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

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

Primary resistance to cetuximab therapy in EGFR FISH-positive colorectal cancer patients

The impact of KRAS mutations on cetuximab sensitivity in epidermal growth factor receptor fluorescence in situ hybridisation-positive (EGFR FISH+) metastatic colorectal cancer patients (mCRC) has not been previously investigated. In the present study, we analysed KRAS, BRAF, PI3KCA, MET, and IGF1R in 85 mCRC treated with cetuximab-based therapy in whom EGFR status was known. KRAS mutations (52.5%) negatively affected response only in EGFR FISH+ patients. EGFR FISH+/KRAS mutated had a significantly lower response rate (P=0.04) than EGFR FISH+/KRAS wild type patients. Four EGFR FISH+ patients with KRAS mutations responded to cetuximab therapy. BRAF was mutated in 5.0% of patients and none responded to the therapy. PI3KCA mutations (17.7%) were not associated to cetuximab sensitivity. Patients overexpressing IGF1R (74.3%) had significantly longer survival than patients with low IGF1R expression (P=0.006), with no difference in response rate. IGF1R gene amplification was not detected, and only two (2.6%) patients, both responders, had MET gene amplification. In conclusion, KRAS mutations are associated with cetuximab failure in EGFR FISH+ mCRC, even if it does not preclude response. The rarity of MET and IGF1R gene amplification suggests a marginal role in primary resistance. The potential prognostic implication of IGF1R expression merits further evaluation.     

Gefitinib (ZD1839): therapy in selected patients with non-small cell lung cancer (NSCLC)?

PURPOSE: To evaluate response rate, toxicity and epidermal growth factor (EGFR) mutations and gene copy number as outcome predictive factors in Italian patients with non-small cell lung cancer (NSCLC) treated with gefitinib (Iressa) in an expanded access program (EAP). PATIENTS AND METHODS: A total of 137 patients with advanced NSCLC received gefitinib as first line treatment or after failure of chemotherapy. In 43 cases, tissue specimens were available for EGFR status evaluation: immunohistochemical (IHC) for EGFR, fluorescence in situ hybridisation (FISH) or Chromogenic in situ hybridisation (CISH)-(ISH) analysis for EGFR and HER2 gene copy number, and PCR-DNA sequencing for mutational analysis of EGFR were performed. RESULTS: In the study population, response rate (PR) was 13%; disease stabilization (DS) 26%; overall disease control rate 39%; median survival 6.3 months and time to progression 2.7 months. Toxicity was mild (G3 skin toxicity in 3% and G3 liver toxicity in 4% of patients). An EGFR-mutation was detected in 9/43 patients: Eight deletions in exon 19 and 1 missense mutation in exon 21. Increased gene copy number for EGFR and/or HER2 was detected in 17/43 patients. Response rate was significantly higher in women, non-smokers, in mutation carriers than in wild type carriers, in EGFR-trisomy/polysomy carriers and HER2-trisomy/polysomy carriers. CONCLUSIONS: In this study, response rate and toxicity to gefitinib treatment were consistent with previously reported data for whites. Female gender, absence of smoking history, EGFR-mutations, EGFR and HER2-polysomy were significantly associated with response to gefitinib therapy in NSCLC patients.     

Integrating anti-EGFR therapies in metastatic colorectal cancer

Colorectal cancer remains one of the most common causes of cancer diagnoses and mortality in the United States. The treatment of metastatic colorectal cancer has evolved significantly over the last decade with near-tripling of patient survival rate. A significant contribution to this outcome was the advent of novel targeted agents, such as the epidermal growth factor (EGFR) inhibitors. In an era of emphasis on refining therapy, the presence of KRAS mutation will predict for resistance and limit exposure to patients who are more likely to benefit. In contrast, the presence of BRAF mutations does not seem to have a predictive value. Agents that are thought to reverse resistance to EGFR inhibitors such as those targeting PI3K, c-MET or IGF-1R are currently under study.EGFR inhibitors have exhibited single agent activity, and seem to synergize very well with standard chemotherapy except for cetuximab and 5-fluorouracil, leucovorin, oxaliplatin (FOLFOX). Preliminary data suggests that EGFR inhibitors have similar effectiveness to vascular endothelial growth factor (VEGF) inhibitors in the first line setting. Skin toxicity remains the main limiting factor for the utilization of EGFR inhibitors, but strategies including the use of agents such as minocycline or doxycycline added to topical care seem to limit the severity of the rash.Key Words: Epidermal growth factor inhibitors (EGFR inhibitor), metastatic colorectal cancer (mCRC), cetuximab, panitumumab, KRAS, targeted therapy     

Epidermal growth factor receptor activation: how exon 19 and 21 mutations changed our understanding of the pathway.

