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Cancer Therapy: Preclinical |
Tobacco Related Malignancy Program, University of Colorado Cancer Center, Departments of 1 Radiation Oncology, 2 Medicine, 3 Pathology, and 4 Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, CO; and 5 Department of Medicine "F. Magrassi", Second University of Naples, Naples, Italy
Requests for reprints: David Raben, Department of Radiation Oncology, Anschutz Cancer Pavilion, University of Colorado Health Sciences Center, 1665 North Ursula Street, F706, Aurora, CO 80010-0510. Phone: 720-848-0116; Fax: 720-848-0222; E-mail: david.raben{at}uchsc.edu.
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ABSTRACT |
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 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Experimental Design: We evaluated the EGFR status of a panel of human NSCLC cancer cell lines by immunohistochemistry and flow cytometry. We then evaluated cetuximab effects on growth, cell cycle distribution, and downstream intracellular signaling molecules in this panel of NSCLC cancer cell lines. NSCLC cell lines were treated with cetuximab alone or in combination with radiation, chemotherapy, or chemoradiation to determine the cooperative effects of cetuximab both in vitro and in vivo in athymic nude mice bearing NSCLC xenografts.
Results: Cetuximab alone inhibited the in vitro growth of some but not all EGFR-expressing NSCLC cell lines in a dose-dependent manner. Flow cytometric analysis of cell cycle distribution after 24 hours of cetuximab treatment revealed a shift into the G0/G1 phase of the cell cycle in cetuximab-sensitive EGFR-expressing cell lines and at concentrations that were growth-inhibitory. There were no cell cycle changes in the EGFR-negative cell lines. After 4 hours of exposure, cetuximab reduced epidermal growth factor (EGF)-induced phosphorylation of EGFR (pEGFR) and HER-2 (pHER2) in cetuximab-sensitive cell lines but not in cetuximab-resistant cell lines. Cetuximab reduced EGF-induced phosphorylation of extracellular signal-regulated kinase-1/2 (pERK) in all EGFR-expressing cell lines. In the absence of EGF, cetuximab alone increased the level of pEGFR and pHER2 above that seen in untreated control cells in both sensitive and resistant cell lines that were EGFR- and HER2-positive, but not in EGFR- or HER2-negative lines. Despite the cetuximab-induced increase in phosphorylation of EGFR and HER2, peak EGF-induced levels of pEGFR and pHER2 were reduced by cetuximab in the cetuximab-sensitive lines but not in the resistant lines. Cooperative (combination index values < 1.0) growth inhibitory effects were observed in vitro combination assays with cetuximab and radiation only in cetuximab-sensitive NSCLC cell lines. A lack of cooperation was seen in cetuximab-insensitive NSCLC cell lines. Similar findings were observed with in vitro combination studies of cetuximab plus cisplatin or paclitaxel. In nude mice bearing EGFR-expressing, cetuximab-sensitive, NSCLC cell line xenografts, cetuximab plus radiation induced a marked improvement in tumor growth inhibition over either agent alone. The growth inhibitory effects of cetuximab-radiation were similar to the growth inhibitory effects of concurrent chemoradiation. Triple combination therapy of cetuximab and chemoradiation yielded a nonsignificant advantage in tumor growth control over doublet combinations (cetuximab and radiation or chemoradiation) in vivo.
Conclusions: Similar results in tumor growth inhibition observed in mice treated with cetuximab-radiation and cisplatin-radiation provide a rationale for the clinical investigation of cetuximab with concurrent radiation in selected patients with locally advanced NSCLC. Local tumor control and treatment toxicity should be evaluated between cetuximab-radiation and chemoradiation regimens. Proper patient selection will be critical to the success of such trials and further studies are needed to identify optimal patient selection criteria.
