Anti-cancer drugs
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Amplification of the human epidermal growth factor receptor-2 (HER2) gene and overexpression of the encoded protein are seen in 20-30% of breast cancers, and are associated with aggressive disease and relatively poor prognosis. Thus, HER2 represents an appropriate target for anticancer treatment and the humanized anti-HER2 monoclonal antibody Herceptin has been developed for this purpose. The efficacy of Herceptin has been confirmed in two pivotal trials-a monotherapy study in 222 women with HER2-positive metastatic breast cancer who had already received one or two chemotherapy regimens for metastatic disease and a study comparing Herceptin plus chemotherapy with chemotherapy alone in 469 patients previously untreated for metastatic disease. ⋯ Most patients respond to conventional supportive treatment. Cardiotoxicity, the most serious adverse event observed, occurred mainly in patients exposed to anthracyclines and was generally manageable. Thus, Herceptin represents a significant development in the management of HER2-positive breast cancer.
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Herceptin extends survival in human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer patients when administered with paclitaxel or anthracycline/cyclophosphamide (AC), and the combination with 3-weekly paclitaxel is the current standard first-line therapy. However, other combinations may be equally effective. This review provides information on recent and ongoing trials of new Herceptin combinations. ⋯ High response rates have been observed in these clinical trials, e.g. up to 80% in combination with vinorelbine. Furthermore, Herceptin in combination with weekly paclitaxel, docetaxel or vinorelbine was well tolerated: there was no significant cardiotoxicity or unexpected toxicity and the combination showed an adverse event profile similar to that seen with monotherapy with the cytotoxic agent. Thus, Herceptin produces additional clinical benefit when added to all the cytotoxic agents with which it has been examined, further demonstrating its potential for use in HER2-positive breast cancer patients.
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The aggressiveness of human epidermal growth factor receptor-2 (HER2)-positive breast cancer and the poor prognosis of women with this disease demand the availability of accurate and reliable tests for HER2 status and the optimization of HER2-targeted therapy. The distinctive clinical pattern of HER2-positive breast cancer underlines the importance of testing for HER2 status and efforts are ongoing to validate the two major methods in use-immunohistochemistry (IHC), which measures cell membrane HER2 expression, and fluorescence in situ hybridization (FISH), which measures gene copy number. ⋯ High levels of concordance between IHC 3+ and FISH-positive status have been observed, and response to treatment with Herceptin is similar for patients whose breast cancers are IHC 3+ and those who are FISH-positive. Observations to date have led to the formulation of an algorithm for HER2 status determination and Herceptin use which recommends that: (i) the HER2 status of all women with breast cancer be determined at presentation, (ii) all IHC 3+ and FISH-positive patients with metastatic disease should receive Herceptin, (iii) Herceptin should be used early in the course of metastatic breast cancer and preferably first line, and (iv) Herceptin therapy should be continued until disease progression.