Molecular determinants of irinotecan efficacy

Molecular markers predicting the efficacy of CPT-11 based chemotherapies in patients with colorectal cancer (CRC) are unknown. Therefore, we investigated whether mRNA levels of drug targets (Topoisomerase I, TS), enzymes involved in 5-FU metabolism (DPD), in angiogenesis (EGFR, IL-8, VEGF) and in DNA-repair/drug detoxification (ERCC1, GST-P1) are associated with the clinical outcome of patients with CRC treated with first-line CPT-11 based chemotherapy. Thirty three patients with metastatic CRC were included in the study. Intratumoral gene expression levels were assessed from paraffin-embedded tissue samples, using laser capture microdissection and quantitative Real-Time PCR. Complete response was observed in 1 patient, partial response in 12 patients, stable disease in 13 patients and progressive disease in 6 patients. Response was inevaluable for 1 patient. Patients with complete response or partial response were classified as responders, while patients with stable disease or progressive disease were classified as nonresponders. High intratumoral mRNA levels of EGFR, ERCC1 and GSPT-P1 were each significantly associated with response to CPT-11 based chemotherapy. Recursive partitioning analysis showed that mRNA levels of EGFR and ERCC1 are primarily responsible for delineating responders from nonresponders. Also, the combination of high intratumoral gene expression levels of both EGFR and ERCC1 was significantly associated with progression-free survival. The mRNA levels of EGFR had a significant correlation with expression levels of ERCC1, GST-P1 and VEGF. This small retrospective study suggests that gene expression levels of EGFR, ERCC1 and GST-P1 may be useful in predicting the clinical outcome of patients with metastatic CRC treated with first-line CPT-11 based chemotherapy.     

Impact of EGFR and EGFR ligand expression on treatment response in patients with metastatic colorectal cancer

Up to 50% of patients with colorectal cancer (CRC) have either synchronous or metachronous hepatic metastases in the course of their disease. Patients with metastatic CRC (mCRC) whose tumors express wild-type KRAS benefit from treatment with monoclonal antibodies (such as cetuximab or panitumumab) that target the epidermal growth factor receptor (EGFR). However, the therapeutic response to these antibodies is variable, and further predictive models are required. The present study examined whether expression of different EGFRs or their ligands in tumors was associated with the response to cetuximab treatment. Tumor tissues, collected during liver resection in 28 patients with mCRC, were analyzed. The protein expression levels of EGFR/ErbB1, ErbB2, ErbB3 and the EGFR ligands heregulin and amphiregulin were determined using Luminex 200^® and enzyme-linked immunosorbent assays. Computed tomography or magnetic resonance imaging was performed 4 weeks before and 6–8 weeks after treatment with cetuximab. Response to treatment was assessed using the response evaluation criteria for solid tumors (RECIST). The association between the protein expression levels of different EGFRs and their ligands with RECIST criteria was then analyzed to determine whether these protein levels could predict the treatment response to cetuximab. A total of 12 patients exhibited a partial response, 9 exhibited stable disease and 7 exhibited progressive disease after cetuximab therapy according to RECIST. The expression levels of EGFRs (EGFR/ErbB1, ErbB2 and ErbB3) and their ligands (heregulin and amphiregulin) were not significantly associated with the response to cetuximab therapy. Therefore, the present study indicated that EGFR or EGFR ligand expression did not predict treatment response in patients with CRC with liver metastases following cetuximab therapy.     

