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  • 1
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 24, No. 7 ( 2006-03-01), p. 1195-1203
    Abstract: To determine the clinical efficacy of imatinib in patients with advanced aggressive fibromatosis (AF) and to identify the molecular basis of response/nonresponse to this agent. Patients and Methods Nineteen patients with AF were treated with imatinib (800 mg/d) as part of a phase II clinical study. Tumor specimens were analyzed for mutations of KIT, PDGFRA, PDGFRB, and CTNNB1 (beta-catenin). Tumor expression of total and activated KIT, PDGFRA, and PDGFRB were assessed using immunohistochemistry and immunoblotting techniques. We also measured plasma levels of PDGF-AA and PDGF-BB in patients and normal patient controls. Results Three of 19 patients (15.7%) had a partial response to treatment, with four additional patients having stable disease that lasted more than 1 year (overall 1 year tumor control rate of 36.8%). No mutations of KIT, PDGFRA, or PDGFRB were found. Sixteen of 19 patients (84%) had mutations involving the WNT pathway (APC or CTNNB1). However, there was no correlation between WNT pathway mutations and clinical response to imatinib. AF tumors expressed minimal to null levels of KIT and PDGFRA but expressed levels of PDGFRB that are comparable with normal fibroblasts. However, PDGFRB phosphorylation was not detected, suggesting that PDGFRB is only weakly activated. AF patients had elevated levels of PDGF-AA and PDGF-BB compared with normal patient controls. Notably, the plasma level of PDGF-BB was inversely correlated with time to treatment failure. Conclusion Imatinib is an active agent in the treatment of advanced AF. Imatinib response in AF patients may be mediated by inhibition of PDGFRB kinase activity.
    Type of Medium: Online Resource
    ISSN: 0732-183X , 1527-7755
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Clinical Oncology (ASCO)
    Publication Date: 2006
    detail.hit.zdb_id: 2005181-5
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  • 2
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 14, No. 9 ( 2008-05-01), p. 2717-2725
    Abstract: Purpose: To evaluate the activity of imatinib in treating advanced, life-threatening malignancies expressing one or more imatinib-sensitive tyrosine kinases. Experimental Design: This was a phase II, open-label, single arm study. Patients ≥15 years old with malignancies showing histologic or molecular evidence of expression/activation of imatinib-sensitive tyrosine kinases were enrolled. Patients were treated with 400 or 800 mg/d imatinib for hematologic malignancy and solid tumors, respectively. Treatment was continued until disease progression or unacceptable toxicity. The primary objective was to identify evidence of imatinib activity with tumor response as the primary end point. Results: One hundred eighty-six patients with 40 different malignancies were enrolled (78.5% solid tumors, 21.5% hematologic malignancies). Confirmed response occurred in 8.9% of solid tumor patients (4 complete, 9 partial) and 27.5% of hematologic malignancy patients (8 complete, 3 partial). Notable activity of imatinib was observed in only five tumor types (aggressive fibromatosis, dermatofibrosarcoma protuberans, hypereosinophilic syndrome, myeloproliferative disorders, and systemic mastocytosis). A total of 106 tumors were screened for activating mutations: five KIT mutations and no platelet-derived growth factor receptor mutations were found. One patient with systemic mastocytosis and a partial response to therapy had a novel imatinib-sensitive KIT mutation (D816T). There was no clear relationship between expression or activation of wild-type imatinib-sensitive tyrosine kinases and clinical response. Conclusion: Clinical benefit was largely confined to diseases with known genomic mechanisms of activation of imatinib target kinases. Our results indicate an important role for molecular characterization of tumors to identify patients likely to benefit from imatinib treatment.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2008
    detail.hit.zdb_id: 1225457-5
    detail.hit.zdb_id: 2036787-9
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