Targeting epidermal growth factor receptor in the treatment of non-small-cell lung cancer

IMPORTANCE OF THE FIELD

The management of non-small-cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade, with the survival advantage demonstrated by the incorporation of anti-epidermal growth factor receptor (EGFR) agents to the standard treatment of advanced/metastatic NSCLC.

AREAS COVERED IN THIS REVIEW

We review the existing data regarding the distinct anti-EGFR agents in the NSCLC treatment and the potential role of the investigated biomarkers in the clinical outcome.

WHAT THE READER WILL GAIN

Tyrosine kinase inhibitors have been used in first-line, second-line and more settings with extremely good results in a subgroup of patients. Cetuximab remains the only anti-EGFR monoclonal antibody to show survival benefit when combined with a cytotoxic agent in the front-line setting. Anti-EGFR treatment is associated with a dramatic clinical benefit in a subgroup of patients, emphasizing the importance of customizing treatment. Several biomarkers have been investigated for their predictive or prognostic value. Validation of identification of biomarkers remains a focus of intense research that may ultimately guide therapeutic decision making, as none of these is considered ideal to discriminate responding from non-responding patients. However, the current evidence of the EGFR mutation analysis from a recent randomised trial suggests that EGFR mutation analysis is quite a good predictive marker for responsiveness to anti-EGFR TKIs. Moreover, the identification of surrogate markers to indicate optimal activity of the anti-EGFR agent is also needed. This review article provides data from large clinical trials using anti-EGFR agents and correlates these results with the tested biomarkers.

TAKE HOME MESSAGE

EGFR inhibition has shown very encouraging results and has improved the outcome of the NSCLC treatment. However, a plateau of significant clinical benefit seems to have been reached and we believe that the time to move away from the traditional treatment approach to more individualizing therapies has come.

Targeted therapies for non-small cell lung cancer: an evolving landscape

Over the past decade, a multitude of targeted agents have been explored in the treatment of advanced non-small cell lung cancer (NSCLC). Thus far, two broad classes of agents have been implemented in clinical practice: (a) vascular endothelial growth factor (VEGF)-directed therapies and (b) antagonists of the epidermal growth factor receptor (EGFR). In the former category, the agent bevacizumab (a monoclonal antibody) has shown landmark improvements in survival when added to cytotoxic therapy. Small molecule tyrosine kinase inhibitors (TKI) targeting the VEGF receptor (i.e., sunitinib, sorafenib, and vandetanib) show activity in phase II clinical studies. With respect to EGFR-directed therapies, the TKIs gefitinib and erlotinib have shown significant benefit, and have uncovered valuable information about the biology of lung cancer. Outside of therapies directed specifically at VEGF- and EGFR-mediated signaling, trials evaluating insulin-like growth factor-1 receptor (IGF-IR)-targeting agents, cyclooxygenase-2 (COX-2) inhibitors, c-met inhibitors, irreversible pan-HER inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase (HDAC) inhibitors are ongoing. Inhibitors of ALK show great promise in patients with the relevant gene translocation. Herein, the clinical development of novel therapies for NSCLC is described, including some discussion of relevant biomarkers and determination of synergy with both cytotoxic therapy and other targeted agents.

Targeted therapy in non-small-cell lung cancer--is it becoming a reality?

Treatment outcomes in advanced or metastatic non-small-cell lung cancer (NSCLC) remain unsatisfactory, with low long-term survival rates. Palliative chemotherapy offers a median survival not exceeding 1 year. To date, various combinations of cytotoxic drugs have not improved treatment results beyond what has been observed with platinum doublets. By contrast, molecular targeted drugs may block important pathways that drive cancer progression and achieve long-term disease control. Conflicting results have demonstrated marginal benefit with EGFR inhibitors, anti-EGFR monoclonal antibodies and antiangiogenic strategies in unselected populations of patients with advanced NSCLC. However, patients with an EGFR mutation are likely to respond to agents that target this gene. Novel targeted therapies that interfere with insulin-like growth factor 1 receptor, or the EML4-ALK fusion protein have shown promising activity. Aberrations in other key signaling pathways and molecules, such as RAS/RAF/MEK, PI3K/AKT/mTOR, or MET kinase, have been identified as crucial targets, especially in resistant patients. Novel drugs aimed at these abnormalities are already in the clinic. This Review outlines the current state-of-the-art research for targeted therapy in NSCLC.

