Skyrizi vs Tremfya for Ulcerative Colitis: Comparing IL-23s

Skyrizi and Tremfya are both IL-23 p19-selective biologics for moderate-to-severe ulcerative colitis. Skyrizi gained UC approval in June 2024 based on INSPIRE and COMMAND. Tremfya gained UC approval in September 2024 based on QUASAR and ASTRO. Patients comparing these two within-class UC options often weigh induction flexibility, maintenance dosing, and trial design. This guide walks through the skyrizi vs tremfya ulcerative colitis comparison.

Same Class, Two Molecules

Skyrizi (risankizumab) and Tremfya (guselkumab) both bind the p19 subunit of interleukin-23, selectively blocking IL-23 signaling while preserving IL-12. IL-23 drives Th17 inflammation central to UC pathology. The risankizumab vs guselkumab UC distinction is a within-class decision: the structural mechanism is shared, but the molecules differ in affinity, half-life, and the clinical programs that support each.

Trial Evidence: INSPIRE/COMMAND vs QUASAR/ASTRO

Skyrizi's UC approval rests on INSPIRE (induction) and COMMAND (maintenance). INSPIRE showed clinical remission rates of 20.3% on Skyrizi versus 6.2% on placebo at week 12, with endoscopic improvement and symptomatic remission also significantly better. COMMAND showed sustained benefit through week 52. Tremfya's UC approval rests on QUASAR, which showed 23% clinical remission on guselkumab versus 8% on placebo at week 12, and ASTRO, which specifically evaluated fully subcutaneous induction and demonstrated that patients could skip IV induction entirely. The ASTRO trial is distinctive because no other UC IL-23 biologic supports a pure SC induction pathway.

Efficacy Comparison

No head-to-head trial has directly compared Skyrizi with Tremfya in UC. Indirect comparisons suggest similar clinical remission rates between the two drugs in biologic-naive UC patients. For skyrizi vs tremfya UC effectiveness, current data does not establish a clear winner, and clinical decision-making often defaults to induction preference and insurance coverage.

Onset of Action

Both drugs produce clinically meaningful UC response by week 12. The trial endpoints are comparable, with individual response variability often mattering more than small differences in trial design.

Administration and Dosing

Skyrizi for UC uses IV induction at weeks 0, 4, and 8 (1200 mg per infusion), followed by subcutaneous maintenance of 180 mg or 360 mg every 8 weeks. Tremfya for UC offers a distinctive dual induction pathway. Patients can choose IV induction (200 mg at weeks 0, 4, and 8) or fully subcutaneous induction (400 mg at weeks 0, 4, and 8) per the QUASAR and ASTRO programs. Maintenance is 100 mg SC every 8 weeks or 200 mg SC every 4 weeks. For UC patients who want to avoid infusion center visits entirely, Tremfya's SC-only induction option is a meaningful practical advantage. Both drugs offer SC maintenance, with Skyrizi's 180/360 mg every 8 weeks and Tremfya's 100 mg every 8 weeks offering comparable cadence.

Safety Profiles

Both drugs have favorable safety profiles consistent with IL-23 p19 class effects. Long-term data from each drug's other indications (psoriasis and Crohn's for both) supports low rates of serious infection and malignancy. For skyrizi vs tremfya side effects, common adverse events on both drugs include upper respiratory infections, injection site reactions, and headache. Neither drug has a black-box warning for lymphoma or other class-level serious adverse events seen with anti-TNFs. TB and hepatitis B screening is recommended before starting either drug.

Injection Experience

Skyrizi's UC maintenance uses an on-body injector cartridge (360 mg) or standard injection pen (180 mg). Tremfya's UC maintenance uses a standard prefilled syringe or One-Press autoinjector. Some patients prefer the quick injection of Tremfya's device, while others find the on-body injector convenient because they can move around during delivery. Device preference is worth discussing with your GI or pharmacy team.

Anti-TNF Experienced Patients

Both Skyrizi's INSPIRE and Tremfya's QUASAR included biologic-experienced UC patients, with meaningful response rates in each population. For UC patients who have already failed an anti-TNF, either drug is a reasonable mechanism-switch option. Your GI will weigh prior biologic exposure pattern, current disease severity, and comorbidities when making the recommendation. In practice, the choice between Skyrizi and Tremfya for anti-TNF experienced patients often comes down to insurance coverage and induction preference.

Cost and Access

Both Skyrizi and Tremfya are branded biologics without biosimilar competition. Insurance coverage varies by plan, and prior authorization is typically required for both drugs in UC. Manufacturer copay assistance programs exist for commercially insured patients on both drugs.

Choosing With Your GI

For a UC patient deciding between Skyrizi and Tremfya, the two drugs are more similar than different. Tremfya tends to win on induction flexibility (SC or IV via QUASAR and ASTRO). Skyrizi tends to win on familiarity for clinicians already using it for Crohn's and on the on-body injector if that delivery style is preferred. Ask your GI which drug they have the most experience with, how response will be measured after induction, what to do if symptoms persist, and how your insurance handles each option. A log of stool frequency, urgency, blood, and any new symptoms between visits gives your care team the data to recognize early loss of response before a full flare returns.