The discovery of epidermal growth factor receptor (EGFR) mutations in never-smokers has been the most relevant finding ever in non-small cell lung cancer. When patients whose tumors bear the sensitizing mutations are treated with the tyrosine kinase inhibitors gefitinib or erlotinib, we witness response rates and durations never before reported, including complete responses. At the same time, the presence of EGFR mutations has raised numerous new questions, tantalizing data, and new challenges for treatment. This is particularly true as we try to generalize the findings in lung cancer to other malignancies. The indiscriminate use of gefitinib or erlotinib in the general lung cancer population results in meager survival benefit for patients. Similarly, the tyrosine kinase inhibitors have limited activity in a variety of tumor types with EGFR overexpression. This has led to the question of whether EGFR remains a viable target in patients other than those whose tumors contain mutations, and whether the modest activity of cetuximab in colorectal cancer and head and neck cancer represents all that we can expect from inhibition of this pathway in the absence of mutation. Mechanisms of pathway activation other than mutation have been discovered in recent years, and include overexpression mediated by gene amplification or by amplification of a dinucleotide repeat in the EGFR promoter, mutation of an extracellular region on EGFR generating a mutant protein termed EGFRvIII, and enhanced signaling due to heterodimerization with other members of the EGFR family, particularly overexpression of HER2/HER3. The extent to which these paths to EGFR activation will confer sensitivity to the tyrosine kinase inhibitors or to EGFR monoclonal antibodies is being explored. Thus far, published clinical data suggest that there is little room for the administration of gefitinib or erlotinib in the absence of EGFR mutations. The five articles in this edition of CCR Focus will address the various mechanisms of EGFR pathway activation and provide insight into the potential for translation into clinical relevance.     

Overview of the current status of human epidermal growth factor receptor inhibitors in lung cancer

Although chemotherapy remains the standard of care for lung cancer, new less toxic drugs are urgently needed. Targeted agents represent a new era in cancer therapy, and non-small-cell lung cancer (NSCLC) is at the forefront of many development programs. An exciting target is the human epidermal growth factor receptor (EGFR, ie, HER1), and agents targeting this receptor, including gefitinib, cetuximab, and erlotinib (OSI-774; Tarceva), are being investigated. These agents have antitumor activity and are less toxic than most therapies. Based on phase II data, gefitinib received US approval for third-line treatment of patients with locally advanced or metastatic NSCLC. Cetuximab is licensed in the United States for patients with metastatic colorectal carcinoma. However, erlotinib, recently approved in the United States for second- and third-line treatment of patients with locally advanced or metastatic NSCLC, is the only agent of this class to improve survival as monotherapy in patients with advanced, refractory NSCLC, as shown in a phase III placebo-controlled trial. Phase III trials of erlotinib and gefitinib combined with chemotherapy were disappointing, which could be the result of drug scheduling, chemotherapy combinations, or other factors. Patient characteristics may also affect outcome, and research is ongoing to identify predictive markers of response to enable patient selection and improve outcome. Recently identified mutations within the HER1/EGFR tyrosine kinase (TK) domain may provide insight into why some patients respond rapidly to HER1/EGFR tyrosine kinase inhibitors. Surrogate markers of efficacy are also being investigated, including rash, which could be used to monitor and optimize antitumor activity. Therefore, although more work is required, data indicate that HER1/EGFR inhibitors will play an important role in treating patients with NSCLC.     

Epidermal growth factor receptor mutations and gene amplification in non-small-cell lung cancer: molecular analysis of the IDEAL/INTACT gefitinib trials.

