Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML) are heterogeneous disorders for which there exist few active therapies and where the standard of care is still considered supportive. Identification of new effective therapies in MDS and CMML is a high priority for hematologic oncologists. We have evaluated the efficacy of single-agent topotecan, a topoisomerase I inhibitor, in patients with MDS (refractory anemia with excess blasts [RAEB] and refractory anemia with excess blasts in transformation [RAEB-T]) and CMML. Sixty patients (MDS = 30; CMML = 30) with a median age of 66 years were treated. Chromosomal abnormalities were present in half of the patients, as was thrombocytopenia. Topotecan was administered at 2 mg/m2 by continuous intravenous infusion over 24 hours daily for 5 days every 4 to 6 weeks until remission, followed by one course every 4 to 8 weeks for a maximum of 10 courses. Nineteen patients (32%) achieved a complete response (CR); seven had hematologic improvement. CRs were observed in 11 of 30 patients with MDS (37%) and eight of 30 patients with CMML (27%). Conversion to diploid karyotype was observed in eight patients with karyotypic abnormalities at diagnosis who later achieved a CR. History of prior chemotherapy and monocytosis was associated with poor prognosis. Mutation of the RAS oncogene was found in six CMML patients (20%), and none responded to topotecan therapy. The estimated 12-month survival rate was 33%, the median survival time was 9.3 months, and the median remission duration was 7 months. The most significant toxicities were gastrointestinal, including mucositis (67%; severe 23%) and diarrhea (38%; severe 17%). Febrile episodes were noted in 85% of the patients, while documented infection occurred in 47%. Topotecan has demonstrated significant single-agent activity in MDS and CMML with generally manageable side effects. Future studies will evaluate topotecan-based combination therapies with topoisomerase II reactive agents, cytarabine, alkylating agents, and hypomethylating agents.
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PMID:Topotecan in the treatment of hematologic malignancies. 977 79

Topotecan, a water-soluble analogue of camptothecin, is a newly available cytotoxic agent which acts as an inhibitor of topoisomerase I, an enzyme necessary for DNA replication. Topotecan is a semisynthetic product derived from camptothecin, which was discovered during a National Cancer Institute cytotoxic drug screening program almost 30 years ago. It acts by forming a stable covalent complex with the DNA/topoisomerase I aggregate, the so-called 'cleavable complex'. This process leads to breaks in the DNA strand resulting in apoptosis and cell death. Topotecan possesses a serum half-life of approximately 3 h, a high volume of distribution with high tissue uptake and a low protein binding. The chemical structure is based on a lactone ring. Topotecan undergoes reversible hydrolysis from its biologically active lactone form to the open ring inactive carboxylate form. It is also able to penetrate the intact blood-brain barrier. Since most of the agent is excreted by the kidneys, dose adjustment is necessary when renal function is impaired. In contrast, pharmacokinetic behavior is unchanged in patients with limited hepatic function. The principal toxicity of topotecan when administered at standard doses is neutropenia, but thrombocytopenia and anemia occur as well, while the nonhematological toxicities are usually mild. Alopecia is frequently observed and some patients may suffer from pronounced fatigue. Most clinical data available are based on the following schedule: 1.5 mg/m2 topotecan given as a 30-min infusion, days 1-5. There are currently only minimal data available regarding a dose-antitumor activity relationship. Other topotecan administration schedules are currently being investigated. Preclinical data suggest that continuous-infusion schedules may be a better application form in terms of both, toxicity and antitumor activity. However, clinical trials could not confirm these results to date. Results of phase II studies suggest considerable antitumor activity of single agent topotecan in small cell lung cancer and ovarian cancer patients. A randomized phase III trial of topotecan versus paclitaxel in ovarian cancer patients pretreated with cisplatin/cyclophosphamide has demonstrated that topotecan is as effective as paclitaxel in the second-line treatment of these patients. Activity of topotecan was also observed in non-small-cell lung cancer, refractory leukemias/myelodysplastic syndromes and in childhood sarcomas. Due to its unique mechanism of action and lack of cross-resistance, cisplatin, etoposide, cytarabine and paclitaxel are potential interacting partners for combination chemotherapy regimens. However, the best combination regimen as well as the optimal combination schedule have yet to be conclusively determined. The potential of topotecan in a variety of solid tumors, as well as its use in combination regimens for ovarian and small cell lung cancer is currently being investigated.
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PMID:Topotecan - A novel topoisomerase I inhibitor: pharmacology and clinical experience. 988 71

