Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Farnesyltransferase inhibitors represent a new class of agents that target signal transduction pathways responsible for the proliferation and survival of diverse malignant cell types. Although these agents were developed to prevent a processing step necessary for membrane attachment and maturation of Ras proteins, recent studies suggest that farnesyltransferase inhibitors block the farnesylation of additional cellular polypeptides, thereby exerting antitumor effects independent of the presence of activating ras gene mutations. Clinical trials of two farnesyltransferase inhibitors--the tricyclic SCH66336 and the methylquinolone R115777--as single agents have demonstrated disease stabilization or objective responses in 10 to 15% of patients with refractory malignancies. Combinations of farnesyltransferase inhibitors with cytotoxic chemotherapies are yielding complete and partial responses in patients with advanced solid tumors. A phase I trial of R115777 in refractory and relapsed acute leukemias induced responses in 8 (32%) of 25 patients with acute myelogenous leukemia (including two complete remissions) and in two of three with chronic myelogenous leukemia in blast crisis. In patients with solid tumors, accessible normal tissues such as peripheral blood lymphocytes or, perhaps more germane to epithelial malignancies, buccal mucosa have provided surrogate tissues that allow confirmation that farnesyltransferase is inhibited in vivo at clinically achievable drug doses. In conjunction with the R115777 acute leukemia trial, serial measurements provided evidence of farnesyltransferase enzyme inhibition, interference with farnesyltransferase function ( ie, protein processing), and blockade of signal transduction pathways in leukemic bone marrow cells. Preclinical studies of farnesyltransferase inhibitor resistance and clinical trials of farnesyltransferase inhibitors in combination with other agents currently are in progress.
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PMID:Current status of clinical trials of farnesyltransferase inhibitors. 1167 87

The treatment of patients with chronic myeloid leukemia (CML) is evolving rapidly. With conventional chemotherapy the clinical course is characterized by a chronic phase (median duration, 4 to 5 years), followed by an accelerated phase with transition to a terminal blast crisis. Treatment with busulfan or hydroxyurea does not alter the natural history. Interferon alfa (IFN-alpha) prolongs life expectancy by approximately 20 months but is associated with significant toxicity. Evidence indicates that bone marrow transplantation from a related human leukocyte antigen (HLA)-identical donor can be curative in younger patients. However, transplantation is available to only a minority of patients and entails severe toxicity and transplant-related mortality. Dramatic advances in the understanding of the molecular pathophysiology of CML have led to a new era of targeted therapy. The specific tyrosine kinase inhibitor imatinib mesylate demonstrates a high level of efficacy in CML with acceptable toxicity. Farnesyltransferase inhibitors (FTIs) are another important class of targeted agents with the potential to act at multiple sites within dysregulated signal transduction networks. ZARNESTRA (formerly R115777, Ortho Biotech Oncology, Raritan, NJ), an oral FTI, has shown activity and is well tolerated in both chronic- and accelerated-phase patients. With their mechanistic specificity, the new modalities offer the promise of increased antileukemic activity and an improved therapeutic index.
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PMID:Chronic myeloid leukemia: current therapies and the potential role of farnesyltransferase inhibitors. 1221 88

Acute leukemia carries a poor prognosis, especially in older patients, emphasizing the need for novel therapies. Reasons for treatment failure include high rates of relapse and treatment-related toxicities. Farnesyltransferase inhibitors (FTIs), a new class of agents that can interfere with intracellular signaling, are good therapeutic candidates for study in these diseases, given the relatively high levels of the target enzyme, farnesyltransferase, expressed in bone marrow and by peripheral circulating lymphocytes. ZARNESTRA (formerly R115777, Ortho Biotech Oncology, Raritan, NJ) is an FTI that has clinical activity in solid tumors and antileukemic activity in vitro. In a phase I trial of Zarnestra in patients with high-risk leukemia (resistant or relapsed acute myeloid leukemia [AML] or acute lymphocytic leukemia [ALL], chronic myeloid leukemia [CML] in blast crisis, or AML in poor prognosis subgroups), patients experienced an overall response rate of 29%. Zarnestra was well tolerated with no dose-limiting toxicities through doses up to 900 mg twice daily. Assays measuring inhibition of farnesyltransferase activity showed a reliable inhibition at doses greater than 300 mg twice daily, and pharmacokinetic studies indicated that Zarnestra accumulated preferentially in the bone marrow in a dose-dependent fashion. These results suggest that Zarnestra should be studied further in patients with myeloid leukemia.
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PMID:Farnesyltransferase inhibitors and myeloid malignancies: phase I evidence of Zarnestra activity in high-risk leukemias. 1221 91

