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

Colorectal Cancer Biomarkers in the Era of Personalized Medicine

The 5-year survival probability for patients with metastatic colorectal cancer has not drastically changed over the last several years, nor has the backbone chemotherapy in first-line disease. Nevertheless, newer targeted therapies and immunotherapies have been approved primarily in the refractory setting, which appears to benefit a small proportion of patients. Until recently, rat sarcoma (RAS) mutations remained the only genomic biomarker to assist with therapy selection in metastatic colorectal cancer. Next generation sequencing has unveiled many more potentially powerful predictive genomic markers of therapy response. Importantly, there are also clinical and physiologic predictive or prognostic biomarkers, such as tumor sidedness. Variations in germline pharmacogenomic biomarkers have demonstrated usefulness in determining response or risk of toxicity, which can be critical in defining dose intensity. This review outlines such biomarkers and summarizes their clinical implications on the treatment of colorectal cancer. It is critical that clinicians understand which biomarkers are clinically validated for use in practice and how to act on such test results.

EGFR Protein Expression of KRAS Wild-Type Colorectal Cancer: Predictive Value of the Sidedness for Efficacy of Anti-EGFR Therapy

Right- and left-sided colorectal cancers (RSCRC and LSCRC, respectively) are different developmentally, genetically and prognostically. Clinical data also indicate that they respond differently to anti-EGFR therapies. The role of EGFR protein expression in KRAS wild type colorectal cancer is also controversial. Here we have used a cohort of anti-EGFR antibody treated KRAS-wild type colorectal cancer patients (n = 97) to analyse the prognostic role of EGFR protein expression in relation to sidedness. In our cohort EGFR copy number, determined by FISH, was not associated with the level of EGFR protein, assessed by immunohistochemistry and measured by H-scoring. There was a significantly higher EGFR H-score detected in RSCRC as compared to LSCRC in primary tumors (p = 0.04). Furthermore, in a proportion of cases (n = 31) metastatic tissues were also available and their analysis also found a significantly higher EGFR H-score in metastases of RSCRC compared to LSCRC (p = 0.018). Kaplan Meyer survival analysis demonstrated that anti-EGFR antibody therapies were more effective in case of LSCRC compared to RSCRC. Although in case of progression-free survival data just indicated a trend (p = 0.065), in case of overall survival the difference was significant favouring LSCRC (p = 0.047). These data demonstrated for the first time that the EGFR protein expression is significantly higher in KRAS wild type RSLCL as compared to LSCRC. Meanwhile it is somewhat unexpected that the lower EGFR protein expression was found to be associated with better efficacy of anti-EGFR antibody therapies of colorectal cancer, the finding of which must be further validated.

Rho GTPase Activating Protein 24 (ARHGAP24) Silencing Promotes Lung Cancer Cell Migration and Invasion by Activating β-Catenin Signaling

BACKGROUND Rho GTPase activating protein (RhoGAPs) is an important negative regulator of the Rho signaling pathway that is involved in tumorigenesis in liver, colon, and renal cancer. However, the mechanism by which Rho GTPase activating protein 24 (ARHGAP24) regulates cell invasion and migration of lung cancer has not been fully explained. MATERIAL AND METHODS In this study, ARHGAP24 expression in lung cancer tissues and cell lines was measured by immunohistochemical and Western blot analysis. Transwell or wound healing analysis was performed to detect the cell migration and invasion of ARHGAP24 modulated A549 and NCI-H1975 cells with β-catenin inhibitor XAV-939 (10 µM) treatment, and the expression of MMP9, VEGF, and β-catenin protein was measured by Western blotting. RESULTS Our results showed that ARHGAP24 expression was downregulated in lung cancer tissues and cell lines. pLVX-Puro-ARHGAP24 transfection in A549 cells significantly inhibited cell invasion and migration, along with increased E-cadherin and decreased MMP9, VEGF, Vimentin, and β-catenin protein expression. pLKO.1-ARHGAP24-shRNA transfection in NCI-H1975 cells significantly promoted cell invasion and migration, accompanied with decreased E-cadherin and increased MMP9, VEGF, and β-catenin protein expression. Moreover, NCI-H1975 cells with XAV-939 treatment showed decreased cell invasion and migration when compared with pLKO.1-ARHGAP24-shRNA transfection. ARHGAP24 silencing promoted the transcriptional activity of β-catenin in NCI-H1975 cells. CONCLUSIONS Our findings indicate that ARHGAP24 silencing promotes lung cancer cell migration and invasion through activating β-catenin signaling.

Immunohistochemistry-Enabled Precision Medicine

Immunohistochemistry (IHC) can be applied to diagnostic aspects of pathologic examination to provide aid in assignment of lineage and histologic type of cancer. Increasingly, however, IHC is widely used to provide prognostic and predictive (theranostic) information about the neoplastic disease. A refinement of theranostic application of IHC can be seen in the use of "genomic probing" where antibody staining results are directly correlated with an underlying genetic alteration in the tumor (somatic mutations) and/or the patient (germline constitution). All these aspects of IHC find their best use in guiding the oncologists in the optimal use of therapy for the patients.

Efficacy and Tolerability of First-Line Cetuximab Plus Leucovorin, Fluorouracil, and Oxaliplatin (FOLFOX-4) Versus FOLFOX-4 in Patients With RAS Wild-Type Metastatic Colorectal Cancer: The Open-Label, Randomized, Phase III TAILOR Trial

PURPOSE

Cetuximab in combination with chemotherapy is a standard-of-care first-line treatment regimen for patients with RAS wild-type (wt) metastatic colorectal cancer (mCRC); however, the efficacy of cetuximab plus leucovorin, fluorouracil, and oxaliplatin (FOLFOX) has never before been proven in a controlled and randomized phase III trial. To our knowledge, the TAILOR trial ( ClinicalTrials.gov identifier: NCT01228734) is the first randomized, multicenter, phase III study of the addition of cetuximab to first-line FOLFOX prospectively choosing a RAS wt population and thus providing confirmative data for the efficacy and safety of cetuximab plus FOLFOX versus FOLFOX alone.

PATIENTS AND METHODS

TAILOR is an open-label, randomized (1:1), multicenter, phase III trial in patients from China comparing FOLFOX-4 with or without cetuximab in RAS wt (KRAS/NRAS, exons 2 to 4) mCRC. The primary end point of TAILOR was progression-free survival time; secondary end points included overall survival time, overall response rate, and safety and tolerability.

RESULTS

In the modified intent-to-treat population of 393 patients with RAS wt mCRC, adding cetuximab to FOLFOX-4 significantly improved the primary end point of progression-free survival time compared with FOLFOX-4 alone (hazard ratio, 0.69; 95% CI, 0.54 to 0.89; P = .004; median, 9.2 v 7.4 months, respectively), as well as the secondary end points of overall survival time (current assessment after 300 events: hazard ratio, 0.76; 95% CI, 0.61 to 0.96; P = .02; median, 20.7 v 17.8 months, respectively) and overall response rate (odds ratio, 2.41; 95% CI, 1.61 to 3.61; P < .001; 61.1% v 39.5%, respectively). Treatment was well tolerated, and there were no new or unexpected safety findings.

CONCLUSION

The TAILOR study met all of its objectives and relevant clinical end points, confirming cetuximab in combination with FOLFOX as an effective standard-of-care first-line treatment regimen for patients with RAS wt mCRC.

TMEM119 promotes gastric cancer cell migration and invasion through STAT3 signaling pathway

Objective

TMEM119 is a member of transmembrane proteins family, which is abnormally expressed in human cancers and associated with tumorigenesis. In this study, we focused on the expression of TMEM119 and its role in cell invasion and migration in gastric cancer.

Methods

Real-time polymerase chain reaction, Western blotting, and immunohistochemistry were performed to examine the expression of TMEM119 in gastric cancer tissues and cell lines. After transfection with TMEM119 siRNA or recombined TMEM119-expressing vector, the invasion and migration ability of MKN45 and SGC-7901 cells was measured by transwell assay. The expression of TMEM119, p-STAT3, STAT3, VEGF, MMP2, and MMP9 proteins in SGC-7901 and MKN45 cells treated with TMEM119 siRNA, TMEM119-expressing vector, or AG490 was measured by Western blotting.

