Seminars in oncology
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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.
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Anthracyclines are potent anti-neoplastic drugs used in the treatment of solid and hematologic cancers. However, their use is limited by cumulative dose-related cardiotoxic adverse effects, which are progressive and irreversible from the first dose. Clinical trial data have shown that anthracycline cardiotoxicity is associated with slowly progressive deterioration of cardiac function, which continues for years after treatment cessation. ⋯ The widespread use of anthracyclines in childhood leukemia has resulted in an improved long-term prognosis; however, these patients are subsequently at high risk of developing long-term cardiac damage, with studies suggesting as many as 65% of survivors of childhood leukemia will develop cardiac abnormalities. Middle aged and elderly patients who are prone to cardiac disease may be more vulnerable to the cardiotoxic effects of anthracyclines. Therapies or strategies to prevent anthracycline-induced cardiotoxicity are essential; ideally, these should be initiated at the beginning of anthracycline therapy to reduce the possibility of cardiac damage and to ensure the optimal use of chemotherapy.
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Seminars in oncology · Jun 2006
ReviewCardiotoxic consequences of anthracycline-containing therapy in patients with breast cancer.
In women, breast cancer is the second most common form of cancer and the leading cause of death caused by malignancy. The anthracycline antibiotics are potent anti-tumor agents used in a wide spectrum of malignancies. They are part of the gold standard adjuvant therapy for breast cancer and in metastatic disease they provide significant increases in response rate, time to disease progression, and overall survival. ⋯ The onset of clinical and subclinical cardiac damage is delayed and occurs more than 3 months after the cessation of treatment, indicating a crucial time for functional impairment to occur and highlighting the ineffectiveness of monitoring left ventricular ejection fraction as an endpoint during anthracycline therapy. Possible future treatment options for managing anthracycline-induced cardiotoxicity include agents such as dexrazoxane that prevent oxygen-free radical generation. Further investigation is required into the use of angiotensin-converting enzyme inhibitors to redress cardiac damage and new methods of identifying patients at high risk of congestive heart failure before cardiac damage has occurred.
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Seminars in oncology · Jun 2006
ReviewAnthracycline-induced cardiotoxicity in adult hematologic malignancies.
Anthracyclines are a highly efficacious treatment for adult hematologic malignancies, including acute myeloid leukemia, acute lymphoblastic leukemia, multiple myeloma, Hodgkin's disease, and non-Hodgkin's lymphoma. The consequences of anthracycline-induced cardiotoxicity have obliged hematologists to set empirical dose limits, above which the cardiotoxic risk is deemed unacceptable. ⋯ Through discontinuing further use of anthracyclines, relapsed patients previously treated with these agents may consequently be treated with second-line therapy that is less effective and possibly less well tolerated. Anthracycline-induced cardiotoxicity is potentially fatal and can significantly impair patients' quality of life, while also substantially increasing health care costs.
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Seminars in oncology · Jun 2006
ReviewExposure to anthracyclines during childhood causes cardiac injury.
The use of anthracyclines in the treatment of acute lymphoblastic leukemia is limited by associated cardiotoxic effects, which can result in cardiomyopathy and congestive heart failure, and may be irreversible. Anthracycline-induced cardiotoxicity in long-term survivors of childhood cancer is characterized by reduced left ventricular wall thickness and mass, which is indicative of decreased cardiac muscle and depressed left ventricular contractility which is indicative of unhealthy heart muscle. Risk factors for anthracycline-induced cardiotoxicity include high cumulative anthracycline doses, high anthracycline dose intensity, and radiotherapy. ⋯ There is evidence that dexrazoxane significantly reduces the cardiotoxicity associated with anthracyclines such as daunorubicin, doxorubicin, and epirubicin in adult patients with a wide range of tumor types. A study of the efficacy of dexrazoxane in reducing doxorubicin-induced cardiotoxicity in children and adolescents with high-risk acute lymphoblastic leukemia, showed that significantly fewer dexrazoxane-treated patients (21%) had elevated serum cardiac troponin (a biomarker of acute myocardial injury) levels than patients treated with chemotherapy alone (50%; P <.001). Dexrazoxane was also shown to have no effect on the event-free survival rate at 2.5 years, emphasizing that it does not detrimentally affect the efficacy of anthracycline therapy.