Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: Preliminary results of a multicentric phase II study

9550 Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma of intermediate malignant potential. Treatment relies on a wide local excision with negative margin with frequent need of reconstructive surgery. A translocation between chromosomes 17 and 22 that places PDGFB under the control of the collagen 1A1 promoter is present in > 90% of the cases leading to an up regulation of PDGFB expression and activation of the tyrosinase kinase PDGFRβ. Anecdotal reports and a report on 8 patients suggest that Imatinib mesylate (IM) has a clinical interest in DFSP. The primary aim of this phase II multicentric study is to define the percentage of clinical responders (RECIST) to a preoperative 2 months 600mg IM daily before wide local excision. The secondary goals are to determine tolerance, imaging (ultrasound and MRI), pathological responses and to analyse PDGFRβ phosphorylation status and tumour cell apoptosis in sequential tissues specimen. Fifteen adults suffering from primary or recurrent DFSP have...