Results

We found that higher TMEM119 expression was found in gastric cancer tissues and cell lines and was associated with lower survival rate. TMEM119 knockdown inhibited SGC-7901 cell invasion and migration, along with the expression of p-STAT3, VEGF, MMP2, and MMP9. TMEM119 overexpression promoted MKN45 cell invasion and migration, along with the expression of p-STAT3, VEGF, MMP2, and MMP9. Additionally, AG490 treatment significantly corrected TMEM119-induced MKN45 cell migration and invasion and expression of p-STAT3, VEGF, MMP9, and MMP2 proteins.

Conclusion

The results indicated that TMEM119 promotes gastric cancer cell migration and invasion through activation of STAT3 signaling pathway, and TMEM119 may therefore act as a novel therapeutic target for gastric cancer.

Imaging biomarkers in oncology: Basics and application to MRI

Cancer remains a global killer alongside cardiovascular disease. A better understanding of cancer biology has transformed its management with an increasing emphasis on a personalized approach, so-called "precision cancer medicine." Imaging has a key role to play in the management of cancer patients. Imaging biomarkers that objectively inform on tumor biology, the tumor environment, and tumor changes in response to an intervention complement genomic and molecular diagnostics. In this review we describe the key principles for imaging biomarker development and discuss the current status with respect to magnetic resonance imaging (MRI).

LEVEL OF EVIDENCE

5 TECHNICAL EFFICACY: Stage 5 J. Magn. Reson. Imaging 2018;48:13-26.

Panitumumab in the treatment of metastatic colorectal cancer, including wild-type RAS, KRAS and NRAS mCRC

The humanized monoclonal antibody panitumumab, targeted against EGFR, plays an important role in patients with metastatic colorectal cancer. This article reviews the body of evidence for panitumumab which demonstrates significant benefits across multiple lines of therapy in those without an extended RAS mutation. The use of panitumumab with RAS mutations is not beneficial and possibly harmful. Panitumumab is well tolerated with manageable toxicities. The role of panitumumab continues to evolve as understanding of sequencing of therapies grows. There is evidence for use as maintenance therapy and conversion therapy for unresectable liver metastases. Future research is likely to focus on biomarkers for improved patient selection and the development of novel therapeutic strategies to overcome resistance.

Colorectal cancer genomics and designing rational trials

The widespread use of next generation sequencing (NGS) has led to a refined understanding of the genomics of colorectal cancer (CRC). However, progress in the use of molecular biomarkers in standard practice has been slow, and there is no approved targeted therapy for CRC based on a positive predictive marker yet. In this review, we will first summarize biomarkers with clinical utility in standard practice or targeted therapy trials and then consider how to rationally design clinical trials to more effectively target CRC. Specifically, we will discuss current clinical applications of genomic information consisting of the use of the MAPK (mitogen-activated protein kinase) pathway genes KRAS, NRAS, and BRAF as prognostic and predictive biomarkers for standard treatment, risk stratification by primary tumor site and consideration of tumor laterality in patient selection for epidermal growth factor receptor (EGFR) antibody treatment, and the evaluation for genomic biomarkers, including BRAF V600E, HER2 amplification, and gene rearrangements, for targeted therapies in clinical trials. Applying lessons from targeted therapy trials in CRC, we now appreciate that both tumor genomics and tissue of origin affect targeted therapy response and that the development of resistance to targeted therapies is dynamic and often subclonal. Based on these understandings, we propose the design of adaptive clinical trials that evaluate real-time pharmacodynamic markers and monitor tumor subpopulations during the course of treatment to overcome challenges targeting genetic drivers in CRC.

Anti-EGFR monoclonal antibodies and EGFR tyrosine kinase inhibitors as combination therapy for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterized by overexpression of epidermal growth factor receptor (EGFR) and activation of its downstream signaling pathways. Dual targeting of EGFR using one monoclonal antibody (mAb; cetuximab or panitumumab) and one tyrosine kinase inhibitor (EGFR-TKI; gefitinib or erlotinib) is a potential therapeutic approach. We investigated the effect of these therapies in EGFR-expressing TNBC cell lines that do or do not harbor the main activating mutations of EGFR pathways. Cell lines were sensitive to EGFR-TKIs, whereas mAbs were active only in MDA-MB-468 (EGFR amplification) and SUM-1315 (KRAS and PTEN wild-type) cells. MDA-MB-231 (KRAS mutated) and HCC-1937 (PTEN deletion) cells were resistant to mAbs. The combined treatment resulted in a synergistic effect on cell proliferation and superior inhibition of the RAS/MAPK signaling pathway in mAb-sensitive cells. The anti-proliferative effect was associated with G1 cell cycle arrest followed by apoptosis. Sensitivity to therapies was characterized by induction of positive regulators and inactivation of negative regulators of cell cycle. These results suggest that dual EGFR inhibition might result in an enhanced antitumor effect in a subgroup of TNBC. The status of EGFR, KRAS and PTEN could be used as a molecular marker for predicting the response to this therapeutic strategy.

MCT4 Expression Is a Potential Therapeutic Target in Colorectal Cancer with Peritoneal Carcinomatosis

Monocarboxylate transporters (MCT) are transmembrane proteins that control the lactate metabolism and are associated with poor prognosis in solid tumors, including colorectal cancer. Here, we aimed to investigate the biological and clinical role of MCTs in colorectal cancer and to assess the potential of therapeutic application. A total of 16 human colorectal cancer cell lines, 11 patient-derived cells from malignant ascites [patient-derived cells (PDC)], and 39 matched pairs of primary colorectal cancer and normal colorectal tissues were used to assess the role of MCT in vitro and in vivo siRNA methodology was used to determine the effect of MCT inhibition and molecular mechanism of hypoxia- and angiogenesis-related factors in addition to MCT4. The effect of MCT inhibition was confirmed in mouse xenograft models. MCT4 expression in surgical tissue was evaluated by IHC and used for survival analysis. Expression of MCTs was demonstrated in colorectal cancer cell lines. siRNA-mediated MCT silencing caused significant decline of cell proliferation both in vitro and in vivo An additive effect of MCT inhibition was induced by combined treatment with chemotherapy or radiotherapy. In particular, the expression of MCT4 was markedly increased in PDCs, and MCT4 inhibition significantly decreased PDC proliferation. Hypoxia-inducible factor 1-α (HIF1α) was also highly expressed in PDCs, whereas HIF1α knockdown reduced MCT4 expression and of other angiogenesis-related mediators. The patients with high MCT4 expression by IHC showed shorter relapse-free survival compared with low expression. These findings suggest that MCT4 may represent a new therapeutic target for colorectal cancer with peritoneal carcinomatosis and serve as a prognostic indicator. Mol Cancer Ther; 17(4); 838-48. ©2018 AACR.

Quantitative assessment of Zirconium-89 labeled cetuximab using PET/CT imaging in patients with advanced head and neck cancer: a theragnostic approach

Biomarkers predicting treatment response to the monoclonal antibody cetuximab in locally advanced head and neck squamous cell carcinomas (LAHNSCC) are lacking. We hypothesize that tumor accessibility is an important factor in treatment success of the EGFR targeting drug. We quantified uptake of cetuximab labeled with Zirconium-89 (⁸⁹Zr) using PET/CT imaging.

Seventeen patients with stage III-IV LAHNSCC received a loading dose unlabeled cetuximab, followed by 10 mg 54.5±9.6 MBq ⁸⁹Zr-cetuximab. PET/CT images were acquired either 3 and 6 or 4 and 7 days post-injection. ⁸⁹Zr-cetuximab uptake was quantified using standardized uptake value (SUV) and tumor-to-background ratio (TBR), and correlated to EGFR immunohistochemistry. TBR was compared between scan days to determine optimal timing.

Uptake of ⁸⁹Zr-cetuximab varied between patients (day 6-7: SUV_peak range 2.5-6.2). TBR increased significantly (49±28%, p < 0.01) between first (1.1±0.3) and second scan (1.7±0.6). Between groups with a low and high EGFR expression a significant difference in SUV_mean (2.1 versus 3.0) and SUV_peak (3.2 versus 4.7) was found, however, not in TBR. Data is available at www.cancerdata.org (DOI: 10.17195/candat.2016.11.1).

In conclusion, ⁸⁹Zr-cetuximab PET imaging shows large inter-patient variety in LAHNSCC and provides additional information over FDG-PET and EGFR expression. Validation of the predictive value is recommended with scans acquired 6-7 days post-injection.

