34% of rheumatologists weren’t aware of this key IL-23 inhibitor fact. Are you?

By Lisa Marie Basile | Fact-checked by Davi Sherman
Published March 25, 2025

Key Takeaways

Industry Buzz

  • “TNF inhibitors are usually used before IL-23 inhibitors in PsA—part of this is due to the fact that insurance might require TNF inhibitors before IL-23 inhibitors. [But] IL-23 inhibitors are very effective, especially when there is a severe skin disease.” — Julius Birnbaum, MD, MHS, associate professor of rheumatology at University of Pittsburgh Medical Center

  • "[IL-23s'] risk is much lower than that of TNF inhibitors, and they are much better at clearing the skin vs TNF inhibitors.” — Stella Bard, MD, rheumatologist at Arthritis & Rheumatology Care PC, Brooklyn

Find more of your peers' perspectives and insights below.

As part of MDLinx’s Smartest Doc Rheumatology Challenge, we asked physicians, “What is a key safety advantage of IL-23 inhibitors over TNF inhibitors in psoriatic arthritis (PsA) treatment?” Surprisingly enough, more than one-third of rheumatologists got this wrong.

The right answer? IL-23s pose a lower risk of infection. Let’s take a closer look at why—and hear what our experts have to say. 

Finding the most appropriate biologic

With a slew of FDA-approved targeted biologic therapies on the market—from TNF inhibitors like adalimumab (Humira) and IL-23 inhibitors like risankizumab (Skyrizi), to T-cell inhibitors like abatacept (Orencia)—treatment possibilities are abundant.[]

But when it comes to safety and efficacy, one biologic in particular shines above the others: IL-23 inhibitors.

Related: IL-23 inhibitors aren’t talked about as much, but they actually have a meaningful competitive advantage

Some of the most commonly used biologics for PsA treatment include TNF inhibitors and IL-23s, which block specific inflammatory cytokines.[][] TNF inhibitors were the first generation of biologics for treating PsA, so many physicians are familiar with them. This is why a physician may treat their patient with a TNF inhibitor before considering other effective biologic options, like risankizumab.

But that’s not the only reason. Julius Birnbaum, MD, MHS, Associate Professor of Rheumatology at the University of Pittsburgh Medical Center, explains: “TNF inhibitors are usually used before IL-23 inhibitors in the treatment of psoriatic arthritis—part of this is due to the fact that insurance companies might require TNF inhibitors before IL-23 inhibitors. [But] IL-23 inhibitors are very effective, especially when there is a severe skin disease.”

Better safety profile, lower risk

Stella Bard, MD, a rheumatologist at Arthritis & Rheumatology Care PC in Brooklyn, NY, agrees. “While IL-23s are still a biologic and carry some risk of infection, the risk is much lower than that of TNF inhibitors, and they are much better at clearing the skin vs TNF inhibitors,” she says, echoing Dr. Birnbaum.

Related: The truth about the most common misconception about biologics for PsA

According to a study published in Immunologic Research, IL-23 inhibitors for PsA “significantly outperform placebo intervention while maintaining a favorable safety profile.”[] Although trials comparing all biologic options don’t exist, the study authors highlight the fact that IL-23 inhibitors “effectively improved joint disease activity in PsA patients while also having a good safety profile.”

Another retrospective cohort of biologic-naive adults with either psoriasis or PsA who’d been treated with IL-17, IL-12/23, or TNF inhibitors and hospitalized due to infection found that IL-12/23 “were associated with a lower risk of infections than TNF.”[]

According to research published in The Lancet, IL-23s in patients show “little evidence of increased risk for serious infections.” They also note their association with a lower risk of serious adverse events compared to TNF inhibitors, likely due to their more targeted immune effects.[]

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