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Single-agent cetuximab is safe and active in elderly patients with advanced colorectal cancer (CRC). A cetuximab-capecitabine combination has not previously been tested in elderly patients with advanced CRC. Material and Methods. Sixty-six patients with advanced CRC were treated with cetuximab as a 400 mg/m2 i.v. infusion followed by 250 mg/m2 i.v. weekly plus capecitabine at a dose of 1,250 mg/m2 every 12 hours. After the inclusion of 27 patients, the protocol was amended for safety reasons, reducing the dose of capecitabine to 1,000 mg/m2 every 12 hours. Thirty-nine additional patients were treated with the reduced dose of capecitabine. Results. The overall response rate was 31.8%. KRAS status was determined in 58 patients (88%). Fourteen of 29 patients with wild-type KRAS tumors responded (48.3%; 95% confidence interval [CI], 29.4%-67.5%), compared with six of 29 patients with mutant KRAS tumors (20.7%; 95% CI, 8.0%-39.7%). The median progression-free survival (PFS) interval was 7.1 months. The median PFS interval for patients whose tumors were wild-type KRAS was significantly longer than for those with mutant KRAS tumors (8.4 months versus 6.0 months; p = .024). The high incidence of severe paronychia (29.6%) declined (7.7%) after capecitabine dose adjustment. Conclusions. Cetuximab plus capecitabine at a dose of 1,000 mg/m2 every 12 hours may be an alternative to more aggressive regimens in elderly patients with advanced wild-type KRAS CRC. [ABSTRACT FROM AUTHOR]

Objective: The anti-epidermal growth factor receptor monoclonal antibody cetuximab has been shown to be effective in patients with wild-type KRAS metastatic colorectal cancer (mCRC). Fragment C γ receptor (FcγR) polymorphisms may predict the effectiveness of cetuximab, but this has not been established. This study investigated the clinical relevance of FcγR gene polymorphisms and KRAS status in iri-notecan-refractory mCRC patients treated with cetuximab. Methods: The total number of irinotecan-refractory mCRC patients studied was 118. Among them, 117 and 107 patients were screened for KRAS mutations and genetic polymorphisms of FcγRIIa-131H/R and FcγRIIIa-158V/F, respectively. The association of FcγR polymorphisms and KRAS mutations with clinical outcome was analyzed. Results:KRAS mutations were found in 33 patients (27.1%). Wild-type KRAS was associated with a better response rate (p < 0.001), longer progression-free survival (p < 0.001) and longer overall survival (p < 0.001). FcγRIIa H/H, H/R and R/R polymorphisms were observed in 54, 49 and 4 patients, respectively, and FcγRIIIa V/V, V/F and F/F polymorphisms were observed in 6, 65, and 36 patients, respectively. Clinical outcomes were not significantly associated with either FcγRIIa or FcγRIIIa polymorphisms or with combinations of KRAS status and FcγR polymorphisms. Conclusion: The FcγRIIa and FcγRIIIa polymorphisms may not be useful molecular biomarkers for the activity of cetuximab in patients with mCRC. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background:Pre-clinical data indicate enhanced anti-tumour activity when combining recombinant human interleukin-21 (rIL-21), a class 1 cytokine, with cetuximab, a monoclonal antibody, targeting the epidermal growth factor receptor. This phase 1 trial assessed the safety and tolerability of escalating doses of rIL-21 in combination with cetuximab in chemo-naïve patients with stage IV colorectal cancer.Patients and methods:Sequential cohorts of PS 0-1, asymptomatic patients, were treated weekly with cetuximab 250 mg m−2 intravenously (i.v.) plus escalating i.v. doses of rIL-21 following an initial loading dose of cetuximab 400 mg m−2. Initial treatment period was 8 weeks, with extension permitted in patients without disease progression.Results:In all, 15 patients were included in this study. Adverse events related to rIL-21 or rIL-21 plus cetuximab included lethargy, nausea/vomiting, stomatitis, lymphopenia and pyrexia and were mainly  grade 2. One dose limiting toxicity occurred (grade 3 diarrhoea). Maximum tolerated dose was not determined because of the premature study closure. Maximum administered dose was 100 μg kg−1 rIL-21 weekly. In all, 60% of the patients had stable disease. Immune activation was confirmed by various T- and NK-cell activation biomarkers, including dose-dependent increases in serum sCD25.Conclusion:rIL-21 weekly combined with cetuximab is well tolerated at doses up to 100 μg kg−1 and results in activation of immune response biomarkers. [ABSTRACT FROM AUTHOR]

BACKGROUND Salvage treatment for metastatic gastric cancer, although administered to nearly every second patient, is not well defined yet. Recently, treatment with irinotecan was established, displaying significant benefit compared to best supportive care. EGFR targeting therapies, especially monoclonal antibodies, are promising approaches in the treatment of gastric cancer. METHODS Data from patients treated with a combination of cetuximab and irinotecan were obtained from two German institutions. Patients refractory to standard fluoropyrimidine and/or platinum-based regimens (at least second line) were eligible for analysis if they received at least 4 weeks of treatment. RESULTS In 13 evaluable patients, the median number of preceding regimens was three (range 1-4). Seven patients have already been pretreated with irinotecan. A total of 176 weekly treatments were administered, median 10 (range 5-41) per patient. Disease control rate was 54% (7 patients) with three patients achieving a partial response. Median time to tumor progression (TTP) and overall survival (OS) were 11 (range 5-45) and 14 (range 10-68) weeks, respectively. Neutropenia grade III/IV was noted in three (23%), grade III diarrhea was noted in four patients (31%). Grade III skin rash occurred in three patients, whereas no allergic reactions were reported. CONCLUSIONS The combination of cetuximab with irinotecan was well tolerated in this small cohort of heavily pretreated patients with mGC. The efficacy observed justifies further testing in a prospective phase II setting. [ABSTRACT FROM AUTHOR]