Development and Clinical Indications of Cetuximab

Cetuximab is a chimeric immunoglobulin G1 monoclonal antibody that targets the extracellular domain of the epidermal growth factor receptor (EGFR) with high specificity and affinity. It competitively inhibits endogenous ligand binding and thereby inhibits subsequent EGFR activation. The EGFR signaling pathways regulate cell differentiation, proliferation, migration, angiogenesis and apoptosis, all of which become deregulated in cancer cells. EGFR is an important target for cancer therapy and many studies have demonstrated that cetuximab is active in several types of cancer, particularly colorectal and head and neck cancer. Cetuximab enhances the effects of many standard cytotoxic agents, including irinotecan, and in combination with chemotherapy it can elicit antitumor responses in tumors that previously failed to respond to that chemotherapy. Cetuximab also enhances radiation-induced apoptosis. On the basis of a pivotal European randomized study (the BOND study) and of 2 clinical studies conducted in the USA, cetuximab has been approved in combination with irinotecan for patients affected by EGFR-expressing metastatic colon cancer after failure with irinotecan. There have only been a few small phase II trials on first-line treatment in metastatic colorectal cancer, but the results suggest promising activity of cetuximab together with irinotecan or oxaliplatin. There is some evidence that additive efficacy can be achieved using EGFR inhibitors in combination with vascular endothelial growth factor receptor inhibitors such as bevacizumab. A correlation between response and the main toxicity (acne-like skin reaction) has been observed but is unclear. EGFR status as a specific marker for EGFR inhibitors is controversial. At the moment, EGFR expression does not appear to be a predictive factor for response to EGFR inhibitors.

The Future of Anti-EGFR Therapy

We report here on the state of our knowledge of the target - namely, the epidermal growth factor (EGF) and its receptor - and the challenges related to the methods of determination of the epidermal growth factor receptor (EGFR) and associated molecular pathways. A critical review of the anti-EGFR therapeutic strategies is also outlined. The chimeric anti-EGFR monoclonal antibody cetuximab has been approved for EGFR-expressing colorectal tumors in patients who progress after irinotecan-based chemotherapy in combination with irinotecan and in squamous cell head and neck carcinomas for patients with locally advanced disease in combination with radiation therapy or after failure of platinum-based chemotherapy in recurrent or metastatic disease (FDA). Cetuximab has the potential to provide an improvement of clinical outcome also in other indications and tumor types, particularly when used as first-line therapy combined with standard chemotherapy for metastatic disease or in the adjuvant setting. Possible strategies to improve the effectiveness of anti-EGFR agents are suggested and include (i) the use of predictive tools capable of making a more rational selection of patients; (ii) the development of standardized predictive biomarkers as surrogates for early monitoring of drug efficacy; and (iii) adequate study design, statistical analysis and proper end points of efficacy to be applied in future prospective trials.

Cetuximab in Colon Cancer

In the last decade remarkable progress has been made in the treatment of metastatic colorectal cancer due to the introduction of oxaliplatin and irinotecan in clinical practice. The addition of biological agents seems to offer a chance to further enhance the activity of conventional chemotherapy. Cetuximab, a chimeric mouse-human monoclonal antibody targeting the extracellular domain of the epidermal growth factor receptor (EGFR), has shown low but detectable activity when employed in pretreated patients either as a single agent or in combination with irinotecan. Cetuximab in combination with irinotecan has been registered in the USA and Europe for the treatment of patients with metastatic colorectal cancer expressing the EGFR after failure of prior irinotecan-based cytotoxic therapy. The role of cetuximab in first-line therapy is still investigational. Some phase II trials assessing cetuximab plus chemotherapy demonstrated a high objective response rate and promising results in terms of time to progression and overall survival; data from phase III trials are pending. Further studies are needed to investigate the efficacy of cetuximab in combination with conventional chemotherapy in the adjuvant/neoadjuvant setting and to define criteria for a better selection of patients for this type of treatment.

Cetuximab response in CRC patient-derived xenografts seems predicted by an expression based RAS pathway signature

Cetuximab is an approved treatment for metastatic colorectal carcinoma (mCRC) with codon 12/13-KRAS mutations, recently questioned for its validity, and alternative mutation-based biomarkers were proposed. We set out to investigate whether an expression signature can also predict response by utilizing a cetuximab mouse clinical trial (MCT) dataset on a cohort of 25 randomly selected EGFR⁺ CRC patient-derived xenografts (PDXs). While we found that the expression of EGFR and its ligands are not predictive of the cetuximab response, we tested a published RAS pathway signature, a 147-gene expression signature proposed to describe RAS pathway activity, against this MCT dataset. Interestingly, our study showed that the observed cetuximab activity has a strong correlation with the RAS pathway signature score, which was also demonstrated to have a certain degree of correlation with a historic clinical dataset. Altogether, the independent validations in unrelated datasets from independent cohort of CRCs strongly suggest that RAS pathway signature may be a relevant expression signature predictive of CRC response to cetuximab. Our data seem to suggest that an mRNA expressing signature may also be developed as a predictive biomarker for drug response, similarly to genetic mutations.

Convection-enhanced delivery of cetuximab conjugated iron-oxide nanoparticles for treatment of spontaneous canine intracranial gliomas

Cetuximab conjugated iron-oxide nanoparticles (cetuximab-IONPs) have shown both in-vitro and in-vivo anti-tumor efficacy against gliomas. The purpose of this pilot study was to evaluate the safety and potential efficacy of cetuximab-IONPs for treatment of spontaneously occurring intracranial gliomas in canines after convection-enhanced delivery (CED). The use of CED allowed for direct infusion of the cetuximab-IONPs both intratumorally and peritumorally avoiding the blood brain barrier (BBB) and limiting systemic effects. A total of eight dogs participated in the study and only two developed mild post-operative complications, which resolved with medical therapy. All canines underwent a single CED treatment of the cetuximab-IONPs over 3 days and did not receive any further adjuvant treatments. Volumetric analysis showed a median reduction in tumor size of 54.9% by MRI at 1-month (4-6 weeks) follow-up. Five dogs were euthanized due to recurrence of neurological signs other than seizures, two due to recurrent seizures, and one dog died in his sleep. Median survival time after surgery was 248 days (mean 367 days).

Anti-EGFR Therapy to Treat Metastatic Colorectal Cancer: Not for All

The development of monoclonal antibodies (mAbs) cetuximab and panitumumab, which target the transmembrane protein epidermal growth factor receptor (EGFR), mark a major step forward in the treatment of metastatic colorectal cancer (mCRC). However, this therapeutic progress proved to be effective only in a very restricted subset of patients. Although several mechanisms of resistance, both primary and acquired, have been identified, the only established predictive tumour biomarker for the treatment of mCRC patients is the RAS mutational status. RAS activating mutations predict a lack of response to these therapies while low levels of primary resistance characterize RAS wild type (WT) patients (only about 15%). However, even WT patients that initially respond to anti-EGFR therapy, eventually undergo tumour progression. In this context, there is still more to be done in the search for effective predictive markers with therapeutic applicability. In this chapter, we provide an overview on the mechanisms that contribute to resistance to EGFR-targeted therapy and highlight what is still missing in our understanding of these molecular mechanisms and approaches to overcome them.

Targeted Therapies: Immunologic Effects and Potential Applications Outside of Cancer

Two pharmacologic approaches that are currently at the forefront of treating advanced cancer are those that center on disrupting critical growth/survival signaling pathways within tumor cells (commonly referred to as "targeted therapies") and those that center on enhancing the capacity of a patient's immune system to mount an antitumor response (immunotherapy). Maximizing responses to both of these approaches requires an understanding of the oncogenic events present in a given patient's tumor and the nature of the tumor-immune microenvironment. Although these 2 modalities were developed and initially used independently, combination regimens are now being tested in clinical trials, underscoring the need to understand how targeted therapies influence immunologic events. Translational studies and preclinical models have demonstrated that targeted therapies can influence immune cell trafficking, the production of and response to chemokines and cytokines, antigen presentation, and other processes relevant to antitumor immunity and immune homeostasis. Moreover, because these and other effects of targeted therapies occur in nonmalignant cells, targeted therapies are being evaluated for use in applications outside of oncology.