PURPOSE: Most cases of non-small-cell lung cancer (NSCLC) with dramatic responses to gefitinib have specific activating mutations in the epidermal growth factor receptor (EGFR), but the predictive value of these mutations has not been defined in large clinical trials. The goal of this study was to determine the contribution of molecular alterations in EGFR to response and survival within the phase II (IDEAL) and phase III (INTACT) trials of gefitinib. PATIENTS AND METHODS: We analyzed the frequency of EGFR mutations in lung cancer specimens from both the IDEAL and INTACT trials and compared it with EGFR gene amplification, another genetic abnormality in NSCLC. RESULTS: EGFR mutations correlated with previously identified clinical features of gefitinib response, including adenocarcinoma histology, absence of smoking history, female sex, and Asian ethnicity. No such association was seen in patients whose tumors had EGFR amplification, suggesting that these molecular markers identify different biologic subsets of NSCLC. In the IDEAL trials, responses to gefitinib were seen in six of 13 tumors (46%) with an EGFR mutation, two of seven tumors (29%) with amplification, and five of 56 tumors (9%) with neither mutation nor amplification (P = .001 for either EGFR mutation or amplification v neither abnormality). Analysis of the INTACT trials did not show a statistically significant difference in response to gefitinib plus chemotherapy according to EGFR genotype. CONCLUSION: EGFR mutations and, to a lesser extent, amplification appear to identify distinct subsets of NSCLC with an increased response to gefitinib. The combination of gefitinib with chemotherapy does not improve survival in patients with these molecular markers.     

Annual Review of Advances in Lung Cancer Clinical Research: A Report for the Year 2009

The use of positron emission tomography compared with conventional staging increases the detection of extrathoracic metastases and reduces the number futile thoracotomies in patients being evaluated for surgical resection. Long-term follow-up of one of the two adjuvant chemotherapy trials revealed a continued overall survival (OS) benefit to adjuvant chemotherapy. In locally advanced non-small cell lung cancer, a phase III trial of chemoradiotherapy alone and with surgical resection revealed no statistically significant difference in OS between the treatment arms. In advanced stage non-small cell lung cancer, a phase III trial compared gefitinib with carboplatin and paclitaxel in a clinically enriched patient population for epidermal growth factor receptor (EGFR) tyrosine kinase (TK) mutations; among patients with an EGFR TK mutation, patients in gefitinib arm compared with carboplatin and paclitaxel arm experienced a statistically significant superior response rate and progression-free survival, and among patients without EGFR TK mutation patients in the gefitinib arm compared with carboplatin and paclitaxel experienced a statistically significant inferior response rate and progression-free survival. A phase III trial of platinum-based therapy with and without cetuximab in the first-line setting revealed improved OS in the cetuximab arm. A phase III trial of maintenance pemetrexed compared with placebo in patients who had not progressed after initial platinum-based therapy revealed an improvement in OS of patients in the pemetrexed arm with nonsquamous histology. In limited-stage small cell lung cancer, a phase III trial compared standard and high-dose prophylactic cranial irradiation and revealed no significant difference in the rate of brain metastases between the two treatment arms.     

Molecular alterations in tumors and response to combination chemotherapy with gefitinib for advanced colorectal cancer.

PURPOSE: Recently, activating mutations of the epidermal growth factor receptor (EGFR) gene were discovered in non-small cell lung cancers sensitive to gefitinib (ZD1839, an EGFR tyrosine kinase inhibitor) but not in gefitinib-resistant cancers. Abnormalities of EGFR and related pathways may have an effect on responsiveness of advanced colorectal cancer to combination chemotherapy with gefitinib. EXPERIMENTAL DESIGN: We examined patients with previously untreated metastatic colorectal cancer, who were enrolled into two phase I/II trials of combination chemotherapy (irinotecan, leucovorin, and 5-fluorouracil) and daily oral gefitinib. We obtained paraffin tissue blocks of primary tumors from 31 patients, sequenced the EGFR, KRAS, and BRAF genes, and did immunohistochemistry for EGFR, phosphorylated AKT1, p53, p21, and p27. RESULTS: Twelve (39%) of the 31 patients experienced a partial objective response to the therapy. A novel EGFR mutation in exon 18 (c.2170G>A, p.Gly724Ser) was identified in only one patient who did not experience an objective tumor response. EGFR immunohistochemistry was not predictive of responsiveness. In contrast, loss of p21 was associated with a higher response rate to therapy (P = 0.05). Moreover, the response rate among patients whose tumors maintained p21 expression and possessed a mutation in p53 was only 9% (1 of 11, P = 0.005). Overexpression of phosphorylated AKT1 also seemed to predict a trend towards resistance to the therapy. CONCLUSIONS: p21 expression in colorectal cancer, especially in combination with p53 mutation, is a predictor of resistance to the combination chemotherapy with gefitinib. Activating EGFR mutations are rare in colorectal cancer and do not seem to confer sensitivity to gefitinib and chemotherapy.     

