Methods: Prospective (pilot) study including 24 adult IBD patients (12 UC patients and 12 CD patients (patients with fistulizing perianal disease will be excluded) with active disease and prior failure to anti-TNFα treatments starting treatment with VDZ. They will received VDZ in standard induction (300mg intravenously, 0-2-6 weeks) and maintenance schemes (300mg intravenously, every 8 weeks).