Molecular Testing for the Treatment of Advanced Colorectal Cancer: An Overview

Concurrent with an expansion in the number of agents available for the treatment of advanced CRC, there has been an increase in our understanding of selection biomarkers to optimize the management of patients with this disease. For CRC patients being considered for anti-EGFR therapy, expanded RAS testing is the standard of care to determine the subset of patients who can benefit from cetuximab or panitumumab in conjunction with chemotherapy. A small fraction of patients have HER2 amplification where emerging data suggest treatment with drugs targeting this alteration. Although advanced CRC patients who harbor the BRAF V600E mutation have a poorer prognosis, they are eligible for combinatorial therapy targeting EGFR/BRAF or BRAF/MEK within the MAP kinase signaling pathway. Once primarily thought to be a negative prognostic marker, BRAF V600E mutation is now considered as a positive predictive factor with an opportunity for clinical intervention. A growing body of evidence also supports MSI testing as clinical benefits with immune checkpoint blockade by cancer immunotherapy have been demonstrated in MSI-high patients whose tumors exhibit high mutational burden. It has been established that UGT1A1*28 polymorphism is associated with irinotecan toxicity, but this test is rarely performed as the management strategy has not been identified. No established predictive biomarker for anti-VEGF therapy has yet to be discovered.It is becoming increasingly apparent that our growing understanding of biomarkers is revolutionizing and improving our strategies in the treatment of advanced CRC. Traditional nonselective cytotoxic chemotherapy is gradually being augmented and even in some cases supplanted by selective targeted agents based on our increasing understanding of tumor signaling and mechanism at the molecular level. The prospect of personalized medicine in directing treatment approaches that are optimally beneficial for patients brings tremendous excitement to the growing field of cancer therapeutics. As discussed in this chapter, the concurrent development of molecular biomarkers with new treatment strategies holds great promise of precision medicine in improving outcomes for patients with advanced CRC.

Molecularly-targeted therapy for the oral cancer stem cells

Human cancer tissues are heterogeneous in nature and become differentiated during expansion of cancer stem cells (CSCs). CSCs initiate tumorigenesis, and are involved in tumor recurrence and metastasis. Furthermore, data show that CSCs are highly resistant to anticancer drugs. Cetuximab, a specific anti-epidermal growth factor receptor (EGFR) monoclonal antibody, is used in cancer treatment. Although development of resistance to cetuximab is well recognized, the underlying mechanisms remain unclear. Lapatinib, a dual inhibitor of epidermal growth factor receptor (EGFR)/ErbB2, has antiproliferative effects and is used to treat patients with ErbB2-positive metastatic breast cancer. In this review, cetuximab and lapatinib-resistant oral squamous cell carcinoma (OSCC) cells proliferation and migration signal transduction passway is discussed by introducing our research.

Cyclic versus Noncyclic Chelating Scaffold for 89Zr-Labeled ZEGFR:2377 Affibody Bioconjugates Targeting Epidermal Growth Factor Receptor Overexpression

Zirconium-89 is an emerging radionuclide for positron emission tomography (PET) especially for biomolecules with slow pharmacokinetics as due to its longer half-life, in comparison to fluorine-18 and gallium-68, imaging at late time points is feasible. Desferrioxamine B (DFO), a linear bifunctional chelator (BFC) is mostly used for this radionuclide so far but shows limitations regarding stability. Our group recently reported on fusarinine C (FSC) with similar zirconium-89 complexing properties but potentially higher stability related to its cyclic structure. This study was designed to compare FSC and DFO head-to-head as bifunctional chelators for ⁸⁹Zr-radiolabeled EGFR-targeting ZEGFR:2377 affibody bioconjugates. FSC-ZEGFR:2377 and DFO-ZEGFR:2377 were evaluated regarding radiolabeling, in vitro stability, specificity, cell uptake, receptor affinity, biodistribution, and microPET-CT imaging. Both conjugates were efficiently labeled with zirconium-89 at room temperature but radiochemical yields increased substantially at elevated temperature, 85 °C. Both ⁸⁹Zr-FSC-ZEGFR:2377 and ⁸⁹Zr-DFO-ZEGFR:2377 revealed remarkable specificity, affinity and slow cell-line dependent internalization. Radiolabeling at 85 °C showed comparable results in A431 tumor xenografted mice with minor differences regarding blood clearance, tumor and liver uptake. In comparison ⁸⁹Zr-DFO-ZEGFR:2377, radiolabeled at room temperature, showed a significant difference regarding tumor-to-organ ratios. MicroPET-CT imaging studies of ⁸⁹Zr-FSC-ZEGFR:2377 as well as ⁸⁹Zr-DFO-ZEGFR:2377 confirmed these findings. In summary we were able to show that FSC is a suitable alternative to DFO for radiolabeling of biomolecules with zirconium-89. Furthermore, our findings indicate that ⁸⁹Zr-radiolabeling of DFO conjugates at higher temperature reduces off-chelate binding leading to significantly improved tumor-to-organ ratios and therefore enhancing image contrast.

Clinical Equipoise for Trials of Novel Biologic Therapies, Therapeutic Success Rates, and Predictors of Success: A Meta-Analysis

Purpose

The demand for more rapid access to novel biologic therapies than randomized controlled trials can deliver is a topic of ongoing study and debate. We aimed to inform this debate by estimating therapeutic success from phase III trials comparing novel biologic therapies with standard of care and identifying predictors of success.

Methods

This was a meta-analysis of phase III trials evaluating novel biologic therapies in advanced breast, colorectal, lung, and prostate cancers. Therapeutic success was defined as statistically significant results for the primary end point favoring novel biologic therapies.

Results

Of 119 included phase III trials (76,726 patients), therapeutic success was 41%, with a statistically significant relative reduction in disease progression and death for novel biologic therapies over standard of care of 20% and 8%. Therapeutic success did not improve over time (pre-2010, 33%; 2010 to 2014, 44%; P = .2). Predictors of success were a biomarker-selected population (odds ratio, 4.74; 95% CI, 2.05 to 10.95) and progression-free survival end point compared with overall survival (odds ratio, 5.22; 95% CI, 2.41 to 11.39). Phase III trials with a biomarker-selected population showed a larger 28% progression-free survival benefit than phase III trials overall (hazard ratio, 0.72; 95% CI, 0.70 to 0.75) but similar 8% overall survival benefit (hazard ratio, 0.92; 95% CI, 0.90 to 0.94). Therapeutic success of phase III trials with and without a preceding phase II trial were 43% and 30%, respectively

Conclusion

Therapeutic success of novel biologic therapies in phase III trials, including therapies with a matching predictive biomarker, was modest and has not significantly improved over time. Equipoise remains and supports the ongoing ethical and scientific requirement for phase III randomized controlled trials to estimate treatment efficacy and assess the value of potential biomarkers.

Overcoming Resistance to Cetuximab with Honokiol, A Small-Molecule Polyphenol

Overexpression and activation of the EGFR have been linked to poor prognosis in several human cancers. Cetuximab is a mAb against EGFR that is used for the treatment in head and neck squamous cell carcinoma (HNSCC) and metastatic colorectal cancer. Unfortunately, most tumors have intrinsic or will acquire resistance to cetuximab during the course of therapy. Honokiol is a natural compound found in the bark and leaves of the Chinese Magnolia tree and is established to have several anticancer properties without appreciable toxicity. In this study, we hypothesized that combining cetuximab and honokiol treatments could overcome acquired resistance to cetuximab. We previously developed a model of acquired resistance to cetuximab in non-small cell lung cancer H226 cell line. Treatment of cetuximab-resistant clones with honokiol and cetuximab resulted in a robust antiproliferative response. Immunoblot analysis revealed the HER family and their signaling pathways were downregulated after combination treatment, most notably the proliferation (MAPK) and survival (AKT) pathways. In addition, we found a decrease in phosphorylation of DRP1 and reactive oxygen species after combination treatment in cetuximab-resistant clones, which may signify a change in mitochondrial function. Furthermore, we utilized cetuximab-resistant HNSCC patient-derived xenografts (PDX) to test the benefit of combinatorial treatment in vivo There was significant growth delay in PDX tumors after combination treatment with a subsequent downregulation of active MAPK, AKT, and DRP1 signaling as seen in vitro Collectively, these data suggest that honokiol is a promising natural compound in overcoming acquired resistance to cetuximab. Mol Cancer Ther; 17(1); 204-14. ©2017 AACR.

