Seo 2020.

Study characteristics
Methods	RCT, placebo‐controlled, double‐blind, parallel arms study Date of study: January 2017 to August 2018 Location: Korea (10 sites)
Participants	Randomised: 62 participants Inclusion criteria Ages eligible: 20 to 85 years Subject has had stable moderate‐to‐severe plaque psoriasis for at least 6 months Subject has involved BSA ≥ 10%, PASI ≥ 12, and sPGA ≥ 3 at screening and at baseline Exclusion criteria Subject diagnosed with erythrodermic psoriasis, pustular psoriasis, guttate psoriasis, or a medication‐induced psoriasis, or other skin conditions (e.g. eczema) at screening that would interfere with study evaluations Subject scheduled to undergo a surgical intervention during the study period Subject has any active infection or history of infections as defined in the study protocol Subject has known history of Crohn's disease Subject has any other significant concurrent medical condition or laboratory abnormalities, as defined in the study protocol Subject has not stopped using certain psoriasis therapies as defined in the study protocol Subject has previously used any anti‐IL‐17 biologic therapy Subject is pregnant or breastfeeding, or planning to become pregnant while enrolled in the study Women of childbearing potential or fertile men who do not agree to use effective contraception from the day of providing consent through 12 weeks after the last dose of investigational product Subject has known history or evidence of suicidal ideation (severity of 4 or 5) or any suicidal behaviour based on an assessment with the Columbia‐Suicide Severity Rating Scale (C‐SSRS) at screening or at baseline Subject has severe depression based on a total score of ≥ 15 on the Patient Health Questionnaire‐8 (PHQ‐8) at screening or at baseline Subject has known history or evidence of a psychiatric disorder that, in the opinion of the investigator, would pose a risk to subject safety or interfere with the study evaluation, procedures or completion Subject has known history of alcohol and/or substance abuse within the last 12 months Baseline characteristics N = 62, mean age of 44 years and 61% men Dropouts and withdrawals 17/62 (27.5%); placebo (8), brodalumab (9) Eligibility criteria: placebo (2), brodalumab (0) Withdrawal consent: placebo (4), brodalumab (6) Private reasons: placebo (1), brodalumab (0) Removal criteria: placebo (0), brodalumab (2) AEs: placebo (1), brodalumab (1)
Interventions	Intervention A. Brodalumab 210 mg SC injection at weeks 1, 2, 4, 6, 8, 10, and Q2W thereafter, until week 62, n = 40 Control intervention B. Placebo SC injection at weeks 1, 2, 4, 6, 8, 10, and Q2W thereafter, until week 62, n = 22
Outcomes	At week 12 Primary outcomes PASI 75 sPGA of "0 (clear)" or "1 (almost clear)" Secondary outcomes PASI 50/75/90/100 at week 64 sPGA of "0 (clear)" or "1 (almost clear)" at week 64 BSA at week 64 Nail Psoriasis Severity Index (NAPSI) score at week 64 Psoriasis scalp Severity Index (PSSI) score at week 64 DLQI at week 64 Treatment‐emergent adverse events (TEAEs) or drug‐related TEAEs at week 64 Laboratory values at week 64 Vital signs at week 64 Anti‐KHK4827 antibodies at week 12, 24, 48, 64 Serum KHK4827 concentration at week 12, 24, 48, 64
Notes	Funding source: Quote (p 816): "funded by Kyowa Kirin Korea Co., Ltd." Declarations of interest: Quote (p 816): "Haeyoun Jeong is a full‐time employee of Kyowa Kirin Korea Co., Ltd. The other authors have no conflicts of interest to declare."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote (p 808): "This phase III, randomized, multicenter study consisted of a 12‐ week double‐blind phase followed by a 52‐week open‐label extension phase... patients were randomized to receive brodalumab 210 mg Q2W or placebo for 12 weeks at a 2:1 ratio and were stratified by bodyweight at screening (≤ 70 kg, > 70 kg), prior use of biologic agents, and investigative site. Randomization was performed through a dynamic allocation procedure using an IWRS. The IP was administrated after coordination with the IWRS vendor, Cenduit, an IQVIA business (Durham, NC, USA)." Comment: probably done
Allocation concealment (selection bias)	Low risk	Quote (p 808): "This phase III, randomized, multicenter study consisted of a 12‐week double‐blind phase followed by a 52‐week open‐label extension phase... patients were randomized to receive brodalumab 210 mg Q2W or placebo for 12 weeks at a 2:1 ratio and were stratified by bodyweight at screening (≤ 70 kg, > 70 kg), prior use of biologic agents, and investigative site. Randomization was performed through a dynamic allocation procedure using an IWRS. The IP was administrated after coordination with the IWRS vendor, Cenduit, an IQVIA business (Durham, NC, USA)." Comment: probably done
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote (p 808): "This phase III, randomized, multicenter study consisted of a 12‐week double‐blind phase followed by a 52‐week open‐label extension phase..." Comment: no description of the method used to guarantee blinding
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote (p 808): "This phase III, randomized, multicenter study consisted of a 12‐week double‐blind phase followed by a 52‐week open‐label extension phase..." Comment: no description of the method used to guarantee blinding of outcome assessment
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dealing with missing data: Quote (p 810): "The populations analyzed were the FAS, which included all randomized patients; the PPS, which included all patients in the FAS but excluded those who had received no treatment, had no post‐dosing primary efficacy data available, failed to meet major eligibility criteria, or had major protocol deviations ... investigative site to examine the treatment difference in the PASI 75 response and sPGA success at week 12 using the last observation carried forward method or non‐responder imputation method for missing data." Randomised 62, analysed 62 Note high rate of dropout: 27%
Selective reporting (reporting bias)	Low risk	Comment: the protocol for the study was available on ClinicalTrials.gov (NCT02982005). The prespecified outcomes and those mentioned in the Methods section appeared to have been reported. No results are posted on ClinicalTrials.gov.