Showing papers on "Cetuximab published in 2012"

Unresponsiveness of colon cancer to BRAF(V600E) inhibition through feedback activation of EGFR

Abstract: Inhibition of the BRAF(V600E) oncoprotein by the small-molecule drug PLX4032 (vemurafenib) is highly effective in the treatment of melanoma. However, colon cancer patients harbouring the same BRAF(V600E) oncogenic lesion have poor prognosis and show only a very limited response to this drug. To investigate the cause of the limited therapeutic effect of PLX4032 in BRAF(V600E) mutant colon tumours, here we performed an RNA-interference-based genetic screen in human cells to search for kinases whose knockdown synergizes with BRAF(V600E) inhibition. We report that blockade of the epidermal growth factor receptor (EGFR) shows strong synergy with BRAF(V600E) inhibition. We find in multiple BRAF(V600E) mutant colon cancers that inhibition of EGFR by the antibody drug cetuximab or the small-molecule drugs gefitinib or erlotinib is strongly synergistic with BRAF(V600E) inhibition, both in vitro and in vivo. Mechanistically, we find that BRAF(V600E) inhibition causes a rapid feedback activation of EGFR, which supports continued proliferation in the presence of BRAF(V600E) inhibition. Melanoma cells express low levels of EGFR and are therefore not subject to this feedback activation. Consistent with this, we find that ectopic expression of EGFR in melanoma cells is sufficient to cause resistance to PLX4032. Our data suggest that BRAF(V600E) mutant colon cancers (approximately 8-10% of all colon cancers), for which there are currently no targeted treatment options available, might benefit from combination therapy consisting of BRAF and EGFR inhibitors.

Emergence of KRAS mutations and acquired resistance to anti-EGFR therapy in colorectal cancer

Abstract: A main limitation of therapies that selectively target kinase signalling pathways is the emergence of secondary drug resistance. Cetuximab, a monoclonal antibody that binds the extracellular domain of epidermal growth factor receptor (EGFR), is effective in a subset of KRAS wild-type metastatic colorectal cancers. After an initial response, secondary resistance invariably ensues, thereby limiting the clinical benefit of this drug. The molecular bases of secondary resistance to cetuximab in colorectal cancer are poorly understood. Here we show that molecular alterations (in most instances point mutations) of KRAS are causally associated with the onset of acquired resistance to anti-EGFR treatment in colorectal cancers. Expression of mutant KRAS under the control of its endogenous gene promoter was sufficient to confer cetuximab resistance, but resistant cells remained sensitive to combinatorial inhibition of EGFR and mitogen-activated protein-kinase kinase (MEK). Analysis of metastases from patients who developed resistance to cetuximab or panitumumab showed the emergence of KRAS amplification in one sample and acquisition of secondary KRAS mutations in 60% (6 out of 10) of the cases. KRAS mutant alleles were detectable in the blood of cetuximab-treated patients as early as 10 months before radiographic documentation of disease progression. In summary, the results identify KRAS mutations as frequent drivers of acquired resistance to cetuximab in colorectal cancers, indicate that the emergence of KRAS mutant clones can be detected non-invasively months before radiographic progression and suggest early initiation of a MEK inhibitor as a rational strategy for delaying or reversing drug resistance.

HER2 amplification: a potential mechanism of acquired resistance to EGFR inhibition in EGFR-mutant lung cancers that lack the second-site EGFRT790M mutation.

Abstract: EGFR-mutant lung cancers eventually become resistant to treatment with EGFR tyrosine kinase inhibitors (TKIs). The combination of EGFR-TKI afatinib and anti-EGFR antibody cetuximab can overcome acquired resistance in mouse models and human patients. Since afatinib is also a potent HER2 inhibitor, we investigated the role of HER2 in EGFR-mutant tumor cells. We show in vitro and in vivo that afatinib plus cetuximab significantly inhibits HER2 phosphorylation. HER2 overexpression or knockdown confers resistance or sensitivity, respectively, in all studied cell line models. Fluorescent in situ hybridization analysis revealed that HER2 was amplified in 12% of tumors with acquired resistance versus only 1% of untreated lung adenocarcinomas. Notably, HER2 amplification and EGFR T790M were mutually exclusive. Collectively, these results reveal a previously unrecognized mechanism of resistance to EGFR TKIs and provide a rationale to assess the status and possibly target HER2 in EGFR mutant tumors with acquired resistance to EGFR TKIs.

