Anti-VEGF agents in metastatic colorectal cancer (mCRC): are they all alike?
ABSTRACT: Bevacizumab is a monoclonal antibody that binds and neutralizes vascular endothelial growth factor (VEGF)-A, a key player in the angiogenesis pathway. Despite benefits of bevacizumab in cancer therapy, it is clear that the VEGF pathway is complex, involving multiple isoforms, receptors, and alternative ligands such as VEGF-B, and placental growth factor, which could enable escape from VEGF-A-targeted angiogenesis inhibition. Recently developed therapies have targeted other ligands in the VEGF pathway (eg, aflibercept, known as ziv-aflibercept in the United States), VEGF receptors (eg, ramucirumab), and their tyrosine kinase signaling (ie, tyrosine kinase inhibitors). The goal of the current review was to identify comparative preclinical data for the currently available VEGF-targeted therapies. Sources were compiled using PubMed searches (2007 to 2012), using search terms including, but not limited to: "bevacizumab," "aflibercept," "ramucirumab," and "IMC-18F1." Two preclinical studies were identified that compared bevacizumab and the newer agent, aflibercept. These studies identified some important differences in binding and pharmacodynamic activity, although the potential clinical relevance of these findings is not known. Newer antiangiogenesis therapies should help further expand treatment options for colorectal and other cancers. Comparative preclinical data on these agents is currently lacking.
Project description:Recognition of the vascular endothelial growth factor (VEGF) pathway as a key mediator of angiogenesis has led to the clinical study of several VEGF and VEGF receptor (VEGFR) targeted therapies in non-small-cell lung cancer (NSCLC). These targeted therapies include neutralizing antibodies to VEGF (bevacizumab and aflibercept) and VEGFR-2 (ramucirumab) and tyrosine kinase inhibitors (TKIs) with selectivity for the VEGFRs. Bevacizumab and ramucirumab are associated with survival advantages in the treatment of advanced NSCLC: bevacizumab in the first-line setting in combination with carboplatin/paclitaxel and ramucirumab in combination with docetaxel in the second-line setting. The VEGFR-2 TKIs have been associated with responses and improved progression-free survival in selected NSCLC settings; however, this level of activity has thus far been insufficient to confer significant survival advantages. This review will focus on the current state of VEGF targeted therapies in NSCLC.
Project description:Several therapies targeting angiogenesis are currently in development for non-small cell lung cancer (NSCLC). This review discusses results of recent clinical trials evaluating chemotherapy plus antiangiogenic therapy for NSCLC. Bevacizumab, an anti-VEGF antibody, is currently approved for the treatment of advanced NSCLC in combination with carboplatin and paclitaxel. Completed phase III trials evaluating bevacizumab plus chemotherapy have shown prolonged progression-free survival; however, not all trials showed significant improvement in overall survival (OS). Phase III trials of the tyrosine kinase inhibitors (TKIs) vandetanib and sorafenib and the vascular disrupting agent ASA404 also failed to improve OS compared with chemotherapy alone. Clinical trials are ongoing involving several new antiangiogenic therapies, including ramucirumab, aflibercept, cediranib, BIBF 1120, sunitinib, pazopanib, brivanib, ABT-869, axitinib, ABT-751, and NPI-2358; several of these agents have shown promising phase I/II results. Results from recently completed and ongoing phase III trials will determine if these newer antiangiogenic agents will be incorporated into clinical practice.
Project description:Metastatic colorectal cancer (mCRC) is a highly heterogeneous disease. Its treatment outcome has been significantly improved over the last decade with the incorporation of biological targeted therapies, including anti-EGFR antibodies, cetuximab and panitumumab, and VEGF inhibitors, bevacizumab, ramucirumab, and aflibercept. The identification of predictive biomarkers has further improved the survival by accurately selecting patients who are most likely to benefit from these treatments, such as RAS mutation profiling for EGFR antibodies. Regorafenib is a multikinase inhibitor currently used as late line therapy for mCRC. The molecular and genetic markers associated with regorafenib treatment response are yet to be characterized. Here, we review currently available clinical evidence of mCRC molecular profiling, such as RAS, BRAF, and MMR testing, and its role in targeted therapies with special focus on regorafenib treatment.
