Membrane peroxidative damage enhancement by the ether lipid class of antineoplastic agents.
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The ether lipid antineoplastic agents have no known interaction with DNA, but rather they appear to target membranes. The primary mechanism of action is unknown but effects on membrane biology are documented. We have studied the effect of two ether lipids on membrane lipids and examined the hypothesis that membrane peroxidative damage may be involved in their mechanism of action. With the use of cells having membranes enriched in polyunsaturated fatty acids of the omega-3 family of fatty acids, we have demonstrated that the prototypical ether lipid 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine and a thioether lipid analogue, 1-O-hexadecylmercapto-2-methoxymethyl-rac-glycero-3-phosphocholine , increase membrane lipid peroxidation and cytotoxicity in a time- and drug concentration-dependent manner. The oxidative cofactors Fe2+ and ascorbic acid were required. The pattern of cell death did not fully correspond to the peroxidation, since cofactors were required for peroxidation but not cytotoxicity. However, the rate of decrease in cell viability after exposure to the drug and cofactors corresponded to the peroxidation rate. In addition, when L1210 cells modified with the monounsaturated fatty acid oleic acid or unmodified cells were used, there was no ether lipid-enhanced peroxidation, and the cells were significantly less sensitive to the drug, with or without cofactors. The lipid-soluble antioxidant vitamin E inhibited 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine peroxidation and cytotoxicity in a concentration-dependent manner in the presence of cofactors but not consistently without them. Depletion of cellular glutathione content of L1210 cells using L-buthionine-(SR)-sulfoximine resulted in 40% augmentation of cofactor-facilitated cytotoxicity of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine and a borderline effect on peroxidation. Another ether lipid, the thio compound 1-O-hexadecylmercapto-2-methoxymethyl-rac-glycero-3-phosphocholine , enhanced peroxidation in the presence of cofactors with kinetics corresponding to those of cytotoxicity. In the presence of ether lipid and cofactors the intensity of ascorbate free radical increased, consistent with oxidative stress. We conclude that the ether lipids stimulate membrane lipid peroxidation in a time- and drug concentration-dependent manner in the presence of oxidative cofactors. Even though peroxidation may not fully explain the cytotoxic effect of the ether lipid class of anticancer drugs, this observation provides further information on the nature of the membrane damage induced by the drugs. Since the ether lipids generate no known free radical intermediates directly, this suggests that membrane damage indirectly results in a process involving a peroxidative reaction. (+info)
Defining and characterizing the late-stage biopharmaceutical pipeline.
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OBJECTIVE: To identify and describe biopharmaceuticals in late-stage development in the United States and to understand their implications for third-party payers. STUDY DESIGN AND METHODS: "Biopharmaceutical" and biopharmaceuticals in late-stage US development (had completed Phase 2 or higher) were identified through reviews of literature, 4 drug-development databases, a clinical trial database, and informal telephone conversations with representatives of the US Food and Drug Administration, faculty at academic institutions, and manufacturers. RESULTS: "Biopharmaceutical" was defined as "any biology-based therapeutic that structurally mimics compounds found within the body." This includes recombinant proteins, monoclonal and polyclonal antibodies, peptides, antisense oligonucleotides, therapeutic genes, and certain therapeutic vaccines. As of April 2003, there were 102 unique biopharmaceuticals in late-stage development for 156 indications in 36 disease categories, affecting at least 22 distinct physician specialties. Cancer agents are most common, with 30 agents (29%) targeting 62 indications (40%). Nearly 90% of the biopharmaceuticals require administration via injection or infusion, nearly 70% will require administration by a healthcare provider, and more than 60% will be administered in ambulatory care settings. All 22 physician specialties are affected by healthcare provider-administered biopharmaceuticals. Excluding cancer-related biopharmaceuticals, 60% of biopharmaceuticals and 54% of indications require chronic administration. Up to 81 biopharmaceuticals for 123 indications may be approved within the next 4 years (including secondary approvals). CONCLUSIONS: The broad range of the late-stage US biopharmaceutical pipeline has significant implications for third-party payers due to their likely premium price, once approved, as well as novel logistical considerations. Payers must prepare for a wide range of clinical, administrative, delivery, and economic issues. (+info)
International Conference on Harmonisation; guidance on Addendum to E2C Clinical Safety Data Management: Periodic Safety Update Reports for Marketed Drugs; availability. Notice.
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The Food and Drug Administration (FDA) is announcing the availability of a guidance entitled "Addendum to E2C Clinical Safety Data Management: Periodic Safety Update Reports for Marketed Drugs" (the ICH E2C guidance). The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). In the Federal Register of May 19, 1997 (62 FR 27470), FDA published the ICH E2C guidance, which recommends a unified standard for the format, content, and reporting frequency for postmarketing periodic safety update reports (PSURs) for drug and biological products. This guidance, an addendum to the ICH E2C guidance, provides additional information on the content and format of PSURs, including clarification of the objectives, general principles, and model for PSURs. This guidance is intended to help harmonize collection and submission of postmarketing clinical safety data. (+info)
Analysis of information submitted by clinical trial sponsors regarding the safety of investigational drugs.