Recent development of molecular-targeted drugs in lung cancer

Numerous molecular target drugs have been introduced for the treatment of advanced malignancies. In the treatment of lung cancer, epidermoid growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) demonstrate striking antitumor activity in selected EGFR mutation positive patients. Patient selection by biomarker is extremely important to obtain successful results. The anti-vascular endothelial growth factor (VEGF) antibody, bevacizumab, shows a markedly increased response rate, progression free survival of advanced non-squamous cell lung cancer when combined with cytotoxic drugs. The classification of lung cancer is rapidly changing based on the advances in molecular biology. Here, the recent development of new molecular target drugs against lung cancer is thoroughly reviewed in addition to EGFR-TKIs and bevacizumab with special emphasis on the clinical application.

The role of EGFR inhibition in the treatment of non-small cell lung cancer

The identification of certain molecular mechanisms underlying lung carcinogenesis and progression has led to the development of targeted agents against different families of growth factors and receptors. The epidermal growth factor receptor (EGFR) is one such target for therapeutic exploitation. Inhibition of EGFR downstream signaling can be accomplished through two primary mechanisms: (a) the direct blocking of intracellular kinase activity with small-molecule tyrosine kinase inhibitors (TKIs) (e.g., gefitinib, erlotinib) and (b) the blocking of EGFR ligand binding using antibodies directed against the extracellular domain of the receptor (e.g., cetuximab). Resistance to available EGFR-targeted treatments has emerged as a substantial clinical issue in non-small cell lung cancer (NSCLC). Several novel agents with the potential to overcome such resistance are currently in clinical development, including irreversible EGFR TKIs, monoclonal antibodies, and TKIs directed against multiple signaling pathways. Here we discuss the clinical application of the currently available EGFR-targeted agents in NSCLC, the underlying mechanisms of resistance, and the novel agents in clinical development that may overcome resistance.

Predictive value of EGFR and HER2 overexpression in advanced non-small-cell lung cancer

Epidermal growth factor receptor (EGFR) and HER2 are cell surface receptor tyrosine kinases (TKs) that transduce growth signals through dimerization with HER family receptors. The heterodimerization of EGFR with HER2 induces a more potent activation of EGFR TK than does EGFR homodimerization. When tumor cells overexpress both EGFR and HER2, they exhibit aggressive tumor cell growth, owing to the increased potential for EGFR/HER2 heterodimerization and signaling. Gefitinib and erlotinib are EGFR TK inhibitors (EGFR TKIs) and have antitumor activity in 8-18% of patients with advanced non-small-cell lung cancer (NSCLC). Certain patient subsets are particularly responsive to EGFR TKIs. Analyses of biomarkers from patients in clinical studies of EGFR TKIs show correlations between objective tumor response and EGFR overexpression, as detected by immunohistochemistry and increased gene copy number measured by fluorescence in situ hybridization analysis. Furthermore, NSCLC tumors that overexpress both EGFR and HER2 are more sensitive to EGFR TKIs than are tumors that overexpress EGFR but are HER2 negative. Therefore, the measurement of EGFR and HER2 protein expression and the gene copy number in NSCLC tumors may have a prognostic value in NSCLC and a predictive value for identifying patients likely to benefit from an EGFR TKI. These considerations suggest that the simultaneous inhibition of EGFR and HER2 may warrant further study in patients with NSCLC.

Dual inhibition of the epidermal growth factor receptor pathway with cetuximab and erlotinib: a phase I study in patients with advanced solid malignancies

PURPOSE

To determine the optimal dose of the antiepidermal growth factor receptor (EGFR) monoclonal antibody cetuximab that can be safely administered in combination with a standard daily dose of erlotinib in patients with advanced solid malignancies.

PATIENTS AND METHODS

Patients with advanced solid malignancies who had failed standard chemotherapies received escalating doses of cetuximab without a loading dose (100, 200, 250 mg/m(2) i.v. weekly) in combination with a fixed dose of erlotinib (150 mg daily orally) until disease progression or unacceptable toxicity.

RESULTS

Twenty-two patients were treated, including 14 patients (64%) with non-small cell lung cancer. Twenty patients received combination treatment at the highest dose level for a median of 5.5 weeks (range, 1-31 weeks). One dose-limiting toxicity was observed: grade 3 skin rash. Overall, the most common adverse events (any grade, grade 3/4) were consistent with the safety profiles of the individual drugs: acneform rash (100%, 9%), diarrhea (77%, 5%), and hypomagnesemia (59%, 12%). Seven of 18 evaluable patients (38.9%) had stable disease lasting for a median of 16.6 weeks (range, 6.1-25.1 weeks).

