.7 months); however, there was no significant difference (P=0.095). The progression-free survival (PFS) and OS in the RAS wild-type group were significantly improved compared with the RAS mutant cohorts (P=0.004 and P=0.031, respectively) in the LiM-only group. In patients with stage IV CRC, those with synchronous LiM-only mCRC had a higher incidence of metastasis but a less favorable PFS and OS compared with patients with LuM-only. RAS mutation status exhibited a significant association with the survival outcome in patients with LiM-only mCRC.

Pyrazole-4-Carboxamide (YW2065): A Therapeutic Candidate for Colorectal Cancer via Dual Activities of Wnt/β-Catenin Signaling Inhibition and AMP-Activated Protein Kinase (AMPK) Activation

Dysregulation of the Wnt/β-catenin signaling pathway has been widely recognized as a pathogenic mechanism for colorectal cancer (CRC). Although numerous Wnt inhibitors have been developed, they commonly suffer from toxicity and unintended effects. Moreover, concerns have been raised in targeting this pathway because of its critical roles in maintaining stem cells and regenerating tissues and organs. On the basis of the anthelmintic drug pyrvinium and previous lead FX1128, we have developed a compound YW2065 (1c) which demonstrated excellent anti-CRC effects in vitro and in vivo. YW2065 achieves its inhibitory activity for Wnt signaling by stabilizing Axin-1, a scaffolding protein that regulates proteasome degradation of β-catenin. Simultaneously, YW2065 also led to the activation of the tumor suppressor AMPK, providing an additional anticancer mechanism. In addition, YW2065 showed favorable pharmacokinetic properties without obvious toxicity. The anti-CRC effect of YW2065 was highlighted by its promising efficacy in a mice xenograft model.

Design, synthesis and biological evaluation of benzoylacrylic acid shikonin ester derivatives as irreversible dual inhibitors of tubulin and EGFR

In this study, a series of shikonin derivatives combined with benzoylacrylic had been designed and synthesized, which showed an inhibitory effect on both tubulin and the epidermal growth factor receptor (EGFR). In vitro EGFR and cell growth inhibition assay demonstrated that compound PMMB-317 exhibited the most potent anti-EGFR (IC₅₀ = 22.7 nM) and anti-proliferation activity (IC₅₀ = 4.37 μM) against A549 cell line, which was comparable to that of Afatinib (EGFR, IC₅₀ = 15.4 nM; A549, IC₅₀ = 6.32 μM). Our results on mechanism research suggested that, PMMB-317 could induce the apoptosis of A549 cells in a dose- and time-dependent manner, along with decrease in mitochondrial membrane potential (MMP), production of ROS and alterations in apoptosis-related protein levels. Also, PMMB-317 could arrest cell cycle at G2/M phase to induce cell apoptosis, and inhibit the EGFR activity through blocking the signal transduction downstream of the mitogen-activated protein MAPK pathway and the anti-apoptotic kinase AKT pathway; typically, such results were comparable to those of afatinib. In addition, PMMB-317 could suppress A549 cell migration through the Wnt/β-catenin signaling pathway in a dose-dependent manner. Additionally, molecular docking simulation revealed that, PMMB-317 could simultaneously combine with EGFR protein (5HG8) and tubulin (1SA0) through various forces. Moreover, 3D-QSAR study was also carried out, which could optimize our compound through the structure-activity relationship analysis. Furthermore, the in vitro and in vivo results had collectively confirmed that PMMB-317 might serve as a promising lead compound to further develop the potential therapeutic anticancer agents.

Farnesoid X receptor represses matrix metalloproteinase 7 expression, revealing this regulatory axis as a promising therapeutic target in colon cancer

The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily of bile acid-activated transcription factors and an important regulator of cell proliferation, apoptosis, and Wnt signaling. Down-regulated expression of FXR plays an important role in some malignancies such as colon cancer, and in rodent models of intestinal neoplasia, FXR knockout increases the size and number of colon tumors. These previous observations implicate FXR as a tumor suppressor, but the underlying molecular mechanisms are unclear. Employing complementary experimental approaches and using human colon cancer specimens, human and murine colon cancer cell lines, and FXR transgenic mice, here we identified an additional, potentially important role for FXR. We observed an inverse relationship between the expression of FXR and matrix metalloproteinase-7 (MMP7), a collagenase and signaling molecule consistently associated with colon cancer progression. We noted that FXR gene ablation increases MMP7 expression. Consistent with this finding, FXR overexpression and a dominant-negative FXR mutation reduced and augmented, respectively, MMP7 expression. Of note, MMP7 was the only MMP gene family member whose expression was down-regulated after FXR activation. FXR-mediated regulation of MMP7 transcription did not require heterodimerization with the retinoid X receptor (RXR), indicating that FXR represses MMP7 expression independently of RXR. Last, we uncovered that FXR suppresses MMP7 transcription by binding to a negative FXR-responsive element in the 5' MMP7 promoter, an event that inhibited colon cancer cell proliferation and invasion. These findings identify the FXR-MMP7 axis as a potential therapeutic target for managing colon cancer.

