Reviews/Psoriasis Psoriatic Arthritis/Bimekizumab versus secukinumab PASI 90
Pso Il17 · PSA-IL17-01 · v2
Borderline: within 4 points of the Established/Likely boundary, so a re-grade could land either side.
The strongest evidence comes from one large head-to-head trial that directly compared the two drugs. In that trial more patients on bimekizumab reached near-complete skin clearance (PASI 90) than on secukinumab, and the gap held over a full year and out to three years [2][3]. The same trial was formally superior on the even harder measure of total skin clearance [1], which makes a better PASI 90 result mechanistically sensible. Two real-world patient cohorts pointed the same way on related skin-clearance measures [6][7]. The main hesitation is that the exact PASI 90 number came from a secondary re-analysis of that single trial, without an independent second trial confirming it.
One pivotal head-to-head phase 3b RCT reports PASI 90 of 85.5% (319/373) for bimekizumab versus 73.8% (273/370) for secukinumab at week 16, with the response continuously maintained through week 48 by 75.9% versus 64.8% of responders [2]. The same trial (BE RADIANT) was formally superior on the more stringent PASI 100 endpoint, an adjusted risk difference of 12.7 percentage points (95% CI 5.8 to 19.6) [1], with PASI 100 superiority durable to three years [3]. Two independent real-world cohorts corroborate the direction: bimekizumab showed the greatest PASI-reduction effect size (Hedges' g 3.662 vs 2.813) [6] and the highest odds of PASI=0 super-response (adjusted OR 17.30) [7]. Every included source points the same way. The contested point: The exact claim endpoint (PASI 90) is carried only by a post-hoc analysis [2] that reports no confidence interval or p-value for the between-arm difference, whereas the formally powered, statistically significant endpoint in the trial was PASI 100 [1]. All three direct sources [1][2][3] draw on the same single trial population, so there is no independent replicating head-to-head RCT for the PASI 90 contrast itself.
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The exact claim endpoint (PASI 90) is carried by a single post-hoc analysis [2] with no confidence interval or p-value reported for the between-arm difference; the formally powered and statistically significant endpoint in BE RADIANT was PASI 100, not PASI 90.
All direct evidence ([1], [2], [3]) derives from one trial population (BE RADIANT) re-analysed; there is no independent replicating head-to-head RCT, so evidential independence for the PASI 90 contrast is weak.
Where it remains uncertain. The exact PASI 90 figure is a post-hoc result with no reported CI or p-value [2], and all direct evidence [1][2][3] comes from one trial with no independent replication.
Aleatory
The PASI 90 point estimates in [2] come from one randomised sample (373 vs 370 patients); ordinary sampling variation around 85.5% vs 73.8% is not bounded because no CI or p-value is reported for that contrast.
Epistemic
All direct evidence ([1], [2], [3]) is from the same BE RADIANT population; no second head-to-head RCT in the corpus tests the PASI 90 contrast independently.
Inferential
The cohorts measure PASI-reduction effect size [6] and PASI=0 super-response [7], not the PASI 90 threshold, so inferring PASI 90 superiority from them requires an extra step.
The load-bearing papers from a corpus of 8, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Establishes formally significant superiority of BKZ over SEC on the more stringent PASI 100 endpoint in the same RCT, making a superior PASI 90 coherent.
“adjusted risk difference, 12.7 percentage points; 95% CI, 5.8 to 19.6); bimekizumab was noninferior and superior to secukinumab”
Panel auditInternal validity: high · scope of inference: Moderate-to-severe plaque psoriasis, bimekizumab vs secukinumab, complete-clearance (PASI 100) efficacy at weeks 16 and 48.Key limitations: PASI 90 not reported in abstract · higher oral candidiasis with bimekizumab
Direct head-to-head evidence on the exact claim endpoint: BKZ PASI 90 85.5% vs SEC 73.8%.
“PASI 90 was continuously maintained at each study visit from Wk16-Wk48 by 242/319 (75.9%) BKZ-treated and 177/273 (64.8%) SEC-treated Wk16 responders”
Panel auditInternal validity: medium · scope of inference: Moderate-to-severe plaque psoriasis, PASI 90 attainment and continuous maintenance to Week 48, bimekizumab vs secukinumab.Key limitations: post-hoc analysis · no statistical test reported for the PASI 90 difference
Corroborates durable superiority of BKZ over SEC on high-clearance response.
“More patients randomized to bimekizumab achieved PASI 100 (modified nonresponder imputation) at year 1 (74.9%) vs. those randomized to secukinumab (52.8%)”
Panel auditInternal validity: medium · scope of inference: Moderate-to-severe plaque psoriasis, long-term (3-year) PASI 100 maintenance for bimekizumab.Key limitations: PASI 90 not reported · open-label extension with treatment switching · no comparative statistics
3 of 8 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Direction is consistent and strongly supported, but the exact endpoint is a single-trial post-hoc without an independent replicating RCT, keeping confidence just below Established.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
No independent replicating head-to-head RCT. Every direct source [1][2][3] is the same trial population, leaving the PASI 90 contrast without independent confirmation. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: A second, independently conducted bimekizumab-versus-secukinumab RCT powered on PASI 90 in moderate-to-severe plaque psoriasis.
Open question: Is the between-arm PASI 90 difference in BE RADIANT statistically significant when analysed with a confidence interval and p-value? Why it is still open: The corpus reports PASI 90 only as raw proportions in a post-hoc analysis [2] with no CI or p-value.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 18 Sep 2026 · protocol v0.19