Association between the serum concentrations and mutational status of IL-8, IL-27 and VEGF and the expression levels of the hERG potassium channel gene in patients with colorectal cancer

The present study aimed to determine the diagnostic value of the serum levels and mutational status of IL-8, IL-27 and VEGF, and the expression levels of human ether-a-go-go-related gene (hERG) in patients with colorectal cancer (CRC). The serum concentrations were determined using the ELISA technique and genotype variations of IL-8, IL-27 and VEGF were examined using Sanger sequencing, and the expression levels of hERG, which encodes a potassium channel, were determined by quantitative PCR, in blood and tissue samples obtained from 80 patients with CRC and 80 healthy individuals. The results of the present study revealed that the percentage of granulocytes and serum concentrations of carcinoembryonic antigen, IL-8 and IL-27 were significantly increased, whereas the percentage of lymphocytes was decreased in patients with CRC. In total, 31 mutations in three genes (eight mutations in VEGF, 13 mutations in IL-27 and 10 mutations in IL-8) were identified in patients with CRC. The relative mRNA expression levels of hERG were also significantly upregulated in tissue and blood samples of patients with CRC compared with those of healthy individuals. In conclusion, the results of the present study indicated that the increased concentrations and genetic variations of IL-8, IL-27 and VEGF may serve important roles in the development and angiogenic processes of CRC. These changes were concomitant with the upregulation of the expression levels of the potassium channel hERG.     

A gene expression predictor of response to EGFR-targeted therapy stratifies progression-free survival to cetuximab in KRAS wild-type metastatic colorectal cancer

Background  

The anti-EGFR monoclonal antibody cetuximab is used in metastatic colorectal cancer (CRC), and predicting responsive patients garners great interest, due to the high cost of therapy. Mutations in the KRAS gene occur in ~40% of CRC and are a negative predictor of response to cetuximab. However, many KRAS-wildtype patients do not benefit from cetuximab. We previously published a gene expression predictor of sensitivity to erlotinib, an EGFR inhibitor. The purpose of this study was to determine if this predictor could identify KRAS-wildtype CRC patients who will benefit from cetuximab therapy.     

Role of tyrosine kinase inhibitors in the treatment of advanced colorectal cancer

Colorectal cancer (CRC) is a common health problem in Western countries. In advanced disease, either FOLFOX (oxaliplatin/5-fluorouracil [5-FU]/leucovorin [LV]) or FOLFIRI (irinotecan/LV/5-FU) are accepted first-line chemotherapy regimens, but median survival appears to plateau with a chemotherapy-only approach. The use of epidermal growth factor receptor (EGFR)- and vascular endothelial growth factor (VEGF)-targeting monoclonal antibodies has increased the median survival of patients with advanced CRC beyond 20 months. However, the precise role of cetuximab, panitumumab and bevacizumab in combination with different chemotherapeutic regimens is still being determined in first- and second-line settings. The activity and tolerance of the EGFR tyrosine kinase inhibitors (TKIs), gefitinib erlotinib, and EKB-569, alone or in combination with chemotherapy, have been explored in patients with metastatic CRC. Regarding VEGF receptor TKIs, 2 phase III clinical trials determined the role of vatalanib in combination with FOLFOX. Efficacy of the oral multitargeted TKIs sorafenib and sunitinib is under investigation. This article aims to review the role of TKIs in advanced CRC.     

大肠癌的靶向治疗

  阐述了贝伐单抗（BV）与西妥昔单抗（C225）治疗晚期或转移性大肠癌（CRC）的作用。分子靶向药物BV与C225能特异性阻断血管内皮生长因子（VEGF）和表皮生长因子受体（EGFR）的生物效应，临床应用治疗CRC有效且耐受良好，它与细胞毒药物不同，主要是抑制肿瘤生长，而不是缩小，与化疗联合应用可望增强疗效，延长生存期与改善生活质量。     

Can we predict the response to epidermal growth factor receptor targeted therapy?