EGFR Downregulation after Anti-EGFR Therapy Predicts the Antitumor Effect in Colorectal Cancer

Anti-EGFR mAb is reported to induce EGFR internalization in colorectal cancer cells. However, the biological relevance of EGFR internalization with anti-EGFR mAb is unknown. Therefore, the relevance of EGFR downregulation with anti-EGFR mAb to antitumor activity in colorectal cancer cells was investigated. Quantification of EGFR on the cell surface before cetuximab treatment was assessed by flow cytometry, and its growth-inhibitory effects were measured by Trypan blue exclusion, in 10 RAS, BRAF wild-type colorectal cancer cell lines, but there was no significant correlation between EGFR number and its growth-inhibitory effect. However, a significant correlation existed between the percentage decrease in the number of EGFRs after cetuximab treatment and its growth-inhibitory effect in those cell lines. Treatment with TGFα, a ligand for EGFR, induced EGFR internalization in colorectal cancer cells, but most EGFRs subsequently recycled to the cell surface, consistent with previous studies. While cetuximab treatment induced EGFR internalization, most receptors subsequently translocated into the late endosome, leading to lysosomal degradation, as revealed by immunoblotting and double immunofluorescence. Cetuximab-sensitive colorectal cancer cells showed greater EGFR internalization, stronger cell growth inhibition, and more augmented apoptotic signals than nonsensitive cells. IHC for EGFR, performed using an EGFR pharmDx Kit (mouse anti-human EGFR mAb clone 2-18C9), in clinical specimens before and after anti-EGFR mAb therapy in 13 colorectal cancer patients showed a significant correlation between the response to anti-EGFR mAb and decreased staining after therapy.Implications: This report clearly demonstrates that anti-EGFR mAb facilitates internalization and subsequent degradation of EGFRs in lysosomes, which is an important determinant of the efficacy of anti-EGFR mAb treatment for colorectal cancer. Mol Cancer Res; 15(10); 1445-54. ©2017 AACR.

Targeted Therapies in the Treatment of Colorectal Cancers

Background:

In solid organ malignancies, no tumor type has seen a greater impact from the development of novel targeted therapies in 2004 than metastatic colorectal cancer.

Methods:

We review the current progress to date with the use of monoclonal antibodies in colorectal cancer and look at newer therapies under investigation.

Results:

Two monoclonal antibodies received Food and Drug Administration approval in early 2004, both for the indication of advanced, metastatic colorectal cancer. A large, randomized, placebo-controlled study demonstrated that the addition of a monoclonal antibody to vascular endothelial growth factor, bevacizumab, led to a statistically significant improvement in overall survival, with tolerable additional toxicity. Chimeric monoclonal antibody therapy directed at the epidermal growth factor receptor was associated with radiographic responses in a significant minority of patients with irinotecan-refractory colon cancer in a randomized phase II study of patients with irinotecan-refractory disease.

Conclusions:

These dramatic successes have led to further clinical studies of targeted therapy in colorectal cancer, making it one of the most promising areas of cancer research.

The Immune System's Contribution to the Clinical Efficacy of EGFR Antagonist Treatment

Epidermal Growth Factor Receptor (EGFR) antagonists were one of the first anti-cancer treatments developed targeting a Receptor Tyrosine Kinase. However, the underlying mode of action of how EGFR antagonist application can explain its clinical efficacy in different types of cancers remains largely unresolved. Numerous findings have suggested that a substantial portion of the effects attributed to EGFR antagonist treatment might not be based on direct influence on the tumor itself. Instead it may be based on indirect effects, potentially mediated via the immune system. In this review the role of the EGFR for the functioning of the immune system is discussed, alongside how EGFR antagonist treatment could be impacting tumor growth by blocking macrophage and FoxP3-expressing regulatory CD4+ T cell function. Based on these findings, we consider implications for current treatment schemes and suggest novel approaches to improve the efficacy of EGFR antagonist treatment in the future. Finally, we propose potential ways to improve EGFR antagonists, in order to enhance their clinical efficacy whilst diminishing unwanted side effects.

Challenges and future of biomarker tests in the era of precision oncology: Can we rely on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) to select the optimal patients for matched therapy?

Molecular techniques have improved our understanding of the pathogenesis of cancer development. These techniques have also fueled the rational development of targeted drugs for patient populations stratified by their genetic characteristics. These novel methods have changed the classic paradigm of diagnostic pathology; among them are IHC, FISH, polymerase chain reaction (PCR) and microarray technology. IHC and FISH detection methods for human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR) and programmed death ligand-1 (PD-L1) were recently approved by the Food and Drug Administration (FDA) as routine clinical practice for cancer patients. Here, we discuss general challenges related to the predictive power of these molecular biomarkers for targeted therapy in cancer medicine. We will also discuss the prospects of utilizing new biomarkers for fibroblast growth factor receptor (FGFR) and hepatocyte growth factor receptor (cMET/MET) targeted therapies for developing new and robust predictive biomarkers in oncology.

ATM mutations and E-cadherin expression define sensitivity to EGFR-targeted therapy in colorectal cancer

EGFR-targeted therapy is a key treatment approach in patients with RAS wildtype metastatic colorectal cancers (CRC). Still, also RAS wildtype CRC may be resistant to EGFR-targeted therapy, with few predictive markers available for improved stratification of patients. Here, we investigated response of 7 CRC cell lines (Caco-2, DLD1, HCT116, HT29, LS174T, RKO, SW480) to Cetuximab and correlated this to NGS-based mutation profiles, EGFR promoter methylation and EGFR expression status as well as to E-cadherin expression. Moreover, tissue specimens of primary and/or recurrent tumors as well as liver and/or lung metastases of 25 CRC patients having received Cetuximab and/or Panitumumab were examined for the same molecular markers. In vitro and in situ analyses showed that EGFR promoter methylation and EGFR expression as well as the MSI and or CIMP-type status did not guide treatment responses. In fact, EGFR-targeted treatment responses were also observed in RAS exon 2 p.G13 mutated CRC cell lines or CRC cases and were further linked to PIK3CA exon 9 mutations. In contrast, non-response to EGFR-targeted treatment was associated with ATM mutations and low E-cadherin expression. Moreover, down-regulation of E-cadherin by siRNA in otherwise Cetuximab responding E-cadherin positive cells abrogated their response. Hence, we here identify ATM and E-cadherin expression as potential novel supportive predictive markers for EGFR-targeted therapy.

Preclinical efficacy of Sym004, novel anti-EGFR antibody mixture, in esophageal squamous cell carcinoma cell lines

Epidermal growth factor receptor (EGFR) is a well-validated oncological target molecule for monoclonal antibody therapies and Sym004 is a novel anti-EGFR antibody mixture comprising two recombinant chimeric IgG1 antibodies against non-overlapping epitopes of EGFR. Because EGFR is highly expressed in the majority of esophageal squamous cell carcinomas (ESCCs), we investigated the efficacy of Sym004 in human ESCC cell lines. Forty eight ESCC cell lines were treated with three kinds of anti-EGFR antibodies (Sym004, cetuximab, and panitumumab). Genetic background was investigated by next generation sequencing. The internalization of anti-EGFR antibodies into ESCC cells and inhibition of the EGFR signaling cascade by anti-EGFR antibodies were investigated in vitro. Furthermore, growth inhibition by anti-EGFR antibody treatment was investigated in vitro and in vivo. Sym004 treatments were more effective at inducing EGFR internalization and degradation than the two other anti-EGFR antibodies. Sym004 was more sensitive significantly to cell lines with EGFR gene amplification than those without amplification (P = 0.002). Growth inhibition of Sym004 was greater than in that of cetuximab or panitumumab in vitro and in vivo. These studies showed that Sym004 exhibited antitumor activity in some ESCC cell lines in preclinical settings and warrant a clinical evaluation in patients with ESCC. EGFR amplification is a potential biomarker of response to Sym004.

Epidermal growth factor receptor (EGFR) inhibitors for metastatic colorectal cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) inhibitors prevent cell growth and have shown benefit in the treatment of metastatic colorectal cancer, whether used as single agents or in combination with chemotherapy. Clear benefit has been shown in trials of EGFR monoclonal antibodies (EGFR MAb) but not EGFR tyrosine kinase inhibitors (EGFR TKI). However, there is ongoing debate as to which patient populations gain maximum benefit from EGFR inhibition and where they should be used in the metastatic colorectal cancer treatment paradigm to maximise efficacy and minimise toxicity.

