O-103 A comparison of the antitumour efficacy of ZD6474 and gefitinib(Iressa™) in patients with NSCLC: Results of a randomized, double-blind Phase II study

Rationale and Clinical Results of Multi-target Treatments in Oncology

During the last 10 years, the concept of targeted biological therapy for the treatment of cancer has emerged. Targeted agents entered clinical practice only recently, and the first drugs with demonstrated clinical efficacy were mainly inhibitors of the ErbB family of receptors (i.e., EGFR and HER-2), either monoclonal antibodies (MAbs) or tyrosine kinase inhibitors (TKIs). After the proof of concept for the clinical efficacy and tolerability of these selective agents, it was conceived that most tumors will depend on more than one signaling pathway for their growth and survival. As a consequence, different strategies were pursued to inhibit multiple signaling pathways or multiple steps in the same pathway, either by the development of multi-targeted agents or the combination of single targeted drugs. The recent FDA and EMEA approval of sorafenib and sunitinib, both multi-targeted TKIs, marked the coming of age of this new generation of drugs. Now a whole new wave of multi-targeted compounds is moving into clinical trials, raising in the minds of investigators important questions about the best strategies to pursue in their use and many doubts about their differences and the seeming redundancies in the pipelines of pharmaceutical companies. This review will deal with the rationale underlying the multi-targeted approach and with the available clinical experience with multi-targeted agents, especially focusing on molecules with anti-EGFR mechanisms of action.

Bevacizumab and erlotinib: a promising new approach to the treatment of advanced NSCLC

Biologic agents that target molecules involved in tumor growth, progression, and pathological angiogenesis--such as the human epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF)--have demonstrated efficacy in patients with non-small cell lung cancer (NSCLC). Erlotinib (Tarceva); OSI Pharmaceuticals, Inc., Melville, NY, Genentech, Inc., South San Francisco, CA, and F. Hoffmann-La Roche Ltd, Basel, Switzerland), a highly selective tyrosine kinase inhibitor that inhibits EGFR, and bevacizumab (Avastin); Genentech, Inc., South San Francisco, CA, and F. Hoffmann-La Roche Ltd, Basel, Switzerland), a VEGF-targeted recombinant humanized monoclonal antibody, have displayed very encouraging activity in a randomized phase II trial in patients with previously treated NSCLC. Because erlotinib and bevacizumab act on two different pathways critical to tumor growth and dissemination, administering these drugs concomitantly may confer additional clinical benefits to cancer patients with advanced disease, by virtue of their complementary (or additive) antitumor activity. The combination of bevacizumab plus erlotinib may prove to be a viable second-line alternative to chemotherapy or erlotinib monotherapy in patients with NSCLC. The benefits of the combination may be further enhanced by selecting for patients who are likely to respond to this therapy. While a number of potential predictive markers have been identified for erlotinib, their value remains to be confirmed in prospective trials. In addition, the application of such personalized therapy will also depend on the availability of validated screening methods.

Targeting the VEGF pathway: antiangiogenic strategies in the treatment of non-small cell lung cancer

The management of advanced non-small cell lung cancer (NSCLC) has evolved considerably in recent years, due to a progressive understanding of tumour biology and the identification of promising molecular targets. Several agents have been developed so far inhibiting vascular endothelial growth factor (VEGF) - a key protein in tumour neoangiogenesis, growth and dissemination - or its receptor signalling system. The finding in study E4599 of a survival benefit for carboplatin-paclitaxel plus bevacizumab - a humanised anti-VEGF monoclonal antibody - over chemotherapy (CT) alone led the U.S. Food and Drug Administration (FDA) to approve the novel combination for first-line treatment of patients with unresectable, locally advanced, recurrent or metastatic non-squamous NSCLC. In a randomised phase III trial presented at the American Society of Clinical Oncology (ASCO) 2007 Annual Meeting, patients receiving cisplatin-gemcitabine plus bevacizumab experienced a significantly longer progression-free survival (PFS) compared to the standard arm. Based on these data, the European Medicines Agency (EMEA) has granted marketing authorisation for bevacizumab in addition to any platinum-based CT for first-line treatment of advanced NSCLC other than predominantly squamous histology. Aim of this report is to provide an overview on bevacizumab in NSCLC, with special emphasis on clinical results presented at ASCO last meeting. Multitargeted tyrosine kinase inhibitors (TKIs), sharing a focus on both the angiogenesis process and additional cell-surface receptors, and VEGF Trap, a novel fusion protein with markedly higher affinity for VEGF than bevacizumab, will be briefly discussed as well.