Key Words: Epidermal growth factor receptor • angiogenesis • apoptosis • cooperative effects
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INTRODUCTION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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One such target is the epidermal growth factor receptor (EGFR), which is widely expressed in NSCLC (4–6). NSCLCs often produce and secrete transforming growth factor-
, amphiregulin, and epidermal growth factor (EGF), which bind to and activate cell surface EGFR (7). Interfering with the EGFR signaling pathway may counteract lung cancer growth. Inhibitors of the EGFR signaling pathway include monoclonal antibodies to the EGFR and small molecule receptor tyrosine kinase inhibitors, which are discussed in great detail in recent reviews (8, 9). Several EGFR-targeted antibodies and receptor tyrosine kinase inhibitors have entered clinical trials in patients with advanced lung cancer. Gefitinib, a receptor tyrosine kinase inhibitor, received Food and Drug Administration approval in May 2003 for use in advanced NSCLC patients refractory to chemotherapy. Under investigation in NSCLC is cetuximab, a chimeric human-mouse monoclonal antibody that binds to the EGFR and inhibits the growth of EGFR-expressing cancer cell lines in vitro and in vivo in athymic nude mice (10, 11).
Although the effectiveness of biological agents, including EGFR inhibitors, as monotherapy may be limited in patients with advanced cancer, it is rational to consider combining agents such as cetuximab with proven therapies such as radiation. Radiation activates EGFR signaling leading to radioresistance by inducing cell proliferation and enhanced DNA repair (12). In addition, the level of EGFR expression is inversely related to the effectiveness of radiation therapy to control cancer cell growth (13). This inverse relationship has important implications in treatment strategies designed to control EGFR-expressing cancer cell clones that survive radiation. Studies have been undertaken to determine whether blocking EGFR signaling improves radiation cytotoxicity. Additive or synergistic (cooperative) growth inhibition was observed when cetuximab was combined with radiotherapy (and chemotherapy) in several preclinical models (14–18).
Because there is little information on the role of EGFR inhibitors with radiation in NSCLC, we investigated the growth inhibitory effects of cetuximab alone and in combination with radiation and/or chemotherapy in NSCLC cell lines in vitro and in vivo in athymic nude mice bearing NSCLC cell line xenografts. We evaluated the relationship between EGFR expression and cetuximab-induced effects on cell cycle distribution, activated signal protein expression, and growth inhibition. We found that cetuximab enhanced the effects of radiation and chemotherapy, both in vitro and in vivo but only in cell lines sensitive to cetuximab alone. In our studies, we observed that in cells that contained no EGFR or HER2 expression, no response was seen to cetuximab in vitro or in vivo. These studies lay the foundation for further combined treatment studies in locally advanced NSCLC patients, especially those sensitive to cetuximab.
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MATERIALS AND METHODS |
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Chemicals and Cetuximab. Paclitaxel was provided by Bristol Myers Squibb (Princeton, NJ) and cisplatin was obtained from Sigma Chemical, Co., St. Louis, MO. Cetuximab was generously provided by ImClone Systems, Inc. (New York, NY).
EGFR Cell Surface Expression by Flow Cytometry and Immunohistochemistry. Cells (5 x 105) were incubated with cetuximab, or an isotype-matched control monoclonal antibody (human myeloma IgG1, Sigma). The cells were counterstained with goat anti-human IgG-FITC (Southern Biotechnology, Birmingham, AL). All staining was done on ice for 45 minutes followed by three washes in Hanks balanced salt solution + 5% fetal bovine serum. Following staining, the cell fluorescence was measured by flow cytometry (Coulter EPICS-XL-MCL, Hialeah, FL). Using the Coulter software, the percentage of positive cells and the median fluorescence intensity (MFI) was determined. The MFIs were standardized for comparison using the following formula: [(MFI-EGFR) – (MFI-Isotype Control)/(MFI-Isotype Control)].
For immunohistochemical analysis, the cell lines were centrifuged into a cell pellet and embedded in paraffin. Antigen retrieval was done at 95°C in citrate buffer for 40 minutes. The slides were cooled to room temperature for 20 minutes, washed thrice for 3 minutes with Tris-buffer, peroxidase-blocked for 5 minutes, and washed as above. The NSCLC cell lines were then incubated for 30 minutes with the primary antibody, anti-EGFR clone 31G7 (Zymed, San Francisco, CA), followed by the secondary antibody (Visualization Reagent) followed by the substrate-chromogen solution (3,3'-diaminobenzidine) and finally counterstained with hematoxylin. Two pathologists (W. Franklin and F. Hirsch) independently quantified EGFR-specific cell membrane staining as 0 to 3+.
