A phase II study of imatinib mesylate (IM) for patients with advanced melanoma harboring somatic alterations of KIT

9001 Background: Three prior phase II studies of Imatinib mesylate (IM) in 62 pts with advanced melanoma reported only 1 response in a pt with acral melanoma. A proportion of melanomas arising from acral, mucosal, and chronic sun damaged (CSD) sites are characterized by KIT mutations (mut) or amplifications (amp) and we hypothesized that this subset of tumors would be sensitive to IM. We thus designed this phase II study of IM restricted to pts with melanoma harboring such alterations in KIT. Methods: Pts with unresectable melanoma arising from acral, mucosal, and CSD sites whose tumor harbored a 4q12 amp by FISH or mut in KIT and who had measureable disease by RECIST were eligible. Pts received IM 400 mg BID continually. Response was assessed every cycle (6 wks). A Simon 2-stage design was employed where initially 16 pts would be treated; if ≥ 2 responses were observed, a total of 25 pts would be enrolled. If ≥5 responses were seen in 25 pts, the study was to be considered positive. Results: Of 81 pt tum...