Yes, Skyrizi (risankizumab) is a monoclonal antibody. Specifically, it is a humanized monoclonal antibody of the IgG1 class, meaning it was engineered from animal antibodies to closely resemble human ones, reducing the chance your immune system will reject it. The FDA first approved it in 2019, and it now treats four inflammatory conditions.
What Type of Antibody Skyrizi Is
Monoclonal antibodies are lab-made proteins designed to lock onto one specific target in the body. Skyrizi’s structure consists of two identical heavy chains and two identical light chains linked together by chemical bonds, the same basic architecture as the antibodies your immune system produces naturally. The difference is precision: every molecule of risankizumab is identical and engineered to bind a single inflammatory protein.
The “humanized” label means the antibody started from a non-human source but was modified so that most of its structure matches human proteins. This matters because fully non-human antibodies tend to trigger immune reactions that reduce the drug’s effectiveness over time. Humanized antibodies largely avoid that problem while keeping a tight grip on their target.
How Skyrizi Works
Skyrizi targets interleukin-23 (IL-23), a signaling molecule that plays a central role in driving inflammation in psoriasis, Crohn’s disease, and related conditions. More specifically, it binds to the p19 subunit of IL-23, blocking the molecule before it can activate downstream immune cells. With IL-23 neutralized, the chain of inflammation that leads to skin plaques, joint pain, or intestinal damage is interrupted at an early stage.
This is a narrower approach than older biologics that suppress broader parts of the immune system. By going after a single signaling molecule, Skyrizi dials down the specific inflammatory pathway causing harm without broadly weakening your immune defenses.
Conditions Skyrizi Treats
The FDA has approved Skyrizi for four conditions:
- Moderate-to-severe plaque psoriasis in adults who are candidates for systemic therapy or phototherapy
- Active psoriatic arthritis in adults
- Moderately to severely active Crohn’s disease in adults
- Moderately to severely active ulcerative colitis in adults
The psoriasis approval came first in 2019, with the other indications added in subsequent years. No biosimilar versions of Skyrizi are currently approved by the FDA.
How It Performs in Clinical Trials
Skyrizi’s clinical data in psoriasis is strong. In the two main trials (called UltIMMa-1 and UltIMMa-2), about 75% of patients achieved 90% skin clearance by week 16. That number climbed to roughly 81 to 82% by week 52 with continued treatment. For context, patients on a placebo cleared at rates of 2 to 5%, and those on ustekinumab (an older biologic) cleared at 42 to 48%.
In a head-to-head trial against adalimumab, one of the most widely used biologics, Skyrizi outperformed across every measure. About 72% of Skyrizi patients hit 90% clearance at week 16, compared to 47% on adalimumab. Among patients who had a partial response to adalimumab and then switched to Skyrizi, 66% reached 90% clearance by week 44, versus just 21% of those who stayed on adalimumab.
Dosing and How It’s Given
For plaque psoriasis and psoriatic arthritis, Skyrizi is a subcutaneous injection (under the skin) of 150 mg. You receive injections at week 0, week 4, and then once every 12 weeks after that. The every-12-week maintenance schedule is one of the longest gaps between doses among biologics in its class, which many patients find convenient.
For Crohn’s disease and ulcerative colitis, the approach is different. Treatment starts with an induction phase: three intravenous infusions of 600 mg, given at weeks 0, 4, and 8, each lasting at least one hour. After the induction phase, patients transition to subcutaneous injections for ongoing maintenance. The higher initial dose delivered by IV is designed to build up enough drug in the body to get severe intestinal inflammation under control before switching to the simpler injection schedule.
How Skyrizi Compares to Other Biologics
Skyrizi belongs to a small group of IL-23 inhibitors that includes guselkumab and tildrakizumab. All three bind the p19 subunit of IL-23, but they differ in their molecular structure and dosing schedules. Older biologics like ustekinumab block both IL-12 and IL-23, casting a wider net over the immune system. TNF inhibitors like adalimumab target an entirely different inflammatory pathway.
The trend in biologic development has moved toward more targeted therapies, and IL-23 inhibitors represent one of the most precise options currently available. In head-to-head data, Skyrizi has consistently matched or exceeded the clearance rates of these older-generation biologics, which is why it has become a preferred option for moderate-to-severe psoriasis and is gaining ground in inflammatory bowel disease treatment as well.