Psoriatic arthritis: significant improvement with bimekizumab

An ACR50 response was observed in over 40% of patients with psoriatic arthritis (PsA) treated with bimekizumab in the phase 3 BE OPTIMAL trial. The study drug demonstrated significant superiority in the primary and all ranked secondary endpoints.

“Bimekizumab is an antibody that blocks IL-17A and IL-17F; it is not bi-specific, there are not 2 different binding arms, it is 1 antibody that happens to bind an epitope that is shared between the 2 cytokines, and so this is actually a new molecular entity, a new combinatorial target,” Prof. Iain McInnes (Glasgow University, United Kingdom) said in his introduction [1]. He presented the late-breaking phase 3 results and the 24-week interim analysis of the BE OPTIMAL study (NCT03895203) assessing bimekizumab in biologics-naïve patients with PsA.

The trial enrolled 852 adult patients with at least 3 tender and 3 swollen joints, and 1 active psoriatic  lesion and/or documented history of psoriasis. As may be expected in a trial for PsA, the baseline features of the cohort included a mean age of around 49 years, over 50% women, and just under 60% on concomitant methotrexate. About 50% of the participants had skin involvement with a body surface area affected by psoriasis of ≥3%.

The 16-week, double-blind phase consisted of 3 study arms, in which participants were treated with placebo (n=281), bimekizumab 160 mg every 4 weeks (n=431), or adalimumab 40 mg every 2 weeks (n=140) in a reference arm. After week 16, an active treatment-blind period followed, in which placebo participants were switched to bimekizumab until week 52. Prof. McInnes underlined that the study was neither designed nor powered for a head-to-head comparison of bimekizumab and adalimumab. The primary endpoint was the ACR50 response at week 16.

The study was positive, with statistically significant more participants in the bimekizumab arm achieving ACR50 than placebo recipients at week 16: 43.9% versus 10.0% (OR 7.1; 95% CI 4.6–11.0; P<0.001). The respective findings for ACR20 and ACR70 were 62.2% versus 23.8% and 24.4% versus 4.3%. “Through week 24, those responses were maintained and consistent, and the placebo patients who crossed over to bimekizumab rapidly recovered rates of response to be broadly similar to those patients who had already achieved response by week 16,” Prof. McInnes further stated. The study also showed similar levels of ACR50 responses between the adalimumab reference arm and the bimekizumab arm.

As for the ranked secondary outcomes, Prof. McInnes highlighted that bimekizumab was significantly superior to placebo when it came to skin amelioration at week 16, with rates of 61.3% versus 2.9% (P<0.001) reaching a Psoriasis Area and Severity Index (PASI)90 and 47.5% versus 2.1% reaching PASI100 (nominal P<0.001). Bimekizumab also significantly outperformed placebo in the achievement of minimal disease activity and inhibition of structural progression.

The safety evaluation revealed no unexpected findings. “I want to point out fungal infections, which occurred more frequently in the recipients of bimekizumab than adalimumab,” Prof. McInnes added. Overall, bimekizumab was deemed well tolerated.

1. McInnes I, et al. Bimekizumab in bDMARD-naïve patients with psoriatic arthritis: 24-week efficacy & safety from BE OPTIMAL, a phase 3, multicentre, randomised, placebo-controlled, active reference study. LB0001, EULAR 2022 Congress, 1–4 June, Copenhagen, Denmark.

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Posted on 21 July 202222 February 2024