De-escalation of Ustekinumab Therapy in Patients With Crohn's Disease and Ulcerative Colitis

The goal of this clinical trial is to evaluate whether disease remission can be maintained when biologic therapy is reduced in patients with Crohn"s disease (CD) and ulcerative colitis (UC) taking ustekinumab (UST). The main question it aims to answer is: Can we de-escalate UST subcutaneous dose either from every 4 weeks (Q4) to every 8 weeks (Q8) or every 8 weeks (Q8) to every 12 weeks (Q12) in CD or UC patients in deep remission without loosing their response? Researchers will follow UST blood levels, inflammation markers and intestinal mucosa integrity and to see if UST dose can be reduced while maintaining clinical remission. Participants will: Change UST dosing from Q4 to Q8 or from Q8 to Q12. Visit the clinic once every 12 weeks for checkups and tests.