Growth Inhibition of NSCLC Cells by Cetuximab Alone. The growth inhibitory effects of cetuximab alone and the effects of cetuximab with radiation, cisplatin, or paclitaxel were evaluated using a modified tetrazolium salt (MTT) assay (19). In the MTT assay, 1,000 to 2,000 viable cells were plated in 100 µL of growth medium in 96-well plates (Corning, Ithaca, NY). Following an overnight incubation, cetuximab was added in varying concentrations and incubated for 6 to 7 days. The tetrazolium salt was added at a concentration of 0.4 mg/mL to each well following the 6- to 7-day treatment. The plates were incubated with the salt for 4 hours at 37°C. At 4 hours, the medium was aspirated off, leaving the dark blue formazan product at the bottom of the wells. The reduced MTT product was solubilized by adding 100 µL of 0.2 N HCl in 75% isopropanol, 23% MilliQ water to each well. Thorough mixing was done using a Titertek multichannel pipetman. The absorbency of each well was measured using an automated plate reader (Molecular Devices, Sunnyvale, CA). All experiments were done in triplicate.
Cell Cycle Distribution. The effects of cetuximab alone on cell cycle distribution were determined by flow cytometric analysis. Cells were stained with saponin/propidium iodide/RNase solution and analyzed by fluorescence-activated cell sorting (FACS) using a Coulter EPICS and ModFit software (Verity House software, Topsham, MN).
Western Blot Analysis. NCI-H292, NCI-H322, NCI-H157, and A549 cells were seeded to reach 80% confluency and then were treated for 4 hours with 100 nmol/L of cetuximab alone or followed by a 15-minute incubation with EGF 10 ng/mL. Precleared cellular lysates were separated on a 4% to 12% SDS-PAGE gel and transferred to polyvinylidene difluoride paper. Protein concentration was determined using the DC Microplate Protein Assay (Bio-Rad, Hercules, CA) and 50 µg of protein was loaded for each sample. Immunoblots for phosphorylated proteins were blocked in 3% protease-free bovine serum albumin (fraction V) (ICN, Aurora, OH) for 1 hour and probed with the following antibodies from Cell Signaling Technology (Beverly, MA): -phospho-Akt (Ser473) antibody 9271, -phospho-EGFR (Tyr1068) antibody 2234, phospho-EGFR (Tyr845) antibody 2231, phospho-EGFR (Tyr992) antibody 2235, phospho-EGFR (Tyr1045) antibody 2237, -phospho-p44/42 extracellular signal-regulated kinase (ERK) 1/2 (Thr202/Tyr204) antibody 9101, and -phospho-HER2 (Tyr877) antibody 2241S. Immunoblots for unphosphorylated proteins were blocked for 1 hour with 10% nonfat dry milk and probed with the following antibodies from Cell Signaling Technology: -EGFR antibody 2232, -HER2 antibody 2242, -Akt antibody 9275, and -p44/42 ERK 1/2 antibody 9102. The immunoblots were detected by Vistra Western enhanced chemiluminescence-Plus Blotting Kit (Amersham, Piscataway, NJ) and visualized with a Storm 860 Fluorimager (Molecular Dynamics, Sunnyvale, CA).
Growth Inhibition of NSCLC Cells by Cetuximab in Combination Studies with Radiation or Chemotherapy. MTT growth assays as described above were used to evaluate cetuximab in combination with radiation and chemotherapy. Following an overnight incubation, cetuximab and cytotoxic chemotherapy agents or radiation were added in varying concentrations and incubated for 6 to 7 days. Cetuximab was added 24 hours prior to radiation. The results from the combination assays were analyzed using the isobologram combination index method of Chou and Talalay (20). Combination indices (CI) < 0.9 are indicative of synergistic interactions between the two agents, additive interactions are indicated by CIs of 0.9 to 1.0 and a CI of > 1.1 indicates antagonism between the two agents. Cooperative effects were considered as interactions with a CI < 1.0. All experiments were done in triplicate.