EGFR expression as a predictor of survival for first-line chemotherapy plus cetuximab in patients with advanced non-small-cell lung cancer: analysis of data from the phase 3 FLEX study

Abstract: Summary Background Findings from the phase 3 First-Line ErbituX in lung cancer (FLEX) study showed that the addition of cetuximab to first-line chemotherapy significantly improved overall survival compared with chemotherapy alone (hazard ratio [HR] 0·871, 95% CI 0·762–0·996; p=0·044) in patients with advanced non-small-cell lung cancer (NSCLC). To define patients benefiting most from cetuximab, we studied the association of tumour EGFR expression level with clinical outcome in FLEX study patients. Methods We used prospectively collected tumour EGFR expression data to generate an immunohistochemistry score for FLEX study patients on a continuous scale of 0–300. We used response data to select an outcome-based discriminatory threshold immunohistochemistry score for EGFR expression of 200. Treatment outcome was analysed in patients with low (immunohistochemistry score Findings Tumour EGFR immunohistochemistry data were available for 1121 of 1125 (99·6%) patients from the FLEX study ITT population. High EGFR expression was scored for 345 (31%) evaluable patients and low for 776 (69%) patients. For patients in the high EGFR expression group, overall survival was longer in the chemotherapy plus cetuximab group than in the chemotherapy alone group (median 12·0 months [95% CI 10·2–15·2] vs 9·6 months [7·6–10·6]; HR 0·73, 0·58–0·93; p=0·011), with no meaningful increase in side-effects. We recorded no corresponding survival benefit for patients in the low EGFR expression group (median 9·8 months [8·9–12·2] vs 10·3 months [9·2–11·5]; HR 0·99, 0·84–1·16; p=0·88). A treatment interaction test assessing the difference in the HRs for overall survival between the EGFR expression groups suggested a predictive value for EGFR expression (p=0·044). Interpretation High EGFR expression is a tumour biomarker that can predict survival benefit from the addition of cetuximab to first-line chemotherapy in patients with advanced NSCLC. Assessment of EGFR expression could offer a personalised treatment approach in this setting. Funding Merck KGaA.

Phase III Trial of Cetuximab With Continuous or Intermittent Fluorouracil, Leucovorin, and Oxaliplatin (Nordic FLOX) Versus FLOX Alone in First-Line Treatment of Metastatic Colorectal Cancer: The NORDIC-VII Study

Abstract: Purpose The NORDIC-VII multicenter phase III trial investigated the efficacy of cetuximab when added to bolus fluorouracil/folinic acid and oxaliplatin (Nordic FLOX), administered continuously or intermittently, in previously untreated metastatic colorectal cancer (mCRC). The influence of KRAS mutation status on treatment outcome was also investigated. Patients and Methods Patients were randomly assigned to receive either standard Nordic FLOX (arm A), cetuximab and FLOX (arm B), or cetuximab combined with intermittent FLOX (arm C). Primary end point was progression-free survival (PFS). Overall survival (OS), response rate, R0 resection rate, and safety were secondary end points. Results Of the 571 patients randomly assigned, 566 were evaluable in intention-to-treat (ITT) analyses. KRAS and BRAF mutation analyses were obtained in 498 (88%) and 457 patients (81%), respectively. KRAS mutations were present in 39% of the tumors; 12% of tumors had BRAF mutations. The presence of BRAF mutations was a strong negative prognostic factor. In the ITT population, median PFS was 7.9, 8.3, and 7.3 months for the three arms, respectively (not significantly different). OS was almost identical for the three groups (20.4, 19.7, 20.3 months, respectively), and confirmed response rates were 41%, 49%, and 47%, respectively. In patients with KRAS wild-type tumors, cetuximab did not provide any additional benefit compared with FLOX alone. In patients with KRAS mutations, no significant difference was detected, although a trend toward improved PFS was observed in arm B. The regimens were well tolerated.

Identification of a mutation in the extracellular domain of the Epidermal Growth Factor Receptor conferring cetuximab resistance in colorectal cancer

Abstract: Antibodies against epidermal growth factor receptor (EGFR)--cetuximab and panitumumab--are widely used to treat colorectal cancer. Unfortunately, patients eventually develop resistance to these agents. We describe an acquired EGFR ectodomain mutation (S492R) that prevents cetuximab binding and confers resistance to cetuximab. Cells with this mutation, however, retain binding to and are growth inhibited by panitumumab. Two of ten subjects studied here with disease progression after cetuximab treatment acquired this mutation. A subject with cetuximab resistance harboring the S492R mutation responded to treatment with panitumumab.

