Phase II Pazopanib Study in Advanced Dermatofibrosarcomas

In relation to the activation of PDGF-mediated signalization due to the fusion gene COL1A1-PDGFb in DFSP, imatinib (800mg/day) has shown activity in advanced DFSP and has became the reference treatment option for these patients. Yet the activity observed does not allow for a downstaging compatible with successful resection in a number of patients and does not prevent subsequent tumour progression in case of residual tumour.Pazopanib in relation to 1) its multi tyrosine kinase inhibiting activity (VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-α, PDGFR-β and c-kit with IC50 values of 10, 30, 47, 71, 84, and 74 nM, respectively) involving in particular PDGFR, and VEGFR which has been shown to be activated in DFSP, 2) its antitumour activity in sarcomas patients, and 3) its acceptable safety profile, is a logical candidate for therapeutic trials in DFSP both in patients not expected to derive a sufficient benefit from imatinib and in patients failing imatinib mesylate. Moreover, using quantitative RT-PCR and immunohistochemistry we have recently demonstrated high levels of VEGF and VEGFR2 expression in dermatofibrosarcoma.