β-Catenin mRNA Silencing and MEK Inhibition Display Synergistic Efficacy in Preclinical Tumor Models

Colorectal carcinomas harbor well-defined genetic abnormalities, including aberrant activation of Wnt/β-catenin and MAPK pathways, often simultaneously. Although the MAPK pathway can be targeted using potent small-molecule drugs, including BRAF and MEK inhibitors, β-catenin inhibition has been historically challenging. RNAi approaches have advanced to the stage of clinical viability and are especially well suited for transcriptional modulators, such as β-catenin. In this study, we report therapeutic effects of combined targeting of these pathways with pharmacologic agents. Using a recently described tumor-selective nanoparticle containing a β-catenin-targeting RNAi trigger, in combination with the FDA-approved MEK inhibitor (MEKi) trametinib, we demonstrate synergistic tumor growth inhibition in in vivo models of colorectal cancer, melanoma, and hepatocellular carcinoma. At dose levels that were insufficient to significantly impact tumor growth as monotherapies, combination regimens resulted in synergistic efficacy and complete tumor growth inhibition. Importantly, dual MEKi/RNAi therapy dramatically improved survival of mice bearing colorectal cancer liver metastases. In addition, pharmacologic silencing of β-catenin mRNA was effective against tumors that are inherently resistant or that acquire drug-induced resistance to trametinib. These results provide a strong rationale for clinical evaluation of this dual-targeting approach for cancers harboring Wnt/β-catenin and MAPK pathway mutations. Mol Cancer Ther; 17(2); 544-53. ©2017 AACR.

Wild‑type blocking pcr coupled with internal competitive amplified fragment improved the detection of rare mutation of KRAS

Mutant KRAS proto-oncogene GTPase (KRAS) serves an important role in predicting the development, diagnosis, treatment and efficacy of targeted drug therapies for colorectal cancer. To improve the detection efficacy of trace amount of mutant KRAS, the locked nucleic acid-based method was modified in the present study. Internal competitive amplification fragments were used to improve the inhibition of wild-type KRAS with a wild-type blocking (WTB) probe and specifically amplify the trace amounts of mutant KRAS. The modified method, quantitative clamp-based polymerase chain reaction technology using WTB coupled with internal competitive reference to enhance the amplification specificity, named WIRE-PCR, completely blocked the amplification of wild-type KRAS in 50–150 ng DNA templates. The added internal competitive amplified fragments were amplified together with the target gene, which were used to reduce base mismatch due to the high number of cycles in PCR and quantify the total amount of DNA. The results demonstrated that WIRE-PCR facilitated the detection of mutated alleles at a single molecular level. In the colorectal biopsies from 50 patients with suspected colorectal cancer, 18 cases (36%) contained mutant KRAS, and the amount of mutant DNA accounted for 18.6–64.2% of the total DNA. WIRE-PCR is a simple, rapid and low-cost quantitative analysis method for the detection of trace amounts of the mutant KRAS.

Rationally co-targeting divergent pathways in KRAS wild-type colorectal cancers by CANscript technology reveals tumor dependence on Notch and Erbb2

KRAS mutation status can distinguish between metastatic colorectal carcinoma (mCRC) patients who may benefit from therapies that target the epidermal growth factor receptor (EGFR), such as cetuximab. However, patients whose tumors harbor mutant KRAS (codons 12/13, 61 and 146) are often excluded from EGFR-targeted regimens, while other patients with wild type KRAS will sometimes respond favorably to these same drugs. These conflicting observations suggest that a more robust approach to individualize therapy may enable greater frequency of positive clinical outcome for mCRC patients. Here, we utilized alive tumor tissues in ex-vivo platform termed CANscript, which preserves the native tumor heterogeneity, in order to interrogate the antitumor effects of EGFR-targeted drugs in mCRC (n = 40). We demonstrated that, irrespective of KRAS status, cetuximab did not induce an antitumor response in a majority of patient tumors. In the subset of non-responsive tumors, data showed that expression levels of EGFR ligands contributed to a mechanism of resistance. Transcriptomic and phosphoproteomic profiling revealed deregulation of multiple pathways, significantly the Notch and Erbb2. Targeting these nodes concurrently resulted in antitumor efficacy in a majority of cetuximab-resistant tumors. These findings highlight the importance of integrating molecular profile and functional testing tools for optimization of alternate strategies in resistant population.

Distribution of KRAS and BRAF Mutations in Metastatic Colorectal Cancers in Turkish Patients

The results of this study demonstrate the potential prognostic and predictive values of KRAS and BRAF gene mutations in patients with colorectal cancer (CRC). It has been proven that KRAS and BRAF mutations are predictive biomarkers for resistance to anti-EGFR monoclonal antibody treatment in patients with metastatic CRC (mCRC). We demonstrated the distribution of KRAS (codons 12, 13 and 61) and BRAF (codon 600) gene mutations in 50 mCRCs using direct sequencing and compared the results with clinicopathological data. KRAS and BRAF mutations were identified in 15 (30%) and 1 (2%) patients, respectively. We identified KRAS mutations in codon 12, 13 and 61 in 73.3% (11/15), 20% (3/15) and 6.67% (1/15) of the positive patients, respectively. The KRAS mutation frequency was significantly higher in tumors located in the ascending colon (p=0.043). Thus, we found that approximately 1/3 of the patients with mCRC had KRAS mutations and the only clinicopathological factor related to this mutation was tumor location. Future studies with larger patient groups should yield more accurate data regarding the molecular mechanism of CRC and the association between KRAS and BRAF mutations and clinicopathological features.

Synthesis, characterization and biological evaluation of formononetin derivatives as novel EGFR inhibitors via inhibiting growth, migration and inducing apoptosis in breast cancer cell line

Novel formononetin derivative 4v inhibited MDA-MB-231 cell proliferation, migration and induced apoptosis through targeting EGFR.

KRAS Mutation Test in Korean Patients with Colorectal Carcinomas: A Methodological Comparison between Sanger Sequencing and a Real-Time PCR-Based Assay

Background

Mutations in the KRAS gene have been identified in approximately 50% of colorectal cancers (CRCs). KRAS mutations are well established biomarkers in anti–epidermal growth factor receptor therapy. Therefore, assessment of KRAS mutations is needed in CRC patients to ensure appropriate treatment.