Project description:Colorectal cancer is the third most frequent cancer worldwide. Overall survival rates have improved greatly over the last few years due, at least in part, to the addition of targeted therapies to standard of care chemotherapy. Angiogenesis plays an important role in colorectal cancer, and therapies directed against the vascular endothelial growth factor (VEGF) axis have contributed significantly to improving the outcome of patients with metastatic colorectal cancer. Over the past few years, several new targeted antiangiogenic agents have been approved for this patient population, confirming the value of inhibiting tumour angiogenesis. The most recent among them is ramucirumab, a fully humanized monoclonal antibody that targets the extracellular domain of VEGF receptor 2. It has proven valuable in multiple tumour types including colorectal cancer. Several phase I and II clinical trials showed a favourable toxicity profile and promising clinical antitumour efficacy in colorectal cancer patients. In the phase III RAISE clinical trial, the addition of ramucirumab to FOLFIRI-based chemotherapy resulted in an improvement of overall survival in patients with metastatic colorectal cancer who had been previously treated with bevacizumab, oxaliplatin and a fluoropyrimidine. On the basis of these results, ramucirumab was approved by the US Food and Drug Administration for this setting. We present an overview of the key preclinical and clinical studies in the development of ramucirumab in the context of metastatic colorectal cancer.
Project description:Gastric cancer is currently the third most common cause of cancer deaths worldwide. Prognosis remains poor with most patients presenting with advanced or metastatic disease. A better understanding of angiogenesis has led to the investigation of drugs that inhibit the vascular endothelial growth factor (VEGF) pathway including anti-VEGF antibody therapy (eg, bevacizumab), inhibitors of angiogenic receptor tyrosine kinases (eg, sunitinib, sorafenib, apatinib, regorafenib), and inhibitors of vascular endothelial growth factor receptors (VEGFRs) (eg, ramucirumab). Ramucirumab, a VEGFR-2 inhibitor, is the first anti-angiogenic agent approved by the US Food and Drug Administration for use in the treatment of advanced gastric cancers. This review will focus on the clinical utility and potential use of ramucirumab in advanced gastric cancer.
Project description:Anti-vascular endothelial growth factor (VEGF) therapies have improved clinical outcomes for patients with cancers and retinal vascular diseases. Three anti-VEGF agents, pegaptanib, ranibizumab, and aflibercept, are approved for ophthalmic indications, while bevacizumab is approved to treat colorectal, lung, and renal cancers, but is also used off-label to treat ocular vascular diseases. The efficacy of bevacizumab relative to ranibizumab in treating neovascular age-related macular degeneration has been assessed in several trials. However, questions persist regarding its safety, as bevacizumab can form large complexes with dimeric VEGF165, resulting in multimerization of the Fc domain and platelet activation. Here, we compare binding stoichiometry, Fc? receptor affinity, platelet activation, and binding to epithelial and endothelial cells in vitro for bevacizumab and aflibercept, in the absence or presence of VEGF. In contrast to bevacizumab, aflibercept forms a homogenous 1:1 complex with each VEGF dimer. Unlike multimeric bevacizumab:VEGF complexes, the monomeric aflibercept:VEGF complex does not exhibit increased affinity for low-affinity Fc? receptors, does not activate platelets, nor does it bind to the surface of epithelial or endothelial cells to a greater degree than unbound aflibercept or control Fc. The latter finding reflects the fact that aflibercept binds VEGF in a unique manner, distinct from antibodies not only blocking the amino acids necessary for VEGFR1/R2 binding but also occluding the heparin-binding site on VEGF165.