Mechanisms of acquired resistance to cetuximab: role of HER (ErbB) family members

The epidermal growth factor receptor (EGFR) is a central regulator of proliferation and progression in human cancers. Five EGFR inhibitors, two monoclonal antibodies and three TKIs, have recently gained FDA approval in oncology (cetuximab, panitumumab, erlotinib, gefitinib and lapatinib). These strategies of EGFR inhibition demonstrate major tumor regressions in approximately 10-20% of advanced cancer patients. However, many tumors eventually manifest acquired resistance to treatment. In this study we established and characterized a model to study molecular mechanisms of acquired resistance to the EGFR monoclonal antibody cetuximab. Using high-throughput screening we examined the activity of 42 receptor tyrosine kinases in resistant tumor cells following chronic exposure to cetuximab. Cells developing acquired resistance to cetuximab exhibited increased steady-state EGFR expression secondary to alterations in trafficking and degradation. In addition, cetuximab-resistant cells manifested strong activation of HER2, HER3 and cMET. EGFR upregulation promoted increased dimerization with HER2 and HER3 leading to their transactivation. Blockade of EGFR and HER2 led to loss of HER3 and PI(3)K/Akt activity. These data suggest that acquired resistance to cetuximab is accompanied by dysregulation of EGFR internalization/degradation and subsequent EGFR-dependent activation of HER3. Taken together these findings suggest a rationale for the clinical evaluation of combinatorial anti-HER targeting approaches in tumors manifesting acquired resistance to cetuximab.     

晚期结直肠癌分子靶向治疗

晚期结直肠癌靶向治疗药物主要包括血管内皮生长因子抑制剂和表皮生长因子受体抑制剂.研究表明贝伐珠单抗和西妥昔单抗改善了晚期结直肠癌的预后,但在联合化疗药物方案的选择上稍有差异.西妥昔单抗和贝伐珠单抗改善K-ras野生型晚期结直肠癌患者总生存期相似.新的靶向药物阿柏西普、瑞格非尼等的出现,为晚期结直肠癌的靶向治疗提供了更多的选择.     

Molecular targeted therapy--non-small-cell lung cancer and gefitinib

Gefitinib (Iressa, ZD 1839) is an orally bioavailable small molecule that selectively inhibits epidermal growth factor receptor(EGFR) tyrosine kinase activity. Gefitinib causes a dramatic response in approximately 10% to 20% of patients with non-small-cell lung cancer (NSCLC) who receive prior chemotherapy. Studies of gefitinib in combination chemotherapy in first-line therapy of advanced NSCLC have, however, failed to show improvement of survival. Gefitinib also failed to prolong survival in a placebo controlled clinical trial for patients with pretreated advanced NSCLC. In addition, gefitinib did not improve survival as maintenance therapy after chemoradiation in patients with Stage III NSCLC. A possible explanation for the lack of a survival benefit seen in these studies might be failure to select of patients suitable for gefitinib treatment. Empirically, and also in phase II trials, a good clinical response has been observed most frequently in women, nonsmokers, patients with adenocarcinomas, and East Asian patients. Recently, mutations and amplifications of the EGFR gene identified in a subset of NSCLC have been reported to be useful for prediction of enhanced sensitivity to gefitinib. It is also known that some recurrent tumors have a secondary mutation in the EGFR kinase domain, T 790 M, conferring drug resistance. In Japan, a significant number of patients often develop fatal interstitial lung disease after the introduction of gefitinib, although it is, in general, well tolerated. In the future, we must demonstrated benefits of gefitinib treatment in prospective clinical trials by recruiting patients selected on the basis of biological characteristics. It is also important to further elucidate various issues that include other determinants of gefitinib sensitivity, other mechanisms of resistance to gefitinib or mechanisms or predictive factors of interstitial lung disease by close collaboration among clinicians and basic researchers.     

