Treatment of advanced dermatofibrosarcoma protuberans with imatinib mesylate with or without surgical resection

Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma of the skin characterized by the presence of specific COL1A1-PDGFB fusion protein, which appears as a consequence of the t(17;22) (q22;q13) translocation.

The aim of the study was to perform an analysis of patients with advanced DFSP treated with imatinib, with or without surgery, in clinical practice outside trials.

We analysed the data of 15 patients (6 male, 9 female; median age 56 years) with locally advanced/initially inoperable and/or metastatic DFSP treated with imatinib 400-800 mg daily between 12/2004 and 06/2009. All diagnoses were ascertained cytogenetically (fluorescent in situ hybridization). Median follow-up time was 16 months (range: 4-81).

Metastases were present in six cases (two lungs, two soft tissue, two lymph nodes). Fibrosarcomatous transformation (FS-DFSP) was confirmed in seven patients (47%). A 2-year progression-free survival (PFS) rate was 60%, and a 2-year overall survival (OS) rate was 78% (median time for PFS/OS was not reached). The best overall responses were: 10 partial responses (67%, including 5 FS-DFSP-1 progressed during the follow-up), 2 stable diseases (13%) and 3 progressive diseases (20%). Seven patients (47%) underwent resection of residual disease and remained free of disease.

We have confirmed the profound anti-tumour effect of imatinib in DFSP harbouring t(17;22) with long-term responses. Imatinib therapy may in some cases lead to tumour resectability of lesser disfiguration.