Project description:Anti-angiogenic therapy is one of the promising strategies for many types of solid cancers. Bevacizumab (Avastin), a recombinant humanized monoclonal antibody of vascular endothelial growth factor (VEGF) A, was approved for the first time as an anti-angiogenic drug for the treatment of metastatic colorectal cancer (CRC) by the Food and Drug Administration (FDA) in 2004. In addition, the other VEGF pathway inhibitors including small molecule tyrosine kinase inhibitors (sunitinib, sorafenib, and pazopanib), a soluble VEGF decoy receptor (aflibercept), and a humanized monoclonal antibody of VEGF receptor 2 (VEGFR2) (ramucirumab) have been approved for cancer therapy. Although many types of VEGF pathway inhibitors can improve survival in most cancer patients, some patients have little or no beneficial effect from them. The primary or acquired resistance towards many oncological drugs, including anti-VEGF inhibitors, is a common problem in cancer treatment. This review summarizes the proposed alternative mechanisms of angiogenesis other than the VEGF pathway. These mechanisms are involved in the development of resistance to anti-VEGF therapies in cancer patients.
Project description:The diverse pathways and molecules involved in angiogenesis, the formation of new blood vessels, have been targeted for the treatment of colorectal and other cancers. Vascular endothelial growth factor (VEGF)-A binding to VEGF receptor (VEGFR)-2 is believed to be the key signaling pathway mediating angiogenesis. Other VEGF pathways involved in angiogenesis include VEGF-A, VEGF-B, and placental growth factor binding to VEGFR-1, and VEGF-C and VEGF-D binding to VEGFR-2 and VEGFR-3. VEGF signaling also intersects with other pathways, including angiopoietin/Tie, Notch, hypoxia-inducible factor, and integrin pathways. The roles of these pathways in tumor angiogenesis and in various human cancers will be explored in this article. In addition, preclinical and clinical data on bevacizumab, aflibercept (known as ziv-aflibercept in the US), and investigational antiangiogenic agents in development for the treatment of colorectal and other cancers will be reviewed.
Project description:Newer active drugs have been recently added to the pharmacological armamentarium for the treatment of metastatic colorectal cancer. Aflibercept, a recombinant fusion protein composed of the extracellular domains of human vascular endothelial growth factor receptors (VEGFR) 1 and 2 and the Fc portion of human immunoglobulin G1 (IgG1), is an attractive second-line option in combination with folfiri for patients who have failed folfox +/- bevacizumab. Ramucirumab, a human IgG1 monoclonal antibody that targets VEGFR-2, provided similar results in the same setting. Tas-102, an oral fluoropyrimidine, and regorafenib, a multi-tyrosine kinase inhibitor, are both able to control the disease in a considerable proportion of patients when all other available treatments have failed. These new therapeutic options along with the emerging concept that previous therapies may also be reitroduced or rechallenged after regorafenib and Tas-102 failure are bringing new hope for thousands of patients and their families.
Project description:Significant progression has been achieved in the treatment of metastatic colorectal cancer (mCRC) in recent years. This has been partly attributed to successfully incorporating new drugs into combination chemotherapy. In addition to the traditional cytotoxic chemotherapeutic agents, molecularly targeted agents began to play an important role in the treatment of advanced solid tumors. To date, two classes of molecularly targeted agents have been approved for treatment of patients with mCRC: (1) antivascular endothelial growth factor (anti-VEGF) agents (such as bevacizumab and aflibercept) and (2) antiendothelial cell growth factor receptor (anti-EGFR) agents (such as cetuximab and panitumumab). Aflibercept is a new member of anti-VEGF agents which has demonstrated efficacy for treatment of mCRC. With the commencement of clinical trials and basic research into aflibercept, more data from the bedside and the bench have been obtained. This review will outline the application of anti-VEGF agents by reviewing clinic experiences of bevacizumab and aflibercept, and try to add perspectives on the use of anti-VEGF agents in mCRC.