In vivo NSCLC Mouse Tumor Model Studies. Athymic nude mice (4 to 6-week-old females) were obtained from the National Cancer Institute (Bethesda, MD). All animal procedures and maintenance were conducted in accordance with the institutional guidelines of the University of Colorado Health Sciences Center. For radiation studies with cetuximab, 2 x 106 human H292 or 5 x 106 H520 NSCLC cells were injected into the flanks of the mice at day 0. Animals were divided into four groups: control, cetuximab, radiation, and cetuximab combined with radiation. Cetuximab was delivered i.p. in 100 µL, twice a week for 2 to 4 weeks at 1 mg/dose depending on the experiment. Control animals were treated i.p. with the same volume of PBS. Radiation was given as a single 8 Gy fraction using a linear accelerator with customized blocking to treat only the flank containing the NSCLC xenograft. In the combination studies of cisplatin and cetuximab with and without radiation, the radiation treatment was fractionated in the H292 xenografts (5 Gy fractions twice a week for 2 weeks) and a single fraction (8 Gy) in the H520 xenografts. Cisplatin was given i.p. at 8 mg/kg twice a week for 2 weeks in both models. Cetuximab was given as above in this series of experiments. Tumor volume measurements were evaluated twice a week in all experiments by caliper and calculated by the formula: V = 3.14 (smaller diameter)2 (larger diameter)/6.
Statistics. A 
2 test was done to compare the fraction of cells in G0/G1 to the S + G2-M phase of the cell cycle. In the animal experiments, the mean difference in tumor volumes were compared among treatment groups at the time treatment began, the day treatment stopped, and the last day of tumor measurements using a one-way ANOVA and adding random animal effects.
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RESULTS |
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90% of cells staining positively for EGFR. The MFI of EGFR cell membrane staining by FACS, ranged from 0 to 21. Figure 1A-D and Table 1 shows the results of the immunohistochemical and FACS analyses. By FACS analysis, five cell lines had an MFI >8 and 90% of the cell population staining positive for EGFR and all were 3+ for EGFR expression by immunohistochemistry. The intensity of EGFR staining by FACS was greater in H292 cells as compared with H332, A549, H157, and Calu3 cells. One NSCLC cell line in our panel, H520, was negative for EGFR expression in both assays. The H358 cell line had the lowest EGFR expression by FACS (89% EGFR+, MFI 4.8).
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As shown in Fig. 4, cetuximab alone also increased the level of p-EGFR at other tyrosine residues above control levels in the cetuximab-sensitive cell line H322. Cetuximab increased the level of p-EGFR at Tyr845, Tyr992, and Tyr1068 above control levels. Cetuximab alone had no effect on p-EGFR Tyr1045 a major docking site for c-Cbl, which results in receptor ubiquitination and degradation. EGF induced significant phosphorylation at Tyr1045 compared with both control and cetuximab-treated cells.
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In vivo Combination Treatment with Cetuximab and Radiation in NSCLC Xenografts. Based on the in vitro studies, we evaluated the effects of cetuximab (i.p.) in combination with single fraction radiation on H292 (EGFR-MFI 21) and H520 (EGFR-MFI 0) tumors propagated in the flanks of athymic nude mice. Treatment began on day 22 when the H292 tumors had reached 3 cm3. On day 60, post-tumor cell implantation, cetuximab alone (1 mg i.p. twice a week for 4 weeks) modestly delayed H292 tumor growth over vehicle control (3.5 versus 5.3 cm3, respectively). The differences in tumor volume were not significant, as shown in Fig. 6A and Table 4. Single fraction radiation alone (8 Gy/week for 2 weeks) produced a slight growth delay but again the differences in H292 tumor growth were not significantly different from controls (5.1 versus 5.3 cm3, respectively). Cetuximab + 8 Gy radiation reduced H292 tumor size on day 60 (1.8 cm3) compared with controls (5.3 cm3) and 8 Gy radiation alone (5.1 cm3) or cetuximab alone (3.5 cm3). However, the difference was only significant for cetuximab + RT versus control (P = 0.005) and cetuximab + RT versus radiation alone (P = 0.015).
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DISCUSSION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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(7). Some of these studies suggested that increased expression of EGFR was associated with a worse prognosis in stage IV patients but this was not universally observed (5, 21–25) . We found that EGFR expression by immunohistochemistry or fluorescence in situ hybridization did not correlate with survival (26). In addition, mutations and/or true gene amplification of the EGFR gene in NSCLC are uncommon. Inhibitors of EGFR, such as the monoclonal antibody cetuximab, were shown to inhibit the growth of some EGFR over-expressing cell lines of various histologies including NSCLC both in vitro and in vivo (8–11). Other studies indicated that combinations of cetuximab with radiation and chemotherapeutic agents produced synergistic growth inhibition in EGFR-expressing and cetuximab-sensitive cell lines both in vitro and in vivo (12, 27–31). The mechanism of growth inhibition seemed to be the inhibition of EGF-induced downstream signaling pathways. Although there are no published single agent data with cetuximab in advanced NSCLC, recent clinical studies indicated that gefitinib produced objective responses in a small minority of advanced chemorefractory NSCLC patients (32, 33). In these NSCLC patients, response did not correlate with EGFR expression level, and combinations of chemotherapy and gefitinib or erlotinib did not improve outcome over chemotherapy alone in untreated stage IV NSCLC patients (34, 35). What do our studies add to this information?
