Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Radiotherapeutic studies with amifostine (WR-2721; Ethyol, US Bioscience, Inc, West Conshohocken, PA) are reviewed, with evidence that it offers clinical normal tissue protection and no evidence of any tumor protection. Conducting clinical trials with amifostine has been difficult because of the unique (toxicity) endpoints and concerns about tumor protection. The Radiation Therapy Oncology Group has conducted phase I studies and a phase II hemibody study, and is now in the process of conducting phase III amifostine studies. Amifostine remains the most promising compound for testing clinical radioprotection, and as new techniques are developed in radiation therapy to deliver higher doses of radiation, the protection of normal tissues will become even more important. This review will cover both the preclinical and clinical studies involving the use of amifostine with radiation therapy.
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PMID:Radiotherapeutic studies with amifostine (Ethyol). 797 75

Amifostine (US Bioscience, West Conshohocken, PA; Ethyol, WR-2721), a phosphorylated thiol developed by the United States Army as a protective agent for military personnel in the event of nuclear warfare, has shown protection of normal tissues from the cytotoxic effects of therapeutic radiation and chemotherapy with preservation of cytotoxic effects on the tumor. The basis of this selective protection derives from the relatively rapid uptake and anabolism of Amifostine into normal tissues and minimal, slower uptake into tumor tissue. Preclinical investigations have demonstrated protection of bone marrow stem cells from the toxic effects of radiation and chemotherapy. Several controlled clinical trials demonstrated this hematoprotective effect. In patients given 1.5 g/m2 cyclophosphamide and month later given Amifostine (740 mg/m2) followed by the same dose of cyclophosphamide, the median nadir neutrophil count was significantly increased and duration of neutropenia was significantly reduced by pretreatment with Amifostine. In women with stage III/IV ovarian cancer treated with 1 g/m2 cyclophosphamide and 100 mg/m2 cisplatin +/- Amifostine 910 mg/m2, treatment with Amifostine before cyclophosphamide and cisplatin resulted in a significant decrease in both the incidence and duration of hospital stays for neutropenic fever compared to cyclophosphamide and cisplatin alone. There were equivalent rates of response and duration of survival in both groups. Other studies have shown Amifostine protects bone marrow purged in vitro with 4-hydroperoxycyclophosphamide before autologous bone marrow transplantation. This preservation of marrow stem cells resulted in a statistically significant decrease in time to marrow engraftment, need for platelet transfusions and antibiotics, and duration of hospital stay. Amifostine-mediated protection of normal bone marrow illustrated in preclinical experiments is also evident in clinical trials. Amifostine preserves trilineage stem cells (red blood cells, platelets, and white blood cells) in contrast to the lineage-specific effects of the colony-stimulating factors. Theoretically, Amifostine and the colony-stimulating factors should provide complementary benefits to bone marrow recovery and function after cytotoxic therapies. These observations offer the promise of using high doses of chemotherapy to exploit antitumor, dose-response relationships in clinical trials.
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PMID:Amifostine-mediated protection of normal bone marrow from cytotoxic chemotherapy. 824 82

The radioprotector S-2-(3-aminopropylamino) ethylphosphorothioic acid (amifostine; WR-2721) was evaluated for its ability to protect against cyclophosphamide-induced mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in mouse splenocytes under conditions that do not interfere with cyclophosphamide's therapeutic effectiveness against fibrosarcoma lung tumors. Mutations at the HPRT locus increase in frequency as a function of the dose of cyclophosphamide used. With a spontaneous mutation frequency in C3H mice of 1.5 x 10(-6), mutation frequencies increased from 6.2 x 10(-6) to 2.0 x 10(-5) as the cyclophosphamide dose increased from 50 to 200 mg/kg. C3H male mice had 3.5 x 10(5) viable fibrosarcoma cells injected into their tail veins. This resulted in an average of 68 tumor colonies per mouse. Four days following injection, animals received cyclophosphamide 100 mg/kg, which provided significant tumor cell killing and a reduction in tumor colony number to an average of less than one per animal. Amifostine at a concentration of 100 mg/kg did not affect cyclophosphamide's therapeutic efficacy. However, amifostine 100 mg/kg was effective in reducing cyclophosphamide-induced HPRT mutation frequency in mice from 160 to 35 per 10(5) viable cells regardless of whether it was administered 30 minutes before or 2 hours after the cyclophosphamide.
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PMID:Antimutagenic effects of amifostine: clinical implications. 878 68