Background: Clinical observations suggested that a non negligible proportion of patients, ranging from 40% to 70%, does not seem to benefit from the use of anti-EGFR targeted antibodies even in the absence of a mutation of the K- RAS gene. The EGFR pathway activation via the Ras-Raf-MAP-kinase and the protein-serine/threonine kinase AKT could determine resistance to anti-EGFR treatment. Methods: We tested the interaction between phosphorylated AKT and MAPK expression in colorectal tumours and corresponding metastases and global outcome in K-RAS wild type patients receiving irinotecan-cetuximab. Results: Seventy-two patients with histologically proven metastatic colorectal cancer, treated with Irinotecan and Cetuximab based chemotherapy, were eligible for our analysis. In metastases pAKT correlated with RR (9% vs. 58%, p = 0.004), PFS (2.3 months vs.9.2 months p<0.0001) and OS (6.1 months vs.26.7 months p<0.0001) and pMAPK correlated with RR (10% vs., 47%, p = 0.002), PFS (2.3 months vs.8.6 months p<0.0001) and OS (7.8 months vs.26 months p = 0.0004). At multivariate analysis pAKT and pMAPK in metastases were able to independently predict PFS. pAKT in metastases independently correlated with RR as well Discussion: pAKT and pMAPK expression in metastases may modulate the activity of EGFR-targeted antibodies. We could speculate that in patients with pAKT and pMAPK metastases expression targeting these factors may be crucial. [ABSTRACT FROM AUTHOR]

The article discusses a single center study which examines the role of multiple gene alterations in response to cetuximab in metastatic colorectal cancer (mCRC). It details the methodology of retrospectively analyzing objective tumor response rate, (ORR) progression-free (PFS) and overall survival (OS) expression in mCRC patients treated with cetuximab. The findings reveal that gene mutations appear to be independent predictors of the effectiveness of cetuximab.

A 31-year-old man with sigmoid colon cancer with concomitant simultaneous multiple liver metastases had received FOLFIRI (leucovorin, fluorouracil and irinotecan) and FOLFOX6 (leucovorin, fluorouracil and oxaliplatin) after an ordinary sigmoidectomy. However, his serum carcinoembryonic antigen (CEA) level increased rapidly during the fifteen months after the operation while he was on FOLFOX6. Abdominal computed tomography revealed expanding multiple liver tumors. As the third line chemotherapy, a combination therapy of cetuximab with irinotecan was given, which markedly reduced his levels of serum CEA, and the size and number of liver tumors. He underwent lateral segmentectomy of the liver and microwave coagulation of the liver metastases in the remnant liver. Thereafter, a good quality of life with tumor dormancy was obtained for 6 months. However, his serum CEA started to rise again in the absence of liver tumors. Therefore, FOLFOX6 with bevacizumab was chosen as the fourth line chemotherapy, and the serum CEA was reduced with tumor dormancy. A good quality of life was obtained again at 3 years after the first surgery. This report indicates the effectiveness of sandwiched liver surgery with the molecular targeting drugs cetuximab and bevacizumab on multiple liver metastases of colon cancer, and suggests the possibility of a regimen consisting of bevacizumab following cetuximab. [ABSTRACT FROM AUTHOR]

The treatment of metastatic colorectal cancer (mCRC) remains one of the largest hurdles in cancer therapeutics to date. The most advanced treatment option for mCRC patients are anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) that bind to and inhibit the activity of EGFR. While the use of anti-EGFR mABs has had great impact in the treatment of mCRC, it has now been widely accepted that mCRC tumors with a mutation in the small GTPase KRAS do not respond to these therapies. KRAS mutations allow for EGFR independent activation of various oncogenic signaling cascades. In attempts to inhibit KRAS mutant tumor growth, BRAF, MEK and farsenyltransferase inhibitors have been used, however, their clinical efficacy is still accruing in the setting of CRC. Recent data suggests that various other inhibitors, including inhibitors of Src family kinases (SFK) and hepatocyte growth factor receptor (MET), may have potential preclinical and clinical success in KRAS mutant tumors. Additionally, it is becoming increasingly clear that different KRAS missense mutations may have varied biological responses to cetuximab, suggesting that cetuximab may still be a potential therapeutic option in some KRAS mutant tumors. In this review, we highlight the importance for both improved multimodality approaches for treating KRAS mutant mCRC tumors and stratification of KRAS mutations in response to different treatment regimes in order to optimize the best possible care for mCRC patients. [ABSTRACT FROM AUTHOR]

The biological agents approved for the treatment of patients with metastatic colorectal cancer - bevacizumab, a monoclonal antibody that targets vascular endothelial growth factor A, along with cetuximab and panitumumab, two monoclonal antibodies that target the epidermal growth factor receptor - are associated with a number of adverse events that range in severity from relatively mild to potentially life threatening. Hypertension, thromboembolic events, proteinuria, bleeding, and gastrointestinal perforation have all been associated with bevacizumab, while dermatologic toxicities are common with cetuximab and panitumumab. Hypersensitivity reactions and hypomagnesemia are also a concern with cetuximab and panitumumab. The frequency of these adverse events in randomized clinical trials is reviewed, and recommendations for managing these events in patients undergoing treatment for metastatic colorectal cancer are provided. [ABSTRACT FROM AUTHOR]

Background: Recent studies have reported associations between a variant allele in a let-7 microRNA complementary site (LCS6) within the 30untranslated region (30UTR) of KRAS (rs61764370) and clinical outcome in metastatic colorectal cancer (mCRC) patients receiving cetuximab. The variant allele has also been associated with increased cancer risk. We aimed to reveal the incidence of the variant allele in a colorectal cancer screening population and to investigate the clinical relevance of the variant allele in mCRC patients treated with 1st line Nordic FLOX (bolus 5-fluorouracil/folinic acid and oxaliplatin) +/− cetuximab. Methods: The feasibility of the variant allele as a risk factor for CRC was investigated by comparing the LCS6 gene frequencies in 197 CRC patients, 1060 individuals with colorectal polyps, and 358 healthy controls. The relationship between clinical outcome and LCS6 genotype was analyzed in 180 mCRC patients receiving Nordic FLOX and355 patients receiving Nordic FLOX + cetuximab in the NORDIC-VII trial (NCT00145314).Results: LCS6 frequencies did not vary between CRC patients (23%), individuals with polyps (20%), and healthy controls (20%) (P = 0.50). No statistically significant differences were demonstrated in the NORDIC-VII cohort even if numerically increased progression-free survival (PFS) and overall survival (OS) were found in patients with the LCS6 variant allele (8.5 (95% CI: 7.3-9.7 months) versus 7.8 months (95% CI: 7.4-8.3 months), P = 0.16 and 23.5 (95% CI: 21.6-25.4 months) versus 19.5 months (95% CI: 17.8-21.2 months), P = 0.31, respectively). Addition of cetuximab seemed to improve response rate more in variant carriers than in wild-type carriers (from 35% to 57% versus 44% to 47%), however the difference was not statistically significant (interaction P = 0.16). Conclusions: The LCS6 variant allele does not seem to be a risk factor for development of colorectal polyps or CRC.No statistically significant effect of the LCS6 variant allele on response rate, PFS or OS was found in mCRC patients treated with 1st line Nordic FLOX +/− cetuximab. [ABSTRACT FROM AUTHOR]