TBCRC 001: Randomized Phase II Study of Cetuximab in Combination With Carboplatin in Stage IV Triple-Negative Breast Cancer

Abstract: Purpose Epidermal growth factor receptor (EGFR) is a targetable receptor frequently overexpressed in basal-like breast cancer, which comprises most triple-negative breast cancers (TNBCs), the only subtype without established targeted therapy. Patients and Methods In this randomized phase II trial, patients with metastatic TNBC received anti-EGFR antibody cetuximab (400 mg/m2 load then 250 mg/m2 per week intravenously [IV]) alone, with carboplatin (area under the curve of 2, once per week IV) added after progression or as concomitant therapy from the beginning. Response rate (RR) was the primary end point; others included time to progression (TTP), overall survival (OS), and toxicity. Embedded correlative studies included molecular subtyping on archival tissue. Fresh tumor tissue before and after 7 to 14 days of therapy was used for microarray analyses exploring EGFR pathway activity and inhibition. Results In 102 patients with TNBC, RRs were 6% (two of 31) to cetuximab and 16% (four of 25) to cetuximab pl...

Effect of oxaliplatin, fluorouracil, and leucovorin with or without cetuximab on survival among patients with resected stage III colon cancer: a randomized trial.

Abstract: Context Leucovorin, fluorouracil, and oxaliplatin (FOLFOX) is the standard adjuvant therapy for resected stage III colon cancer. Adding cetuximab to FOLFOX benefits patients with metastatic wild-type KRAS but not mutated KRAS colon cancer. Objective To assess the potential benefit of cetuximab added to the modified sixth version of the FOLFOX regimen (mFOLFOX6) in patients with resected stage III wild-type KRAS colon cancer. Design, Setting, and Participants A randomized trial of 2686 patients aged 18 years or older at multiple institutions across North America enrolled following resection and informed consent between February 10, 2004, and November 25, 2009. The primary randomized comparison was 12 biweekly cycles of mFOLFOX6 with and without cetuximab. KRAS mutation status was centrally determined. The trial was halted after a planned interim analysis of 48% of predicted events (246/515) occurring in 1863 (of 2070 planned) patients with tumors having wild-type KRAS. A total of 717 patients with mutated KRAS and 106 with indeterminate KRAS were accrued. The 2070 patients with wild-type KRAS provided 90% power to detect a hazard ratio (HR) of 1.33 (2-sided α = .05), with planned interim efficacy analyses after 25%, 50%, and 75% of expected relapses. Main Outcome Measures Disease-free survival in patients with wild-type KRAS mutations. Secondary end points included overall survival and toxicity. Results Median (range) follow-up was 28 (0-68) months. The trial demonstrated no benefit when adding cetuximab. Three-year disease-free survival for mFOLFOX6 alone was 74.6% vs 71.5% with the addition of cetuximab (HR, 1.21; 95% CI, 0.98-1.49; P = .08) in patients with wild-type KRAS, and 67.1% vs 65.0% (HR, 1.12; 95% CI, 0.86-1.46; P = .38) in patients with mutated KRAS, with no significant benefit in any subgroups assessed. Among all patients, grade 3 or higher adverse events (72.5% vs 52.3%; odds ratio [OR], 2.4; 95% CI, 2.1-2.8; P Conclusion Among patients with stage III resected colon cancer, the use of cetuximab with adjuvant mFOLFOX6 compared with mFOLFOX6 alone did not result in improved disease-free survival. Trial Registration clinicaltrials.gov Identifier: NCT00079274

Multicenter Randomized Phase II Clinical Trial Comparing Neoadjuvant Oxaliplatin, Capecitabine, and Preoperative Radiotherapy With or Without Cetuximab Followed by Total Mesorectal Excision in Patients With High-Risk Rectal Cancer (EXPERT-C)

Abstract: Purpose To evaluate the addition of cetuximab to neoadjuvant chemotherapy before chemoradiotherapy in high-risk rectal cancer. Patients and Methods Patients with operable magnetic resonance imaging-defined high-risk rectal cancer received four cycles of capecitabine/oxaliplatin (CAPOX) followed by capecitabine chemoradiotherapy, surgery, and adjuvant CAPOX (four cycles) or the same regimen plus weekly cetuximab (CAPOX + C). The primary end point was complete response (CR; pathologic CR or, in patients not undergoing surgery, radiologic CR) in patients with KRAS/BRAF wild-type tumors. Secondary end points were radiologic response (RR), progression-free survival (PFS), overall survival (OS), and safety in the wild-type and overall populations and a molecular biomarker analysis. Results One hundred sixty-five eligible patients were randomly assigned. Ninety (60%) of 149 assessable tumors were KRAS or BRAF wild type (CAPOX, n = 44; CAPOX + C, n = 46), and in these patients, the addition of cetuximab did not improve the primary end point of CR (9% v 11%, respectively; P = 1.0; odds ratio, 1.22) or PFS (hazard ratio [ HR], 0.65; P = .363). Cetuximab significantly improved RR (CAPOX v CAPOX + C: after chemotherapy, 51% v 71%, respectively; P = .038; after chemoradiation, 75% v 93%, respectively; P = .028) and OS (HR, 0.27; P = .034). Skin toxicity and diarrhea were more frequent in the CAPOX + C arm. Conclusion Cetuximab led to a significant increase in RR and OS in patients with KRAS/BRAF wild-type rectal cancer, but the primary end point of improved CR was not met.