Epidermal growth factor receptor (EGFR) targeted therapy interferes with a molecular pathway that significantly regulates tumor growth, progression, and survival. Several clinical trials on EGFR targeted therapy revealed objective responses, and also improved survival in patients with different solid tumors. However, considerable differences in therapeutic efficacy were recognized across patient populations that might rely on specific characteristics of the individual patient, the tumor dependence on the EGFR pathway or alternative signaling pathways. Therefore, molecular markers that predict responsiveness to the specific targeted therapy are essential. Predictive markers will help to identify which individual patients might benefit the most from targeted therapy, and thus will help to increase efficacy and decrease toxicities. The occurrence of an acne-like skin rash was the first clinical surrogate marker in EGFR targeted therapy significantly associated with response rate. In gastrointestinal cancer patients promising predictive molecular markers have now been identified within the EGFR signaling pathway. K-ras mutations are associated with resistance to EGFR monoclonal antibodies (mAbs) in metastatic colorectal cancer patients. Moreover, high gene expression levels of EGFR ligands amphiregulin and epiregulin are indicative for improved progression-free survival (PFS) in response to EGFR targeted therapy. Favorable response to EGFR targeted therapy has been correlated with low gene expression levels of vascular endothelial growth factor (VEGF). Furthermore, germline polymorphisms within the genes of epidermal growth factor (EGF) and EGFR, cyclooxygenase-2 (Cox-2), cyclin D1, and FCGR2A/3A are of predictive value. However, these first encouraging findings are limited mostly due to the small patient numbers evaluated in retrospective studies. Thus, large prospective clinical trials are needed to validate these data.     

DPD is a molecular determinant of capecitabine efficacy in colorectal cancer

Capecitabine is a fluoropyrimidine-based drug that offers physicians a more convenient treatment for advanced colorectal cancer (CRC), with manageable toxicity and antitumor activity comparable to that of continuous-infusion therapies with 5-fluorouracil (5-FU). However, there are no validated and established predictive factors for clinical outcome of capecitabine efficacy in CRC. The gene expressions of the pyrimidine metabolism enzymes dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP) and thymidylate synthase (TS) have previously been shown to be response determinants of fluoropyrimidine-based drugs in various tumors. Therefore, we investigated whether intratumoral mRNA expression levels of these genes are also associated with the clinical outcome of patients with metastatic CRC treated with first-line capecitabine. Thirty-seven patients with metastatic CRC were enrolled in this study and treated with single agent capecitabine. The intratumoral mRNA levels of DPD, TP and TS were assessed from paraffin-embedded tissue samples using laser-capture-microdissection methods and quantitative real-time PCR. There were 20 women and 17 men with a median age of 61 years (range 49-74). The median progression-free survival was 6.7 months (95% CI, 4.8-11.6 months), with a median follow-up of 14.4 months (range 1.3-18.7 months). Complete response was observed in 1 (3%), partial response in 6 (20%), stable disease in 14 (47%) and progressive disease in 9 (30%) patients (response was inevaluable in 7 patients). Higher gene expression levels of DPD were associated with resistance to capecitabine (P=0.032; Kruskal-Wallis test). Patients with a lower mRNA amount of DPD (相似文献   

Ras mutational status is a biomarker for resistance to EGFR inhibitors in colorectal carcinoma

The epidermal growth factor receptor (EGFR) has been validated as a therapeutic target in several human tumours, including colorectal cancer (CRC). Although EGFR expression is used for patient selection, clinical experience shows that levels of EGFR expression (measured by immunohistochemistry) do not predict clinical benefit. Ras mutations in codons 12, 13 and 61 (found in 40-45% of CRC cases) result in inhibition of GTPase activity, thus leading to the constitutive activation of the ras proteins, which may render tumour cells independent of EGFR signalling and thereby, resistant to cetuximab, panitumumab and EGFR TKIs. Data from several recently published studies, as reviewed in this article, in patients with metastatic CRC (OPUS, CRYSTAL) clearly indicated that benefit from cetuximab, when added to chemotherapy, was only restricted to patients with wild-type K-ras tumours. These results showed that K-ras mutations predict the lack of clinical benefit from cetuximab and panitumumab therapies in CRC and indicate that K-ras status should be considered when selecting CRC patients as candidates for these antibodies. Moreover, the results from these studies should also trigger retrospective analyses of K-ras mutations from all available trials in CRC (as well as non-small cell lung cancer and pancreatic cancer). These studies may enable further establishment of the correlation between K-ras mutations and resistance to cetuximab and panitumumab in CRC patients.     

