Extraskeletal myxoid chondrosarcoma: tumor response to sunitinib

Since July 2011, 2 patients with progressive pretreated metastatic EMCS (Patient1: woman, 58 years, PS1; Patient2: man, 63 years, PS1) have been treated with continuous SM 37.5 mg/day, on an individual use basis. Both patients are evaluable for response. In both cases diagnosis was confirmed by the presence of the typical EWSR1-CHN translocation.Both patients are still on treatment (11 and 8 months). Patient 1 got a RECIST response after 4 months from starting sunitinib, together with a complete response by PET. An interval progression was observed after stopping sunitinib for toxicity (abscess around previous femoral fixation), but response was restored after restarting sunitinib. Patient 2 had an initial tumor disease stabilization detected by CT scan at 3 months. Sunitinib was increased to 50 mg/day, with evidence of a dimensional response 3 months later.Sunitinib showed antitumor activity in 2 patients with advanced EMCS. Further studies are needed to confirm these preliminary results.Extraskeletal myxoid chondrosarcoma (EMCS) is a rare soft-tissue sarcoma (STS) first described in 1972 [1,2]. EMCS is now considered a unique entity of uncertain differentiation (convincing evidence of a cartilaginous differentiation is lacking in most cases) [3]. Besides, EMCS can have a neuroendocrine differentiation [4-6].It is market by a specific chromosomal translocation, t(9;22)(q22.3;q12.2), fusing CHN to EWSR1[7,8]. Less frequently two different translocations, t(9;17)(q22.3;q12) and t(9;15)(q22.3;q21.3) are found, resulting in RBP56CHN and TCF12CHN fusion-genes, respectively [9,10]. The fusion-proteins promote cellular growth and differentiation [11]. Furthermore, the EWSR1-CHN fusion-protein may activate the PPARG nuclear receptor gene [12]. Microscopically, EMCS can be subdivided into a conventional well-differentiated and a cellular high-grade EMCS, which is marked by epithelioid cells with prominent nucleoli, high mitotic rate and necrosis [13]. Dedifferentiated ECMS