Association of KRAS G13D Tumor Mutations With Outcome in Patients With Metastatic Colorectal Cancer Treated With First-Line Chemotherapy With or Without Cetuximab

Abstract: Purpose We investigated in the first-line setting our previous finding that patients with chemorefractory KRAS G13D‐mutated metastatic colorectal cancer (mCRC) benefit from cetuximab treatment. Methods Associations between tumor KRAS mutation status (wild-type, G13D, G12V, or other mutations) and progression-free survival (PFS), survival, and response were investigated in pooled data from 1,378 evaluable patients from the CRYSTAL and OPUS studies. Multivariate analysis correcting for differences in baseline prognostic factors was performed. Results Of 533 patients (39%) with KRAS-mutant tumors, 83 (16%) had G13D, 125 (23%) had G12V, and 325 (61%) had other mutations. Significant variations in treatment effects were found for tumor response (P .005) and PFS (P.046) in patients with G13D-mutant tumors versus all other mutations (including G12V). Within KRAS mutation subgroups, cetuximab plus chemotherapy versus chemotherapy alone significantly improved PFS (median, 7.4 v 6.0 months; hazard ratio [HR], 0.47; P .039) and tumor response (40.5% v 22.0%; odds ratio, 3.38; P .042) but not survival (median, 15.4 v 14.7 months; HR, 0.89; P .68) in patients with G13D-mutant tumors. Patients with G12V and other mutations did not benefit from this treatment combination. Patients with KRAS G13D‐mutated tumors receiving chemotherapy alone experienced worse outcomes (response, 22.0% v 43.2%; odds ratio, 0.40; P .032) than those with other mutations. Effects were similar in the separate CRYSTAL and OPUS studies. Conclusion The addition of cetuximab to first-line chemotherapy seems to benefit patients with KRAS G13D‐mutant tumors. Relative treatment effects were similar to those in patients with KRAS wild-type tumors but with lower absolute values. J Clin Oncol 30. © 2012 by American Society of Clinical Oncology

Characterization of a large panel of patient-derived tumor xenografts representing the clinical heterogeneity of human colorectal cancer.

Abstract: Purpose: Patient-derived xenograft models are considered to represent the heterogeneity of human cancers and advanced preclinical models. Our consortium joins efforts to extensively develop and characterize a new collection of patient-derived colorectal cancer (CRC) models. Experimental Design: From the 85 unsupervised surgical colorectal samples collection, 54 tumors were successfully xenografted in immunodeficient mice and rats, representing 35 primary tumors, 5 peritoneal carcinoses and 14 metastases. Histologic and molecular characterization of patient tumors, first and late passages on mice includes the sequence of key genes involved in CRC (i.e., APC , KRAS , TP53 ), aCGH, and transcriptomic analysis. Results: This comprehensive characterization shows that our collection recapitulates the clinical situation about the histopathology and molecular diversity of CRC. Moreover, patient tumors and corresponding models are clustering together allowing comparison studies between clinical and preclinical data. Hence, we conducted pharmacologic monotherapy studies with standard of care for CRC (5-fluorouracil, oxaliplatin, irinotecan, and cetuximab). Through this extensive in vivo analysis, we have shown the loss of human stroma cells after engraftment, observed a metastatic phenotype in some models, and finally compared the molecular profile with the drug sensitivity of each tumor model. Through an experimental cetuximab phase II trial, we confirmed the key role of KRAS mutation in cetuximab resistance. Conclusions: This new collection could bring benefit to evaluate novel targeted therapeutic strategies and to better understand the basis for sensitivity or resistance of tumors from individual patients. Clin Cancer Res; 18(19); 5314–28. ©2012 AACR .