The study of the proliferation and differentiation of the MDS clone at the molecular level, including the details of apoptosis, may hopefully lead to more effective differentiation-induction/antiapoptotic agents. The study of the cytokines at the cellular/molecular level may lead to more effective trails of combination therapy with differentiation-induction agents, chemotherapy, and/or early-acting cytokines. Further phenotypic characterization of the MDS clone may lead to negative selection of these cells or positive selection of normal stem cells as part of an autotransplant strategy, as is presently being done in chronic-phase chronic myeologenous leukemia. The use of agents such as the topoisomerase I inhibitors (e.g., topotecan), which have mechanisms of action disparate from agents already used in MDS, may increase the efficacy of chemotherapy for MDS. The further clinical refinements in reducing treatment-related mortality and the study of T cells at the molecular level may hopefully lead to improvement in the prevention and therapy of graft-versus-host disease, in turn increasing the upper age limit of allogeneic BMT for MDS and increasing the feasibility of matched unrelated allogeneic BMT. At present, we can tailor the approach to a MDS patient based on his or her IPSS risk stratification, degree of cytopenia, and age, as outlined in Figure 2. At present, we can tailor the approach to a MDS patient based on his or her IPSS risk stratification, degree of cytopenia, and age, as outlined in Figure 2.
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PMID:Advances in the therapy of the myelodysplastic syndromes. 989 74

The National Comprehensive Cancer Network (NCCN) guidelines for patients with myelodysplastic syndromes (MDS) list myelosuppressive chemotherapy as an option for patients who have MDS with International Prognostic Scoring System (IPSS) scores of "intermediate" or "high." Myelodysplastic syndromes with these IPSS scores have an unfavorable natural history. Topotecan is a myelosuppressive drug that interacts with topoisomerase I and that has been used in the treatment of refractory AML. Its use in MDS has recently received considerable publicity. This paper reviews M. D. Anderson's results with topotecan and topotecan + ara-C in patients with MDS, focusing on comparisons of the results with ara-C and ara-C + fludarabine +/- idarubicin. While it is clear that the drug can produce complete responses, it is less clear that it differs from these other regimens. On average, complete response and survival rates are similar following administration of topotecan + ara-C or the other regimens. On the other hand, among patients with abnormalities of chromosomes 5 and/or 7, complete response rates are higher following topotecan + ara-C than for ara-C alone, or other ara-C combinations. The improvement in complete response rate among patients with abnormalities of chromosomes 5 and/or 7 has not resulted in an improvement in their survival (actuarial median about 6 months), largely reflecting a poor outcome following complete response. Indeed, the frequency of relapse in these patients suggests that any inherent increase in antileukemia activity in patients with abnormalities of chromosomes 5 and/or 7 is minimal. Given the overall results, topotecan +/- ara-C should not be regarded as standard therapy for MDS. The drug is nonetheless interesting and attempts to add to its efficacy are in progress.
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PMID:Incorporating new modalities into guidelines. Topotecan for myelodysplastic syndromes. 1002 4

The myelodysplastic syndromes (MDS) are a heterogeneous group of disorders characterized by peripheral blood cytopenias with a hypercellular bone marrow exhibiting dyspoiesis. The MDS range from those with a relatively indolent course (e.g., refractory anemia with or without ringed sideroblasts) to more aggressive disorders (e.g., refractory anemia with excess blasts [RAEB], and RAEB in transformation [RAEB-T]), which may exhibit a clinical course indistinguishable from acute myeloid leukemia (AML). Supportive care is the standard treatment for most patients, particularly those who are elderly, with the judicious use of blood components and antibiotics. For younger patients with RAEB and RAEB-T, antileukemic therapy might be considered, since the outcome is similar to that of patients with AML. Promising new chemotherapy agents currently in clinical trials include the topoisomerase I inhibitor, topotecan. The only curative treatment for MDS is allogeneic bone marrow transplantation, with long-term survival in approximately 40%, but with treatment-related deaths in 25%-40%. Factors predicting outcome include age, cytogenetics, number of blasts, and others. Myeloid growth factors (e.g., G-CSG, GM-CSF), increase the granulocyte count in most patients and may be useful in the setting of an active infection, although the prophylactic use of these agents does not improve survival. Erythropoietin increases the hematocrit in about 20% of patients. Growth factors being evaluated for their role in enhancing platelet counts include interleukin 11, stem cell factor, and megakaryocyte growth and development factor (thrombopoietin). Newer strategies to improve the outcome of patients with MDS should be based on an increased understanding of the biology of these disorders.
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PMID:The Myelodysplastic Syndromes. 1038 27