Significant advances have been made in the development of targeted interventions for hematologic malignancies. Progress has been made in defining the molecular pathogenesis of human leukemias. Data indicate that nonrandom, somatically acquired translocations, inversions, and other abnormalities occur in many acute leukemias. In the treatment of acute promyelocytic leukemia (APL), targeted therapy with all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy leads to dramatic improvements in disease-free survival. Imatinib mesylate, a signal transduction inhibitor that inhibits tyrosine kinase activity, the protein product of the ABL proto-oncogene, has remarkable activity in patients with chronic myeloid leukemia (CML) and Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL). Farnesyltransferase inhibitors (FTIs), a promising class of agents that target multiple pathways including Ras proteins, are potential anticancer therapy for a wide range of malignancies, including leukemias and myelodysplastic syndromes (MDS). There also is evidence that recombinant human erythropoietin therapy (r-HuEPO) can benefit patients with chronic lymphocytic leukemia (CLL), multiple myeloma, and lymphomas. This supplement will discuss advances in our understanding of human leukemias, including the use of unconjugated monoclonal antibodies such as Campath-1H (Wellcome, Beckenham, UK, and Ilex Oncology, San Antonio, TX) and rituximab and immunoconjugates such as gemtuzumab ozogamicin and BL-22. Although these novel therapies are beginning to fulfill their promise, continued research efforts are needed to determine the optimal role of targeted therapy in acute and chronic leukemias.
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PMID:Advancing the treatment of hematologic malignancies through the development of targeted interventions. 1244 45

Farnesyltransferase inhibitors (FTIs) target multiple pathways including the Ras pathway implicated in the pathogenesis of some hematologic malignancies. R115777 and BMS-214662, selective FTIs in clinical development, exhibit preclinical activity against cell lines and tumor xenografts with or without ras mutations. Phase I dose-escalating trials at M.D. Anderson Cancer Center have explored the potential of these agents as monotherapy for leukemias and myelodysplastic syndrome (MDS). In 20 patients with MDS, two cycles of oral R115777 for 3 consecutive weeks followed by a 1-week rest produced an overall response rate of 30%, consistent with 29% reported in poor-prognosis acute leukemia or blast-phase chronic myelogenous leukemia (CML). Administration of BMS-214662 as a weekly intravenous infusion produced a decrease in bone marrow blasts of greater than 50% in 23% of patients with acute leukemia or MDS; 18% achieved normalization of blast counts to less than 5%. In both studies, most responding patients did not have ras mutations. The most common side effects at maximum tolerated doses of R115777 (400 mg twice daily) and BMS-214662 (118 mg/m(2) weekly) were myelosuppression and nausea, respectively. Further evaluation of FTIs for hematologic malignancies clearly is warranted. Future research should address whether molecular techniques can identify patients most likely to respond to an FTI, optimal administration schedules for these agents, and the value of incorporating an FTI into combination regimens for difficult-to-treat hematologic malignancies.
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PMID:Clinical development of farnesyltransferase inhibitors in leukemias and myelodysplastic syndrome. 1244 48

Farnesyltransferase inhibitors (FTIs) inhibit certain cellular signal transduction pathways, and are being evaluated for activity in hematologic malignancies. Tipifarnib and lonafarnib are orally available FTIs that are active against a variety of targets and inhibit several pathways involved in the pathogenesis of hematologic malignancies. FTIs have demonstrated activity in a variety of hematologic diseases, including acute myeloid leukemia, myelodysplastic syndrome, chronic myeloid leukemia, and multiple myeloma. This article reviews the clinical experience with tipifarnib and lonafarnib in the treatment of hematologic malignancies.
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PMID:Farnesyltransferase inihibitors in hematologic malignancies. 1729 17

Farnesyltransferase inhibitors (FTIs) represent a new class of signal transduction inhibitors that block the processing of cellular polypeptides that have cysteine terminal residues and, by so doing, interdict multiple pathways involved in proliferation and survival of diverse malignant cell types. Tipifarnib is an orally bioavailable, nonpeptidomimetic methylquinolone FTI that has exhibited clinical activity in patients with myeloid malignancies including elderly adults with acute myelogenous leukemia (AML) who are not candidates for traditional cytotoxic chemotherapy, patients with high-risk myelodysplasia, myeloproliferative disorders, and imatinib-resistant chronic myelogenous leukemia. Because of its relatively low toxicity profile, tipifarnib provides an important alternative to traditional cytotoxic approaches for elderly patients who are not likely to tolerate or even benefit from aggressive chemotherapy. In this review, we will focus on the clinical development of tipifarnib for treatment of newly diagnosed AML, both as induction therapy for elderly adults with poor-risk AML and as maintenance therapy following achievement of first complete remission following induction and consolidation therapies for poor-risk AML. As with all other malignancies, the optimal approach is likely to lie in rational combinations of tipifarnib with cytotoxic, biologic and/or immunomodulatory agents with non-cross-resistant mechanisms of action. Gene expression profiling has identified networks of differentially expressed genes and gene combinations capable of predicting response to single agent tipifarnib. The clinical and correlative laboratory trials in progress and under development will provide the critical foundations for defining the optimal roles of tipifarnib and in patients with AMl and other hematologic malignancies.
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PMID:Tipifarnib in the treatment of newly diagnosed acute myelogenous leukemia. 1970 79