Interaction between the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF) pathways: a rational approach for multi-target anticancer therapy

Over the last decade, the concept of targeted biological therapy for the treatment of cancer has emerged. However, a better understanding of these targets and their role in tumor cells and in the surrounding stromal cells is required. Two interesting biological targets are the epidermal growth factor receptor (EGFR) and the vascular endothelia growth factor (VEGF) and its receptors. A number of agents that target these pathways have been described. Many of these are currently in clinical trials and a few have recently been approved by the regulatory authorities in USA and in the European Union. The molecular pathways involved in the proliferation of cancer cells and in tumor-related angiogenesis are very complex and the interference with only a single step of these pathways may often reveal an insufficient therapeutic approach. Moreover, cancer cells have an inherent ability to harness different growth factor signaling pathways for growth advantage and cell survival, a process that may even be facilitated by the use of selective targeted agents. Because of these escape mechanisms, monotherapy with selective targeted agents is unlikely to be a fully effective cancer treatment. For these reasons, targeting different pathways is an attractive and effective therapeutic strategy with a strong rationale for investigating this approach in the clinic. This review focuses on the preclinical rationale of combining targeted agents such as EGFR and VEGF inhibitors in the treatment of cancer and on the clinical trials that have emerged from these studies.

Vascular endothelial growth factor receptor tyrosine kinase inhibitors vandetanib (ZD6474) and AZD2171 in lung cancer

Vascular endothelial growth factor (VEGF) is a rational target for advanced non-small cell lung cancer (NSCLC), a hypothesis validated by the recent Eastern Cooperative Oncology Group E4599 trial showing that the addition of the VEGF monoclonal antibody bevacizumab to chemotherapy prolongs overall survival. Several new tyrosine kinase inhibitors targeting the VEGF pathway are currently in advanced clinical development for NSCLC and offer several possible advantages compared with monoclonal antibodies, including oral administration, more flexible dosing, a broader spectrum of target inhibition, and different toxicity profiles. Among these agents, vandetanib (ZD6474), an inhibitor of the VEGF receptor (VEGFR)-2 and epidermal growth factor receptor tyrosine kinase, has been the most extensively studied. In a randomized phase II study of patients with platinum-refractory NSCLC, including squamous histology, vandetanib prolonged progression-free survival compared with gefitinib. In another phase II trial, an improvement in progression-free survival was observed for vandetanib in combination with docetaxel compared with docetaxel alone. AZD2171 is an inhibitor of VEGFR-1, VEGFR-2, and VEGFR-3 and other tyrosine kinases that has shown clinical activity in NSCLC in combination with carboplatin and paclitaxel. Several phase III trials are under way testing these agents either as monotherapy or in combination with chemotherapy in patients with lung cancer. Early results with these agents, and others being tested, raise the possibility that there will eventually be multiple VEGF-targeted therapies available in the clinic that can potentially benefit a broader range of patients with advanced-stage NSCLC.

Combined targeted therapies in non-small cell lung cancer: a winner strategy?

PURPOSE OF REVIEW

Current treatment modalities provide limited improvement in the natural course of lung cancer, and prognosis remains poor. Lung cancer is a malignancy with great molecular heterogeneity. The complexity of the signalling process leading to cancer cell proliferation and to the neoplastic phenotype supports the necessity of interfering at different stages to avoid cancer cell resistance to therapy.

RECENT FINDINGS

Use of several agents with multiple growth factor receptor or intracellular targets has shown encouraging results in phase I and II clinical trials in non-small cell lung cancer. ZD6474 is a dual epidermal growth factor receptor and vascular endothelial growth factor receptor 2 small-molecule tyrosine kinase inhibitor; sorafenib is an oral kinase inhibitor of Raf-1 and is also active against vascular endothelial growth factor receptors 2 and 3, platelet-derived growth factor receptor beta, and c-KIT. Sunitinib is a vascular endothelial growth factor receptor 1, 2, and 3, c-KIT, and platelet-derived growth factor receptor alpha and beta tyrosine kinase inhibitor.