The topoisomerase I inhibitor topotecan has shown activity in acute myeloid leukemia (AML) and myelodysplastic syndromes. The present study was designed to assess whether topotecan with cytosine arabinoside (ara-C) or with etoposide (VP-16) should be studied in phase II trials in patients with refractory or relapsed AML. Patients with refractory or relapsed AML were assigned to one of 3 strata defined by expected CR rates of 7%, 20% and 40%, then randomly assigned to receive topotecan (dl-5) and ara-C (1 g/m2 over 2 hours; dl-5), topotecan (d1-5) followed by VP-16 (250 mg/m2 twice daily, d6-7), or VP-16 (250 mg/m2 twice daily dl-2) followed by topotecan (d3-d7). A dose-finding phase was conducted in the poorest stratum of each arm (topotecan starting dose: 1.0 mg/m2/day x 5). A Bayesian pre-phase II selection design was used to assess whether the CR rate with a given arm was sufficient to merit investigation in phase II. Thirty-seven patients, median age 58 years, were treated. Their median first CR duration was 28 weeks and 24% were primary refractory. Grade 3-4 mucositis occurred in the initial patients in the topotecan --> VP-16, but not in the topotecan + ara-C or VP-16 --> topotecan arms. Consequently, in subsequent patients, the topotecan dose was lower in the topotecan --> VP-16 than in the other 2 arms (1.0 vs 1.25 mg/m2 daily x 5) and the VP-16 dose was lower in the topotecan --> VP-16 arm (200 vs 250 mg/m2 twice daily x 2). One CR occurred (topotecan --> VP-16 arm), and the treatment arms were terminated after 10, 15, and 12 patients were treated on the topotecan + ara-C, topotecan --> VP-16, and VP-16 --> topotecan arms, respectively. The principal cause of failure was insufficient anti-leukemia effect rather than death on study, and toxicity was minimal at the final doses used. We concluded that none of the combinations studied here warrants phase II evaluation in very poor prognosis AML salvage patients.
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PMID:Combination of topotecan with cytarabine or etoposide in patients with refractory or relapsed acute myeloid leukemia: results of a randomized phase I/II study. 1055 27

The severe combined immunodeficient (SCID) mouse model of human acute myelogenous leukemia (AML) is a unique system for preclinical in vivo evaluation of the activity and toxicity of new agents. The topoisomerase I (topo I) inhibitor topotecan is active in patients with AML and myelodysplastic syndromes. DX-8951f is a novel topo I inhibitor with more potent antitumor effects than topotecan or CPT-11 in vitro. To study the in vivo activity of DX-8951f, 6-week-old female SCID mice received injections into the tail vein with 2 x 10(7) exponentially growing KBM-3 cells. In each experiment, three to five sets of five mice were treated with DX-8951f doses ranging from 7.5 to 80 mg/kg and at schedules of 1, 3, and 5 days; a control set of five mice was treated with the drug vehicle alone. One group received DX-8951f on day 7 of the inoculation with KBM-3 (early-treatment group). To study the activity of DX-8951f in advanced disease, a second group was treated 1 month after the inoculation, when the animals were developing symptoms (late-treatment group). The study end point was the duration of survival until death from leukemia, which was assessed clinically and by the presence of the human DQ alpha gene in tissue samples by PCR. Six experiments were conducted with 170 animals. Survival was higher in both the early- and late-treatment groups than in untreated controls, and the treated groups had significantly less central nervous system disease. Significantly improved survival was observed in animals treated early with 60 and 80 mg/kg as a single injection, with 15 and 20 mg/kg over 3 days, and with 7.5 and 10 mg/kg over 5 days. In the late-disease model (treatment starting on days 28-35), improved survival was observed with a single dose of 80 or 20 mg/kg over 5 days. Dose escalation was limited by dilution problems at the 1-day schedule and by toxicity (mainly gastrointestinal) of the prolonged schedules. Both efficacy and toxicity were dose schedule dependent, increasing with higher doses and prolonged exposure. By establishing the antileukemic activity of DX-8951f against human AML transplanted into SCID mice at doses below the LD10, our data provide a rationale for clinical evaluation of the drug in patients with AML and favor the use of prolonged administration.
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PMID:The topoisomerase I inhibitor DX-8951f is active in a severe combined immunodeficient mouse model of human acute myelogenous leukemia. 1069 May 60