Methods

We compared the analytical performance of the cobas test to Sanger sequencing in 264 CRC cases. In addition, discordant specimens were evaluated by 454 pyrosequencing.

Results

KRAS mutations for codons 12/13 were detected in 43.2% of cases (114/264) by Sanger sequencing. Of 257 evaluable specimens for comparison, KRAS mutations were detected in 112 cases (43.6%) by Sanger sequencing and 118 cases (45.9%) by the cobas test. Concordance between the cobas test and Sanger sequencing for each lot was 93.8% positive percent agreement (PPA) and 91.0% negative percent agreement (NPA) for codons 12/13. Results from the cobas test and Sanger sequencing were discordant for 20 cases (7.8%). Twenty discrepant cases were subsequently subjected to 454 pyrosequencing. After comprehensive analysis of the results from combined Sanger sequencing–454 pyrosequencing and the cobas test, PPA was 97.5% and NPA was 100%.

Conclusions

The cobas test is an accurate and sensitive test for detecting KRAS-activating mutations and has analytical power equivalent to Sanger sequencing. Prescreening using the cobas test with subsequent application of Sanger sequencing is the best strategy for routine detection of KRAS mutations in CRC.

Cadmium-transformed cells in the in vitro cell transformation assay reveal different proliferative behaviours and activated pathways

The in vitro Cell Transformation Assay (CTA) is a powerful tool for mechanistic studies of carcinogenesis. The endpoint is the classification of transformed colonies (foci) by means of standard morphological features. To increase throughput and reliability of CTAs, one of the suggested follow-up activities is to exploit the comprehension of the mechanisms underlying cell transformation. To this end, we have performed CTAs testing CdCl2, a widespread environmental contaminant classified as a human carcinogen with the underlying mechanisms of action not completely understood. We have isolated and re-seeded the cells at the end (6weeks) of in vitro CTAs to further identify the biochemical pathways underlying the transformed phenotype of foci. Morphological evaluations and proliferative assays confirmed the loss of contact-inhibition and the higher proliferative rate of transformed clones. The biochemical analysis of EGFR pathway revealed that, despite the same initial carcinogenic stimulus (1μM CdCl2 for 24h), transformed clones are characterized by the activation of two different molecular pathways: proliferation (Erk activation) or survival (Akt activation). Our preliminary results on molecular characterization of cell clones from different foci could be exploited for CTAs improvement, supporting the comprehension of the in vivo process and complementing the morphological evaluation of foci.

Signaling mechanisms of resistance to EGFR- and Anti-Angiogenic Inhibitors cancer

Colorectal cancer is among four most common malignancies and the second leading cause of cancer death in the western world. Epidermal Growth Factor Receptor (EGFR) and Vascular Endothelial Growth Factor (VEGF) are often overexpressed in colorectal cancer and are associated with inferior outcomes. More recently, further improvements in survival have occurred due to the use of novel targeted therapies such EGFR Tyrosine Kinase Inibitors (EGFR-TKIs), EGFR monoclonal antibodies (EGFR-mAb), and VEGF antibodies. Despite the initial clinical efficacy of these inhibitors in such cancer, resistance invariably develops, typically within 1 to 2 years. Over the past several years, multiple molecular mechanisms of resistance have been identified, and some common themes have emerged. One is the development of resistance mutations in the drug target and another it is activation of alternative signaling of key downstream pathways despite sustained inhibition of the original drug target. In this mini-review, we summarize the concepts underlying EGFR- and VEGF-mediated resistance, the specific examples known to date, and the challenges of applying this knowledge to develop improved therapeutic strategies to prevent or overcome resistance.

Role of the Aryl Hydrocarbon Receptor in Colon Neoplasia

For both men and women, colorectal cancer (CRC) is the second leading cause of cancer death in the United States, primarily as a consequence of limited therapies for metastatic disease. The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor with diverse functions in detoxification of xenobiotics, inflammatory responses, and tissue homeostasis. Emerging evidence indicates that AhR also plays an important role in regulating intestinal cell proliferation and tumorigenesis. Here, we review both the pro- and anti-carcinogenic properties of AhR signaling and its potential role as a therapeutic target in CRC.

Potential antitumor therapeutic application of Grimontia hollisae thermostable direct hemolysin mutants

We report on the preparation of a new type of immunotoxin by conjugation of an epidermal growth factor receptor (EGFR)-binding peptide and an R46E mutation of thermostable direct hemolysin from Grimontia hollisae, (Gh-TDH^R46E/EB). The hybrid immunotoxin was purified to homogeneity and showed a single band with slight slower mobility than that of Gh-TDH^R46E. Cytotoxicity assay of Gh-TDH^R46E/EB on EGFR highly, moderately, low, and non-expressed cells, A431, MDA-MB-231, HeLa, and HEK293 cells, respectively, showed apparent cytotoxicity on A431 and MDA-MB-231 cells but not on HeLa or HEK293 cells. In contrast, no cytotoxicity was observed for these cells treated with either Gh-TDH^R46E or EB alone, indicating enhanced cytotoxic efficacy of Gh-TDH^R46E by the EGFR binding moiety. Further antitumor activity assay of Gh-TDH^R46E/EB in a xenograft model of athymic nude mice showed obvious shrinkage of tumor size and degeneration, necrosis, and lesions of tumor tissues compared to the normal tissues. Therefore, the combination of Gh-TDH^R46E with target affinity agents opens new possibilities for pharmacological treatment of cancers and potentiates the anticancer drug's effect.

