Long-term outcomes of oral vinorelbine in advanced, progressive desmoid fibromatosis and influence of CTNNB1 mutational status

Purpose: Desmoid-type fibromatosis (DF) are locally aggressive neoplasms, with a need for effective systemic treatment in case of progression to avoid the short- and long-term complications of local treatments. Experimental Design: We retrospectively analyzed the outcomes of adult patients with DF treated with oral vinorelbine (90 mg once weekly) at Gustave Roussy Cancer Institute (Villejuif, Paris, France). Only patients with documented progressive disease according to RECIST v1.1 for more than 3 months (+2 weeks) before treatment initiation were included. Results: From 2009 to 2019, 90 out of 438 patients with DF were eligible for this analysis. Vinorelbine was given alone in 56 patients (62%), or concomitantly with endocrine therapy in 34 patients, for a median duration of 6.7 months. A partial response was observed in 29% and stable disease in another 57%. With a median follow-up of 52.4 months, the median time to treatment failure (TTF) was not reached. Progression-free rates at 6 and 12 months were 88.7% and 77.5%, respectively. Concomitant endocrine therapy was associated with longer TTF in women [HR, 2.16; 95% confidence interval (CI), 1.06-4.37; P ¼ 0.03). Among 64 patients with documented CTNNB1 mutational status, p.S45F or p.S45P mutations were associated with longer TTF compared with p.T41A or wild-type tumors (HR, 2.78; 95% CI, 1.23-6.27; P ¼ 0.04). Toxicity profile was favorable, without grade 3-4 toxicity, except for one grade 3 neutropenia. Conclusions: Oral vinorelbine is an effective, affordable, and well-tolerated regimen in patients with advanced, progressive DF. Prolonged activity was observed in patients with tumors harboring CTNNB1 p.S45F or p.S45P mutations.