Background: KRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor (EGFR) antibodies in metastatic colorectal cancer (mCRC). Novel predictive markers are required to further improve the selection of patients for this treatment. We assessed the influence of modification of KRAS by gene copy number aberration (CNA) and microRNAs (miRNAs) in correlation to clinical outcome in mCRC patients treated with cetuximab in combination with chemotherapy and bevacizumab. Methods: Formalin-fixed paraffin-embedded primary tumour tissue was used from 34 mCRC patients in a phase III trial, who were selected based upon their good (n = 17) or poor (n = 17) progression-free survival (PFS) upon treatment with cetuximab in combination with capecitabine, oxaliplatin, and bevacizumab. Gene copy number at the KRAS locus was assessed using high resolution genome-wide array CGH and the expression levels of 17 miRNAs targeting KRAS were determined by real-time PCR. Results: Copy number loss of the KRAS locus was observed in the tumour of 5 patients who were all good responders including patients with a KRAS mutation. Copy number gains in two wild-type KRAS tumours were associated with a poor PFS. In KRAS mutated tumours increased miR-200b and decreased miR-143 expression were associated with a good PFS. In wild-type KRAS patients, miRNA expression did not correlate with PFS in a multivariate model. Conclusions: Our results indicate that the assessment of KRAS CNA and miRNAs targeting KRAS might further optimize the selection of mCRC eligible for anti-EGFR therapy. [ABSTRACT FROM AUTHOR]

Treatment of metastasized colorectal cancer (mCRC) patients with anti-epidermal growth factor receptor (EGFR)-directed monoclonal antibodies is driven by the results of the KRAS mutational status (wild type [WT]/mutated [MUT]). To find out as to what extent the treatment selection based on the KRAS status had impact on overall costs, a retrospective analysis was performed. Of 73 mCRC patients 31.5% were MUT carriers. Costs of EGFR inhibitor treatment for WT patientswere significantly higher compared to those for patients with MUT (p = 0.005). Higher treatment costs in WT carriers reflect a significantly higher number of treatment cycles (p = 0.012) in this cohort of patients. Savings of drug costs minus the costs for the determination of KRAS status accounted for EUR 779.42 (SD ±336.28) per patient per cycle. The routine use of KRAS screening is a cost-effective strategy. Costs of unnecessary monoclonal EGFR inhibitor treatment can be saved in MUT patients. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The ability of molecular targeting agents to improve overall survival (OS) in metastatic colorectal cancer (MCRC) patients who underwent oxaliplatin-based chemotherapy remains controversial. Methods: We retrospectively analyzed 331 patients with MCRC who underwent first-line oxaliplatin-based chemotherapy. Treatment outcomes were compared between patients who started chemotherapy from April 2005 to March 2007 (cohort A; n = 157) and those who started it from April 2007 to March 2009 (cohort B; n = 174). To evaluate the impact of exposure to agents, we applied time-varying covariate analysis to avoid possible lead-time bias. Results: Median OS of cohorts A and B was 21.3 and 28.6 months, respectively (HR 0.66, 95% CI 0.50-0.87, p = 0.003). Exposure to bevacizumab (25 vs. 76%), anti-epidermal growth factor receptor (EGFR) (18 vs. 33%) or curative surgery after chemotherapy (4 vs. 10%) was significantly higher in cohort B. According to a multivariate Cox model with exposure to each agent or treatment as a time-varying covariate, hazard ratios of death were 0.71 (95% CI, 0.51-0.96; p = 0.03) for bevacizumab, 0.62 (95% CI, 0.40-0.89; p = 0.01) for anti-EGFR and 0.22 (95% CI, 0.06-0.57; p = 0.004) for surgery. Conclusions: Increased exposure to molecular targeting agents or surgery after chemotherapy appears to contribute to an improvement in OS in recent patients with MCRC who have undergone oxaliplatin-based chemotherapy. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Purpose: Treatment effects of advanced gastric cancer (AGC) are unsatisfactory, and novel therapeutic approaches are much needed. The epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab inhibits the growth of several human cancer cells but has been tested rarely for the treatment of GC. The synergy between cetuximab and irinotecan has been reported in colorectal cancer, but the mechanisms are still not fully clarified. Consequently, we hypothesized cetuximab/irinotecan combination should enhance the antitumor activity of irinotecan in GC cells. Methods: The in vitro antiproliferative, pro-apoptotic, cell cycle arrest effects and induction of senescence were examined in SGC-7901 and MKN-45 GC cell lines. The effects of cetuximab or irinotecan as single agents or the combination on the expression of p53, p16, and EGFR signaling pathways were also studied. Results: The study revealed that cetuximab alone did not show any antiproliferative, pro-apoptotic, cell cycle arrest or cellular senescence effect on GC cells but when combined with irinotecan synergistically inhibits GC cell proliferation and induces apoptosis and G2/M phase arrest. Irinotecan increases phosphorylation of EGFR, MAPK, and AKT and decreases the expression of P27, which could be all abrogated by its combination with cetuximab. The combination could also inhibit the expression of Cyclin D1 and phosphorylated mTOR while had no impact on p53, p16, PTEN, and HIF-1alpha. Conclusions: Cetuximab enhances the activities of irinotecan on GC cells via the downregulation of the EGFR pathway upregulated by irinotecan. Combination therapy with cetuximab and irinotecan, a novel therapeutic approach, warrants further study in GC. [ABSTRACT FROM AUTHOR]

The mutation status of the KRAS gene in the tumors of patients with metastatic colorectal cancer (mCRC) is a predictive biomarker for the efficacy of epidermal growth factor receptor monoclonal antibody therapy. The establishment of KRAS mutation testing in this setting represents a significant change to standard diagnostic procedures and a major advance in the personalization of cancer care. Against a changing regulatory background, three cross-sectional surveys of physicians in 14 countries in Europe, Latin America and Asia were conducted in 2008, 2009, and 2010 to investigate the uptake and outcome of KRAS testing for patients with mCRC. Physicians in each year answered questions on four patients (last patient seen and last seen in first-, second- and third-line settings). Fieldwork was carried out February-May 2008, January-April 2009, and January-April 2010. Data from 3,819, 3,740 and 3,820 anonymized, uncoded patient records were collated. The frequency of KRAS testing in patients with mCRC increased from 3% in 2008 to 47% in 2009 and 69% in 2010. The 2010 survey revealed that test results were available within 15 days for 82%, 51% and 98% of the 1679, 679, and 261 tested patients in the European, Latin American and Asian regions, respectively. Cetuximab was the most commonly administered targeted agent in tested patients with KRAS wild-type mCRC (798/1607 patients; 50%) and bevacizumab was the most commonly administered targeted agent in tested patients with KRAS mutant tumors (396/893; 44% overall). In conclusion, KRAS testing is now widely established as a routine diagnostic procedure for patients with mCRC and is used increasingly to guide treatment selection. [ABSTRACT FROM AUTHOR]