CONCLUSION

Dual EGFR inhibition with cetuximab and erlotinib is feasible; the observed toxicities were manageable and consistent with the safety profiles of the individual drugs. The recommended doses for phase II studies are 250 mg/m(2) i.v. weekly for cetuximab and 150 mg daily orally for erlotinib.

Recent advances of novel targeted therapy in non-small cell lung cancer

Lung cancer is the leading cause of cancer deaths world-wide. Recent advances in cancer biology have led to the identification of new targets in neoplastic cells and the development of novel targeted therapies. At this time, two targeted agents are approved by the FDA in advanced non-small cell lung cancer (NSCLC): the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) erlotinib, and the anitangiogenic bevacizumab. A third agent, cetuximab, which was recently shown to enhance survival when used with cisplatin and vinorelbine as first line therapy for advanced NSCLC, will likely be approved by regulatory agencies. With more than 500 molecularly targeted agents under development, the prospects of identifying novel therapies that benefit individual patients with lung cancer are bright.

Cetuximab in combination with carboplatin and docetaxel for patients with metastatic or advanced-stage nonsmall cell lung cancer: a multicenter phase 2 study

BACKGROUND

Cetuximab, an immunoglobulin (Ig) G1 chimeric monoclonal antibody against the epidermal growth factor receptor, has demonstrated evidence of activity in nonsmall cell lung cancer (NSCLC). When administered in combination with carboplatin and docetaxel, a commonly used regimen for advanced NSCLC, cetuximab has exhibited synergistic interaction in preclinical studies. Therefore, a phase 2 study was conducted to evaluate the efficacy of the combination of cetuximab, carboplatin, and docetaxel for the treatment of advanced NSCLC.

METHODS

Chemotherapy-naïve patients aged >or=18 years with stage IIIB (with effusion) or stage IV NSCLC received cetuximab (at a dose of 400 mg/m(2) on Day 1 and 250 mg/m(2) on Days 8 and 15) plus docetaxel (at a dose of 75 mg/m(2) on Day 1) and carboplatin (area under the concentration vs time curve [AUC]=6 on Day 1) every 21 days for up to 6 cycles (graded according to the American Joint Committee on Cancer Staging System). Thereafter, patients without evidence of disease progression were continued on single-agent cetuximab for a maximum of 1 year or until disease progression. The primary endpoint was response rate.

RESULTS

Eighty patients were enrolled. The median number of cycles administered was 4 (range, 1-6 cycles). The objective response rate was 15.2%, with a median progression-free survival of 4.6 months and a median overall survival of 10.3 months. The salient grades 3 of 4 adverse events were neutropenia (30%), hypotension (3%), hypokalemia (4%), and hypomagnesemia (3%). Twenty-five patients received single-agent cetuximab (median duration, 12 weeks) and this was well tolerated.

CONCLUSIONS

The results of this large, multicenter, phase 3 study indicate that the novel combination of cetuximab with docetaxel and carboplatin demonstrate modest anticancer activity for patients with advanced and metastatic NSCLC and has an acceptable toxicity profile.

First-generation epidermal growth factor receptor inhibitors in non-small cell lung cancer: clinical impact of the epidermal growth factor receptor fluorescence in situ hybridization assay

Epidermal growth factor receptor (EGFR) inhibitors have been proven to improve survival in advanced non-small cell lung cancer patients, even after failure of previous chemotherapy. However, how to identify the patients, who will benefit from this treatment, is still not known. Clinical and demographic factors, i.e., females, never-smokers, patients with Asian ethnicity, or histology of adenocarcinoma, seem all to be favorable factors for clinical outcome, but not sufficient for patient selection. Increased EGFR gene copy number detected by fluorescence in situ hybridization has consistently been shown in several retrospective studies to be a good predictive "marker," especially for EGFR tyrosine kinase inhibitors. Nevertheless, most of the data obtained so far are retrospective, and prospective validation is ongoing. The current review summarizes the clinical data based on the first generation EGFR inhibitors and discusses future strategies for exploring the role of EGFR fluorescence in situ hybridization as a selection marker for EGFR inhibitor therapy in non-small cell lung cancer.

