Anti-cancer drugs
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Ecteinascidin-743 (ET-743) has shown promise as a new and effective treatment for soft-tissue sarcomas. Two independent, multicenter, Phase II studies have been performed in the USA for patients with unresectable soft-tissue sarcomas (either chemotherapy-naïve or pretreated patients). The patients received ET-743 at a dose of 1500 micrograms/m2 as a 24 h continuous intravenous infusion every 3 weeks on an outpatient basis. ⋯ The side effects were reversible, non-cumulative and manageable. There were no treatment-associated deaths. In conclusion, ET-743 is an active chemotherapeutic agent that can induce objective responses and clinical benefit in a subset of patients with metastatic or advanced soft-tissue sarcoma.
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Initial evidence of clinical benefit with ecteinascidin-743 (ET-743) in patients with sarcoma was provided during a Phase I pharmacokinetic study in which 52 patients received ET-743 at doses of 50-1800 micrograms/m2 as a 24 h continuous infusion every 3 weeks. Neutropenia and thrombocytopenia were the dose-limiting toxicities; liver toxicity (a severe but transient and reversible increase in transaminase concentrations) was not treatment limiting. In conjunction with results obtained with ET-743 in a compassionate-use program, these indications of activity in heavily pretreated patients with sarcoma prompted initiation of a French multicenter Phase II study of ET-743 in this population. ⋯ Progression-free survival at 6 months was 26.5% and the overall survival rate at 12 months was almost 50%. The response rate was uninfluenced by tumor metastatic site, size or anthracycline sensitivity status. These results, combined with the lack of cumulative toxicity, confirm the role of ET-743 in the treatment of advanced STS.
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STI571 (imatinib mesylate) is an example of the successful development of a targeted agent. Its target is the constitutively active tyrosine kinase (p210bcr-abl) in a hematologic neoplasm, chronic myelogenous leukemia (CML). ⋯ This article reviews the pre-clinical and clinical development of this agent and also discusses some of the prevailing theories to explain the emerging problem of resistance. Future directions for this drug, possibly directed at other targets, are also discussed.
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Recombinant rIL-2 was reported to be able to decrease P-glycoprotein (P-gp) expression in cultured cells from human colon carcinoma. P-gp is considered an important factor in the control of Taxol efflux from tumor cells. Based on the premise that Taxol pharmacokinetic parameters could be modified as a result of diminished P-gp expression induced by recombinant interleukin (rIL)-2 and that this might elicit an interaction between the two drugs, we evaluated the pharmacokinetics of a novel strategy combining i.p. immunotherapy with rIL-2 and a cytotoxic agent, Taxol. ⋯ We conclude that rIL-2 pretreatment is able to decrease P-gp activity and paclitaxel metabolism in vivo. This is the first study to demonstrate a decrease in P-gp activity and expression in organs such as the brain in vivo. A novel strategy combining immunotherapy with rIL-2 and a cytotoxic agent could potentially improve clinical results, particularly in brain cancer.
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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.