Quantitative Cell-Free DNA, KRAS, and BRAF Mutations in Plasma from Patients with Metastatic Colorectal Cancer during Treatment with Cetuximab and Irinotecan

Abstract: Purpose: The present study investigated the levels of circulating cell-free DNA (cfDNA) in plasma from patients with metastatic colorectal cancer (mCRC) in relation to third-line treatment with cetuximab and irinotecan and the quantitative relationship of cfDNA with tumor-specific mutations in plasma. Experimental Design: Inclusion criteria were histopathologically verified chemotherapy-resistant mCRC, adequate Eastern Cooperative Oncology Group performance status, and organ function. Treatment consisted of irinotecan being administered at 350 mg/m 2 for 3 weeks and weekly administration of 250 mg/m 2 cetuximab until progression or unacceptable toxicity. A quantitative PCR method was developed to assess the number of cfDNA alleles and KRAS and BRAF mutation alleles in plasma at baseline. Results: The study included 108 patients. Only three patients were positive for BRAF mutations. The majority of KRAS mutations detected in tumors were also found in the plasma [32 of 41 (78%)]. Plasma cfDNA and plasma mutant KRAS levels (pm KRAS ) were strongly correlated ( r = 0.85, P −4 ). The disease control rate was 77% in patients with low cfDNA ( 75% quartile ( P = 0.009)]. Patients with pm KRAS levels higher than 75% had a disease control rate of 0% compared with 42% in patients with lower pm KRAS ( P = 0.048). Cox analysis confirmed the prognostic importance of both cfDNA and pm KRAS. High levels were clear indicators of a poor outcome. Conclusions: KRAS analysis in plasma is a viable alternative to tissue analysis. Quantitative levels of cfDNA and pm KRAS are strongly correlated and hold promise of clinical application. Clin Cancer Res; 18(4); 1177–85. ©2012 AACR .

Mutant KRAS Codon 12 and 13 Alleles in Patients With Metastatic Colorectal Cancer: Assessment As Prognostic and Predictive Biomarkers of Response to Panitumumab

Abstract: Purpose Panitumumab, a fully human monoclonal antibody targeting the epidermal growth factor receptor (EGFR), has demonstrated significant improvements in progression-free survival (PFS) in patients with wild-type KRAS metastatic colorectal cancer (mCRC) in studies 20050203 (first line), 20050181 (second line), and 20020408 (monotherapy). Mutations in KRAS codons 12 and 13 are recognized biomarkers that predict lack of response to anti-EGFR antibody therapies. This retrospective analysis of three randomized phase III studies assessed the prognostic and predictive impact of individual mutant KRAS codon 12 and 13 alleles. Patients and Methods Patients were randomly assigned 1:1 to FOLFOX4 (infusional fluorouracil, leucovorin, and oxaliplatin) in study 20050203, FOLFIRI (fluorouracil, leucovorin, and irinotecan) in study 20050181, or best supportive care in study 20020408 with or without panitumumab 6.0 mg/kg once every 2 weeks. In all, 441 (20050203), 486 (20050181), and 126 (20020408) patients with mutant ...

Antitumor Activity of BRAF Inhibitor Vemurafenib in Preclinical Models of BRAF-Mutant Colorectal Cancer

Abstract: The protein kinase BRAF is a key component of the RAS-RAF signaling pathway which plays an important role in regulating cell proliferation, differentiation, and survival. Mutations in BRAF at codon 600 promote catalytic activity and are associated with 8% of all human (solid) tumors, including 8% to 10% of colorectal cancers (CRC). Here, we report the preclinical characterization of vemurafenib (RG7204; PLX4032; RO5185426), a first-in-class, specific small molecule inhibitor of BRAF(V600E) in BRAF-mutated CRC cell lines and tumor xenograft models. As a single agent, vemurafenib shows dose-dependent inhibition of ERK and MEK phosphorylation, thereby arresting cell proliferation in BRAF(V600)-expressing cell lines and inhibiting tumor growth in BRAF(V600E) bearing xenograft models. Because vemurafenib has shown limited single-agent clinical activity in BRAF(V600E)-mutant metastatic CRC, we therefore explored a range of combination therapies, with both standard agents and targeted inhibitors in preclinical xenograft models. In a BRAF-mutant CRC xenograft model with de novo resistance to vemurafenib (RKO), tumor growth inhibition by vemurafenib was enhanced by combining with an AKT inhibitor (MK-2206). The addition of vemurafenib to capecitabine and/or bevacizumab, cetuximab and/or irinotecan, or erlotinib resulted in increased antitumor activity and improved survival in xenograft models. Together, our findings suggest that the administration of vemurafenib in combination with standard-of-care or novel targeted therapies may lead to enhanced and sustained clinical antitumor efficacy in CRCs harboring the BRAF(V600E) mutation.

