The purpose of this study is to compare the effectiveness and safety of Risankizumab versus Ustekinumab and compare how well these drugs work in patients with moderate to severe Crohn's disease. Participants who are aged 18 to 80 years with moderately to severely active Crohn's disease and have intolerance or inadequate response to one or more anti-TNF (tumor necrosis factor) therapies may be eligible. Anti-TNF drugs include Etanercept (Enbrel) and Infliximab (Remicade).

Participants will either take Risankizumab or Ustekinumab for 48 weeks and see if their Crohn's disease get improved. The chance of being randomized (like drawing names out of a hat) into Risankizumab group and receiving Risankizumab is 50%. The chance of being randomized into Ustekinumab group and receiving Ustekinumab is 50%.

Participants in the Risankizumab group will receive three IV infusions at week 0, week 4, and week 8 respectively, and then subcutaneous (under the skin) injection every 8 weeks. Participants in the Ustekinumab group will receive 1 IV infusion at week 0, and then subcutaneous injection every 8 weeks.

The purpose of this study is to see whether oral Ozanimod is safe and effective for treating Crohn's disease. Adult participants (at least 18 years old) with moderately to severely active Crohn's disease may be eligible.

Only participants who complete the induction and/or maintenance study will be eligible to join this open-label study.

All participants in this study receive active study drug. The dose of study drug you will receive will depend on your prior study. There is no chance of placebo in this study.

This study is designed to last up to 234 weeks (4.5 years). Participants are expected to come to MUSC every 8 or 12 weeks for study visits.

The purpose of this study is to see whether Ozanimod is safe and effective for treating Crohn's disease. Adult participants (at least 18 years old) with moderately to severely active Crohn's disease may be eligible.

To do this, a comparison will be made between subjects who receive active drug and subjects who receive placebo (a ‘dummy treatment' that looks like the active drug but contains no active ingredient). The chance of being randomized (like drawing names out of a hat) into ozanimod group and receiving ozanimod is 50%. The chance of being randomized into placebo group and receiving placebo is 50%.

If participants' Crohn's disease condition get worse during the study, they will be invited to participate the open-label study, which has no placebo.

This is a one-year study, and participants are expected to come to MUSC every 8 weeks for study visits.

The purpose of this study is to see whether Ozanimod is safe and effective for treating Crohn's disease. Participants who are aged 18 to 75 years with moderately to severely active Crohn's disease may be eligible.

To do this, a comparison will be made between subjects who receive active drug and subjects who receive placebo (a ‘dummy treatment' that looks like the active drug but contains no active ingredient). The chance of being randomized (like drawing names out of a hat) into ozanimod group and receiving ozanimod is 67%. The chance of being randomized into placebo group and receiving placebo is 33%.

This study is designed to last up to 30 weeks, including 2 screening visits, 4 study visits, and 2 follow-up visits. The study drug may improve participant's Crohn's disease condition, but this cannot be guaranteed.

The purpose of this study is to evaluate if an investigational new drug (not FDA-approved yet), named Cx601, is safe and effective in treating perianal fistulas in patients with Crohn's disease.

To do this, a comparison will be made between subjects who receive study drug and subjects who receive placebo (a ‘dummy treatment' that looks like the active drug but contains no active ingredient). The chance of being randomized (like drawing names out of a hat) into study drug group is 50%. The chance of being randomized into placebo group is 50%.

This study is designed to last 18 months. Eligible participants will have 1 screening visit, 1 preparation visit, 1 drug administration visit, and 6 follow-up visits.

The purpose of this study is to determine if an additional intravenous (IV) dose of Ustekinumab is safe and effective in helping Crohn's disease patients, whose initial response to Ustekinumab was followed by loss of response to Ustekinumab, to regain response to Ustekinumab for the treatment of their disease.

This study is designed to last 10 months. Eligible participants will have 2 screening visits, 3 drug administration visits, and 2 follow-up visits.

Participants have a 50% chance of being randomized (like drawing names out of a hat) into either the Ustekinumab re-induction group or the continuous maintenance group. Participants in the Ustekinumab re-induction group will receive intravenous Ustekinumab at the baseline visit. Participants in the continuous maintenance group will receive subcutaneous Ustekinumab at the baseline visit. All participants will receive subcutaneous Ustekinumab 90 mg for subsequent visits.