SUMMARY

Combined use of epidermal growth factor receptor-tyrosine kinase inhibitor erlotinib and the humanized vascular endothelial growth factor receptor monoclonal antibody bevacizumab in advanced, chemotherapy-refractory non-small cell lung cancer has shown promising results.

Tyrosine kinase inhibitors of vascular endothelial growth factor receptors in clinical trials: current status and future directions

Angiogenesis plays a central role in the process of tumor growth and metastatic dissemination. The vascular endothelial growth factor (VEGF) family of peptide growth factors and receptors are key regulators of this process. Agents directed either against VEGF or VEGF receptors (VEGFRs) have been developed. The tyrosine kinase inhibitors of VEGFRs are low-molecular-weight, ATP-mimetic proteins that bind to the ATP-binding catalytic site of the tyrosine kinase domain of VEG-FRs, resulting in blockade of intracellular signaling. Several of these agents are currently in different phases of clinical development. Large randomized phase III trials have demonstrated the efficacy of sunitinib and sorafenib in the treatment of patients affected by gastrointestinal stromal tumors and renal cancer refractory to standard therapies, respectively. Positive results also have been reported with the combination of ZD6474 and chemotherapy in previously treated non-small cell lung cancer patients. For other agents, such as vatalanib, contrasting outcomes in metastatic colorectal cancer patients have been reported: the final results of these trials are expected in 2006. However, several key questions remain to be addressed, regarding the choice of an adequate dose or schedule, the presence of "off-target" effects, the safety of long-term administration, and the research of new clinical end points or methodological approaches for the optimal clinical development of these agents.

Epidermal growth factor receptor as a major anticancer drug target

Epidermal growth factor receptor (EGFR) is the best characterised member of the ErbB family of receptors. A lot of effort has been made to exploit the therapeutic potential of drugs acting on this receptor pathway. Monoclonal antibodies and oral tyrosine kinase inhibitors have undergone a thorough evaluation, both as single agents and in combination. However, over recent years, cancer cells have been shown to be able to harness different growth factor signalling pathways, so that single-agent therapy may not be the best way to use anti-EGFR drugs. Combinations with downstream effectors or other receptor-targeted therapies, or antiangiogenic compounds can be looked at more optimistically as effective weapons.

Epidermal growth factor receptor inhibition and non-small cell lung cancer

The majority of non-small cell (NSC) lung cancers express epidermal growth factor receptor (EGFR). Many studies have evaluated the clinical effect from targeted therapy achieved by blocking EGFR in patients with NSC lung cancer. Treatment of biologically unselected patients with NSC lung cancer with two reversible quinazole EGFR inhibitors, gefitinib and erlotinib, gave negative results in all controlled trials but one. Ten percent to 20% of patients with NSC lung cancers have somatic mutations in EGFR, and these patients have a significantly higher response rate (73%) to treatment with EGFR inhibitors than patients with wild-type EGFR (10%). Patients with Asian background, women, non-smokers, and patients with adenocarcinoma had higher response rates than other patients, and the differences may be due to an association between the clinical characteristics and EGFR mutations. Further studies are needed to fully evaluate the effect of EGFR inhibitor-treatment for subgroups of patients with NSC lung cancer with favorable biological and clinical characteristics.

Combining targeted agents: blocking the epidermal growth factor and vascular endothelial growth factor pathways

Bevacizumab is a recombinant, humanized monoclonal antibody against vascular endothelial growth factor. Erlotinib HCl is a reversible, highly selective epidermal growth factor receptor tyrosine kinase inhibitor. Additionally, both agents have shown benefit in patients with previously treated non-small cell lung cancer (NSCLC). Preclinical data in xenograft models produced greater growth inhibition with the combination than with either agent alone. A phase I/II study in two centers examined combined erlotinib and bevacizumab treatment in patients with nonsquamous stage IIIB/IV NSCLC with one or more prior chemotherapy. In phase I, 150 mg/d erlotinib orally plus 15 mg/kg bevacizumab i.v. every 21 days was established as the phase II dose. A total of 40 patients were enrolled and treated in this study (34 patients at phase II dose): 21 were female, 30 had adenocarcinoma histology, 9 were never smokers, and 22 had two or more prior regimens. The most common adverse events were mild to moderate rash, diarrhea, and proteinuria. Preliminary data showed no pharmacokinetic interaction between erlotinib and bevacizumab. Eight patients (20.0%) had partial responses and 26 (65.0%) had stable disease as their best response. The median overall survival for the 34 patients treated at the phase II dose was 12.6 months, with progression-free survival of 6.2 months. Encouraging antitumor activity and safety of erlotinib plus bevacizumab support further development of this combination for patients with advanced NSCLC. A randomized phase II trial has been completed, and a phase III trial is ongoing.