Current treatment options for metastatic head and neck cancer.

Abstract: Head and neck squamous cell carcinoma is now the 8th most common cancer affecting men in the United States largely due to a rising epidemic of oropharynx cancer (tonsil and tongue base) associated with the human papillomavirus (HPV). The median overall survival for recurrent or metastatic head and neck cancer (R/M HNSCC) remains less than 1 year despite modern chemotherapy and targeted agents. Palliative chemotherapy and the epidermal growth factor receptor inhibitor, cetuximab, constitute the backbone of treatment for patients with R/M HNSCC. Platinum doublets studied in phase III trials include cisplatin/5-FU, cisplatin/paclitaxel, and cisplatin/pemetrexed. Platinum chemotherapy in combination with 5-fluorouracil and cetuximab has resulted in the longest median overall survival. Combination platinum regimens increase response rates and toxicity but not survival and should be reserved for patients who are symptomatic from their disease for whom the benefit of a partial response may be worth the cost of increased treatment-related side effects. For many patients who are asymptomatic with a low disease burden, single agent regimens are appropriate to balance treatment with side effects. Drugs commonly used as single agents in the treatment of R/M HNSCC include docetaxel, paclitaxel, cetuximab, capecitabine, pemetrexed, and methotrexate. Best supportive care alone is often appropriate for poor performance status patients. Palliative radiation therapy is beneficial for treating symptomatic metastatic sites. Aggressive symptom management is imperative for all patients and often should include referral to experts in palliative care and pain management. New therapies currently under investigation include mTOR inhibitors, anti-angiogenic agents, and IGF1R inhibitors. Given the poor prognosis for most patients with R/M HNSCC, enrollment in clinical trials investigating novel approaches to therapy should be encouraged.

Inhibition of MEK and PI3K/mTOR Suppresses Tumor Growth but Does Not Cause Tumor Regression in Patient-Derived Xenografts of RAS-Mutant Colorectal Carcinomas

Abstract: Purpose: Gene mutations along the Ras pathway ( KRAS , NRAS , BRAF , PIK3CA ) occur in approximately 50% of colorectal cancers (CRC) and correlate with poor response to anti–EGF receptor (EGFR) therapies. We assessed the effects of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK) and phosphoinositide 3-kinase (PI3K)/mTOR inhibitors, which neutralize the major Ras effectors, in patient-derived xenografts from RAS/RAF/PIK3CA-mutant metastatic CRCs (mCRC). Experimental Design: Forty mCRC specimens harboring KRAS , NRAS , BRAF , and/or PIK3CA mutations were implanted in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. Each xenograft was expanded into four treatment arms: placebo, the MEK inhibitor AZD6244, the PI3K/mTOR inhibitor, BEZ235, or AZD6244 + BEZ235. Cases initially treated with placebo crossed over to AZD6244, BEZ235, and the anti-EGFR monoclonal antibody cetuximab. Results: At the 3-week evaluation time point, cotreatment of established tumors with AZD6244 + BEZ235 induced disease stabilization in the majority of cases (70%) but did not lead to overt tumor regression. Monotherapy was less effective, with BEZ235 displaying higher activity than AZD6244 (disease control rates, DCRs: AZD6244, 27.5%; BEZ235, 42.5%). Triple therapy with cetuximab provided further advantage (DCR, 88%). The extent of disease control declined at the 6-week evaluation time point (DCRs: AZD6244, 13.9%; BEZ235, 16.2%; AZD6244 + BEZ235, 34%). Cross-analysis of mice harboring xenografts from the same original tumor and treated with each of the different modalities revealed subgroups with preferential sensitivity to AZD6244 (12.5%), BEZ235 (35%), or AZD6244 + BEZ235 (42.5%); another subgroup (10%) showed equivalent response to any treatment. Conclusions: The prevalent growth-suppressive effects produced by MEK and PI3K/mTOR inhibition suggest that this strategy may retard disease progression in patients. However, data offer cautionary evidence against the occurrence of durable responses. Clin Cancer Res; 18(9); 2515–25. ©2012 AACR.

EGFR activation is a potential determinant of primary resistance of hepatocellular carcinoma cells to sorafenib.