Inhibition of SLC1A5 sensitizes colorectal cancer to cetuximab

Cetuximab resistance is a key barrier in treating metastatic colorectal cancer (mCRC). Targeting of metabolic resources import could resensitize drug‐resistant cancer cells to anticancer treatments. Here we showed that the expression of the glutamine transporter solute carrier 1 family member 5 (SLC1A5) in clinical CRC samples of patients resisted to cetuximab was significantly higher than in those of patients responded to cetuximab. Inhibition of SLC1A5 by shRNA‐mediated gene silencing or pharmacological inhibitor significantly suppressed the growth of CRC. Moreover, inhibition of SLC1A5 significantly enhanced the inhibitory efficacy of cetuximab on CRC proliferation both in vitro and in vivo. Mechanistically, SLC1A5 inhibition facilitated EGFR degradation through the ubiquitin‐proteasome pathway, and decreased the expression of nuclear EGFR, both of which might have contribution to the improved response to cetuximab. This study provides the metabolic molecule SLC1A5 as a potential therapeutic target to increase the efficacy of cetuximab on CRC.     

Integration of novel agents in the treatment of colorectal cancer

Two of the most promising new targets in the treatment of colorectal cancer are the epithelial growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF). Agents that inhibit the EGFR or bind to VEGF have demonstrated clinical activity as single agents and in combination with chemotherapy in phase II and phase III clinical trials. The most promising of these agents are cetuximab, which blocks the binding of EGF and transforming growth factor alpha (TGF-alpha) to EGFR, and bevacizumab, which binds free VEGF. Cetuximab and irinotecan have been evaluated in two clinical studies in the USA (IMCL CP02-0141 and IMCL CP02-9923). Study IMCL CP02-0141 evaluated the antitumor activity of single-agent cetuximab in patients with irinotecan-refractory, EGFR-positive metastatic colorectal carcinoma. There were 6 partial responses in 57 treated patients, for a response rate of 10.5%. Study IMCL CP02-9923 evaluated the combination of cetuximab and irinotecan in a total of 139 patients enrolled at 27 study sites. In this trial 22.5% of patients with progressive disease on irinotecan achieved an objective response (19% by investigator assessment) showing that the combination of cetuximab and irinotecan has antitumor activity in this population. A large randomized phase II trial evaluating similar study populations in Europe confirmed these findings, demonstrating response rates for cetuximab/irinotecan and cetuximab alone of 22.9% and 10.8%, respectively. The other promising agent bevacizumab is a humanized variant of the anti-VEGF monoclonal antibody. VEGF is produced by healthy and neoplastic cells. Its activities are mediated by two receptor tyrosine kinases. VEGF signaling is often a rate-limiting step in physiologic and pathologic angiogenesis. Bevacizumab has been studied as an antiangiogenic cancer therapeutic as a single agent and in combination with chemotherapy in patients with stage III and IV colon cancer. In addition to its direct antiangiogenic effects, bevacizumab may allow more efficient delivery of chemotherapy by altering tumor vasculature and decreasing the elevated interstitial pressure common in tumors. In this regard, some of the most robust phase II data using bevacizumab are from a randomized study of chemotherapy [fluorouracil (5-FU) and leucovorin (LV)] with or without bevacizumab in metastatic colorectal cancer. In this study, treatment with bevacizumab plus 5-FU/LV resulted in higher response rates, longer median time to disease progression, and longer median survival. Recently, a phase III, multicenter, double-blind, randomized, placebo-controlled trial was designed to investigate the addition of bevacizumab to first-line irinotecan, 5-FU, and LV chemotherapy (IFL). The trial showed a higher response rate, longer time to tumor progression, and prolonged overall survival in patients with metastatic colorectal cancer. It was the first large, randomized, phase III survival trial to assess the importance of targeting VEGF and tumor angiogenesis for the treatment of human cancer. Integration of novel agents targeting VEGF and EGFR with irinotecan-based chemotherapy has shown clinical activity in patients with metastatic colorectal cancer. The goal in the future will be to predict which specific chemotherapy and targeted agent combination will most likely benefit individual patients.     