CT versus FDG-PET/CT response evaluation in patients with metastatic colorectal cancer treated with irinotecan and cetuximab

We compared morphologic computed tomography (CT)-based to metabolic fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT-based response evaluation in patients with metastatic colorectal cancer and correlated the findings with survival and KRAS status. From 2006 to 2009, patients were included in a phase II trial and treated with cetuximab and irinotecan every second week. They underwent FDG-PET/CT examination at baseline and after every fourth treatment cycle. Response evaluation was performed prospectively according to Response Evaluation Criteria in Solid Tumors (RECIST 1.0) and retrospectively according to Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). Best overall responses were registered. Sixty-one patients were eligible for response evaluation. Partial response (PR) rate was 18%, stable disease (SD) rate 64%, and progressive disease (PD) rate 18%. Partial metabolic response (PMR) rate was 56%, stable metabolic disease rate 33%, and progressive metabolic disease (PMD) rate 11%. Response agreement was poor, κ-coefficient 0.19. Hazard ratio for overall survival for responders (PR/PMR) versus nonresponders (PD/PMD) was higher for CT- than for FDG-PET/CT evaluation. Within patients with KRAS mutations, none had PR but 44% had PMR. In conclusion, morphologic and metabolic response agreement was poor primarily because a large part of the patients shifted from SD with CT evaluation to PMR when evaluated with FDG-PET/CT. Furthermore, a larger fraction of the patients with KRAS mutations had a metabolic treatment response.

High-sensitivity PCR method for detecting BRAF V600E mutations in metastatic colorectal cancer using LNA/DNA chimeras to block wild-type alleles

The response to epidermal growth factor receptor (EGFR)-targeted therapy in metastatic colorectal cancer (mCRC) is variable because of intra-tumor heterogeneity at the genetic level, and consequently, it is important to develop sensitive and selective assays to predict patient responses to therapy. Low-abundance BRAF V600E mutations are associated with poor response to treatment with EGFR inhibitors. We developed a method for the detection of BRAF V600E mutations in mCRC using real-time wild-type blocking PCR (WTB-PCR), in which a chimera composed of locked nucleic acids and DNA is incorporated to amplify the mutant allele at high efficiency while simultaneously inhibiting the amplification of wild-type alleles. Mixing experiments showed that this method is exquisitely sensitive, with detection of the mutated allele at a mutant/wild-type ratio of 1:10,000. To demonstrate the applicability of this approach for mCRC patients, we assessed the V600E mutations in 50 clinical cases of mCRC by real-time WTB-PCR. The percentage of patients with V600E mutation as determined by WTB-PCR (16%, 8/50) was higher than by traditional PCR (10%, 5/50), suggesting an increased sensitivity for WTB-PCR. By calculating the ΔC q for real-time traditional PCR, which amplifies all BRAF alleles, versus WTB-PCR, which selectively amplifies mutant BRAF, we demonstrated that among the V600E-positive mCRC patient samples, the percentage of BRAF DNA with the V600E mutation ranged from 0.05 to 52.32%. In conclusion, WTB-PCR provides a rapid, simple, and low-cost method to detect trace amounts of mutated BRAF V600E gene.

Targeting epidermal growth factor receptor signaling in the treatment of head and neck cancer

In this review, key aspects of epidermal growth factor receptor (EGFR) biology and the fruitful translation of these fundamental findings into recent treatment advances in head and neck squamous cell cancer (HNSCC) are highlighted. In contrast to a number of contemporary reviews of the EGFR, many of which focus on colorectal and nonsmall cell lung cancer, this review discusses the EGFR as a validated therapeutic target in HNSCC. Recent data confirm a survival advantage for the addition of the anti-EGFR monoclonal antibody cetuximab to definitive radiation therapy in locoregionally advanced HNSCC patients, as well as palliative benefits for patients with incurable recurrent and metastatic HNSCC. Small-molecule EGFR tyrosine kinase inhibitors also show considerable promise in this disease, both alone and in combination with radiation and chemotherapy. Both classes of anti-EGFR agent are generally well tolerated, with side effects (notably skin rash) that are distinct from the toxicities of conventional chemotherapy. Ongoing clinical trials will more clearly define the role for EGFR inhibitors in all treatment phases of HNSCC.

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.

New approaches to EGFR inhibition for locally advanced or metastatic squamous cell carcinoma of the head and neck (SCCHN)

Despite recent advances in radiotherapy and chemotherapy, survival rates for squamous cell carcinoma of the head and neck (SCCHN) have remained poor. The focus of SCCHN therapy has more recently shifted to the molecular level, particularly the epidermal growth factor receptor (EGFR/ErbB) pathway. Several agents that target the EGFR pathway, including monoclonal antibodies and tyrosine kinase inhibitors, are under investigation for SCCHN. Searches of PubMed and results of key oncology congresses were performed to identify relevant articles and abstracts. The EGFR-targeted monoclonal antibody cetuximab is approved for the treatment of locally advanced SCCHN in combination with radiotherapy, for first-line treatment of recurrent or metastatic SCCHN in combination with platinum-based chemotherapy and 5-fluorouracil, and for recurrent or metastatic SCCHN following progression with platinum-based chemotherapy. Other investigational EGFR-targeted monoclonal antibodies (e.g., panitumumab, nimotuzumab, zalutumumab) are in clinical development for SCCHN. Inhibition of the tyrosine kinase domain of EGFR has also been explored as a therapeutic approach in SCCHN using small-molecule reversible inhibitors, such as gefitinib and erlotinib. However, a key challenge in SCCHN is the development of resistance, and strategies are being pursued to delay or overcome resistance to EGFR-targeted agents. These strategies include development of agents that inhibit multiple ErbB receptors simultaneously (e.g., lapatinib) or that bind multiple ErbB family receptors irreversibly (e.g., afatinib, PF-00299804) and investigation of combinations of agents that target multiple pathways implicated in the pathogenesis of SCCHN. Ongoing large clinical trials are evaluating these emerging agents and combinations for the treatment of SCCHN.