OBJECTIVE The aim of this study was to carry out a multivariate meta-analysis of studies which investigated the predictive value of KRAS mutations in the efficacy of cetuximab in patients suffering from colorectal cancer. METHOD A systematic literature search was made in the PubMed, Medline and Cochrane databases using a combination of the key words "cetuximab", "anti-egfr" "KRAS or K-RAS" and "colorectal cancer". A 2-dimensional random-effects model was used for the analysis of sensitivity and specificity. Data from each study was entered in 2×2 tables from which sensitivities, specificities and predictive values (negative and positive) were estimated. The statistical program Stata 10 (StataCorp) was used for all the statistical analyses and significant results were considered those with p-value <0.05. RESULTS A total of 26 relevant reports were found from the search of the databases, of which 13 were appropriate for this specific meta-analysis. Initially, it was found that in these studies the specificities were much higher than the sensitivities. On combining the data from the 13 studies, it was found that mutations in the KRAS gene constitute a negative predictive biomarker for the response to cetuximab, with very high specificity, 0.96 (0.84-0.99), but low sensitivity, 0.47 (0.43-0.50), and that publication bias may often occur. CONCLUSIONS The clinical importance of these findings is that cetuximab should be administrated only to patients who have the wild type KRASw oncogene. Mutations in the KRAS gene are a negative predictive factor for the response to cetuximab, with very high specificity and low sensitivity. The low value of sensitivity is probably due to the presence of additional mechanisms of resistance to anti-EGFR therapies, such as mutations in BRAF. [ABSTRACT FROM AUTHOR]

Background: The efficacy and safety of cetuximab for irinotecan-intolerant patients has not yet been evaluated in detail. Methods: We retrospectively analyzed the efficacy and safety of cetuximab monotherapy for patients with metastatic colorectal cancer (MCRC) that was intolerant to irinotecan. Results: Among 105 patients who received cetuximab-containing chemotherapy until March 2010, 22 patients were treated with cetuximab monotherapy due to irinotecan intolerance. Cetuximab was given at the approved dosage to all patients. The performance status was 2 or 3 in 17 patients (77%). All but 1 patient had wild-type KRAS tumors. The causes of irinotecan intolerance were icterus ( n = 9; 41%; median serum total bilirubin, 6.3 mg/dl), symptomatic peritoneal metastasis or obstruction ( n = 8; 36%), and thrombocytopenia ( n = 1; 5%). Four patients (18%) refused irinotecan due to previous irinotecan-associated toxicity. Two patients achieved a partial response with an apparent drop of serum bilirubin, for a response rate of 9.1%. The median progression-free survival and overall survival were 1.6 and 3.5 months, respectively. No grade 3 or 4 adverse events or treatment-related deaths were experienced. Conclusion: Cetuximab monotherapy for irinotecan-intolerant MCRC is feasible. However, the overall efficacy was modest in the present cohort, despite the fact that most of the patients had wild-type KRAS tumors; further effective therapies should be evaluated to improve the prognosis of this patient population. [ABSTRACT FROM AUTHOR]

Background: Until recently there has been no proven second-line therapy for patients with advanced gastro-esophageal cancer (GEC). Since 2004, Denmark has had a national health program where non-proven therapy can be offered to patients with advanced cancer, after approval by an expert panel appointed by the National Board of Health. This program has accelerated the introduction and implementation of new therapies in Denmark. Inspired by therapy in metastatic colorectal cancer, a combination of cetuximab and irinotecan (Cetiri) was chosen for second-line therapy in GEC patients. We report our experience with Cetiri as second-line therapy in patients with GEC. Methods: All patients had histologically confirmed GEC and all patients had progressive disease during or after first-line platinum-containing chemotherapy. The patients received cetuximab 500 mg/m on day 1 and irinotecan 180 mg/m on day 1 every 2nd week until progression or unacceptable toxicity. Toxicity was prospectively evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 3.0. Results: From December 2007 to February 2009, 50 consecutive patients received Cetiri as second-line therapy. Median performance status (PS) was 1. The median number of courses was seven. Seven patients (14%) had a partial response. Median progression-free survival (PFS) was 3.3 months and overall survival (OS) was 5.5 months; two patients are still alive without progressive disease. Major toxicities were: diarrhea (8%), fatigue (10%), neutropenia (16%), and febrile neutropenia (2%). Conclusion: Cetiri every two weeks is a convenient and well-tolerated second-line regimen in GEC patients. A promising effect was seen in patients with PS 0-1 and in patients who developed a rash. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies against the epidermal growth factor receptor (anti-EGFR) when used in the treatment of metastatic colorectal cancer are associated with improved survival. Patients whose tumours harbor a KRAS mutation in codon 12 or 13 have been shown not to benefit from anti-EGFR antibodies. The importance of KRAS mutation status in the management of patients with metastatic colorectal cancer has led to the elaboration of Canadian consensus recommendations on KRAS testing, with the aim of standardizing practice across Canada and reconciling testing access with the clinical demand for testing. The present guidelines were developed at a Canadian consensus meeting held in Montreal in April 2010. The best available evidence and expertise were used to develop recommendations for various aspects of KRAS testing, including indications and timing for testing, sample requirements, recommendations for reporting requirements, and acceptable turnaround times. [ABSTRACT FROM AUTHOR]