OBJECTIVES

To determine the efficacy, safety profile, and potential harms of EGFR inhibitors in the treatment of people with metastatic colorectal cancer when given alone, in combination with chemotherapy, or with other biological agents.The primary outcome of interest was progression-free survival; secondary outcomes included overall survival, tumour response rate, quality of life, and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library, Issue 9, 2016; Ovid MEDLINE (from 1950); and Ovid Embase (from 1974) on 9 September 2016; and ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) on 14 March 2017. We also searched proceedings from the major oncology conferences ESMO, ASCO, and ASCO GI from 2012 to December 2016. We further scanned reference lists from eligible publications and contacted corresponding authors for trials for further information where needed.

SELECTION CRITERIA

We included randomised controlled trials on participants with metastatic colorectal cancer comparing: 1) the combination of EGFR MAb and 'standard therapy' (whether chemotherapy or best supportive care) to standard therapy alone, 2) the combination of EGFR TKI and standard therapy to standard therapy alone, 3) the combination of EGFR inhibitor (whether MAb or TKI) and standard therapy to another EGFR inhibitor (or the same inhibitor with a different dosing regimen) and standard therapy, or 4) the combination of EGFR inhibitor (whether MAb or TKI), anti-angiogenic therapy, and standard therapy to anti-angiogenic therapy and standard therapy alone.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures defined by Cochrane. Summary statistics for the endpoints used hazard ratios (HR) with 95% confidence intervals (CI) for overall survival and progression-free survival, and odds ratios (OR) for response rate (RR) and toxicity. Subgroup analyses were performed by Kirsten rat sarcoma viral oncogene homolog (KRAS) and neuroblastoma RAS viral (V-Ras) oncogene homolog (NRAS) status - firstly by status of KRAS exon 2 testing (mutant or wild type) and also by status of extended KRAS/NRAS testing (any mutation present or wild type).

MAIN RESULTS

We identified 33 randomised controlled trials for analysis (15,025 participants), including trials of both EGFR MAb and EGFR TKI. Looking across studies, significant risk of bias was present, particularly with regard to the risk of selection bias (15/33 unclear risk, 1/33 high risk), performance bias (9/33 unclear risk, 9/33 high risk), and detection bias (7/33 unclear risk, 11/33 high risk).The addition of EGFR MAb to standard therapy in the KRAS exon 2 wild-type population improves progression-free survival (HR 0.70, 95% CI 0.60 to 0.82; high-quality evidence), overall survival (HR 0.88, 95% CI 0.80 to 0.98; high-quality evidence), and response rate (OR 2.41, 95% CI 1.70 to 3.41; high-quality evidence). We noted evidence of significant statistical heterogeneity in all three of these analyses (progression-free survival: I² = 76%; overall survival: I² = 40%; and response rate: I² = 77%), likely due to pooling of studies investigating EGFR MAb use in different lines of therapy. Rates of overall grade 3 to 4 toxicity, diarrhoea, and rash were increased (moderate-quality evidence for all three outcomes), but there was no evidence for increased rates of neutropenia.For the extended RAS wild-type population (no mutations in KRAS or NRAS), addition of EGFR MAb improved progression-free survival (HR 0.60, 95% CI 0.48 to 0.75; moderate-quality evidence) and overall survival (HR 0.77, 95% CI 0.67 to 0.88; high-quality evidence). Response rate was also improved (OR 4.28, 95% CI 2.61 to 7.03; moderate-quality evidence). We noted significant statistical heterogeneity in the progression-free survival analysis (I² = 61%), likely due to the pooling of studies combining EGFR MAb with chemotherapy with monotherapy studies.We observed no evidence of a statistically significant difference when EGFR MAb was compared to bevacizumab, in progression-free survival (HR 1.02, 95% CI 0.93 to 1.12; high quality evidence) or overall survival (HR 0.84, 95% CI 0.70 to 1.01; moderate-quality evidence). We noted significant statistical heterogeneity in the overall survival analysis (I² = 51%), likely due to the pooling of first-line and second-line studies.The addition of EGFR TKI to standard therapy in molecularly unselected participants did not show benefit in limited data sets (meta-analysis not performed). The addition of EGFR MAb to bevacizumab plus chemotherapy in people with KRAS exon 2 wild-type metastatic colorectal cancer did not improve progression-free survival (HR 1.04, 95% CI 0.83 to 1.29; very low quality evidence), overall survival (HR 1.00, 95% CI 0.69 to 1.47; low-quality evidence), or response rate (OR 1.20, 95% CI 0.67 to 2.12; very low-quality evidence) but increased toxicity (OR 2.57, 95% CI 1.45 to 4.57; low-quality evidence). We noted significant between-study heterogeneity in most analyses.Scant information on quality of life was reported in the identified studies.

AUTHORS' CONCLUSIONS

The addition of EGFR MAb to either chemotherapy or best supportive care improves progression-free survival (moderate- to high-quality evidence), overall survival (high-quality evidence), and tumour response rate (moderate- to high-quality evidence), but may increase toxicity in people with KRAS exon 2 wild-type or extended RAS wild-type metastatic colorectal cancer (moderate-quality evidence). The addition of EGFR TKI to standard therapy does not improve clinical outcomes. EGFR MAb combined with bevacizumab is of no clinical value (very low-quality evidence). Future studies should focus on optimal sequencing and predictive biomarkers and collect quality of life data.

Epidermal growth factor receptor (EGFR) inhibitors for metastatic colorectal cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) inhibitors prevent cell growth and have shown benefit in the treatment of metastatic colorectal cancer, whether used as single agents or in combination with chemotherapy. Clear benefit has been shown in trials of EGFR monoclonal antibodies (EGFR MAb) but not EGFR tyrosine kinase inhibitors (EGFR TKI). However, there is ongoing debate as to which patient populations gain maximum benefit from EGFR inhibition and where they should be used in the metastatic colorectal cancer treatment paradigm to maximise efficacy and minimise toxicity.

OBJECTIVES

To determine the efficacy, safety profile, and potential harms of EGFR inhibitors in the treatment of people with metastatic colorectal cancer when given alone, in combination with chemotherapy, or with other biological agents.The primary outcome of interest was progression-free survival; secondary outcomes included overall survival, tumour response rate, quality of life, and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library, Issue 9, 2016; Ovid MEDLINE (from 1950); and Ovid Embase (from 1974) on 9 September 2016; and ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) on 14 March 2017. We also searched proceedings from the major oncology conferences ESMO, ASCO, and ASCO GI from 2012 to December 2016. We further scanned reference lists from eligible publications and contacted corresponding authors for trials for further information where needed.

SELECTION CRITERIA

We included randomised controlled trials on participants with metastatic colorectal cancer comparing: 1) the combination of EGFR MAb and 'standard therapy' (whether chemotherapy or best supportive care) to standard therapy alone, 2) the combination of EGFR TKI and standard therapy to standard therapy alone, 3) the combination of EGFR inhibitor (whether MAb or TKI) and standard therapy to another EGFR inhibitor (or the same inhibitor with a different dosing regimen) and standard therapy, or 4) the combination of EGFR inhibitor (whether MAb or TKI), anti-angiogenic therapy, and standard therapy to anti-angiogenic therapy and standard therapy alone.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures defined by Cochrane. Summary statistics for the endpoints used hazard ratios (HR) with 95% confidence intervals (CI) for overall survival and progression-free survival, and odds ratios (OR) for response rate (RR) and toxicity. Subgroup analyses were performed by Kirsten rat sarcoma viral oncogene homolog (KRAS) and neuroblastoma RAS viral (V-Ras) oncogene homolog (NRAS) status - firstly by status of KRAS exon 2 testing (mutant or wild type) and also by status of extended KRAS/NRAS testing (any mutation present or wild type).