Analysis of HER-3, insulin growth factor-1, nuclear factor-kB and epidermal growth factor receptor gene copy number in the prediction of clinical outcome for K-RAS wild-type colorectal cancer patients receiving irinotecan-cetuximab

BackgroundA large proportion of colorectal cancer patients does not benefit from the use of anti-epidermal growth factor receptor (EGFR) treatment although in the absence of a mutation of the K-RAS gene. Preliminary observations suggested that HER-3, insulin-like growth factor-1 (IGF-1), nuclear factor-kB (NF-kB) and EGFR gene copy number (GCN) might identify patients not likely to benefit from anti-EGFR therapy. We tested the interaction between HER-3, IGF-1, NF-kB, EGFR GCN and K-RAS mutational analysis to verify the relative ability of these variables to identify a subgroup of patients more likely to benefit from EGFR-targeted treatment among those harbouring a K-RAS wild-type status.Patients and methodsWe retrospectively collected tumours from 168 patients with metastatic colorectal cancer treated with irinotecan–cetuximab. K-RAS was assessed with direct sequencing, EGFR amplification was assessed by chromogenic in situ hybridisation (CISH) and HER-3, IGF-1 and NF-kB were assessed by immunohistochemistry.ResultsIn patients with K-RAS wild-type tumours, the following molecular factors resulted independently associated with response rate: HER-3 [odds ratio (OR) = 4.6, 95% confidence interval (CI) 1.8–13.6, P = 0.02], IGF-1 (OR = 4.2, 95% CI 2–10.2, P = 0.003) and EGFR GCN (OR = 4.1, 95% CI 1.9–26.2, P = 0.04). These factors also independently correlated with overall survival as follows: HER-3 [hazard ratio (HR) = 0.4, 95% CI 0.28–0.85, P = 0.008], IGF-1 (HR = 0.47, 95% CI 0.24–0.76, P < 0.0001) and EGFR GCN (HR = 0.59, 95% CI 0.22–0.89, P = 0.04).DiscussionWe believe that our data may help further composing the molecular mosaic of EGFR-resistant tumours. The role of HER-3, IGF-1 and CISH EGFR GCN should be prospectively validated in clinical trials investigating anti-EGFR treatment strategies in colorectal cancer patients.     

Epidermal growth factor receptor as a therapeutic target in colorectal cancer

The epidermal growth factor receptor (EGFR) is widely expressed in advanced colorectal cancers (CRCs), and higher levels of EGFR are inversely related to survival in these patients. Two general strategies have been used to block EGFR signaling: preventing ligand binding with anti-EGFR monoclonal antibodies (eg, cetuximab and ABX-EGF) and inhibiting its intrinsic tyrosine kinase with small molecules (eg, gefitinib [Iressa] and erlotinib [OSI-774,Tarceva]). Phase II trials of cetuximab suggest that it might be an effective treatment option alone or in combination with standard therapies as first- or second-line therapy. Phase I studies evaluating other EGFR inhibitors in patients with CRC have been reported. The inclusion of anti-EGFR therapies into standard treatment is the subject of current clinical trials.     

Epidermal growth factor receptor targeting in cancer

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase of the ErbB family that is abnormally activated in many epithelial tumors. Several mechanisms lead to the receptor's aberrant activation that is observed in cancer, including receptor overexpression, mutation, ligand-dependent receptor dimerization, and ligand-independent activation. Two classes of anti-EGFR agents are currently approved for the treatment of patients with cancer: cetuximab, a monoclonal antibody directed at the extracellular domain of the receptor, and gefitinib and erlotinib, oral, low-molecular-weight (MW), adenosine triphosphate (ATP)-competitive inhibitors of the receptor's tyrosine kinase. Anti-EGFR monoclonal antibodies have demonstrated activity in the therapy of advanced colorectal carcinoma and in a variety of epithelial tumor types, including head and neck cancer and non-small cell lung cancer (NSCLC). The development of low MW, anti-EGFR tyrosine kinase inhibitors (TKIs) has been focused until recently on NSCLC, although responses have been reported for other types of cancer. Erlotinib was the only agent approved based on demonstrating improved survival, which was observed in patients with advanced NSCLC who previously had been treated with chemotherapy. Recent major advances in the EGFR field include the discovery of EGFR somatic mutations in NSCLC that have important implications for biology, treatment, clinical trial design, and methods for mutation detection. Clinical and survival benefits with anti-EGFR agents have been demonstrated in additional tumor types such as head and neck and pancreatic carcinomas. New agents with clinical activity are entering the clinic and new combinatorial approaches with anti-EGFR agents are being explored. Major efforts are, belatedly, attempting to identify molecular markers that can predict patients more likely to respond to anti-EGFR therapy.     

