Momelotinib in VEXAS Syndrome

Multicenter, phase II trial with safety run-in to evaluate the efficacy and safety of momelotinib in patients with VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory and Somatic) syndrome with or without associated myelodysplastic syndrome (MDS). The study will consist of two consecutive steps, a dose-finding safety run-in and a single-arm prospective phase II. During safety run-in phase, three fixed dose levels will be tested according to a 3+3 design, using cohorts of size 3 in order to establish the maximum tolerated dose. After this safety run-in phase, patients included in phase II will be treated with momelotinib at the maximum tolerated dose preliminary fixed. Patients included in the phase II will receive momelotinib continuously until disease progression or loss of response, at physician's discretion. All patients included in the study will receive glucocorticoids (prednisone/prednisolone equivalent) at baseline (at least \> 10mg/day). Response assessment regarding VEXAS related symptoms will be evaluated after 4, 12, 24 and 48 weeks. Response assessment regarding MDS features will be evaluated at 12 and 24 weeks.