Src-mediated cross-talk between farnesoid X and epidermal growth factor receptors inhibits human intestinal cell proliferation and tumorigenesis

Besides its essential role in controlling bile acid and lipid metabolism, the farnesoid X receptor (FXR) protects against intestinal tumorigenesis by promoting apoptosis and inhibiting cell proliferation. However, the mechanisms underlying these anti-proliferative actions of FXR remain to be elucidated. In the present study, we examined the effects of FXR activation (FXR overexpression and treatment with an FXR agonist GW4064) and inactivation (treatment with FXR siRNA and an FXR antagonist guggulsterone) on colon cancer cell proliferation in vitro using human colon cancer cell lines (H508, SNU-C4 and HT-29) and in vivo using xenografts in nude mice. Blocking FXR activity with guggulsterone stimulated time- and dose-dependent EGFR (Tyr845) phosphorylation and ERK activation. In contrast, FXR overexpression and activation with GW4064 attenuated cell proliferation by down-regulating EGFR (Tyr845) phosphorylation and ERK activation. Treatment with guggulsterone and GW4064 also caused dose-dependent changes in Src (Tyr416) phosphorylation. In stably-transfected human colon cancer cells, overexpression of FXR reduced EGFR, ERK, Src phosphorylation and cell proliferation, and in nude mice attenuated the growth of human colon cancer xenografts (64% reduction in tumor volume; 47% reduction in tumor weight; both P<0.01). Moreover, guggulsterone-induced EGFR and ERK phosphorylation and cell proliferation were abolished by inhibiting activation of Src, EGFR and MEK. Collectively these data support the novel conclusion that in human colon cancer cells Src-mediated cross-talk between FXR and EGFR modulates ERK phosphorylation, thereby regulating intestinal cell proliferation and tumorigenesis.

Src-mediated aryl hydrocarbon and epidermal growth factor receptor cross talk stimulates colon cancer cell proliferation

The aryl hydrocarbon receptor (AhR) mediates many toxic effects of environmental pollutants. AhR also interacts with multiple growth factor-driven signaling pathways. In the course of examining effects of growth factors on proliferation of human colon cancer cells, we identified cross talk between AhR and the epidermal growth factor receptor (EGFR). In the present work, we explored underlying signal transduction mechanisms and functional consequences of this interaction. With the use of two human colon cancer cell lines, H508 and SNU-C4, we examined the effects of AhR ligands including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on cell proliferation and activation of EGFR, ERK1/2, and Src kinases. In colon cancer cells, 5-day incubation with TCDD stimulated a twofold dose-dependent increase in cell proliferation that was detectable with 1 nM and maximal with 30 nM TCDD. TCDD induced dose- and time-dependent phosphorylation of EGFR (Tyr845) and ERK1/2; maximal phosphorylation was observed 5 to 10 min after addition of 30 nM TCDD. Both TCDD-induced ERK1/2 phosphorylation and cell proliferation were abolished by AhR small interfering RNA, AhR-specific inhibitor CH223191, Src kinase inhibitor PP2, neutralizing antibodies against matrix metalloproteinase 7, heparin-binding-EGF-like growth factor and EGFR, EGFR inhibitors (AG1478 and PD168393), and MEK1 inhibitor PD98059. Coimmunoprecipitation experiments revealed that AhR forms a protein complex with Src and regulates Src activity by phosphorylating Src (Tyr416) and dephosphorylating Src (Tyr527). These data support novel observations that, in human colon cancer cells, Src-mediated cross talk between aryl hydrocarbon and EGFR results in ERK1/2 activation, thereby stimulating cell proliferation.

EGFR protein overexpression correlates with chromosome 7 polysomy and poor prognostic parameters in clear cell renal cell carcinoma

Background

The role of epidermal growth factor (EGF) and its receptor (EGFR) in the pathogenesis and progression of various malignant tumors has long been known, but there is still disagreement concerning prognostic significance of EGFR expression in clear cell renal cell carcinoma (CCRCC). The present study was designed to analyze more objectively the protein EGFR expression in CCRCC and to compare its value with EGFR gene copy number changes and clinicopathologic characteristics including patient survival.

Methods

The protein EGFR expression was analyzed immunohistochemically on 94 CCRCC, and gene copy number alterations of EGFR by FISH analysis on 41 CCRCC selected according to distinct membrane EGFR staining.

Results

Membrane EGFR expression in tumor cells was heterogeneous with respect to the proportion of positive cells and staining intensity. FISH analysis did not reveal EGFR gene amplification, while polysomy of chromosome 7 found in 41% was associated with higher EGFR membrane expression. Moreover, EGFR overexpression was associated with a higher nuclear grade, larger tumor size and shorter patient's survival, while there was no connection with pathological stage.

Conclusion

In conclusion, the protein expression of EGFR had an impact on prognosis in patients with CCRCC, while an increased copy number of chromosome 7 could be the possible reason for EGFR protein overexpression in the absence of gene amplification.

Validation of KRAS testing for anti-EGFR therapeutic decisions for patients with metastatic colorectal carcinoma

CONTEXT

KRAS mutation status is a molecular marker for predicting patient response to treatment with anti-EGFR antibodies (cetuximab and panitumumab) in metastatic colorectal carcinoma. Different approaches may be taken to detect KRAS mutations. There currently are no US Food and Drug Administration-approved assays for the detection of KRAS mutations. For assays that are not approved by the US Food and Drug Administration, the performance characteristics of the assay must be determined and validated by the clinical laboratory before implementation.

OBJECTIVE

To provide an example of how a KRAS mutation-analysis assay may be validated in a clinical laboratory.