Combining targeted therapies and drugs with multiple targets in the treatment of NSCLC

The first generation of clinical trials of targeted agents in non-small cell lung cancer (NSCLC) treatment has concluded. To date, only a few of these new agents can offer hope of a substantial impact on the natural history of the disease. Nevertheless, clinically meaningful advances have already been achieved. In chemotherapy-refractory advanced NSCLC patients, gefitinib and erlotinib, two epidermal growth factor receptor tyrosine kinase inhibitors, represent a further chance for tumor control and symptom palliation. In chemotherapy-naive, advanced, nonsquamous NSCLC patients, the combination of the anti-vascular endothelial growth factor monoclonal antibody bevacizumab with chemotherapy was demonstrated to produce better survival outcomes than with chemotherapy alone. The relative failure of first-generation targeted therapies in lung cancer may be a result of multilevel cross-stimulation among the targets of the new biological agents. Thus, blocking only one of these pathways allows others to act as salvage or escape mechanisms for cancer cells. Preclinical evidence of the synergistic antitumor activity achievable by combining targeted agents that block multiple signaling pathways has recently been emerging. Clinical trials of multitargeted therapy may represent the second generation of studies in this field, and some of these are already ongoing. In a recent phase I/II trial, the combination of erlotinib and bevacizumab demonstrated very promising activity in the treatment of advanced NSCLC pretreated with chemotherapy. Whether the multitargeted approach is best performed using combinations of selective agents or agents that intrinsically target various targets is a matter of debate.

Improving the design of phase II trials of cytostatic anticancer agents

This paper examines the design of phase II trials in oncology and recommends departing from the traditional uncontrolled trial design. Entrance into phase II clinical evaluation represents a key milestone in the development of any new cancer therapy. As novel molecular-targeted therapies are introduced, whose primary action is to slow the growth of tumors, it will be important to ensure that the clinical trial design will effectively capture any clinical benefit of these agents. The objective of a phase II trial should, in addition to identifying active therapies, be extended to identifying those that are likely to be successful in pivotal trials. It is therefore necessary to quantify the likelihood of either incorrectly halting the development of an active agent or continuing development of an ineffective agent. We believe only randomized studies with comparative intent and including a concurrent active control, can reliably assess these risks corresponding to significance and power. Given that the objective of phase II studies is to identify promising treatments, it is important not be constrained by conventional levels of significance. This paper will review the various approaches to phase II trial design in oncology and provide a framework for fully powered randomized trials of a moderate size. For example, a randomized trial of just 100 patients could lead to the termination of development of 90% of inactive agents whereas at least 80% of agents with a meaningful and realistic increase in progression-free survival would be identified for confirmatory study. We believe randomized studies with progression-free survival endpoints are the most powerful and economical method of determining the clinical activity of new cytostatic agents.

New antiangiogenetic agents and non-small cell lung cancer

New blood vessel formation, known as angiogenesis is a fundamental event in the process of tumor growth and metastatic dissemination. Due to its central role in tumor angiogenesis, the vascular endothelial growth factor (VEGF) and its receptor have been a major focus of basic research and drug development in the field of oncology, including the treatment of non-small cell lung cancer (NSCLC). Approaches targeting VEGF include monoclonal antibodies and vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs). Bevacizumab (Avastin) is an anti-VEGF recombinant humanized monoclonal antibody. A very recent randomized phase III trial demonstrated a statistically significant advantage in median survival favouring the combination of bevacizumab plus chemotherapy versus chemotherapy alone in the treatment of advanced non-squamous NSCLC. This study represents the first evidence of superior efficacy of targeted therapy combined with chemotherapy over chemotherapy alone in the treatment of NSCLC. ZD6474 is an orally bioavailable inhibitor of VEGFR-2 tyrosine kinase. First evidences of antitumor activity and its excellent toxicity profile make it a promising targeted agent for the treatment of NSCLC. A recent phase I/II study examined the combination of Epidermal Growth Factor Receptor (EGFR)-TKI erlotinib and bevacizumab in patients with non-squamous stage IIIB/IV NSCLC. Data on antitumor activity of this combination have to be considered very promising. Clinical trials of multiple targeted therapy may represent the second generation studies in the treatment of NSCLC.