Purpose: This study compared the efficacy and toxicities of cetuximab combined with chemotherapy versus chemotherapy for patients with metastatic colorectal cancer (mCRC). The influence of KRAS mutation status on the outcomes was also investigated. Methods: Literature retrieval, trials selection and assessment, data collection, and statistical analysis were performed according to the Cochrane Handbook 5.0.2. The outcome measures were tumor response rate, progression-free survival, overall survival, and adverse effects. Results: Four randomized controlled trials, comprising totally 2,912 patients, were included. Meta-analysis showed higher response rate (RR 1.93; 95% CI, 1.14-3.26) and significant improvement in progression-free survival (PFS; HR 0.80; 95% CI, 0.67-0.95) in cetuximab-chemotherapy groups versus chemotherapy groups. There was no significant difference between the two treatment groups regarding overall survival (OS; HR 0.95; 95% CI, 0.87-1.05). In wild-type KRAS patients, treatment with cetuximab plus chemotherapy significantly increased response rate (RR 1.44; 95% CI, 1.20-1.73) and improved PFS (HR 0.64; 95% CI, 0.50-0.84), as compared with chemotherapy groups, but not for OS (HR 0.84; 95% CI, 0.64-1.11). In mutant KRAS patients, there was no significant difference between those treated with cetuximab plus chemotherapy and those with chemotherapy alone regarding response rate (RR 0.81; 95% CI, 0.61-1.08), PFS (HR 1.37; 95% CI, 0.81-2.31), and OS (HR 1.03; 95% CI, 0.74-1.44). The risk of grade 3/4 rash, diarrhea, neutropenia, and fatigue was significantly increased in cetuximab combination groups as compared with chemotherapy groups. Conclusions: The use of cetuximab in addition to chemotherapy was a valid alternative for patients with mCRC. Benefit of cetuximab was only limited to patients with wild-type KRAS tumors. [ABSTRACT FROM AUTHOR]

Background: We aimed to compare the sensitive and quality-controlled KRAS testing with direct sequencing and to assess the impact on decision making of treatment.Patients and Methods: We analysed genomic DNA isolated from macrodissected formalin-fixed paraffin-embedded specimens by direct sequencing and an amplification refractory mutation system-Scorpion assay (ARMS/S) method. Cetuximab was administered to patients identified as having wild-type (WT) KRAS using direct sequencing. Therapeutic effects were evaluated according to their KRAS status as determined by ARMS/S.Results: Among the 159 patients, the overall mutation rate was determined to be 37.0% by direct sequencing and 44.0% by ARMS/S. For the patients diagnosed as WT by direct sequencing and treated with cetuximab (n=47), a response rate of 16.0% was observed for 38 ARMS/S WT patients, whereas 9 ARMS/S mutant (MUT) patients failed to respond. The ARMS/S WT patients showed significant improvement in progression-free survival (PFS) and overall survival (OS) compared with ARMS/S MUT patients (PFS median 5.0 vs 1.7 months, hazards ratio (HR)=0.29, P=0.001; OS median 12.1 vs 3.8 months, HR=0.26, P=0.001).Conclusion: Sensitive and quality-controlled KRAS testing may provide improved predictive power to determine the efficacy of anti-epidermal growth factor antibodies. [ABSTRACT FROM AUTHOR]

Background: The AIO KRK-0104 randomised phase II trial investigated the efficacy and safety of two capecitabine-based regimens: combination of capecitabine and irinotecan (CAPIRI) plus cetuximab (CAPIRI-C) and combination of capecitabine with oxaliplatin (CAPOX) plus cetuximab (CAPOX-C) in the first-line treatment of metastatic colorectal cancer (mCRC). Treatment-related skin toxicity (ST) was evaluated separately for capecitabine and cetuximab. The present analysis investigates the correlation of capecitabine-attributed ST (Cape-ST) and parameters of treatment efficacy.Methods: Patients with mCRC were randomised to cetuximab (400 mg m(-2), day 1, followed by 250 mg m(-2) weekly) plus CAPIRI (irinotecan 200 mg m(-2), day 1; capecitabine 800 mg m(-2), twice daily, days 1-14, every 3 weeks), or cetuximab plus CAPOX (oxaliplatin 130 mg m(-2), day 1; capecitabine 1000 mg m(-2), twice daily, days 1-14, every 3 weeks).Results: Of 185 recruited patients, 149 (CAPIRI-C, n=78; CAPOX-C, n=71) received study treatment beyond the first tumour assessment and were evaluable for efficacy. Capecitabine-attributed ST, predominantly hand-foot syndrome, was observed in 32.2% of patients. Capecitabine-attributed ST grade 1-3 was associated with a significantly higher disease control rate (DCR) (97.9 vs 86.1%, P=0.038) compared with grade 0 toxicity. Moreover, Cape-ST grade 1-3 related to a markedly longer progression-free survival (PFS) (9.9 vs 5.6 months, P<0.001) and overall survival (OS) (32.8 vs 22.4 months, P=0.008). Separate analyses of treatment arms indicated that the effect of Cape-ST on PFS remained significant for both arms, whereas the effect on OS remained apparent as a strong trend.Conclusion: This analysis supports the hypothesis that for the evaluated regimens, a correlation exists between Cape-ST and treatment efficacy regarding DCR, PFS, and OS. [ABSTRACT FROM AUTHOR]

Background: Anti-epidermal growth factor receptor monoclonal antibodies (panitumumab [P] and cetuximab [C]) are approved and effective only in KRAS wild-type patients with advanced colorectal cancer. The purpose of our meta-analysis is to evaluate the real effects of C and P in KRAS wild-type patients treated in randomized trials. Patients and methods: Eligible studies included prospective, randomized, and controlled trials in which either C or P had been added to standard antineoplastic therapy or best supportive care and data for KRAS wild-type patients only had been calculated. Six thousand three hundred ninety-five patients' tumor samples have been analyzed (total wild-type n = 3,254; experimental arm n = 1,608; control arm n = 1,646). Relative risks (RRs) with 95% confidence intervals (CIs) for response rate were calculated, as well as hazard ratios (HRs)for progression-free survival (PFS) and overall survival. Results: The overall RR of response rate is 1.69 ( p = 0.003) in all trials. The overall HRs for PFS and survival are 0.65 ( p = 0.0006) and 0.84 ( p = 0.03), respectively, and both are significant. The HRs for PFS and survival in C trials are 0.64 and 0.79, respectively, and 0.65 and 0.87, respectively, in P trials, although only the results achieved in P trials are significant ( p = 0.0007 and p = 0.03). Both response rate (RR = 10.94) and PFS (HR = 0.51) have increased more in pretreated patients than in first-line trials. Conclusion: The addition of anti-EGFR monoclonal antibodies to standard anticancer therapy in KRAS wild-type colorectal cancer showed an overall significantly increased risk of objective response rate and increased progression-free and overall survival. Only the results achieved in P randomized trials are significant, and the strongest results have been achieved in pretreated patients. [ABSTRACT FROM AUTHOR]