DESIGN

Describing the approach used by an individual laboratory to compare different assays for validation of KRAS mutation analysis in metastatic colon carcinoma.

RESULTS

Specific validation data are provided, illustrating how a laboratory established assay performance characteristics for KRAS mutation analysis.

CONCLUSIONS

All clinical laboratories must establish several performance specifications mandated by the Clinical Laboratory Improvement Amendments of 1988 before implementation of any laboratory-developed test. Approaches to the validation of such assays may vary among laboratories. We describe an approach used for validation of a KRAS mutation-analysis assay by one laboratory.

Attenuated expression of HRH4 in colorectal carcinomas: a potential influence on tumor growth and progression

BACKGROUND

Earlier studies have reported the production of histamine in colorectal cancers (CRCs). The effect of histamine is largely determined locally by the histamine receptor expression pattern. Recent evidence suggests that the expression level of histamine receptor H4 (HRH4) is abnormal in colorectal cancer tissues. However, the role of HRH4 in CRC progression and its clinical relevance is not well understood. The aim of this study is to evaluate the clinical and molecular phenotypes of colorectal tumors with abnormal HRH4 expression.

METHODS

Immunoblotting, real-time PCR, immunofluorescence and immunohistochemistry assays were adopted to examine HRH4 expression in case-matched CRC samples (n = 107) and adjacent normal tissues (ANTs). To assess the functions of HRH4 in CRC cells, we established stable HRH4-transfected colorectal cells and examined cell proliferation, colony formation, cell cycle and apoptosis in these cells.

RESULTS

The protein levels of HRH4 were reduced in most of the human CRC samples regardless of grade or Dukes classification. mRNA levels of HRH4 were also reduced in both early-stage and advanced CRC samples. In vitro studies showed that HRH4 over-expression caused growth arrest and induced expression of cell cycle proteins in CRC cells upon exposure to histamine through a cAMP -dependent pathway. Furthermore, HRH4 stimulation promoted the 5-Fu-induced cell apoptosis in HRH4-positive colorectal cells.

CONCLUSION

The results from the current study supported previous findings of HRH4 abnormalities in CRCs. Expression levels of HRH4 could influence the histamine-mediated growth regulation in CRC cells. These findings suggested a potential role of abnormal HRH4 expression in the progression of CRCs and provided some new clues for the application of HRH4-specific agonist or antagonist in the molecular therapy of CRCs.

Intracellular trafficking considerations in the development of natural ligand-drug molecular conjugates for cancer

Overexpressed receptors, characteristic of many cancers, have been targeted by various researchers to achieve a more specific treatment for cancer. A common approach is to use the natural ligand for the overexpressed receptor as a cancer-targeting agent which can deliver a chemically or genetically conjugated toxic molecule. However, it has been found that the therapeutic efficacy of such ligand-drug molecular conjugates can be limited, since they naturally follow the intracellular trafficking pathways of the endogenous ligands. Therefore, a thorough understanding of the intracellular trafficking properties of these ligands can lead to novel design criteria for engineering ligands to be more effective drug carriers. This review presents a few commonly used ligand/receptor systems where intracellular trafficking considerations can potentially improve the therapeutic efficacy of the ligand-drug molecular conjugates.

Detection of KRAS and BRAF mutations in colorectal carcinoma roles for high-sensitivity locked nucleic acid-PCR sequencing and broad-spectrum mass spectrometry genotyping

KRAS and BRAF mutations predict the resistance of colorectal carcinomas to therapy targeted to the epidermal growth factor receptor, but their detection can be challenging because of high testing volume, frequently low tumor content, and the spectrum of rarer mutations in these genes. To address these issues, we evaluated a locked nucleic acid (LNA)-PCR sequencing assay to detect low levels of mutant DNA, and we also evaluated a mass spectrometry genotyping assay (Sequenom, San Diego, CA) that is suitable for broad mutation screening. Clinical cases (n = 308) previously tested for KRAS and BRAF by standard sequencing were retested by LNA-PCR sequencing incorporating an LNA oligonucleotide to suppress amplification of nonmutant DNA, and by a Sequenom assay panel targeting common mutations in both genes. Standard sequencing detected 121 KRAS (39%) and 10 BRAF mutations; retesting with the LNA-based method and the Sequenom assay detected 19 (140/308, 45%) and 6 (127/308, 41%) additional KRAS mutants, respectively. One additional BRAF mutant was detected by the Sequenom assay. The analytical sensitivities were 0.3% for both KRAS and BRAF by LNA-PCR and from 1% to 10% for the Sequenom assays, depending on the specific mutation. Given these results, standard sequencing is suboptimal for mutation detection in metastatic and treated lesions even with predissection for tumor enrichment. High-sensitivity LNA-PCR sequencing detects significantly more mutations, whereas the Sequenom platform shows intermediate sensitivity but offers significant advantages for broader mutation screening.

Efficacy of the monoclonal antibody EGFR inhibitors for the treatment of metastatic colorectal cancer

Two anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) have been approved in Canada for the treatment of metastatic colorectal cancer (mCRC) - cetuximab, a mouse-human chimeric MoAb, and panitumumab, a fully human MoAb. This paper reviews the efficacy of the anti-EGFR monoclonal antibodies cetuximab and panitumumab - both as monotherapy and in combination with cytotoxic chemotherapy - in the treatment of mCRC. Both cetuximab and panitumumab have demonstrated clinical efficacy in monotherapy in patients with mCRC, an advantage that has recently been found to be limited largely to those with wild-type KRAS tumors. Advantages of using these agents in monotherapy include reduced cost and toxicity. While the addition of cetuximab to irinotecan has shown superior progression-free survival and response compared with cetuximab monotherapy, there is currently no evidence for a benefit of panitumumab in combination with irinotecan.

