Rob Volansky , 2025-06-25 09:30:00
Guselkumab, whether administered every 4 or 8 weeks, demonstrates “significant inhibition” of structural damage in patients with active psoriatic arthritis, according to data presented at the EULAR 2025 Congress.
“The objective of this phase 3b study is to more closely evaluate the ability of both Q4- and Q8-week dosing to inhibit structural damage progression,” Philip J. Mease, MD, of the Providence Swedish Medical Center, in Seattle, told attendees.
Mease described guselkumab (Tremfya, Janssen) as a fully human monoclonal antibody that selectively targets the interleukin (IL)-23p19 subunit, which may inhibit IL-23 signaling.
“It is dual acting,” he said. “That means that it not only binds to IL-23, but it also binds to the CD64 receptor on IL-23, producing myeloid cells. It is there in the room where the action is.”
In the APEX trial, a randomized, double-blind, placebo-controlled study, Mease and colleagues defined active PsA as three or more tender and swollen joints, elevated C-reactive protein and two or more joints with radiographic erosion despite prior therapeutic intervention.
The analysis included 273 patients treated with guselkumab 100 mg every 4 weeks; 371 patients treated with guselkumab 100 mg at weeks 0 and 4, and then every 8 weeks thereafter; or placebo every 4 weeks.
The proportion of patients achieving ACR20 respose at 24 weeks served as the primary endpoint. A co-primary endpoint of mean change from baseline in PsA modified van der Heijde-Sharp (vdH-S) score at week 24 also was also assessed.
According to the researchers, 67% of patients who received guselkumab 100 mg every 4 weeks, and 68% of those who received guselkumab 100 mg every 8 weeks, achieved the ACR20 endpoint at 24 weeks, compared with 47% of patients in the placebo group (P < .001).
“As you can see, the [primary endpoint] was met,” Mease said.
The guselkumab arms additionally demonstrated less radiographic progression, according to the researchers. The 4-week group showed a least squares mean change in PsA-modified vdH-S score of 0.55 (P = .002 vs. placebo), compared with 0.54 in the 8-week group (P < .001 vs. placebo) and 1.35 among those who received placebo.
“As you can see, in both dose arms, whether the patient was receiving guselkumab every 8 weeks or every 4 weeks, there was significant inhibition of structural damage progression as compared with placebo,” Mease said. “This is the key slide of the presentation.”
Changes in joint space narrowing and erosion scores followed similar trends, as did the proportions of patients with no radiographic progression, he added.
Adverse events occurred in 38% and 42% of the Q4- and Q8-week treatment groups, respectively, compared with 37% among those who received placebo. Serious adverse event rates were 3% or lower for all groups. The researchers identified no new safety signals.
“This study met its primary endpoint of an ACR20 response vs. placebo in both dose arms of guselkumab,” Mease said. “There were significantly lower rates of radiographic progression in both dose arms.”
Sources/Disclosures
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Mease PJ. Abstract LB0010. Presented at: EULAR 2025 Congress; June 11-14, 2025, Barcelona, Spain.
Disclosures:
Mease reports receiving grants from AbbVie, Acelyrin, Amgen, Bristol Myers Squibb, Eli Lilly, Johnson & Johnson, Novartis and UCB; consulting fees from AbbVie, Acelyrin, Amgen, Bristol Myers Squibb, Century, Cullinan, Eli Lilly, Immagene, Johnson & Johnson, Novartis, Pfizer, Spyre, Takeda and UCB; and speaking fees from AbbVie, Amgen, Eli Lilly, Johnson & Johnson, Novartis, Pfizer and UCB.
