Anti-cancer drugs
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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.
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Comparative Study
Antitumor activity of XR5944, a novel and potent topoisomerase poison.
Inhibitors of topoisomerases are widely used in the treatment of cancer, including inhibitors of topoisomerase I (camptothecin analogs such as irinotecan and topotecan) and topoisomerase II (etoposide and doxorubicin). The novel bis-phenazine, XR5944, is a joint inhibitor of topoisomerase I and II as shown by the stabilization of topoisomerase-dependent cleavable complexes. XR5944 demonstrated exceptional activity against human and murine tumor cells in vitro and in vivo. ⋯ In the H69 model, low doses of XR5944 (5 mg/kg i.v., qdx5/week for 2 weeks or 10-15 mg/kg i.v., q4dx3), induced complete tumor regression in the majority of animals. In contrast, topotecan (20 mg/kg i.v., q4dx3) or etoposide (30 mg/kg i.v., q5dx5) only slowed the tumor growth rate. These studies show that XR5944 is a highly active novel anticancer agent that is well tolerated at efficacious doses.
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Docetaxel is an active single agent in both first- and second-line therapy of patients with advanced non-small cell lung cancer (NSCLC). Randomized trials versus best supportive care have documented an improvement in overall survival for docetaxel therapy in both settings. Docetaxel also produced a significant 1-year survival rate improvement when compared with vinorelbine or ifosfamide as second-line therapy. ⋯ However, the combination of docetaxel with gemcitabine was associated with significantly less grade III/IV neutropenia, diarrhea and nausea/vomiting. Three drug regimens combining docetaxel with, for example, gemcitabine and carboplatin or with ifosfamide and cisplatin, are producing very high response rates in phase II trials. Whether three-drug combinations including docetaxel will result in an improved outcome for patients with advanced NSCLC remains to be determined.
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Single-agent docetaxel induces a response in 21-42% of patients with recurrent squamous cell cancer of the head and neck (SCCHN). When used in combination with 5-fluorouracil (5-FU), response rates (RRs) of between 24 and 27% have been reported. In contrast, in combination with cisplatin, docetaxel has achieved a RR of 33% in previously treated patients and 86% in a subgroup of chemotherapy-naive advanced stage patients. ⋯ The rate of pathological complete response was also high. The toxicities with TPF therapy were similar to those seen with cisplatin/5-FU regimens without docetaxel. A phase III trial of this approach is currently being conducted.