Lack of AKT activation in lung cancer cells with EGFR mutation is a novel marker of cetuximab sensitivity

Epidermal growth factor receptor (EGFR) mutation is the best marker of sensitivity to the EGFR tyrosine kinase inhibitor gefitinib, but a marker for the anti-EGFR antibody cetuximab has not been identified in lung cancer. The present study investigated markers for sensitivity to cetuximab. Sensitivity to cetuximab and gefitinib was compared with EGFR expression, EGFR and KRAS mutation, and EGFR gene copy numbers in lung cancer cell lines. We also studied the effect of these agents on the activation of EGFR, ERK, AKT, and STAT3 in cetuximab-sensitive and -resistant cell lines. We found one cetuximab-sensitive cell line with EGFR mutation among 19 lung cancer cell lines. Analysis of molecules downstream from EGFR revealed that AKT phosphorylation was suppressed in this cell line. Augmentation of AKT phosphorylation by transfection of a plasmid induced resistance to cetuximab. Acquisition of cetuximab resistance was associated with AKT activation in this cell line, while pharmacological inhibition of AKT markedly enhanced the growth inhibitory effect of cetuximab. Dephosphorylation of AKT in association with EGFR mutation is a candidate marker for sensitivity to cetuximab, and combined use of an AKT pathway inhibitor with cetuximab could be a novel therapeutic strategy for lung cancer.     

Use of Cetuximab After Failure of Gefitinib in Patients With Advanced Non–Small-Cell Lung Cancer

BackgroundGefitinib and cetuximab are both epidermal growth factor receptor (EGFR) target therapies used to treat patients with non–small-cell lung cancer (NSCLC) with different mechanisms. To clarify the effectiveness of cetuximab after failure of gefitinib treatment, we investigated the clinical features of patients with NSCLC who received cetuximab-containing chemotherapy after failure of gefitinib.Patients and MethodsWe analyzed the clinical data and mutational studies of patients with NSCLC in the National Taiwan University Hospital who had received gefitinib and, after failure of gefitinib, cetuximab-containing chemotherapy.ResultsFifteen patients who received cetuximab-containing chemotherapy after failure of gefitinib were identified. Four were responders to gefitinib therapy, and 3 were responders to cetuximab-containing chemotherapy. Ten were sequenced for EGFR and KRAS mutations. Six of the 10 patients had EGFR mutations, and all 10 patients had wild-type (WT) KRAS. In the 4 patients who had the gefitinib-resistant EGFR T790M mutation, 2 were responders to cetuximab-containing chemotherapy. The other cetuximab responder had WT EGFR.ConclusionCetuximab might add benefit in treatment after failure of gefitinib, regardless of EGFR mutational status. Treatment with cetuximab should be further explored, even in patients who have previously received gefitinib treatment.     

EGFR-directed monoclonal antibodies in non-small cell lung cancer

Several monoclonal antibodies directed against the epidermal growth factor receptor (EGFR) have been evaluated in patients with non-small cell lung cancer (NSCLC). Cetuximab, a chimeric monoclonal antibody, has been studied in combination with first-line chemotherapy in phase II and two phase III trials in patients with advanced NSCLC. The phase III FLEX trial demonstrated an increase in survival for cisplatin/vinorelbine plus cetuximab compared to chemotherapy alone in patients with advanced EGFR-expressing NSCLC. Cetuximab added to carboplatin/paclitaxel failed to improve progression-free survival in the BMS099 phase III trial. However, a meta-analysis of four randomized trials confirmed a significant survival benefit for platinum-based chemotherapy plus cetuximab compared to chemotherapy alone. High EGFR expression of tumor cells was then shown to predict the benefit of cetuximab, whereas KRAS mutations and EGFR fluorescent in situ hybridization analysis were without predictive value. Matuzumab and panitumumab have also been studied in phase II trials. Necitumumab, a fully human monoclonal antibody, is currently evaluated in combination with chemotherapy in two phase III trials in patients with advanced NSCLC. Cetuximab is also studied in combination with chemoradiotherapy in patients with locally advanced NSCLC.