An open-label international multicentric phase II study of nilotinib in progressive pigmented villo-nodular synovitis (PVNS) not amenable to a conservative surgical treatment by Ray-Coquard, I, Gelderblom, H, Chevreau, C, Kroep, JR, Italiano, A, Stacchiotti, S, Le Cesne, A, Piperno-Neumann, S, Ferraresi, V, Duffaud, F, Penel, N, Cassier, P, Tatersall, M, Hassan, A, Nguyen, B, Branchu, V, Guillemaut, S, Cropet, C, Perol, D, Blay, J