Abstract: Sorafenib is currently the medical treatment of reference for hepatocellular carcinoma (HCC), but it is not known whether sorafenib is equally active in all HCC Here, our aim was to explore intrinsic differences in the response of HCC cells to sorafenib, to identify potential mechanisms leading to primary resistance to this treatment We analyzed a panel of six human HCC cell lines and compared the activity of the main oncogenic kinase cascades, their clonogenic potential, proliferation and apoptosis upon exposure to sorafenib We report that HCC cells present important differences in their response to sorafenib, and that some cell lines are more resistant to the actions of sorafenib than others We identify the activated epidermal growth factor receptor (EGFR) as a parameter that promotes the resistance of HCC cells to sorafenib In resistant cells, the efficacy of sorafenib was increased when EGFR was inhibited, as was demonstrated using two chemical inhibitors (erlotinib or gefitinib), a monoclonal antibody directed against EGFR (cetuximab), and RNA interference directed against EGFR A combination of EGFR inhibitors and sorafenib affords a better control over HCC proliferation, most likely through an improved blockade of the RAF kinases Our findings therefore confirm the importance of RAF kinases as therapeutic targets in HCC, and identify EGFR as a determinant of the sensitivity of HCC cells to sorafenib Our findings bear possible implications for the improvement of the efficacy of sorafenib in HCC, and might be useful for the identification of predictive biomarkers in this context

Targeting Stat3 Abrogates EGFR Inhibitor Resistance in Cancer

Abstract: Purpose: EGF receptor (EGFR) is upregulated in most epithelial cancers where signaling through EGFR contributes to cancer cell proliferation and survival. The limited clinical efficacy of EGFR inhibitors suggests that identification of resistance mechanisms may identify new pathways for therapeutic targeting. STAT3 is upregulated in many cancers and activated via both EGFR-dependent and -independent pathways. In the present study, we tested the consequences of STAT3 inhibition in EGFR inhibitor–resistant head and neck squamous cell carcinoma (HNSCC) and bladder cancer models to determine whether STAT3 blockade can enhance responses to EGFR targeting. Experimental Design: pSTAT3 expression was assessed in human HNSCC tumors that recurred following cetuximab treatment. Cetuximab-sensitive and -resistant cell lines were treated with a STAT3 decoy to determine EC 50 concentrations and the effects on STAT3 target gene expression by Western blotting. In vivo assays included evaluation of antitumor efficacy of STAT3 decoy in cetuximab-sensitive and -resistant models followed by immunoblotting for STAT3 target protein expression. Results: Targeting STAT3 with a STAT3 decoy reduced cellular viability and the expression of STAT3 target genes in EGFR inhibitor resistance models. The addition of a STAT3 inhibitor to EGFR blocking strategies significantly enhanced antitumor effects in vivo . Biopsies from HNSCC tumors that recurred following cetuximab treatment showed increased STAT3 activation compared with pretreatment biopsies. Conclusions: These results suggest that STAT3 activation contributes to EGFR inhibitor resistance both in HNSCC and bladder cancer where concomitant targeting of STAT3 may represent an effective treatment strategy. Clin Cancer Res; 18(18); 4986–96. ©2012 AACR .

Intrapatient Cetuximab Dose Escalation in Metastatic Colorectal Cancer According to the Grade of Early Skin Reactions: The Randomized EVEREST Study

Abstract: PURPOSE: Skin toxicity in patients receiving cetuximab has been associated positively with clinical outcome in several tumor types. This study investigated the effect of cetuximab dose escalation in patients with irinotecan-refractory metastatic colorectal cancer who had developed no or mild skin reactions after 21 days of treatment at the standard dose. This article reports clinical and pharmacokinetic (PK) data. PATIENTS AND METHODS: After 21 days of standard-dose cetuximab (400 mg/m(2) initial dose, then 250 mg/m(2) per week) plus irinotecan, patients with ≤ grade 1 skin reactions were randomly assigned to standard-dose (group A) or dose-escalated (to 500 mg/m(2) per week; group B) cetuximab. Patients with ≥ grade 2 skin reactions continued on standard-dose cetuximab plus irinotecan (group C). RESULTS: The intent-to-treat population comprised 157 patients. PK profiles reflected the dose increase and were predictable across the dose range investigated. Weekly cetuximab doses of up to 500 mg/m(2) were well tolerated, and grade 3 and 4 adverse events were generally comparable between treatment groups. Dose escalation (n = 44) was associated with an increase in skin reactions ≥ grade 2 compared with standard (n = 45) dosing (59% v 38%, respectively). Dose escalation, compared with standard dosing, showed some evidence for improved response rate (30% v 16%, respectively) and disease control rate (70% v 58%, respectively) but no indication of benefit in relation to overall survival. In an exploratory analysis, dose escalation seemed to increase response rate compared with standard dosing in patients with KRAS wild-type but not KRAS mutant tumors. CONCLUSION: Cetuximab serum concentrations increased predictably with dose. Higher dose levels were well tolerated. The possible indication for improved efficacy in the dose-escalation group warrants further investigation.

