Tysabri vs Skyrizi for Crohn's Disease: Which to Choose?

Tysabri and Skyrizi represent two different generations and positions in the Crohn's biologic landscape. Skyrizi (risankizumab) is an IL-23 p19-selective biologic approved for Crohn's in June 2022 based on ADVANCE, MOTIVATE, and FORTIFY, increasingly prescribed as a first-line or second-line option. Tysabri (natalizumab) is an integrin-blocking biologic restricted by the TOUCH program due to progressive multifocal leukoencephalopathy (PML) risk and typically reserved for refractory cases. This guide walks through the tysabri vs skyrizi crohn's comparison.

Integrin vs IL-23 p19 Mechanism

Tysabri binds alpha-4 integrin, blocking lymphocyte trafficking to both gut and brain tissue. Skyrizi binds the p19 subunit of interleukin-23, selectively blocking IL-23 signaling while preserving IL-12. IL-23 is a central driver of Th17-mediated inflammation in Crohn's. The natalizumab vs risankizumab distinction is foundational: Tysabri's broad integrin mechanism creates PML risk, while Skyrizi's selective IL-23 blockade produces a favorable safety profile.

Crohn's Efficacy

Skyrizi's Crohn's efficacy rests on ADVANCE and MOTIVATE (induction) and FORTIFY (maintenance). ADVANCE and MOTIVATE showed significantly higher clinical remission and endoscopic response on Skyrizi vs placebo at week 12. FORTIFY confirmed durability through week 52. Tysabri's Crohn's efficacy rests on ENACT-1, ENACT-2, and ENCORE. No head-to-head trial has directly compared Tysabri with Skyrizi in Crohn's. Indirect comparisons suggest Skyrizi produces strong response in biologic-naive and biologic-experienced Crohn's patients, with endoscopic outcomes that are particularly strong. Tysabri is typically reserved for patients refractory to Skyrizi and other biologic classes.

PML Risk and TOUCH Program

Tysabri carries a black-box warning for PML. The TOUCH program requires enrollment, JC virus antibody testing, routine monitoring, and prescriber/pharmacy/infusion center certification. Most gastroenterologists reserve Tysabri for Crohn's patients who have failed multiple other biologic classes and who test negative for JC virus antibodies. Skyrizi has no such restricted access program.

Skyrizi Safety Profile

Skyrizi's Crohn's safety data from ADVANCE, MOTIVATE, and FORTIFY has been favorable, consistent with its broader psoriasis experience. Long-term data for IL-23 p19 biologics consistently shows low rates of serious systemic infection and malignancy. For tysabri vs skyrizi side effects, Skyrizi is the clear winner for patients with infection concerns, cancer history, or complex comorbidities.

Refractory Crohn's Biologic

For refractory Crohn's patients who have failed anti-TNFs, Stelara, and other biologic classes, both Tysabri and Skyrizi can be considered. Skyrizi is generally tried first because of its favorable safety profile. Tysabri is reserved for patients who have failed Skyrizi and who test JC virus antibody negative. For refractory crohn's biologic selection, treatment algorithms typically place Tysabri last.

Administration and Dosing

Tysabri is administered as a 300 mg IV infusion every 4 weeks at a TOUCH-certified infusion center, per Biogen's prescribing information. Skyrizi for Crohn's uses IV induction at weeks 0, 4, and 8 (600 mg per infusion), followed by subcutaneous maintenance of 360 mg every 8 weeks via a prefilled cartridge and on-body injector, per AbbVie's prescribing information. Skyrizi transitions patients to SC maintenance after IV induction, eliminating ongoing infusion center visits. Tysabri requires lifelong monthly IV infusions at a TOUCH-certified center.

When Tysabri Might Be Considered

For Crohn's patients who have failed multiple biologic classes including Skyrizi, Tysabri may be considered, particularly in patients who test negative for JC virus antibodies. This is a narrow population, and shared decision-making with a gastroenterologist experienced in refractory Crohn's is essential.

Anti-TNF Experienced Patients

For Crohn's patients with prior anti-TNF exposure, Skyrizi has strong evidence from MOTIVATE. Tysabri also has efficacy in biologic-experienced patients, but the PML risk typically drives clinicians to try mechanism-class alternatives like Skyrizi, Stelara, or Entyvio before Tysabri.

Biosimilar Availability

Skyrizi is branded with no biosimilar. Tysabri has a biosimilar (Tyruko) approved in 2023, though real-world utilization in IBD remains low given TOUCH program requirements apply equally to biosimilars.

Practical Access

Skyrizi can be administered at a variety of infusion centers for induction, and SC maintenance can be self-administered at home. Tysabri requires infusion at a TOUCH-certified center. For patients with complex schedules or geographic barriers, Skyrizi's accessibility is a practical advantage.

Choosing With Your GI

For a Crohn's patient deciding between Tysabri and Skyrizi, Skyrizi is preferred for most patients because of its established efficacy in biologic-naive and biologic-experienced populations, favorable safety profile, SC maintenance convenience, and absence of TOUCH program restrictions. Tysabri is a niche option reserved for patients who have exhausted other biologic classes including Skyrizi and who test JC virus antibody negative. If you are considering Tysabri, ask your GI about JC virus antibody status, prior treatment history, and the specific risk-benefit rationale. A log of stool frequency, urgency, abdominal pain, and any new neurological symptoms between visits is particularly important for patients on Tysabri.