Topotecan is a topoisomerase I inhibitor with significant activity in patients with myelodysplastic syndrome and chronic myelomonocytic leukemia. Pre-clinical data suggest a synergistic activity with DNA damaging agents such as cyclophosphamide, where topotecan might prevent the repair of cyclophosphamide-induced DNA damage. We thus designed a combination including cyclophosphamide 500 mg/m2 every 12 hours given on days 1 to 3; topotecan 1.25 mg/m2/day by continuous infusion on days 2 to 6, and cytosine arabinoside (ara-C) 2 g/m2 over 4 hours daily for 5 days on days 2 to 6 (CAT). Sixty six (63 evaluable) patients were treated. Fifty two patients had refractory (n=12) or relapsed (n=40) acute myelogenous leukemia (AML), and eleven had acute lymphocytic leukemia (ALL) (refractory n=3, relapsed n=8); their median age was 57 years (range, 18 to 79 years). Eleven patients (17%) achieved a complete remission (CR), and two patients (3%) had a hematologic improvement (HI; met all criteria for CR except for platelets < 100x10(9)/L), for an overall response rate of 20%. Responses occurred in 12 of 52 AML patients (23%), including 10 CR (19%) and 2 HI (4%), and in 1 of 11 patients with ALL (9%). Myelosuppression was universal; there were 23 episodes of pneumonia or sepsis and 18 episodes of fever of unknown origin complicating 74 courses of CAT. Non-hematologic toxicity was mostly gastrointestinal, including nausea, vomiting, diarrhea and mucositis, but was severe in only 8%. In summary, the CAT regimen is well tolerated and has significant anti-leukemia activity which warrants further investigation.
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PMID:Cyclophosphamide, ara-C and topotecan (CAT) for patients with refractory or relapsed acute leukemia. 1078 92

Topotecan, a soluble semisynthetic derivative of camptothecin, is a specific inhibitor of topoisomerase I and is endowed of potent antiproliferative effect in vitro and in vivo on tumoral cell lines as well as on endothelial cells. Moreover, topotecan is able to interfere with the development of blood vessels in many in vivo experimental models. During the last years, several phase I clinical studies have demonstrated that the five-daily schedule is the most effective for the treatment of neoplastic diseases of children and adults. In particular, the best clinical results have been obtained in patients affected by metastatic ovarian cancer, small cell (SCLC) and non-small cell lung carcinoma (NSCLC), as well as mammary and gastrointestinal neoplasms. High response rates have been observed in myelodysplastic syndromes and myeloma. The clinical effectiveness of topotecan has been also demonstrated in ovarian carcinoma, even after failure of first or second line chemotherapy and in SCLC, where the response rate is 39%, while the percentage decreases up to 7% in case of drug resistance, with a median survival of 5.4 months. Toxicologic profile of topotecan is foreseeable and manageable, and the most frequent and severe toxicity is represented by myelosuppression. Leukopenia and neutropenia, which follow the administration of topotecan, are non-cumulative and self-limiting and unfrequently complicated by infections, whereas non-hematologic toxicities are uncommon and generally of mild-to-moderate degree. Topotecan is under continuous clinical evaluation for the treatment of neoplasms other than those reported above, alone or in combination with antineoplastic drugs in poly-chemotherapeutic protocols.
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PMID:[Preclinical pharmacology and clinical uses of topotecan]. 1078 94


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