Our studies showed that cetuximab inhibited the growth of some, EGFR-expressing cell lines and that cetuximab sensitivity did not clearly correlate with EGFR expression levels. In our studies, cetuximab failed to inhibit the growth of EGFR-null cell lines. In cetuximab-sensitive cell lines, changes in EGF-induced activated cell signal protein expression were noted at 4 hours after exposure. These early changes in phosphorylation of activated cell signal proteins were followed by a G1 arrest that was apparent at 24 hours and lasted through at least 72 hours. These changes appeared only in cell lines that responded to cetuximab.
EGFR expression did not predict changes in phosphorylation states, G1 arrest, or growth inhibition, but there was a correlation between changes in phosphorylation of signal proteins, G1 arrest, and growth inhibition. For example, the cell lines H322 and A549 have similar expression levels of EGFR, but cetuximab produced greater changes in signal protein phosphorylation, G1 arrest and growth inhibition in H322 cells then in the A549 cells. H322 cells express the HER-2 receptor in addition to the EGFR, whereas the A549 line has extremely low HER2 expression. Cetuximab inhibited EGF-induced phosphorylation of HER2 as well as EGFR in the H322 cells but to a lesser degree in the A549 cells. Thus, expression of other erbB family receptors may be one factor affecting sensitivity to EGFR inhibitors.
Other factors affecting sensitivity to EGFR inhibitors may include autocrine production of EGF and transforming growth factor-, or mutations in or expression levels of downstream signaling proteins such as ras, PTEN, Akt, or STAT-3. Recent studies seem to corroborate the latter hypothesis. Persistent signaling of either the mitogen-activated protein kinase or phosphatidylinositol 3'-kinase/Akt pathways or both were observed in serum-starved NSCLC cell lines treated with either cetuximab or gefitinib for 2 hours followed by EGF for 5 minutes (36). The moderately cetuximab-sensitive cell lines H358 and A549 and the cetuximab-resistant line H157 have a mutant ras gene, whereas the cetuximab-sensitive line H322 has wild-type ras suggesting wild-type ras may also play a role in cetuximab sensitivity (ATCC.org). PTEN expression however, does not seem to account for differences in cetuximab sensitivity, as H157 (cetuximab-resistant) does not express PTEN, whereas both H292 (cetuximab-sensitive), and A549 (moderate cetuximab sensitivity) express PTEN (37). Additional studies to assess the effect of ras mutations and PTEN expression are needed. We have insufficient data from these cell lines to determine which of these factors, if any, plays the most important role in predicting sensitivity to EGFR inhibitors.
We found that cetuximab alone enhanced the level of basal phosphorylation of EGFR and HER2 in EGFR-expressing NSCLC lines. This enhancement of basal phosphorylation of EGFR was not observed with gefitinib treatment (data not shown). The phosphorylation of the EGFR induced by cetuximab alone was still associated with a G1 arrest and growth inhibition in cetuximab-sensitive cell lines. Therefore, cetuximab did not induce normal EGF-induced survival signaling. Furthermore, cetuximab inhibited EGF-induced signaling as described above in RESULTS.
Prior studies indicated that the combination of cetuximab with radiotherapy produced synergistic growth inhibition in cell lines of other tumor types (14–18). Invariably, these studies were done in cetuximab-sensitive cell lines. Our studies reported here show that the combination of cetuximab with radiation produces cooperative interactions (additivity, CI, 0.9-1; or synergy, CI, < 0.9) in cetuximab-sensitive cell lines such as H292 and H322, and in the moderately cetuximab-sensitive line A549. Synergy was also seen with radiation in the cetuximab-sensitive line Calu3 and in the moderately sensitive line H358 (data not shown). Despite the fact that H157 does not respond well to cetuximab alone, some evidence for additivity (CI, 0.86-1.0) was observed in combination with cetuximab and radiation. Additivity to antagonism (CI, 0.96-1.2) was noted in the H520 cell line, which neither expresses EGFR nor responds to cetuximab.