Background: The objectives of this phase I study were to determine the safety, pharmacokinetics (PK), pharmacodynamics and efficacy of brivanib combined with full-dose cetuximab in patients with advanced gastrointestinal malignancies.Methods: Patients with advanced gastrointestinal malignancies who had failed prior therapies received brivanib (320, 600 or 800 mg daily) plus cetuximab (400 mg m(-2) loading dose then 250 mg m(-2) weekly). Assessments included adverse events, PK, tumour response, 2[18F]fluoro-2-deoxyglucose positron-emitting tomography and K-Ras mutation analyses.Results: Toxicities observed were manageable; the most common treatment-related toxicities (>10% of patients) were fatigue, diarrhoea, anorexia, increase in aspartate aminotransferase and alanine aminotransferase, acneiform dermatitis, headache, mucosal inflammation, nausea, dry skin, vomiting, hypertension, pruritus, proteinuria and weight loss. Of 62 patients, 6 (9.7%) had objective radiographic partial responses, with an overall response rate of 10%. Median duration of response was 9.2 months; median progression-free survival was 3.9 months.Conclusions: The acceptable toxicity profile and efficacy of brivanib observed in this study were promising. These findings are being further evaluated in a phase III study of brivanib plus cetuximab vs cetuximab alone in patients previously treated with combination chemotherapy for K-Ras wild-type advanced metastatic colorectal cancer. [ABSTRACT FROM AUTHOR]

Objectives. Previous research has indicated a high incidence of cetuximab hypersensitivity reactions in the southern US. This study documents the incidence of hypersensitivity reactions in North Carolina, and explores whether factors such as patient demographics, allergy history, premedications, and cancer type are potential predictors for cetuximab reactions.Methods. This retrospective chart review consisted of 72 consecutively treated patients from Duke University’s Morris Oncology treatment center between September 2005 and August 2007. Data regarding stage of malignancy, premedications, and hypersensitivity reactions were collected from electronic databases. The number and type of reactions were characterized. Patients with and without hypersensitivity reactions were compared using bivariate statistics and multivariate logistic regression.Results. Of the 72 patients, 21 (29%) experienced hypersensitivity reactions. The majority of reactions (62%) were grades III or IV. Of the 21 patients having a reaction, 9 (43%) were sent to the emergency room and 5 (24%) had an overnight hospitalization. Three hospitalized patients were admitted to the intensive care unit. Both male gender (p = 0.039) and head/neck cancer (p = 0.014) were related to an increased likelihood of hypersensitivity reaction in bivariate analyses. In multivariate analyses, controlling for demographics, allergy history, premedications, and cancer type/stage, only type of cancer was predictive of hypersensitivity reaction (colon vs head/neck OR = 0.177; 95% CI 0.036—0.858).Conclusion. This study confirms a high rate of cetuximab hypersensitivity reactions in a southern region of the US. Patients with head/neck cancers were significantly more likely to have hypersensitivity reactions than patients with colon cancers. J Oncol Pharm Practice (2011) 17: 125—130. [ABSTRACT FROM PUBLISHER]

Background: Epidermal growth factor receptor (EGFR) promoter methylation may be responsible for the loss of EGFR expression in neoplastic cells. The primary aim of our study was to verify a possible correlation between EGFR gene promoter methylation and clinical outcome in metastatic colorectal cancer patients receiving chemotherapy with irinotecan and cetuximab.Methods: Colorectal samples from patients treated with irinotecan-cetuximab were analysed for EGFR promoter methylation and EGFR immunohistochemistry.Results: Fifty-two patients were analysed. Thirty patients (58%) showed EGFR promoter hypermethylation. In EGFR promoter methylated and EGFR promoter unmethylated patients, we observed a partial response in 3 (10%) and 13 (59%) patients, respectively (P=0.03), progressive disease was obtained in 19 (63%) and 2 (9%) patients, respectively, with EGFR promoter methylated and EGFR promoter unmethylated tumours (P=0.0001). Median progression-free survival was 2.4 months in patients showing EGFR promoter methylated tumours and 7.4 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 1). Median overall survival was 6.1 months in patients showing EGFR promoter methylated tumours and 17.8 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 2).Conclusion: EGFR promoter hypermethylation, after confirmation in larger data set, may represent a valuable asset in further studies investigating EGFR as a therapeutic target in colorectal cancer. [ABSTRACT FROM AUTHOR]

Background Metastatic colorectal cancer (CRC) patients with v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are resistant to treatment with cetuximab, a monoclonal antibody that targets the epidermal growth factor receptor. Statins have reported antitumor activity, but it is unknown whether simvastatin can reverse cetuximab resistance in KRAS mutant CRC. Methods Human CRC cell lines with KRAS mutations (LS153, LS174T, DLD1, LoVo, SW403, SW480, SNU175, and LS1034) or with v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations (DiFi, SW48, HT29, and RKO) were used to test the effect of cetuximab, simvastatin, and cetuximab plus simvastatin on cell proliferation and apoptosis in vitro. Because BRAFV600E mutant may be responsible for cetuximab resistance in KRAS wild-type cells, we measured the growth of xenograft tumors originating from KRAS mutant and BRAF mutant cells in mice treated with cetuximab alone or plus simvastatin (n = 5 mice per treatment group). We used immunoblot assays to study RAS-regulated activation of BRAF protein after simvastatin treatment. All statistical tests were two-sided. Results Addition of simvastatin (0.2 μM) to cetuximab (0.03–1.0 μM) reduced cell proliferation of KRAS mutant (P < .001) but not of BRAF mutant CRC cells in vitro. Treatment of KRAS mutant cells with simvastatin reduced BRAF activity and induced apoptosis. Treatment with cetuximab and simvastatin reduced the growth of xenograft tumors originating from KRAS mutant cells compared with cetuximab alone (eg, for tumors originating from DLD1 cells, cetuximab vs cetuximab + simvastatin, mean tumor volume = 49.4 vs 20.2 cm3, mean difference = 29.2 cm3, 95% confidence interval = 19.7 to 38.5, P < .001); treatment with cetuximab alone or in combination with simvastatin had no effect on the growth of BRAF mutant tumors. Conclusion Simvastatin may overcome cetuximab resistance in colon cancer cells with KRAS mutations by modulating BRAF activity and inducing apoptosis. [ABSTRACT FROM PUBLISHER]

