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What Baseline Disease Severity Hides in PsA Trial Data, With David Oberlin, MD
David Oberlin, MD, on why trial enrichment, not mechanistic superiority, likely explains differing radiographic results in PsA drug trials.
David Oberlin, MD, a board-certified dermatologist at Forefront Dermatology in Grand Rapids, Michigan, spoke with HCPLive about a commentary he co-authored with Jesse Veenstra, MD, PhD, of Henry Ford Health, in the Journal of the American Academy of Dermatology (JAAD).1,2
The piece examines a May 2026 US Food and Drug Administration (FDA) label update crediting guselkumab (Tremfya) with inhibiting radiographic joint damage in psoriatic arthritis (PsA), based on the phase 3b APEX trial (NCT04882098), and asks whether its enriched population reflects general dermatology patients.3
Oberlin said APEX enrolled biologic-naive patients with erosive disease, elevated CRP, and PsA duration beyond 6 months, criteria he called far more restrictive than those used in comparator trials such as DISCOVER-2 and KEEPsAKE 1. He and Veenstra found baseline joint damage closely tracked how much a trial's placebo arm progressed on radiographic Sharp scores, making a statistically significant treatment effect easier to reach in a more enriched population regardless of the drug's mechanism.
Oberlin said this relationship helps explain why APEX reached significance on its radiographic endpoint while DISCOVER-2, also testing guselkumab, and KEEPsAKE 1, testing risankizumab (Skyrizi), did not, despite guselkumab and risankizumab both working through interleukin (IL)-23 inhibition. He noted no head-to-head trial exists comparing the 2 drugs directly on joint damage outcomes.
"The biggest message we want to get across to providers is make sure the baseline characteristics of the trial represent the patient in front of you. If the patient in front of you fits the APEX trial, then you may be able to inhibit radiographic progression, but otherwise you cannot look at that study and say it has mechanistic superiority compared to other IL-23 agents," Oberlin said.
Oberlin said APEX alone would not change how he selects a biologic for psoriatic disease. He weighs oral versus injectable preference, disease severity, comorbidities, how quickly a patient needs to clear, dosing frequency, and formulary coverage, and said dermatologists now have enough effective IL-23 and IL-17 options, so no single trial should dictate the choice.
Editor’s note: Oberlin disclosed having received honoraria for serving as a key opinion leader for Amgen, AbbVie, UCB, and Arcutis, and for participating on advisory boards for AbbVie, Sensus, UCB, Sanofi, Incyte, and Apogee. This transcript has been edited for grammar and clarity using artificial intelligence tools.
References
Oberlin D, Veenstra J. Interpreting radiographic outcomes across IL-23 inhibitor trials in psoriatic arthritis: the role of trial design. J Am Acad Dermatol. Published online 2026. doi:10.1016/j.jaad.2026.06.135.
Smith T. Trial Design Drives Radiographic Outcomes Across IL-23 Inhibitors in PsA. HCPLive. August 26, 2026. Accessed September 9, 2026. https://www.hcplive.com/view/trial-drives-radiographic-outcomes-il-23-inhibitors-psa.
FDA approves label expansion cementing Tremfya as the only IL-23 inhibitor proven to help stop further joint damage. Johnson & Johnson. Published May 28, 2026. Accessed September 9, 2026.
