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

Summary

Desmoid-type fibromatosis (DF) are locally aggressive neoplasms, with a need for effective systemic treatment in case of progression, in order to avoid the short- and long-term complications of local treatments. We retrospectively analyzed the outcomes of adult patients with DF treated with oral vinorelbine (90 mg once weekly) at Gustave Roussy Cancer Institute. Only patients with documented progressive disease (PD) according to RECIST v1.1 over 3 months (±2 weeks) before treatment initiation were included. From 2009 to 2019, of 438 patients with DF, 90 were eligible for this analysis. Vinorelbine was given alone in 56 patients (62%), or concomitantly with endocrine therapy in 34, 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%CI: 1.06-4.37, p = 0.03). Among 64 patients with documented CTNNB1 mutational status, p.S45F or p.S45P mutations were associated with longer TTF compared to p.T41A or wild type tumors (HR : 2.78, 95%CI: 1.23-6.27, p = 0.04). Toxicity profile was favorable, without grade 3-4 toxicity but one grade 3 neutropenia. 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.