The combination results between cetuximab and cisplatin or paclitaxel were similar in pattern and magnitude. Synergistic to moderately synergistic interactions were observed with chemotherapy in the cetuximab-sensitive cell lines (H292, H322, and Calu3) and in the moderately cetuximab-sensitive cell lines (H358, A549) and additivity to antagonism was observed in the cetuximab-resistant cell lines (H157, H520).
Our studies indicated similar tumor growth inhibition between animals bearing cetuximab-sensitive NSCLC xenografts treated with cetuximab-radiation and cisplatin-radiation. No tumor growth inhibition was observed in mice bearing cetuximab-insensitive xenografts. Therefore, it may be reasonable to consider clinical trials that compare targeted therapy in combination with radiation to conventional chemoradiation regimens with regards to toxicity (which can be substantial in chemoradiation regimens) and response rates.
Our preclinical results indicate that it could be beneficial to combine cetuximab with standard therapy regimens for NSCLC for some patients but detrimental in other patients. It is possible that these observations could account for the negative results in the INTACT 1-2 trials and a recent trial comparing erlotinib and chemotherapy to chemotherapy alone (34, 35). In contrast to the negative chemotherapy + EGFR-TKIs trials sited above, recent combination clinical trials of cetuximab and docetaxel showed promising response rates in chemorefractory NSCLC patients (40). Phase III studies of cetuximab and concurrent chemotherapy as first line therapy in EGFR-positive advanced stage NSCLC patients also showed positive response benefits over chemotherapy alone (41). Based on positive phase III trial outcomes in patients with advanced, chemorefractory colon cancer, cetuximab has recently been approved by the Food and Drug Administration for treatment with concurrent chemotherapy in patients with advanced colon cancer.
From a radiation therapy standpoint, cetuximab combined with radiation showed encouraging response rates with no significant increase in toxicity in a phase I study in locally advanced head and neck cancer (42). Results from a completed phase III trial comparing radiation alone to radiation plus cetuximab in head and neck cancer are pending.
The studies presented in this manuscript suggest that it is critical to give combination cetuximab chemo or radiation therapy to a select group of patients and that selection of patients for clinical trials based on EGFR expression alone may not be helpful. The need for preselection of patients based on biologic/genetic factors that predict sensitivity/resistance is likely to be true for combinations of cetuximab with radiation in combination with radiation and chemotherapy. Studies are ongoing in our laboratory and other laboratories to define and validate tumor markers that will predict sensitivity or resistance to EGFR inhibitors. These studies are evaluating genes and proteins identified through gene expression profiling and proteomic analysis that are involved in EGFR signaling pathways as well as novel genes and proteins.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 4/16/04; accepted 6/29/04.
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REFERENCES |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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is frequent in resectable non-small cell lung cancer but does not predict tumor progression. Clin Cancer Res 1997;3:515–22.[Abstract]
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F. M. Johnson, B. Saigal, M. Talpaz, and N. J. Donato Dasatinib (BMS-354825) Tyrosine Kinase Inhibitor Suppresses Invasion and Induces Cell Cycle Arrest and Apoptosis of Head and Neck Squamous Cell Carcinoma and Non-Small Cell Lung Cancer Cells Clin. Cancer Res., October 1, 2005; 11(19): 6924 - 6932. [Abstract] [Full Text] [PDF]
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 J. D. Minna, M. J. Peyton, and A. F. Gazdar Gefitinib Versus Cetuximab in Lung Cancer: Round One J Natl Cancer Inst, August 17, 2005; 97(16): 1168 - 1169. [Full Text] [PDF]
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T. Mukohara, J. A. Engelman, N. H. Hanna, B. Y. Yeap, S. Kobayashi, N. Lindeman, B. Halmos, J. Pearlberg, Z. Tsuchihashi, L. C. Cantley, et al. Differential Effects of Gefitinib and Cetuximab on Non-small-cell Lung Cancers Bearing Epidermal Growth Factor Receptor Mutations J Natl Cancer Inst, August 17, 2005; 97(16): 1185 - 1194. [Abstract] [Full Text] [PDF]
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