Crohn Disease Involving Terminal in Medicine / Internal Medicine — 32yo Man | Gastroenterology | SMLE Q#12184

A 32-year-old man with Crohn disease involving the terminal ileum and colon has 3 weeks of frequent bloody diarrhea (6 stools/day), left-sided crampy abdominal pain, and tenesmus. He has taken oral prednisone 40 mg daily for 4 weeks with minimal improvement and cannot taper without worsening symptoms. Stool culture and Clostridioides difficile toxin are negative. Flexible sigmoidoscopy shows patchy colitis with friable mucosa and multiple aphthous ulcers in the left colon; biopsies show active inflammation without dysplasia. Which of the following is the most appropriate next step in management to induce and maintain remission?