KRAS, BRAF, EGFR and HER2 gene status in a Spanish population of colorectal cancer

To evaluate the KRAS, BRAF, EGFR, and HER2 gene status in colorectal cancer by novel techniques and evaluate whether anti-HER2 therapies could be offered in the treatment of these patients. There are conflicting data on the prevalence of BRAF mutations and EGFR and HER2 gene amplification in colorectal KRAS wild type patients. In our study we tried to evaluate these expressions and their relationship to future treatment assays. Clinical-pathological data and paraffin-embedded specimens were collected from 186 patients who underwent colorectal resections at General Yagüe Hospital in Burgos, Spain. KRAS and BRAF status was analyzed by real-time PCR in all patients. EGFR and HER2/NEU gene amplification was detected using fluorescent in situ hybridisation technique (FISH) in 38 KRAS and BRAF wild type patients. KRAS mutations were present in 48% of the colorectal cancer patients. BRAF mutations were present in 6.25% of the KRAS wild type patients. EGFR and HER2 gene amplification was observed in 5.3% and 26.3%, respectively, of KRAS and BRAF wild type colorectal cancer patients. HER2, but not EGFR gene amplification, was frequently observed in KRAS and BRAF wild type colorectal cancer patients. These data indicate that HER2 amplification could be one of the genes to be considered in the therapeutic management of colorectal cancer.

EGFR and Ki-67 expression in oral squamous cell carcinoma using tissue microarray technology

OBJECTIVE

Our aim was to validate the use of tissue microarrays (TMA) in oral squamous cell carcinomas (OSCC) to analyse epidermal growth factor receptor (EGFR) and Ki-67 expression. We also analysed the relationship that the expression of these markers may have with clinical, pathological and survival variables.

PATIENTS AND METHODS

The study sample comprised 39 unselected patients diagnosed and treated for OSCC. We analysed Ki-67 and EGFR expression by immunohistochemistry on formalin-fixed, paraffin-embedded surgical specimens. Whole sections (WS) were compared with double 1.5 mm core-tissue microarrays.

RESULTS

High EGFR expression was observed both on TMA (in 98% of the cases) and WS (in 100% of the cases) with substantial agreement kappa value (0.720). EGFR expression was not significantly associated with clinical, pathological and survival variables on TMA and WS. Ki-67 analysis showed a Spearman correlation of 0.741 with a Ki-67 mean labelling index of 45% in TMA and 56.8% in WS. We found a significant relationship between gender and Ki-67 labelling index on WS (P = 0.022) and TMA (P = 0.002). Clinical stage was the only parameter in multivariate analysis that had a significant predictive value.

CONCLUSION

We demonstrate that dual 1.5 mm core TMA is a valid, rapid, economical and tissue-saving way to study OSCC biopsies and that it presents strong correlation with the WS. EGFR overexpression in OSCC suggests that these tumours may be a candidate for therapy investigation directed to EGFR.

TAp73 is one of the genes responsible for the lack of response to chemotherapy depending on B-Raf mutational status

BACKGROUND

Although there have been many studies on the p73 gene, some of its functions still remain unclear. There is little research on the relationship between p73 gene transcription and its protein expression and the response to certain drugs such as oxaliplatin and cetuximab, which are drugs currently used in colorectal cancer.The purpose of this study was to evaluate the impact of TAp73 expression on oxaliplatin and cetuximab-based chemotherapy in colorectal cancer cell lines with different K-Ras and B-Raf mutational status.

METHODS

TAp73 was analyzed in three colorectal tumor cell lines HT-29, SW-480 and Caco-2. mRNA TAp73 was determined using Real time PCR; TAp73 protein by immunoblotting and cell viability was analyzed by the MTT method.

RESULTS

We found that mRNA and TAp73 protein were decreased in cells treated with oxaliplatin (in monotherapy or combined with cetuximab) when B-Raf is mutated. This was statistically significant and was also associated with higher cell viability after the treatment.

CONCLUSIONS

Here, for the first time we report, that there is a signaling loop between B-Raf activation and p73 function.Low expression of TAp73 in colorectal cancer cell lines with mutated B-Raf may be involved in the lack of response to oxaliplatin in monotherapy or combined with cetuximab.

Targeting the extracellular signature of metastatic colorectal cancers

BACKGROUND

Colorectal cancer is a leading cause of tumor death, a consequence primarily of the spreading of malignant cells to liver and lung. Despite a range of interventions for liver metastases, the present knowledge of few specific molecular targets may contribute to late diagnosis and poorly effective therapy.

OBJECTIVE

To review the most innovative methodology employed to profile the signature(s) of metastatic colorectal cancer (mCRC) and to address diagnostic/therapeutic agents.

METHODS

A broad range Medline search was conducted, with particular attention to the search terms 'liver metastasis signature', in combination with 'targeting' and 'nanotechnology'.

RESULTS/CONCLUSIONS

Studies aimed at the discovery of molecular signatures of cancers and metastasis are ongoing; the future of cancer/metastasis targeting is nanoparticle-mediated drug delivery.