Amifostine selectively protects normal, but not tumor, tissue from the cytotoxic damage induced by radiation therapy and chemotherapy. In a broad range of preclinical and phase II and III clinical studies, amifostine has been shown to substantially reduce anticancer drug-induced neutropenia, thrombocytopenia, nephrotoxicity, neurotoxicity (including ototoxicity and peripheral neuropathy), musculoskeletal toxicity, cardiotoxicity, and mutagenicity. Based on the rapidly expanding clinical trials database, there is strong rationale to design phase II and III studies of amifostine as a cytoprotective agent in patients with early and/or advanced breast, bladder, cervix, head and neck, small cell and non-small cell lung, ovarian, and rectal cancers, as well as melanoma, pediatric sarcomas, and lymphomas, including Hodgkin's disease. In this article, we have attempted to survey recently completed and ongoing phase II and III clinical studies and suggest specific designs for future clinical trials to establish the ultimate role of amifostine as a broad-spectrum cytoprotective agent.
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PMID:Future development of amifostine in cancer treatment. 878 74

Testicular germ cell tumors are so exquisitely sensitive to cisplatin that the majority of patients with this cancer are now cured with modern platinum-based chemotherapy. In contrast to some other tumor types, testicular germ cell tumors are known to express alkaline phosphatases (ALP). Amifostine is an aminothiol pro-drug which is rapidly dephosphorylated by ALP at the ell surface of healthy tissues and which exerts a clinically proven protective effect against chemotherapy associated toxicity. The aim of this pre-clinical study was to assess the potential of amifostine to protect platinum-sensitive non-seminomatous germ cell tumor (NSGCT) nude mouse xenografts established from an ALP-positive embryonal carcinoma (EC) cell line, from the cytotoxicity of cisplatin when both were administered at their individual maximally tolerated doses (MTD). The %T/C values calculated at day 30 for nude mice carrying H12.1 NSGCT xenografts treated with amifostine alone, amifostine plus cisplatin or cisplatin alone were, respectively, 93, 3 or 3%. Mean tumor volumes were not significantly different between mice treated with the combination versus cisplatin alone at day 14 or 30. The results of this study revealed no evidence of tumor protection by amifostine, confirming previous results in other tumor types.
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PMID:Amifostine does not alter the antitumor activity of cisplatin in a pre-clinical model of testicular cancer. 894 93

Originally developed against the effects of ionizing radiations, amifostine is an organic thiophosphate compound shown able to selectively protect normal tissues against cytotoxic agents in cellular and animal models, without protecting tumor tissues. Amifostine is a prodrug which is dephosphorylated into its active metabolite, a free thiol derivative, by membrane alkaline phosphatase of the target issue. This unique metabolism supports its cellular selectivity and its preferential uptake by normal tissues. In phase II clinical trials, a decreased toxicity has been demonstrated in patients given alkylating agents; however, reduction of the response has not been observed. On the basis of these results, a prospective, randomized, phase III study has been conducted in patients with ovarian carcinoma receiving a combination of cisplatinum and cyclophosphamide. A significant decrease in hematologic, renal and neurologic toxicity was observed in the amifostine-treated patients compared with the control group, and response rates did not significantly differ between the two groups. Insufficient or emerging data are only available for other applications, including either in vitro manipulation of hematopoietic grafts or in vivo treatment of non-Hodgkin's lymphoma, head and neck carcinoma, non-small cell lung cancer and radioprotection. No data are yet available in regard to the potential protective effects of amifostine against mutagenicity and cancerogenicity of both chemo- and radiotherapy.
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PMID:[Amifostine: current and future applications in cytoprotection]. 895 58

