Seminars in oncology
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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. ⋯ 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.
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Seminars in oncology · Aug 2006
ReviewRole of Raf kinase in cancer: therapeutic potential of targeting the Raf/MEK/ERK signal transduction pathway.
Improvements in our understanding of the molecular basis of cancer have led to the clinical development of protein kinase inhibitors, which target pivotal molecules involved in intracellular signaling pathways implicated in tumorigenesis and progression. These novel targeted agents have demonstrated activity against a wide range of solid tumors, are generally better tolerated than standard chemotherapeutics, and may revolutionize the management of advanced refractory cancer. The ubiquitous Raf serine/threonine kinases are pivotal molecules within the Raf/mitogen extracellular kinase (MEK)/extracellular signal-related kinase (ERK) signaling pathway, which regulates cellular proliferation and survival. ⋯ In this review, the role of Raf in normal cells and in cancer is discussed, and an overview is given of Raf inhibitors currently in development, focusing on sorafenib tosylate (BAY 43-9006 or sorafenib). Sorafenib is the first oral multi-kinase inhibitor to be developed that targets Raf kinases (Raf-1, wild-type B-Raf, and b-raf V600E), in addition to receptor tyrosine kinases associated with angiogenesis (vascular endothelial growth factor receptor [VEGFR]-2/-3, platelet-derived growth factor receptor [PDGFR]-beta) or tumor progression (Flt-3, c-kit). Preclinical and clinical sorafenib data that led to its recent approval for the treatment of advanced RCC are summarized, along with current thinking on sorafenib's mechanism of effect on the tumor and tumor vasculature in melanoma and RCC.