Background: Circadian rhythm disruption was linked to high serum levels of Transforming Growth Factor Receptor α, an Epidermal Growth Factor Receptor (EGFR) ligand and poor survival in patients with metastatic colorectal cancer (mCRC). We hypothesized that EGFR blockade with cetuximab would enhance the activity of chronotherapy as a result of improved circadian coordination. Methods: All the patients with mCRC referred to our unit for progression on prior chemotherapy over a 30-month-period received weekly cetuximab and fortnightly chronotherapy. Results: Fifty-six patients were treated with a median of six courses of fluoropyrimidine-based chemotherapy and irinotecan (61%), oxaliplatin (25%) or both (14%) after a median of three prior regimens. We found no EFGR amplification by FISH in the tumor of 27 consecutive patients. Acneiform rash and diarrhea were the most common toxicities. Objective response rate was 32.1% and positively correlated with rash grade ( p = 0.025). None of the responders had K-Ras mutation in their tumor. Median progression-free and overall survival were 4.6 and 13.7 months, respectively. Complete macroscopic resections of metastases in liver, lung or other abdominopelvic sites were performed following tumor downstaging by the treatment regimen in 11 patients (21%), 8 of whom being alive at 3 years. These figures are twice as high as those reported for first-line combination of cetuximab with conventional chemotherapy or for third line chronotherapy. Conclusions: The addition of cetuximab to chronotherapy allowed safe and effective therapeutic control of metastases, including their complete resection, despite previous failure of several treatment regimens. [ABSTRACT FROM AUTHOR]

Background. Cetuximab was demonstrated by clinical trials to improve response rate and survival of patients with metastatic and nonresectable colorectal cancer or carcinoma of the head and neck. Appropriate management of skin toxicity associated with epidermal growth factor receptor inhibitor (EGFR-i) therapy is necessary to allow adequate drug administration and to improve quality of life and outcomes. Methods. A group of Italian Experts produced recommendations for skin toxicity management using the RAND/UCLA Appropriateness Method. Statements were generated on the basis of a systematic revision of the literature and voted twice by a panel of 40 expert physicians; the second vote was preceded by a meeting of the panelists. Results. Skin toxicity included skin rash, skin dryness, pruritus, paronychia, hair abnormality, and mucositis. Recommendations for prophylaxis and therapeutic interventions for each type of toxicity were proposed. Conclusions. Interventions that were considered appropriate to improve compliance and outcomes of cancer patients treated with EGFR-i were identified. [ABSTRACT FROM AUTHOR]

BACKGROUND Salvage treatment for metastatic gastric cancer, although administered to nearly every second patient, is not well defined yet. Recently, treatment with irinotecan was established, displaying significant benefit compared to best supportive care. EGFR targeting therapies, especially monoclonal antibodies, are promising approaches in the treatment of gastric cancer. METHODS Data from patients treated with a combination of cetuximab and irinotecan were obtained from two German institutions. Patients refractory to standard fluoropyrimidine and/or platinum-based regimens (at least second line) were eligible for analysis if they received at least 4 weeks of treatment. RESULTS In 13 evaluable patients, the median number of preceding regimens was three (range 1-4). Seven patients have already been pretreated with irinotecan. A total of 176 weekly treatments were administered, median 10 (range 5-41) per patient. Disease control rate was 54% (7 patients) with three patients achieving a partial response. Median time to tumor progression (TTP) and overall survival (OS) were 11 (range 5-45) and 14 (range 10-68) weeks, respectively. Neutropenia grade III/IV was noted in three (23%), grade III diarrhea was noted in four patients (31%). Grade III skin rash occurred in three patients, whereas no allergic reactions were reported. CONCLUSIONS The combination of cetuximab with irinotecan was well tolerated in this small cohort of heavily pretreated patients with mGC. The efficacy observed justifies further testing in a prospective phase II setting. [ABSTRACT FROM AUTHOR]

KRAS mutation is a predictive biomarker for resistance to cetuximab (Erbitux) in metastatic colorectal cancer (mCRC). This study sought to determine if KRAS mutant CRC lines could be sensitized to cetuximab using dasatinib (BMS-354825, Sprycel), a potent, orally bioavailable inhibitor of several tyrosine kinases, including the Src family kinases (SFKs). We analyzed 16 CRC lines for: (1) KRAS mutation status, (2) dependence on mutant KRAS signaling and (3) expression level of epidermal growth factor receptor (EGFR) and SFKs. From these analyses, we selected three KRAS mutant (LS180, LoVo and HCT116) cell lines and two KRAS wild-type cell lines (SW48 and CaCo2). In vitro, using poly-D-lysine/laminin plates, KRAS mutant cell lines were resistant to cetuximab, whereas KRAS wild-type lines showed sensitivity to cetuximab. Treatment with cetuximab and dasatinib showed a greater antiproliferative effect on KRAS mutant lines when compared with either agent alone in vitro and in vivo. To investigate potential mechanisms for this antiproliferative response in the combinatorial therapy, we performed Human Phospho-Kinase Antibody Array analysis, measuring the relative phosphorylation levels of 39 intracellular proteins in untreated, cetuximab, dasatinib or the combinatorial treatment in the KRAS mutant lines LS180, LoVo and HCT116 cells. The results of this experiment showed a decrease in a broad spectrum of kinases centered on the β-catenin pathway, the mitogen-activated protein kinase (MAPK) pathway, AKT/mammalian target of rapamycin (mTOR) pathway and the family of signal transducers and activators of transcription (STATs) when compared with the untreated control or monotherapy treatments. Next, we analyzed tumor growth with cetuximab, dasatinib or their combination in vivo. KRAS mutant xenografts showed resistance to cetuximab therapy, whereas KRAS wild type demonstrated an antitumor response when treated with cetuximab. KRAS mutant tumors exhibited minimal response to dasatinib monotherapy. However, as in vitro, KRAS mutant lines exhibited a response to the combination of cetuximab and dasatinib. Combinatorial treatment of KRAS mutant xenografts resulted in decreased cell proliferation, as measured by Ki67, and higher rates of apoptosis, as measured by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling). The data presented in this study indicate that dasatinib can sensitize KRAS mutant CRC tumors to cetuximab and may do so by altering the activity of several key signaling pathways. Furthermore, these results suggest that signaling via EGFR and SFKs may be necessary for cell proliferation and survival of KRAS mutant CRC tumors. These data strengthen the rationale for clinical trials combining cetuximab and dasatinib in the KRAS mutant CRC genetic setting. [ABSTRACT FROM AUTHOR]