MAIN RESULTS

We identified 33 randomised controlled trials for analysis (15,025 participants), including trials of both EGFR MAb and EGFR TKI. Looking across studies, significant risk of bias was present, particularly with regard to the risk of selection bias (15/33 unclear risk, 1/33 high risk), performance bias (9/33 unclear risk, 9/33 high risk), and detection bias (7/33 unclear risk, 11/33 high risk).The addition of EGFR MAb to standard therapy in the KRAS exon 2 wild-type population improves progression-free survival (HR 0.70, 95% CI 0.60 to 0.82; high-quality evidence), overall survival (HR 0.88, 95% CI 0.80 to 0.98; high-quality evidence), and response rate (OR 2.41, 95% CI 1.70 to 3.41; high-quality evidence). We noted evidence of significant statistical heterogeneity in all three of these analyses (progression-free survival: I2 = 76%; overall survival: I2 = 40%; and response rate: I2 = 77%), likely due to pooling of studies investigating EGFR MAb use in different lines of therapy. Rates of overall grade 3 to 4 toxicity, diarrhoea, and rash were increased (moderate-quality evidence for all three outcomes), but there was no evidence for increased rates of neutropenia.For the extended RAS wild-type population (no mutations in KRAS or NRAS), addition of EGFR MAb improved progression-free survival (HR 0.60, 95% CI 0.48 to 0.75; moderate-quality evidence) and overall survival (HR 0.77, 95% CI 0.67 to 0.88; high-quality evidence). Response rate was also improved (OR 4.28, 95% CI 2.61 to 7.03; moderate-quality evidence). We noted significant statistical heterogeneity in the progression-free survival analysis (I2 = 61%), likely due to the pooling of studies combining EGFR MAb with chemotherapy with monotherapy studies.We observed no evidence of a statistically significant difference when EGFR MAb was compared to bevacizumab, in progression-free survival (HR 1.02, 95% CI 0.93 to 1.12; high quality evidence) or overall survival (HR 0.84, 95% CI 0.70 to 1.01; moderate-quality evidence). We noted significant statistical heterogeneity in the overall survival analysis (I2 = 51%), likely due to the pooling of first-line and second-line studies.The addition of EGFR TKI to standard therapy in molecularly unselected participants did not show benefit in limited data sets (meta-analysis not performed). The addition of EGFR MAb to bevacizumab plus chemotherapy in people with KRAS exon 2 wild-type metastatic colorectal cancer did not improve progression-free survival (HR 1.04, 95% CI 0.83 to 1.29; very low quality evidence), overall survival (HR 1.00, 95% CI 0.69 to 1.47; low-quality evidence), or response rate (OR 1.20, 95% CI 0.67 to 2.12; very low-quality evidence) but increased toxicity (OR 2.57, 95% CI 1.45 to 4.57; low-quality evidence). We noted significant between-study heterogeneity in most analyses.Scant information on quality of life was reported in the identified studies.

AUTHORS' CONCLUSIONS

The addition of EGFR MAb to either chemotherapy or best supportive care improves progression-free survival (moderate- to high-quality evidence), overall survival (high-quality evidence), and tumour response rate (moderate- to high-quality evidence), but may increase toxicity in people with KRAS exon 2 wild-type or extended RAS wild-type metastatic colorectal cancer (moderate-quality evidence). The addition of EGFR TKI to standard therapy does not improve clinical outcomes. EGFR MAb combined with bevacizumab is of no clinical value (very low-quality evidence). Future studies should focus on optimal sequencing and predictive biomarkers and collect quality of life data.

Mutations of the Epidermal Growth Factor Receptor Gene in Triple-Negative Breast Cancer

Purpose

Epidermal growth factor receptor (EGFR) is considered a potential therapeutic target for anti-EGFR therapy in triple-negative breast cancer (TNBC). However, the frequency of EGFR gene mutation in TNBC is low and varies with ethnicity. This study aimed to investigate the incidence of EGFR gene mutation in TNBC.

Methods

EGFR protein expression was evaluated by immunohistochemistry in tissue microarrays of 493 TNBC cases using four different primary antibodies, which included mutation-specific antibodies. For cases with an immunoreactivity level ≥1+, we performed pyrosequencing analysis for EGFR gene mutation. A case was considered mutation-positive when its mutation frequency minus its limit of detection (LOD) was >10%. Cases with mutation frequency higher than LOD were assessed for EGFR gene mutation status using the Cobas assay and by peptide nucleic acid-mediated polymerase chain reaction (PNA-clamping).

Results

Among 493 TNBCs, 148 (30.0%) exhibited staining ≥1+ for EGFR, including 78 with 1+, 49 with 2+, and 21 with 3+. Positive EGFR expression (≥2+) was significantly associated with lymphovascular invasion (p=0.010), but not with overall survival (p=0.444) or disease-free survival (p=0.388). None of the 493 TNBCs harbored an EGFR gene mutation. Among 148 cases with an EGFR staining result ≥1+, five (3.4%) showed mutation frequencies (4.4%–10.9%) higher than LOD (2.6%–4.3%) in exons 19 (L747_P753>Q) or 21 (L858R and L861Q) as determined by pyrosequencing. However, Cobas and PNA-clamping failed to detect the presence of EGFR gene mutation in these five cases.

Conclusion

No activating mutation of EGFR gene of clinical significance was observed in 148 TNBC cases using three commercially available methods. Thus, EGFR gene mutation appears to be an extremely rare event in patients with TNBC.

Effect of First-Line Chemotherapy Combined With Cetuximab or Bevacizumab on Overall Survival in Patients With KRAS Wild-Type Advanced or Metastatic Colorectal Cancer: A Randomized Clinical Trial

IMPORTANCE

Combining biologic monoclonal antibodies with chemotherapeutic cytotoxic drugs provides clinical benefit to patients with advanced or metastatic colorectal cancer, but the optimal choice of the initial biologic therapy in previously untreated patients is unknown.

OBJECTIVE

To determine if the addition of cetuximab vs bevacizumab to the combination of leucovorin, fluorouracil, and oxaliplatin (mFOLFOX6) regimen or the combination of leucovorin, fluorouracil, and irinotecan (FOLFIRI) regimen is superior as first-line therapy in advanced or metastatic KRAS wild-type (wt) colorectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

Patients (≥18 years) enrolled at community and academic centers throughout the National Clinical Trials Network in the United States and Canada (November 2005-March 2012) with previously untreated advanced or metastatic colorectal cancer whose tumors were KRAS wt chose to take either the mFOLFOX6 regimen or the FOLFIRI regimen as chemotherapy and were randomized to receive either cetuximab (n = 578) or bevacizumab (n = 559). The last date of follow-up was December 15, 2015.

INTERVENTIONS

Cetuximab vs bevacizumab combined with either mFOLFOX6 or FOLFIRI chemotherapy regimen chosen by the treating physician and patient.

MAIN OUTCOMES AND MEASURES

The primary end point was overall survival. Secondary objectives included progression-free survival and overall response rate, site-reported confirmed or unconfirmed complete or partial response.

RESULTS

Among 1137 patients (median age, 59 years; 440 [39%] women), 1074 (94%) of patients met eligibility criteria. As of December 15, 2015, median follow-up for 263 surviving patients was 47.4 months (range, 0-110.7 months), and 82% of patients (938 of 1137) experienced disease progression. The median overall survival was 30.0 months in the cetuximab-chemotherapy group and 29.0 months in the bevacizumab-chemotherapy group with a stratified hazard ratio (HR) of 0.88 (95% CI, 0.77-1.01; P = .08). The median progression-free survival was 10.5 months in the cetuximab-chemotherapy group and 10.6 months in the bevacizumab-chemotherapy group with a stratified HR of 0.95 (95% CI, 0.84-1.08; P = .45). Response rates were not significantly different, 59.6% vs 55.2% for cetuximab and bevacizumab, respectively (difference, 4.4%, 95% CI, 1.0%-9.0%, P = .13).

CONCLUSIONS AND RELEVANCE

Among patients with KRAS wt untreated advanced or metastatic colorectal cancer, there was no significant difference in overall survival between the addition of cetuximab vs bevacizumab to chemotherapy as initial biologic treatment.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT00265850.

Epidermal Growth Factor Receptor Cell Proliferation Signaling Pathways

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.

Epidermal Growth Factor Receptor Cell Proliferation Signaling Pathways

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.

In vivo and ex vivo cetuximab sensitivity assay using three-dimensional primary culture system to stratify KRAS mutant colorectal cancer

In clinic, cetuximab, an anti-EGFR antibody, improves treatment outcomes in colorectal cancer (CRC). KRAS-mutant CRC is generally resistant to cetuximab, although difference of the sensitivity among KRAS-mutants has not been studied in detail. We previously developed the cancer tissue-originated spheroid (CTOS) method, a primary culture method for cancer cells. We applied CTOS method to investigate whether ex vivo cetuximab sensitivity assays reflect the difference in sensitivity in the xenografts. Firstly, in vivo cetuximab treatment was performed with xenografts derived from 10 CTOS lines (3 KRAS-wildtype and 7 KRAS mutants). All two CTOS lines which exhibited tumor regression were KRAS-wildtype, meanwhile all KRAS-mutant CTOS lines grew more than the initial size: were resistant to cetuximab according to the clinical evaluation criteria, although the sensitivity was quite diverse. We divided KRAS-mutants into two groups; partially responsive group in which cetuximab had a substantial growth inhibitory effect, and resistant group which exhibited no effect. The ex vivo signaling assay with EGF stimulation revealed that the partially responsive group, but not the resistant group, exhibited suppressed ERK phosphorylation ex vivo. Furthermore, two lines from the partially responsive group, but none of the lines in the resistant group, exhibited a combinatory effect of cetuximab and trametinib, a MEK inhibitor, ex vivo and in vivo. Taken together, the results indicate that ex vivo signaling assay reflects the difference in sensitivity in vivo and stratifies KRAS mutant CTOS lines by sensitivity. Therefore, coupling the in vivo and ex vivo assays with CTOS can be a useful platform for understanding the mechanism of diversity in drug sensitivity.

