Reviews/Psoriasis Psoriatic Arthritis/IL-17 inhibitors versus ustekinumab PASI 90
Pso Il17 · PSA-IL17-04 · v2
Doctors want to know whether drugs that block IL-17A clear psoriasis skin better than ustekinumab, an older biologic. Across three separate phase 3 head-to-head trials — one testing ixekizumab and two testing secukinumab — the IL-17A drug cleared skin in far more patients on the strictest common measure (near-total clearance), and the advantage held from early treatment out to a full year [1][2][3][4][5][6]. A real-world study of everyday patients pointed the same way [8]. The panel noted that the eight papers really describe only three trials, that each trial was run by the drug's own maker, and that only two of several IL-17A drugs were tested. Even so, the advantage was large, repeated across two different molecules, and consistent every time, so the panel treated the finding as firmly established.
The corpus contains three independent phase 3 head-to-head RCTs. IXORA-S showed ixekizumab superior to ustekinumab on PASI 90 at week 12 (72.8% vs 42.2%, difference 32.1%, P < 0.001) [2] and week 52 (76.5% vs 59.0%, P < .01) [1]. CLEAR showed secukinumab superior at week 16 (79.0% vs 57.6%, P < .0001) [3] and week 52 (76% vs 61%, P < .0001) [4]. CLARITY showed secukinumab superior at week 12 (66.5% vs 47.9%, p < 0.0001) [5] and week 52 (73.2% vs 59.8%; OR 1.84, P < 0.0001) [6]. A CLEAR Asian subgroup [7] and a retrospective cohort [8] concur directionally. The contested point: The panel divides only on how much weight the evidence carries, not its direction: eight papers reduce to three trials plus one cohort, every trial was sponsor-conducted and favoured the sponsor's own agent, and the class-level claim rests on just ixekizumab and secukinumab. None of these disturbs the size, significance or direction of the effect.
All 8 papers behind this claim with their DOIs and what each does to it, the panel’s arbitration, the evidence gap map and the open research questions. Free, and sent to your inbox.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
The eight papers collapse to three distinct trials (IXORA-S = [1]/[2], CLEAR = [3]/[4]/[7], CLARITY = [5]/[6]) plus one cohort, so evidential independence is lower than the paper count suggests.
Every head-to-head is manufacturer-conducted and each favours the sponsor's own IL-17A agent, a consistent sponsorship-direction bias.
Where it remains uncertain. All three trials were manufacturer-conducted and the eight papers collapse to three trials plus one cohort [8], and only two IL-17A agents were tested, so evidential independence and class breadth are narrower than the paper count implies.
Aleatory
Response rates are proportions from finite randomised samples (e.g. 676 subjects in CLEAR [4]); individual outcomes carry irreducible chance variation, though effects remain significant.
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.
Durable ixekizumab superiority on PASI 90 at 52 weeks.
“At week 52, significantly more ixekizumab-treated patients (P < .01) reported PASI 90 (104 [76.5%]) than did ustekinumab-treated patients (PASI 90, 98 [59.0%]).”
Panel auditInternal validity: high · scope of inference: Ixekizumab vs ustekinumab on 52-week PASI 90 in the population studied in IXORA-S.Key limitations: denominator/total n not in abstract · single trial · randomisation and blinding not stated in abstract
Large early PASI 90 advantage for ixekizumab, sustained to week 24.
“At week 12, IXE (n = 99, 72.8%) was superior to UST (n = 70, 42.2%) in PASI 90 response (response difference 32.1%, P < 0.001).”
Panel auditInternal validity: high · scope of inference: Ixekizumab vs ustekinumab on week 12 to 24 PASI 90 in the IXORA-S population.Key limitations: denominator/total n not in abstract · same trial as [1] · randomisation and blinding not stated in abstract
Independent second IL-17A molecule superior on PASI 90.
“Secukinumab (79.0%) was superior to ustekinumab (57.6%) as assessed by PASI 90 response at week 16 (P < .0001).”
Panel auditInternal validity: high · scope of inference: Secukinumab vs ustekinumab on week 16 PASI 90 in the CLEAR population.Key limitations: sample size not in abstract · single trial · blinding not stated in abstract
A higher PASI 90 proportion was achieved with secukinumab than ustekinumab at weeks 16 and 52 with significant p values.
Panel auditInternal validity: medium · scope of inference: Secukinumab vs ustekinumab on PASI 90 in Asian subjects only, within CLEAR.Key limitations: subgroup / post-hoc analysis · Asian-only population · sample size not in abstract
4 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.
Multiple independent randomised head-to-head trials consistently and significantly favour IL-17A inhibitors on PASI 90 through 52 weeks.
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.
Independent (non-sponsor) head-to-head. Every trial in the corpus was manufacturer-conducted and favoured the sponsor's agent, so an independently funded trial would test whether sponsorship inflates the gap. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: An investigator-initiated, publicly funded randomised head-to-head of an IL-17A inhibitor versus ustekinumab on PASI 90.
Open question: Would the PASI 90 advantage over ustekinumab persist in an independently funded, non-manufacturer trial? Why it is still open: All head-to-heads in the corpus [1][2][3][4][5][6] are sponsor-conducted and each favours the sponsor's own agent.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 18 Sep 2026 · protocol v0.19