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During performance of clinical trials in medical institutions, information regarding the safety of investigational drugs is submitted by trial sponsors according to guidelines for good clinical practice. In the present study, reports of clinical trials conducted at the University of Tokyo Hospital were examined, focusing on the safety information provided to the Institutional Review Board (IRB). Two hundred two reports (52 protocols) of safety information were submitted to the IRB by clinical trial sponsors between April 2000 and March 2001, of which 185 contained a total of 3021 cases of adverse events. Of those, 194 reports were judged by clinical investigators/physicians not to be associated with any significant problems and the trials were continued. For 157 of those 194 reports, it was considered unnecessary to inform the test subjects of the report contents, including the adverse events. The decision of whether or not the test subjects should be informed of such contents tended to depend on the causal relationship between the adverse events and drug intake, as well as the predictability of the adverse events. For 8 of those 194 reports, the IRB recommended that the clinical investigators/ physicians provide information to the test subjects and/or submit detailed information on the status of these subjects to the IRB. From these results, we suggest that establishment of a system to unify and evaluate drug safety information is necessary to provide safe and efficient clinical trials. (+info)
High-dose imatinib mesylate therapy in newly diagnosed Philadelphia chromosome-positive chronic phase chronic myeloid leukemia.
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Imatinib mesylate (STI571) is effective in chronic phase chronic myelogenous leukemia (CML). However, most patients treated with 400 mg imatinib daily have variable levels of residual molecular disease. We treated 114 patients with newly diagnosed chronic phase CML with 400 mg imatinib twice daily. Overall, 109 patients (96%) had a major cytogenetic response (Philadelphia chromosome [Ph] < 35%), and 103 (90%) had a complete response (Ph 0%). With a median follow-up of 15 months, no patient has progressed to accelerated or blastic phase. The estimated 2-year survival rate was 94%. By quantitative polymerase chain reaction (QPCR) studies, 71 (63%) of 112 patients showed BCR-ABL/ABL percentage ratios decrease to less than 0.05%, and 31 (28%) to undetectable levels. Compared with standard-dose imatinib, high-dose imatinib was associated with significantly better complete cytogenetic response (P =.0005), major molecular response (QPRC < 0.05%; P =.00001), and complete molecular response (undetectable BCR-ABL; P =.001). High-dose imatinib was well tolerated but resulted in more frequent myelosuppression; 82% of patients continue to receive 600 mg or more of imatinib daily. In conclusion, high-dose imatinib induced higher rates of complete cytogenetic response and of molecular response in patients with newly diagnosed chronic phase CML. (+info)
Supplements and other changes to an approved application. Final rule.
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The Food and Drug Administration (FDA) is amending its regulations on supplements and other changes to an approved application to implement the manufacturing changes provision of the Food and Drug Administration Modernization Act of 1997 (the Modernization Act). The final rule requires manufacturers to assess the effects of manufacturing changes on the identity, strength, quality, purity, and potency of a drug or biological product as those factors relate to the safety or effectiveness of the product. The final rule sets forth requirements for changes requiring supplement submission and approval before the distribution of the product made using the change, changes requiring supplement submission at least 30 days prior to the distribution of the product, changes requiring supplement submission at the time of distribution, and changes to be described in an annual report. (+info)
Drug-induced torsades de pointes and implications for drug development.
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Torsades de pointes is a potentially lethal arrhythmia that occasionally appears as an adverse effect of pharmacotherapy. Recently developed understanding of the underlying electrophysiology allows better estimation of the drug-induced risks and explains the failures of older approaches through the surface ECG. This article expresses a consensus reached by an independent academic task force on the physiologic understanding of drug-induced repolarization changes, their preclinical and clinical evaluation, and the risk-to-benefit interpretation of drug-induced torsades de pointes. The consensus of the task force includes suggestions on how to evaluate the risk of torsades within drug development programs. Individual sections of the text discuss the techniques and limitations of methods directed at drug-related ion channel phenomena, investigations aimed at action potentials changes, preclinical studies of phenomena seen only in the whole (or nearly whole) heart, and interpretation of human ECGs obtained in clinical studies. The final section of the text discusses drug-induced torsades within the larger evaluation of drug-related risks and benefits. (+info)
Advances in antiretroviral therapy. Highlights of the 11th Conference on Retroviruses and Opportunistic Infections, February 8-11, 2004, San Francisco, California, USA.
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Antiretroviral therapy was focus of many of the studies reported at the 11th CROI. This year, data on new drugs, refinements in the management of treatment-naive and treatment-experienced persons, the impact of drug resistance (particularly following exposure to a single dose of nevirapine), and the growing experience with antiretrovirals in the developing world were the dominant themes. This reviews summarizes new information relevant to clinicians and clinical researchers. (+info)