Serum concentrations of interleukin-8, vascular endothelial growth factor, and epidermal growth factor receptor in patients with squamous cell cancer of the head and neck

Squamous cell cancer of the head and neck (SCCHN) is associated with production of pro-inflammatory and pro-angiogenic cytokines. We hypothesized that cytokine serum levels will correlate with tumor volume and aggressiveness. We investigated interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and epidermal growth factor receptor (EGFR) in SCCHN. The patient population consisted of normal and irradiated controls: patients with newly diagnosed SCCHN, and patients with recurrent or metastatic disease. Pretreatment sera were studied by ELISA. Serum IL-8 levels, as opposed to VEGF or EGFR, were consistently elevated in patients with recurrent or metastatic disease. The differences in mean serum IL-8, compared to controls, were significant (p=0.02). Serum levels of IL-8 are consistently elevated in patients with recurrent or metastatic SCCHN and elevated levels may correlate with advanced or aggressive disease. Further, more intensive, study of IL-8 as a biomarker in SCCHN is warranted.     

Predictive factors of response to anti-EGFR treatments in colorectal cancer

Among the targeted therapies used in the treatment of metastatic colorectal cancer (CRC), cetuximab was registered in France in 2004. This chimeric antibody inhibiting the Epidermal Growth receptor (EGFR) has been demonstrated to be efficient in the treatment of irinotecan-resistant metastatic CRC expressing the EGFR. Panitumumab, a fully humanized anti-EGFR antibody should soon be registered after failure of conventional chemotherapies. However, these costly and potentially toxic treatments are efficient in a little proportion of patients. It is so necessary to identify some factors able to better define whose patients will benefit from these treatments. The major potential predictive factors of response to cetuximab and/or panitumumab that have been evaluated in the literature, which are summarized in this review, are molecular factors involved more or less directly in the EGF signaling pathway. Among them, KRAS mutations, EGFR gene copy number and, more recently, epiregulin and amphiregulin expression are those, along with skin toxicity, which appear to be the most relevant and which will have to be evaluated in future clinical trials to be validated before being incorporated in therapeutic strategy of CRC.     

Targeted drugs in metastatic colorectal cancer with special emphasis on guidelines for the use of bevacizumab and cetuximab: an Acta Oncologica expert report

From having been a 'single-drug not very interesting cancer type' from a medical treatment perspective, treatment of colorectal cancer (CRC) has during the past five years become a more complex issue of the appropriate use of several cytotoxic drugs sometimes integrated with advanced metastatic surgery with curative intent. The new drugs have provided significant benefit to the patients, so far mostly in the metastatic setting but also in adjuvant treatment. The significant progress in molecular and tumour biology has produced a great number of new 'targeted' drugs that are now in various stages of clinical development. Two of these drugs, the monoclonal antibodies bevacizumab (Avastin™) and cetuximab (Erbitux™), directed against VEGF and EGFR, respectively, have recently been approved within the EU for use in metastatic CRC. This Nordic Expert Consensus Report summarizes the current status of chemotherapy in metastatic CRC, overviews the clinical status of targeted drugs in CRC and, finally, provides guidelines for the routine clinical use of bevacizumab and cetuximab based on the most recently available clinical data.     