Targeting EGFR in pancreatic cancer treatment.

Abstract: The prognosis of patients with pancreatic cancer is extremely poor, and current systemic therapies provide marginal survival benefits for treated patients. The era of targeted therapies has offered a new avenue to search for potentially more effective strategies. Epidermal growth factor receptor (EGFR) is a member of the erbB/human epidermal growth factor receptor family of tyrosine kinases, which includes erbB2/HER2, erbB3/HER3 and erbB4/HER4. Epidermal growth factor receptor overexpression may be detected in up to 90% of pancreatic tumors. Two pharmacologic approaches have been successfully used to inhibit epidermal growth factor receptor function in cancer treatment: neutralizing monoclonal antibodies and small molecule tyrosine inhibitors. The randomized trials studying the addition of EGFR targeted agents to gemcitabine compared with gemcitabine alone have been disappointing, although results with the EGFR tyrosine kinase inhibitor erlotinib were statistically significant but clinically of marginal benefit. In this article, we review the epidermal growth factor receptor signaling network in pancreatic cancer, the strategies to increase the effectiveness of epidermal growth factor receptor inhibitors, and the clinical trials of these inhibitors in pancreatic cancer.

Are KRAS/BRAF mutations potent prognostic and/or predictive biomarkers in colorectal cancers?

Abstract: KRAS and BRAF mutations lead to the constitutive activation of EGFR signaling through the oncogenic Ras/Raf/Mek/Erk pathway. Currently, KRAS is the only potential biomarker for predicting the efficacy of anti-EGFR monoclonal antibodies (mAb) in colorectal cancer (CRC). However, a recent report suggested that the use of cetuximab was associated with survival benefit among patients with p.G13D-mutated tumors. Furthermore, although the presence of mutated BRAF is one of the most powerful prognostic factors for advanced and recurrent CRC, it remains unknown whether patients with BRAF-mutated tumors experience a survival benefit from treatment with anti-EGFR mAb. Thus, the prognostic or predictive relevance of the KRAS and BRAF genotype in CRC remains controversial despite several investigations. Routine KRAS/BRAF screening of pathological specimens is required to promote the appropriate clinical use of anti-EGFR mAb and to determine malignant phenotypes in CRC. The significance of KRAS/BRAF mutations as predictive or prognostic biomarkers should be taken into consideration when selecting a KRAS/BRAF screening assay. This article will review the spectrum of KRAS/BRAF genotype and the impact of KRAS/BRAF mutations on the clinicopathological features and prognosis of patients with CRC, particularly when differentiating between the mutations at KRAS codons 12 and 13. Furthermore, the predictive role of KRAS/BRAF mutations in treatments with anti-EGFR mAb will be verified, focusing on KRAS p.G13D and BRAF mutations.

Targeting the epidermal growth factor receptor in non-small cell lung cancer cells: the effect of combining RNA interference with tyrosine kinase inhibitors or cetuximab

Abstract: Background The epidermal growth factor receptor (EGFR) is a validated therapeutic target in non-small cell lung cancer (NSCLC). However, current single agent receptor targeting does not achieve a maximal therapeutic effect, and some mutations confer resistance to current available agents. In the current study we have examined, in different NSCLC cell lines, the combined effect of RNA interference targeting the EGFR mRNA, and inactivation of EGFR signaling using different receptor tyrosine kinase inhibitors (TKIs) or a monoclonal antibody cetuximab.

Phase II Trial of Cetuximab With or Without Paclitaxel in Patients With Advanced Urothelial Tract Carcinoma

Abstract: Purpose The benefit of salvage chemotherapy is modest in metastatic urothelial cancer. We conducted a randomized, noncomparative phase II study to measure the efficacy of cetuximab with or without paclitaxel in patients with previously treated urothelial cancer. Patients and Methods Patients with metastatic urothelial cancer who received one line of chemotherapy in the perioperative or metastatic setting were randomly assigned to 4-week cycles of cetuximab 250 mg/m2 with or without paclitaxel 80 mg/m2 per week. We used early progression as an indicator of futility. Either arm would close if seven of the initial 15 patients in that arm progressed at the first disease evaluation at 8 weeks. Results We enrolled 39 evaluable patients. The single-agent cetuximab arm closed after nine of the first 11 patients progressed by 8 weeks. The combination arm completed the full accrual of 28 patients, of whom 22 patients (78.5%) had visceral disease. Twelve of 28 patients had progression-free survival greater than 16 w...