Increased EGFR gene copy number detected by fluorescent in situ hybridization predicts outcome in non-small-cell lung cancer patients treated with cetuximab and chemotherapy

PURPOSE

Epidermal growth factor receptor (EGFR) gene copy number detected by fluorescent in situ hybridization (FISH) has proven to be useful for selection of non-small-cell lung cancer (NSCLC) patients for treatment with EGFR tyrosine kinase inhibitors. Here, we evaluate EGFR FISH as a predictive marker in NSCLC patients receiving the EGFR monoclonal antibody inhibitor cetuximab plus chemotherapy.

PATIENTS AND METHODS

Two hundred twenty-nine chemotherapy-naive patients with advanced-stage NSCLC were enrolled onto a phase II selection trial evaluating sequential or concurrent chemotherapy (paclitaxel plus carboplatin) with cetuximab.

RESULTS

EGFR FISH was assessable in 76 patients with available tumor tissue and classified as positive (four or more gene copies per cell in >/= 40% of the cells or gene amplification) in 59.2%. Response (complete response/partial response) was numerically higher in FISH-positive (45%) versus FISH-negative (26%) patients (P = .14), whereas disease control rate (complete response/partial response plus stable disease) was statistically superior (81% v 55%, respectively; P = .02). Patients with FISH-positive tumors had a median progression-free survival time of 6 months compared with 3 months for FISH-negative patients (P = .0008). Median survival time was 15 months for the FISH-positive group compared with 7 months for patients who were FISH negative. (P = .04). Furthermore, survival favored FISH-positive patients receiving concurrent therapy.

CONCLUSION

These results are the first to suggest that EGFR FISH is a predictive factor for selection of NSCLC patients for cetuximab plus chemotherapy. Prospective validation of these findings is warranted.

Randomized phase II study of gemcitabine plus cisplatin or carboplatin [corrected], with or without cetuximab, as first-line therapy for patients with advanced or metastatic non small-cell lung cancer

PURPOSE

To evaluate the efficacy of cetuximab added to first-line gemcitabine/platinum in chemotherapy-naïve patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

In this noncomparative, randomized trial, chemotherapy-naïve patients with recurrent/metastatic NSCLC (stage IV or stage IIIB with malignant pleural effusion) were eligible. Patients received cisplatin (75 mg/m2 i.v., every 3 weeks) or carboplatin (area under the concentration-versus-time curve of 5 intravenously [i.v.], every 3 weeks), and gemcitabine (1,250 or 1,000 mg/m2 i.v., days 1 and 8) plus cetuximab (400 mg/m2 i.v. day 1, followed by 250 mg/m2 weekly), in arm A, or chemotherapy alone, in arm B. Response rate was the primary end point; safety, progression-free survival, and overall survival were secondary end points.

RESULTS

Sixty-five patients were randomly assigned to arm A and 66 to arm B. Partial responses were observed in 18 patients (27.7%; 95% CI, 17.3 to 40.2) in arm A and 12 (18.2%; 95% CI, 9.8 to 29.6) in arm B. Median progression-free survival was 5.09 months for arm A (95% CI, 4.17 to 5.98) and 4.21 months (95% CI, 3.81 to 5.49) in arm B. Median overall survival was 11.99 months (95% CI, 8.80 to 15.18) and 9.26 months (95% CI, 7.43 to 11.79) in arms A and B, respectively. Overall toxicity was acceptable and consistent with the profiles of the individual agents.

CONCLUSION

First-line treatment with cetuximab plus gemcitabine/platinum is well tolerated and can be administered safely in patients with advanced NSCLC. Differences in response rate, progression-free survival, and overall survival suggest that the addition of cetuximab to platinum/gemcitabine may improve clinical outcomes. Larger studies are in progress to address this hypothesis.

Cetuximab in non-small cell lung cancer

Advanced non-small cell lung carcinoma (NSCLC) remains a challenge to treat due to its high local and systemic recurrence. The overall survival remains poor despite the approval of several new chemotherapeutic agents in the management of advanced NSCLC. Overexpression or mutations in the EGFR have been shown to be associated with a significant percentage of NSCLC. The development of targeted agents, such as cetuximab, against the EGFR is therefore a rational objective. Several preclinical and clinical studies suggest that cetuximab is active against NSCLC. This paper reviews the application of cetuximab in NSCLC.