Where next for gefitinib in patients with lung cancer?

Gefitinib belongs to the small-molecule class of epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors. It was given conditional approval by the US Food and Drug Administration (FDA) in 2003 for treatment of advanced, chemorefractory non-small-cell lung cancer (NSCLC), but was relabelled for restricted use for patients that were already receiving and benefiting from it after the negative result of the phase III Iressa Survival Evaluation in Advanced Lung Cancer (ISEL) trial. By contrast, erlotinib, another EGFR tyrosine-kinase inhibitor, showed an overall survival benefit compared with placebo and best supportive care in the National Cancer Institute of Canada's BR21 trial, and now has full FDA approval for treatment of patients with NSCLC who have progressed after treatment with chemotherapy. Although the ISEL trial result was negative overall, preplanned subgroup analyses showed a significant overall survival benefit for gefitinib treatment in never-smokers and in patients of Asian origin. Here, we review the clinical experience with gefitinib and, in light of the licensing of erlotinib, address the lessons learned, the ongoing trials, and whether scope remains for clinical development of gefitinib in selected patients.

Second-Line Treatment Options in Non–Small Cell Lung Cancer: A Comparison of Cytotoxic Agents and Targeted Therapies

Current options for the second-line treatment of non-small cell lung cancer (NSCLC) include cytotoxic drugs, such as docetaxel and pemetrexed, and targeted therapies. Docetaxel was approved in the United States and Europe in 2000 after two phase III trials showed drug superiority versus best supportive care alone and versus alternative single-agent chemotherapy. Pemetrexed was approved in the United States and Europe in 2004 after a phase III trial showed that, compared with docetaxel, it had comparable activity (median survival time of approximately 8 months in both arms) and a more favorable toxicity profile: grade 3-4 neutropenia was observed in 5.3% versus 40.2% of patients in the pemetrexed and docetaxel arms, respectively, while febrile neutropenia was observed in 1.9% versus 12.7% of patients, respectively. In the United States, gefitinib and erlotinib have also been approved for the treatment of recurrent NSCLC (in 2003 and 2004, respectively), while in Europe the registration of these agents is currently under evaluation. This review focuses on the use of docetaxel and pemetrexed for the second-line treatment of NSCLC and compares these drugs with targeted therapies, highlighting the latest developments in pharmacogenomics that might lead to a more tailored approach to treatment.

The Emerging Role of Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitors

In the United States, non-small cell lung cancer (NSCLC) constitutes 85% of all newly diagnosed lung cancers. Over the past 40 years, the 5-year survival rates in NSCLC have improved from 6% to 15%, with surgery remaining the most curative approach. However, resection is feasible in less than 35% of patients at diagnosis, and 40% to 50% of newly diagnosed patients present with metastatic disease. Platinum-based combination chemotherapy is standard treatment for these patients, but improvement beyond platinum doublets has not been achieved. Therefore, a clear-cut need exists for new treatment approaches for NSCLC. Targeted therapies, particularly angiogenesis inhibitors, are hoped to facilitate therapeutic progress. Neovascularization not only allows for the continued growth of the primary tumor, but also provides migrating tumor cells access to the systemic circulation, facilitating metastasis. A number of studies have shown a clear correlation between vascular endothelial growth factor (VEGF) expression, microvessel density, and impaired prognosis. Monoclonal antibodies directed against the VEGF and VEGF receptor have been studied in depth in advanced NSCLC. A randomized phase III trial evaluated the role of the anti-VEGF-A antibody bevacizumab in combination with paclitaxel and carboplatin versus chemotherapy alone in NSCLC. Based on toxicity observations from a phase II study, this trial excluded patients with squamous histology, brain metastases, or an ongoing need for therapeutic anti-coagulation or non-steroidal anti-inflammatory agents. Preliminary data confirmed a survival advantage of 12.5 months for patients in the bevacizumab arm compared with 10.2 months in the control arm (P = .0075), which showed that antiangiogenic therapies can be effective in NSCLC. Antiangiogenic therapies, including antibodies against VEGF, and, in particular, new small-molecule inhibitors of the VEGF receptor, are reviewed and discussed in detail.