Serum and tissue markers in colorectal cancer: State of art

Colorectal cancer (CRC) represents one of the most commonly diagnosed cancers worldwide. It is the second leading cause of cancer death in Western Countries. In the last decade, the survival of patients with metastatic CRC has improved dramatically. Due to the advent of new drugs (irinotecan and oxaliplatin) and target therapies (i.e. bevacizumab, cetuximab, panitumab, aflibercept and regorafenib), the median overall survival has risen from about 12 mo in the mid nineties to 30 mo recently. Molecular studies have recently widened the opportunity for testing new possible markers, but actually, only few markers can be recommended for practical use in clinic. In the next future, the hope is to have a complete panel of clinical biomarkers to use in every setting of CRC disease, and at the same time: 1) to receive information about prognostic significance by their expression and 2) to be oriented in the choice of the adequate treatment. Moreover, molecular analyses have shown that the natural history of all CRCs is not the same. Individual patients with same stage tumors may have different long-term prognosis and response to therapy. In addition, some prognostic variables are likely to be more important than others. Here we review the role of serum and tissue markers according to the recently published English literature. This paper is an extension of the article "Biological and clinical markers in colorectal cancer: state of art" by Cappellani A published in Jan 2010.

Biomarker in Colorectal Cancer

In the last 20 years, improvements in metastatic colorectal cancer treatment lead to a radical raise of outcomes with median survival reaching now more than 30 months. Despite that, the identification of predictive and/or prognostic biomarker still represents a challenging issue, and until today, although clinician and researchers might face with a deeper knowledge of biological mechanisms related to colorectal cancer, many pieces of evidence underline the heterogeneity and the dynamism of such disease. In the present review, we describe the road leading to the discovery of RAS mutations, BRAF V600E mutation, and microsatellite instability role in colorectal cancer; second, we discuss some of the possible major pitfalls of biomarker research, and lastly, we give new suggestions for future research in this field.

Plasticity of Resistance and Sensitivity to Anti-Epidermal Growth Factor Receptor Inhibitors in Metastatic Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent cancers and the second leading cause of cancer mortality worldwide. Survival in the metastatic setting has been gradually improved by the addition to cytotoxic chemotherapy of agents targeting the vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR). Considerable heterogeneity exists within CRC due to the varied genetic and epigenetic mechanisms involved in differing pathways of carcinogenesis. The knowledge of molecular abnormalities underlying colorectal tumourigenesis and the progression of dysplastic precursors to invasive and ultimately metastatic lesions has advanced in recent years by comprehensive sequencing studies. From these genome-scale analyses, we know that a handful of genes are commonly affected by somatic mutations, whereas recurrent copy-number alterations and chromosomal translocations are rarer in this disease. Even though some of these molecular abnormalities make genes acting as drivers of cancer progression, translation of this recognition for therapeutic purposes is still limited, encompassing only as standard of care the exclusion of RAS-mutated cancers for better selecting patients to candidate to EGFR-targeted therapy with monoclonal antibodies. However, the effort of ameliorating molecular selection should not be considered exhausted by demonstration of RAS and BRAF-induced resistance, as the genomic landscape of response to EGFR blockade has been demonstrated to be wider and dynamically multifaceted. In this chapter we will review main molecular biomarkers of de novo (primary) and acquired (secondary) resistance to EGFR-targeted monoclonal antibodies in metastatic CRC and discuss therapeutic implications.

EGFR Gene Amplification and KRAS Mutation Predict Response to Combination Targeted Therapy in Metastatic Colorectal Cancer

Genetic variability in KRAS and EGFR predicts response to cetuximab in irinotecan refractory colorectal cancer. Whether these markers or others remain predictive in combination biologic therapies including bevacizumab is unknown. We identified predictive biomarkers from patients with irinotecan refractory metastatic colorectal cancer treated with cetuximab plus bevacizumab. Patients who received cetuximab plus bevacizumab for irinotecan refractory colorectal cancer in either of two Phase II trials conducted were identified. Tumor tissue was available for 33 patients. Genomic DNA was extracted and used for mutational analysis of KRAS, BRAF, and p53 genes. Fluorescence in situ hybridization was performed to assess EGFR copy number. The status of single genes and various combinations were tested for association with response. Seven of 33 patients responded to treatment. KRAS mutations were found in 14/33 cases, and 0 responded to treatment (p = 0.01). EGFR gene amplification was seen in 3/33 of tumors and in every case was associated with response to treatment (p < 0.001). TP53 and BRAF mutations were found in 18/33 and 0/33 tumors, respectively, and there were no associations with response to either gene. EGFR gene amplification and KRAS mutations are predictive markers for patients receiving combination biologic therapy of cetuximab plus bevacizumab for metastatic colorectal cancer. One marker or the other is present in the tumor of half of all patients allowing treatment response to be predicted with a high degree of certainty. The role for molecular markers in combination biologic therapy seems promising.

KRAS Mutation as a Potential Prognostic Biomarker of Biliary Tract Cancers

BACKGROUND

The aim of this study was to identify the unique molecular characteristics of biliary tract cancer (BTC) for the development of novel molecular-targeted therapies.

MATERIALS AND METHODS

We performed mutational analysis of KRAS, BRAF, PIK3CA, and FBXW7 and immunohistochemical analysis of EGFR and TP53 in 63 Japanese patients with BTC and retrospectively evaluated the association between the molecular characteristics and clinicopathological features of BTC.

RESULTS

KRAS mutations were identified in 9 (14%) of the 63 BTC patients; no mutations were detected within the analyzed regions of BRAF, PIK3CA, and FBXW7. EGFR overexpression was observed in 5 (8%) of the 63 tumors, while TP53 overexpression was observed in 48% (30/63) of the patients. Overall survival of patients with KRAS mutation was significantly shorter than that of patients with the wild-type KRAS gene (P = 0.005). By multivariate analysis incorporating molecular and clinicopathological features, KRAS mutations and lymph node metastasis were identified to be independently associated with shorter overall survival (KRAS, P = 0.004; lymph node metastasis, P = 0.015).

CONCLUSIONS

Our data suggest that KRAS mutation is a poor prognosis predictive biomarker for the survival in BTC patients.

Current Status of Cetuximab for the Treatment of Patients with Solid Tumors

Objective:

To review the pharmacology, pharmacokinetics, clinical evidence, and safety, as well as the potential directions for use, of the epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab.

Data Sources:

A MEDLINE search (1966–December 2005) was conducted using the following terms: cetuximab, Erbitux, C225, epidermal growth factor receptor, and EGFR. Additional information was obtained via meeting abstracts, bibliographies from relevant articles, national guidelines, and the manufacturer.

Study Selection and Data Extraction:

Preclinical and clinical trials utilizing cetuximab in the treatment of solid tumors were selected from the data sources. All published, randomized clinical trials involving cetuximab in treatment of metastatic colorectal cancer and studies providing a description of the pharmacology, pharmacokinetics, safety, or efficacy were included in this review.

Data Synthesis:

Many solid tumors overexpress EGFR, making it an ideal target for anticancer agents. Cetuximab is the only EGFR monoclonal antibody commercially available and is approved for the treatment of EGFR-expressing, metastatic colorectal cancer in patients refractory or intolerant to irinotecan. Data on patients with other solid tumors are encouraging with cetuximab used as monotherapy or in combination with chemotherapy, radiation, or other targeted agents. Common adverse effects include dermatologic and hypersensitivity reactions.

Conclusions:

Further clinical data are necessary to clearly define the role of cetuximab in the treatment of patients with solid malignancies, with emphasis on survival and quality-of-life benefits relative to its cost.