Imatinib for the treatment of aggressive fibromatosis (desmoid tumors) failing local treatment. A phase II trial of the French Sarcoma Group

9516 Background: Background: Aggressive fibromatosis/desmoid tumors (AF/DT) are rare tumors with loco regional spreading. Few options are available when local treatments have failed. Although cytotoxic agents, hormonal treatment have been reported to induced responses and tumor control in some patients, only few prospective phase II trials have been reported in the literature. Recently, antitumor activity of imatinib in AF/DT was reported. We report a phase II trial of imatinib in AF/DT after failure of local treatment options. Methods: Pts ≥ 18 years with advanced AF/DT from all sites in whom neither surgery nor radiotherapy was possible were eligible. The principal inclusion criterias were: disease not amenable to surgery and/or radiation with curative intent, systemic pre-treatments allowed and presence of a measurable lesion with evidence of progression. Imatinib was given at the dose of 400 mg/d and increased to 800 mg/d if progression. Primary endpoint was the rate of progression free at 3 months. A...