BACKGROUND: The relationship of epidermal growth factor receptors (EGFR) pathway, such as PI3K, K-ras, and B-raf, with response to EGFR-targeted antibodies is less well studied. AIM: To assess sorafenib with cetuximab in treating metastatic colorectal cancer. SETTINGS AND DESIGN: Thirty-five patients with metastatic colorectal cancer were randomized to receive cetuximab with or without oral sorafenib. PATIENTS AND METHODS: Patients received cetuximab IV weekly for four weeks and oral sorafenib twice daily on days 1 - 28, with recycling every four weeks. The primary end point was the response rate (partial and complete), while the secondary end points were the adverse effects, time to progression and overall survival. STATISTICAL ANALYSIS was made using the Statistical Product and Service Solutions, using SPSS 10.0, with estimation of both time to progression and overall survival time by the Kaplan-Meier method and comparing the two groups with the use of a log-rank test. RESULTS: Partial response was higher in cetuximab-sorafenib (EN), which constituted 33.3% compared to 17.6% in the cetuximab group (P = 0.44). Progression-free survival had a statistically higher significant difference in wild K-ras compared to mutant K-ras cases (P = .0001). Median overall survival was seven and five months in the (EN) and (E) groups respectively (P = 0.49). CONCLUSION: K-ras and B-raf was a predictor of response, so genotyping of tumors was needed for defining the patient population that was likely to benefit from the targeted therapy. A combination of therapy that simultaneously targets K-ras and B-raf could be a useful approach to increase the number of patients who may benefit from anti-EGFR therapy. [ABSTRACT FROM AUTHOR]

Metastatic colorectal cancer (mCRC) is primarily treated with cytotoxic chemotherapy. However, limitations in efficacy and tolerability clearly exist with the use of these agents. Molecularly targeted agents offer alternatives to chemotherapy or in many cases, can be used in combination with chemotherapy to synergistically enhance responses and patient survival. Monoclonal antibodies targeting the epidermal growth factor receptor (EGFR) have emerged as a therapeutic option to potentiate chemotherapeutic response and outcome in mCRC patients. However, in unselected populations, the advantages are modest. Thus, biomarkers that predict patients who will benefit from combination regimens employing both EGFR-targeted agents and chemotherapy are necessary to limit unnecessary toxicity and healthcare costs. This review will discuss the use of the EGFR monoclonal antibody cetuximab in combination with chemotherapy in mCRC patients with respect to toxicity, response, and predictive biomarkers of activity. [ABSTRACT FROM AUTHOR]

Cetuximab, a monoclonal antibody that blocks the epidermal growth factor receptor (EGFR), is currently approved for the treatment of several types of solid tumors. We previously showed that cetuximab can inhibit hypoxia-inducible factor-1 alpha (HIF-1α) protein synthesis by inhibiting the activation of EGFR downstream signaling pathways including Erk, Akt, and mTOR. 1, 9-pyrazoloanthrone (1, 9 PA) is an anthrapyrazolone compound best known as SP600125 that specifically inhibits c-jun N-terminal kinase (JNK). Here, we report 1, 9 PA can downregulate HIF-1α independently of its inhibition of JNK. This downregulatory effect was abolished when the oxygen-dependent domain (ODD) of HIF-1α (HIF-1α-ΔODD, the domain responsible for HIF-1α degradation) was experimentally deleted or when the activity of HIF-1α prolyl hydroxylase (PHD) or the 26S proteasomal complex was inhibited, indicating that the 1, 9 PA downregulates HIF-1α by promoting PHD-dependent HIF-1α degradation. We found that the combination of 1, 9 PA and cetuximab worked synergistically to induce apoptosis in cancer cells in which cetuximab or 1, 9 PA alone had no or only weak apoptotic activity. This synergistic effect was substantially decreased in cancer cells transfected with HIF-1α-ΔODD, indicating that downregulation of HIF-1α was the mechanism of this synergistic effect. More importantly, 1, 9 PA can downregulate HIF-1α in cancer cells that are insensitive to cetuximab-induced inhibition of HIF-1α expression due to overexpression of oncogenic Ras (RasG12V). Our findings suggest that 1, 9 PA is a lead compound of a novel class of drugs that may be used to enhance the response of cancer cells to cetuximab through a complementary effect on the downregulation of HIF-1α. [ABSTRACT FROM AUTHOR]

Background: Cetuximab, a monoclonal antibody directed against the epidermal growth factor receptor, improves progression-free survival and overall survival in patients with metastatic colorectal cancer (mCRC). However, patients with a KRAS gene mutation do not benefit from cetuximab therapy. Methods: We performed a cost-effectiveness analysis of KRAS testing and cetuximab treatment as last-line therapy for patients with mCRC in Japan. In our analysis, we considered three treatment strategies. In the 'KRAS-testing strategy' (strategy A), KRAS testing was performed to guide treatment: patients with wild-type KRAS received cetuximab, and those with mutant KRAS received best supportive care (BSC). In the 'no-KRAS-testing strategy' (strategy B), genetic testing was not conducted and all patients received cetuximab. In the 'no-cetuximab strategy' (strategy C), genetic testing was not conducted and all patients received BSC. To evaluate the cost effectiveness of KRAS testing, the KRAS-testing strategy was compared with the no-KRAS-testing strategy; to evaluate the cost effectiveness of KRAS testing and cetuximab, the KRAS-testing strategy was compared with the no-cetuximab strategy; and to evaluate the cost effectiveness of cetuximab treatment without KRAS testing, the no-KRAS-testing strategy was compared with the nocetuximab strategy. A three-state Markov model was used to predict expected costs and outcomes for each group. Outcomes in the model were based on those reported in a retrospective analysis of data from the National Cancer Institute of Canada Clinical Trials Group CO.17 study. We included only direct medical costs from the perspective of the Japanese healthcare payer. A 3% discount rate was used for both costs and outcome. Two outcomes, life-years (LYs) gained and quality-adjusted life-years (QALYs) gained, were used to calculate the incremental cost-effectiveness ratio (ICER). Results: Our cost-effectiveness analysis revealed that the KRAS-testing strategy was dominant compared with the no-KRAS-testing strategy, with an expected cost reduction of ¥0.5 million per patient and an estimated budget impact of ¥3-5 billion ($US42-59 million; July 2010 values) per year. The ICER of the KRAS-testing strategy compared with the no-cetuximab strategy was ¥11 million ($US120 000) per LY gained and ¥16 million ($US160 000) per QALY gained, whereas the ICER of the KRAS-testing strategy compared with the no-KRAS-testing strategy was ¥14 million ($US180 000) per LY gained and ¥21 million ($US230 000) per QALY gained. These results were supported by the sensitivity analysis. Conclusions: KRAS testing is recommended before administering cetuximab as last-line therapy for patients with mCRC. However, our analysis suggests that the ICER of cetuximab treatment (with or without KRAS testing) is too high, even if treatment is limited to patients with wild-type KRAS. [ABSTRACT FROM AUTHOR]