Combined inhibition of the VEGFR and EGFR signaling pathways in the treatment of NSCLC

Multitargeted agents represent the next generation of targeted therapies in solid tumors. The benefits of individually targeting the vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) signaling pathways have been clinically validated in recent years in a number of solid tumor types including non-small cell lung cancer (NSCLC). Given the heterogeneity of this tumor type and potential crosstalk between these key signaling pathways (which are known to play a critical role in tumor growth, metastasis, and angiogenesis), dual inhibition of the VEGFR and EGFR signaling pathways has the potential to offer additional clinical benefits in NSCLC. A number of approaches to inhibiting both VEGFR and EGFR signaling are currently under investigation, including monotherapy with a multitargeted tyrosine kinase inhibitor (e.g., vandetanib, AEE788, XL647, BMS-690514) or a combination of single-targeted therapies (e.g., bevacizumab, cetuximab, erlotinib, gefitinib). Preclinical and early clinical data (phase I and II trials) support combined inhibition of the VEGFR and EGFR pathways in NSCLC. Overall, combined inhibition strategies are well tolerated and have shown promise in early clinical studies. Ongoing phase II and phase III trials will determine the clinical potential of a number of dual inhibition strategies in the treatment of advanced NSCLC.

Beyond RECIST: molecular and functional imaging techniques for evaluation of response to targeted therapy

The development of targeted therapies is a major breakthrough in the treatment of cancer. By evoking necrosis and cavitation, evaluation based on tumour size alone, as is done in the RECIST criteria, is no longer an adequate method. New molecular and functional imaging techniques are developed. This review focuses on the use of new imaging modalities for the evaluation of treatment response of pathway based targeted therapies. First, the basic principles of functional and molecular imaging modalities are briefly discussed. Thereafter, their clinical application in targeted therapies is correlated to the underlying biological mechanism. In this way, the best method for response evaluation for a new agent can be identified.

Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer

PURPOSE Cetuximab or panitumumab are effective in 10% to 20% unselected metastatic colorectal cancer (CRC) patients. KRAS mutations account for approximately 30% to 40% patients who are not responsive. The serine-threonine kinase BRAF is the principal effector of KRAS. We hypothesized that, in KRAS wild-type patients, BRAF mutations could have a predictive/prognostic value. PATIENTS AND METHODS We retrospectively analyzed objective tumor responses, time to progression, overall survival (OS), and the mutational status of KRAS and BRAF in 113 tumors from cetuximab- or panitumumab-treated metastatic CRC patients. The effect of the BRAF V600E mutation on cetuximab or panitumumab response was also assessed using cellular models of CRC. Results KRAS mutations were present in 30% of the patients and were associated with resistance to cetuximab or panitumumab (P = .011). The BRAF V600E mutation was detected in 11 of 79 patients who had wild-type KRAS. None of the BRAF-mutated patients responded to treatment, whereas none of the responders carried BRAF mutations (P = .029). BRAF-mutated patients had significantly shorter progression-free survival (P = .011) and OS (P < .0001) than wild-type patients. In CRC cells, the introduction of BRAF V600E allele impaired the therapeutic effect of cetuximab or panitumumab. Treatment with the BRAF inhibitor sorafenib restored sensitivity to panitumumab or cetuximab of CRC cells carrying the V600E allele. CONCLUSION BRAF wild-type is required for response to panitumumab or cetuximab and could be used to select patients who are eligible for the treatment. Double-hit therapies aimed at simultaneous inhibition of epidermal growth factor receptor and BRAF warrant exploration in CRC patients carrying the V600E oncogenic mutation.

Epidermal growth factor receptor (EGFR) expression in prostatic adenocarcinoma after hormonal therapy: a fluorescence in situ hybridization and immunohistochemical analysis

BACKGROUND

The progression of normal prostatic epithelium to androgen-dependent cancer and, eventually, hormone-refractory prostate cancer is a complex process involving many different growth regulatory signals. Activation of epidermal growth factor receptor (EGFR) has been implicated in prostate cancer cell growth.

METHODS

This study was undertaken to investigate both amplification of EGFR gene by fluorescence in situ hybridization (FISH) and over-expression of EGFR by immunohistochemical staining in prostate tissue from 71 patients treated by hormonal therapy.

RESULTS

EGFR gene amplification was present in 1 of 71 tumors, and polysomy of chromosome 7 was present in 24 of 71 tumors. Immunohistochemically, EGFR expression was demonstrable in 57 of 71 tumors. Membranous immunostaining for EGFR was observed in >75% of tumor cells in 11% of cases, in 51-75% of tumor cells in 20% of cases, in 26-50% of tumor cells in 21% of cases, in 11-25% of tumor cells in 21% of cases, and in 1-10% of tumor cells in 7% of cases. No immunostaining for EGFR was seen in 20% of cases. There was no correlation between EGFR protein expression and gene amplification. There was also no correlation between EGFR expression and clinicopathological characteristics or clinical outcome.

CONCLUSIONS

We found that EGFR gene expression was detectable in 35% of this large series of hormone-treated prostate cancer, and that EGFR protein is frequently expressed in tissue from these patients. EGFR over-expression may serve as a reasonable target for therapeutic intervention in this otherwise difficult to treat subset of prostate cancer.

Systemic treatment of colorectal cancer

Colorectal cancer is the fourth most common noncutaneous malignancy in the United States and the second most frequent cause of cancer-related death. Over the past 12 years, significant progress has been made in the systemic treatment of this malignant condition. Six new chemotherapeutic agents have been introduced, increasing median overall survival for patients with metastatic colorectal cancer from less than 9 months with no treatment to approximately 24 months. For patients with stage III (lymph node positive) colon cancer, an overall survival benefit for fluorouracil-based chemotherapy has been firmly established, and recent data have shown further efficacy for the inclusion of oxaliplatin in such adjuvant treatment programs. For patients with stage II colon cancer, the use of adjuvant chemotherapy remains controversial, but may be appropriate in a subset of individuals at higher risk for disease recurrence. Ongoing randomized clinical trials are evaluating how best to combine currently available therapies, while smaller studies are evaluating new agents, with the goal of continued progress in prolonging life among patients with metastatic colorectal cancer and increasing cure rates among those with resectable disease.