The mechanism of action, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of amifostine are reviewed. Amifostine is a prodrug converted by alkaline phosphatase to the active sulfhydryl compound WR-1065. WR-1065 protects normal cells by scavenging free radicals, donating hydrogen ions to free radicals, depleting oxygen, and binding to active derivatives of antineoplastic agents. The immediate conversion of amifostine to WR-1065, its small volume of distribution, and the limited amount of drug and metabolite recovered in the urine suggest that amifostine is rapidly dephosphorylated and enters cells as its active metabolite. The selectivity of amifostine for normal tissue is hypothesized to be a results of the decreased vascularity of tumors, decreased activity of alkaline phosphatase in tumor cells, and pH dependence of WR-1065 uptake. In clinical studies, amifostine decreased the frequency of cisplatin-induced nephrotoxicity, ototoxicity, neurotoxicity, and myelosuppression. Amifostine has demonstrated an ability to decrease the hematologic toxicity of cyclophosphamide, carboplatin, mitomycin, and antineoplastic drug combinations. Amifostine has FDA-approved labeling for use in reducing cumulative renal toxicity in patients receiving repeat doses of cisplatin for advanced ovarian cancer and non-small-cell lung cancer. The recommended dose in adults is 910 mg/m2 administered as a 15-minute infusion 30 minutes before the start of chemotherapy. The major adverse effects of amifostine include hypotension and emesis. The benefits of amifostine must be weighted against its potential adverse effects, and the drug's impact on the efficacy of antineoplastics should be further investigated. Amifostine has shown promise in protecting non-malignant cells from the toxic effects of antineoplastics, apparently without compromising toxicity against cancer cells.
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PMID:Amifostine for protection from antineoplastic drug toxicity. 977 47

The administration of intensive chemotherapy according to a rigid schedule improves response rates and duration of response. However, dose-limiting toxicities and resulting delays in therapy often interfere with therapy intensification. In recent years, cytoprotective agents have been developed that can protect normal cells, but not tumor cells, from chemotherapeutic or radiation damage. Amifostine (Ethyol), dexrazoxane (Zinecard), and mesna (Mesnex) are true cytoprotectors administered shortly before chemotherapy. Colony-stimulating factors (CSFs) are administered after chemotherapy to rescue the bone marrow and stimulate hematologic recovery. In the appropriate settings, use of these agents has facilitated the intensification of chemotherapy and has significantly attenuated the impact of chemotherapy on normal cells.
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PMID:Current role of protective agents in cancer treatment. 913 Feb 73

Amifostine (WR-2721, Ethyol), S-2[3-aminopropylamino]-ethyl-phosphorothioic acid, was selected as a clinically usable radioprotector from more than 4,400 compounds in the 1950s. A considerable amount of preclinical work suggested that amifostine, or its activated thiol WR-1065, protected normal cells effectively against the adverse effects of irradiation and several anticancer drugs without exhibiting tumor protection. In non-randomized and randomized trials in malignant melanoma, colorectal cancer, head and neck cancer, non-small cell lung cancer, and epithelial ovarian carcinoma, amifostine significantly reduced the hematological and non-hematological toxicity of DNA-damaging agents such as alkylators, platinum compounds, or mitomycin C. In more recent studies, the drug also protected patients from side effects produced by taxanes or topoisomerase I inhibitors and is thus likely to allow higher cytostatic doses to be administered. Currently, there is no evidence that amifostine compromises the antineoplastic effect of the drugs studied. Otherwise, W/R-2721 may even improve the therapeutic efficacy of agents like cisplatin, carboplatin, or paclitaxel. Moreover, amifostine appears to produce growth-factor like properties resulting in growth-promoting effects on primitive blood progenitor cells ex vivo. Amifostine offers a rational approach to protect patients against chemotherapy-specific and often dose-limiting effects and is thus likely to improve therapeutic outcome significantly. Future studies should be focused on both new indications like childhood cancer, myelodysplastic syndromes, dose-intensified or high- dose chemotherapy, and multimodality approaches and optimization of amifostine dosage in order to reduce dose-limiting side effects. Then, the drug may play a major role in more specific and individualized oncologic strategies.
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PMID:Chemoprotection in anticancer therapy: the emerging role of amifostine (WR-2721). 970 84

Amifostine (Ethyol, ALZA Pharmaceuticals, Palo Alto, CA/US Bioscience, West Conshohocken, PA) is a phosphorylated cysteamine derivative that was originally developed by the US Army Walter Reed Institute (Washington, DC) as a radioprotectant. Amifostine, a prodrug, is metabolized by the enzyme alkaline phosphatase to an active sulfhydryl compound (WR-1065) capable of scavenging radiation-generated free radicals and preventing cell damage. The disulfides of WR-1065 are structurally analogous to endogenous polyamines, which can bind to DNA molecules and stabilize them in a compact form less vulnerable to damage by cytotoxic agents. Preclinical and clinical studies show that amifostine is a selective radioprotectant that reduces both early and late radiation-induced toxicities to normal tissues while leaving tumor cells exposed to the cytotoxic effects of radiation. Preclinical data indicate that amifostine could reduce the risk of secondary cancers caused by radiation and certain forms of chemotherapy.
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PMID:Radioprotectants: pharmacology and clinical applications of amifostine. 979 95


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