An open-label international multicentric phase II study of nilotinib in progressive pigmented villo-nodular synovitis (PVNS) not amenable to a conservative surgical treatment.

10516 Background: PVNS, also known as tenosynovial giant cell tumor (TGCT), is a rare pathological entity affecting the synovium in young adults. This neoplastic disease is driven by a t(1;2) translocation resulting in the fusion of COL6A3 and M-CSF genes. Nilotinib has inhibitory properties on M-CSF receptor pathway which could be of therapeutic interest in patient (pts) with non resectable PVNS. Methods: In this open-label international, multicentric, non-randomized, phase II study the primary objective is to evaluate the efficacy of nilotinib treatment (800 mg/day) in pts with progressive or relapsing PVNS not amenable to surgery or in whom surgery would be mutilating, as measured by the 12-week progression-free rate (12-w PFR) validated by an independent committee. Using a Bayesian design with a futility stopping rule and a maximum sample size set to 50 evaluable pts, interim analyses (IA) were planned after the inclusion of 10 and then every 5 pts. Results: From December 2010 to September 2012, 56 pts with progressive disease were enrolled by 17 institutions from Europe and Australia. Successive previous IA led to positive results in favour of the study continuation. 47 pts (median age 37 y (range: 18-74), 51% of males) were evaluable at the time of the last IA, with a median follow-up of 11.2 months (range: 0.6-12.7). Median time since diagnosis was 2.5 years (range: 0.02-26). Primary tumour was mainly located on knee (25 pts, 53%), hip (6 pts, 13%), ankle (6 pts, 13%). 4 pts had already received imatinib, 76% of pts had undergone a previous surgery. The 12-w PFR was 93.6% (95%CI, 82.5%-98.7%), without any OR. PR were observed later (2 at w-24 and 1 at w-48). Nilotinib was well tolerated, with only 4 pts experiencing grade 3 adverse events (anorexia: 1 pt; prurit: 1 pt; diarrhea: 1 pt; hepatic failure: 1 pt). 8 pts (17%) had a dose reduction and/or temporary discontinuation of nilotinib due to toxicity. Final results will be further presented. Conclusions: Nilotinib treatment induces disease stabilisation in a large proportion of PVNS patients with non resectable disease or in whom resection would be mutilating. Clinical trial information: NCT01261429.