Combined molecular targeted drug therapy for EGFR and HER-2 in head and neck squamous cell carcinoma cell lines

The epidermal growth factor receptor (EGFR) and related family member, HER-2, are often overexpressed simultaneously in patients with a variety of malignant tumors, and the combination may cooperatively promote cancer cell growth and survival. The purpose of this study was to examine antitumor effects of the combination treatment of cetuximab and trastuzumab on head and neck squamous cell carcinoma (HNSCC) using 16 HNSCC cell lines in terms of antiproliferative effect and antibody-dependent cell-mediated-cytotoxicity (ADCC). Previously we have reported the expression levels of EGFR mRNA on 16 HNSCC cell lines. All cell lines expressed mRNA for EGFR, HER-2 and HER-3; 12 cell lines expressed mRNA for HER-4; and 4 cell lines did not express mRNA for HER-4. In in vitro proliferation assay, the combination treatment of cetuximab and trastuzumab significantly lowered cell viability compared to either drug alone. The mRNA expression levels of EGFR and HER-2 were not correlated with the efficacy of the combination treatment of cetuximab and trastuzumab and the expression levels of HER-3 and HER-4 also showed no correlation with the efficacy of the combination treatment. We evaluated the gene status of HER-2 exons 23 and 24 in 16 HNSCC cell lines, but there was no mutation of HER-2 in any of the cell lines. Either drug showed ADCC in the 3 cell lines using peripheral blood mononuclear cells (PBMCs), however, a significant combination effect was not observed. Combined molecular targeted antibody drug therapy for EGFR and HER-2 may be useful in the treatment of HNSCC.     

Current status of small-molecule tyrosine kinase inhibitors targeting epidermal growth factor receptor in colorectal cancer

The epidermal growth factor receptor (EGFR) is expressed in the majority of colorectal cancers (CRCs) and is associated with poor clinical outcome. Ample evidence suggests that inhibition of this pathway by monoclonal antibodies directed against EGFR leads to antitumor activity in CRC. Small-molecule tyrosine kinase inhibitors (TKIs) provide distinct advantages over monoclonal antibodies by virtue of lower production costs, ease of oral administration, and ability to target multiple cellular survival pathways. Despite theoretical advantages, multiple early-phase trials of EGFR TKIs fail to demonstrate single-agent activity in CRC. However, the unusually high response rates observed when gefitinib, an EGFR TKI, is combined with chemotherapy for patients with metastatic CRC suggest a possible synergistic effect. This effect is not seen in non-small-cell lung cancer (NSCLC), for which larger phase III trials have been conducted. The differences between NSCLC and CRC with respect to EGFR expression and mutation status do not completely explain this dichotomy, and further investigation into the pharmacogenomics of EGFR tyrosine kinase inhibition in CRC is under way. Significant effort is directed toward newer strategies targeted at the EGFR in CRC. A new generation of small-molecule TKIs is emerging in which multiple receptor pathways, including ErbB2 and vascular endothelial growth factor receptor, can be simultaneously targeted with EGFR. These agents are still in early-phase clinical trials, and specific data for patients with CRC are forthcoming.     

Role of targeted agents in metastatic colorectal cancer

Despite a decrease in incidence and mortality, colorectal cancer (CRC) still represents the second leading cause of cancer worldwide. Recurrence following surgery and adjuvant treatment and the metastatic disease are still a major problem with a median overall survival of approximately 24 months. Nevertheless, there has been an improvement in outcome due to the introduction into clinical practice of new cytotoxic and targeted agents. The targeted agents that have improved the efficacy of the available chemotherapeutic regimens in CRC are the ones that target the vascular endothelial growth factor (VEGF) and the epidermal growth factor receptor (EGFR). In particular, bevacizumab, a recombinant humanized monoclonal antibody against VEGF, cetuximab, and panitumumab, two monoclonal antibodies that target the EGFR, have been approved for the treatment of metastatic CRC (mCRC). While for anti-EGFR agents, predictive biomarkers have been found, no good biomarkers have been found yet for anti-VEGF agents. Aflibercept and regorafenib have recently also been approved in patients with mCRC. This article reviews in an extensive way the data of large randomized clinical trials for the use of anti-VEGF and anti-EGFR in CRC. Aim of this review is also to describe the current status of biomarkers discovery and highlight how to improve the therapeutic index of these targeted agents by selecting in advance the subgroup of patients who will benefit from these treatments.