A Phase 3 Study in Participants With Moderate to Severe Psoriasis

Percentage of Participants Maintaining sPGA 0 or 1 After Re-Randomization at Start of Maintenance Dosing Period

The sPGA is the physician's determination of the participant's Ps lesions overall at a given time point. Lesions were categorized by descriptions for induration, erythema, and scaling. Participants Ps were assessed as 0 (clear), 1 (minimal), 2 (mild), 3 (moderate), 4 (severe), or 5 (very severe).

Time frame: Week 60

Percentage of Participants With Itch Numeric Rating Scale (Itch NRS) Score ≥4 Point Reduction From Baseline

The Itch NRS is a participant-administered, 11-point horizontal scale anchored at 0 (no itch) and 10 (worst itch imaginable). Overall severity of a participant's itching from Ps is indicated by circling the number that best describes the worst level of itching in the past 24 hours.

Time frame: Baseline, Week 12

Change From Baseline in Dermatology-Specific Quality of Life Index (DLQI) Score

DLQI is a participant-administered, 10-question, validated, quality-of-life questionnaire that covers 6 domains, including symptoms and feelings, daily activities, leisure, work and school, personal relationships, and treatment. Response categories include 0 (not at all), 1 (a little), 2 (a lot), and 3 (very much) and unanswered ("not relevant") responses were scored as "0." Total scores range from 0 to 30, with higher score indicating greater quality of life is impairment. A 5-point change from baseline is considered clinically relevant. Least squares (LS) mean change from baseline was calculated using mixed model repeated measures (MMRM).

Time frame: Baseline, Week 12

Change From Baseline in Nail Psoriasis Severity Index (NAPSI)

The NAPSI is a numeric, reproducible, objective tool for evaluation of fingernail Ps. This scale is used to evaluate the severity of fingernail bed Ps and fingernail matrix Ps by area of involvement in the fingernail unit. The fingernail is divided with imaginary horizontal and longitudinal lines into quadrants. Each fingernail is given a score for fingernail bed Ps 0 (none) to 4 (Ps in 4 quadrants of the fingernail) and fingernail matrix Ps 0 (none) to 4 (Ps in 4 quadrants of the matrix), depending on the presence (score of 1) or absence (score of 0) of any of the features of fingernail bed or matrix Ps in each quadrant. The NAPSI score of a fingernail is the sum of scores in fingernail bed and fingernail matrix from each quadrant (maximum of 8). Each fingernail is evaluated, then the sum of all fingernails equals the total NAPSI score with a range from 0 to 80 with higher scores indicating more severe psoriasis. LS mean change from baseline was calculated using MMRM.

Time frame: Baseline, Week 12

Percent of Body Surface Area (BSA) Involvement of Ps

BSA is a physician rating of the percentage of involvement of Ps for each participant. BSA is assessed on a continuous scale from 0% (no involvement) to 100% (full involvement), where 1% corresponds to the size of the participants hand (includes the palm, fingers and thumb). Total BSA is the sum of handprints from the affected areas. LS mean change from baseline was calculated using MMRM.

Time frame: Week 12

Change From Baseline in Psoriasis Scalp Severity Index (PSSI)

The PSSI is a physician assessment of erythema, induration and desquamation and percent of scalp that is covered with a scores range from 0 (none) to 4 (very severe). The composite score is derived from the sum of scores for erythema, induration, and desquamation multiplied by the score recorded for the extent of the scalp area involved, 1 (\<10%) to 6 (90%-100%) with a total scores range from 0 to 72, with lower scores indicating less severity. LS mean change from baseline was calculated using MMRM.

Time frame: Baseline, Week 12

Change From Baseline in All Scores of the Work Productivity Activity Impairment Questionnaire-Psoriasis (WPAI-PSO) Quality of Life and Outcome Assessments. Measures: Participant Reported Outcomes (PRO)

WPAI-PSO is a participant administered, 6-item instrument used to assess the impact of Ps on the productivity impairment within the past 7 days. WPAI-PSO has 4 domains: absenteeism, presenteeism (reduced productivity while at work), an overall work impairment score, and impairment in daily activities performed outside of work. Four scores are derived as percentages: absenteeism, presenteeism (reduced productivity while at work), overall work impairment (absenteeism and presenteeism), and impairment in activities performed outside of work. Percentage is calculated as: each score \* 100 with greater scores indicating greater impairment. LS mean change from baseline was calculated using analysis of covariance (ANCOVA).

Time frame: Baseline, Week 12

Change From Baseline in Quick Inventory of Depressive Symptomatology-Self Reported 16 Items (QIDS-SR16)

QIDS-SR16 is a participant-administered, 16-item instrument intended to assess the existence and severity of symptoms of depression. A participant is asked to consider each statement as it relates to the way they have felt for the past 7 days and rate each on a 4-point scale: 0 (best) to 3 (worst). The sum of the 16 items corresponding to 9 depression domains \[sad mood, concentration, self-criticism, suicidal ideation, interest, energy/fatigue, sleep disturbance (initial, middle and late insomnia or hypersomnia), decrease/increase in appetite/weight, and psychomotor agitation/retardation\] to give a single total scores range from 0 to 27, with higher scores indicating greater symptom severity. LS mean change from baseline was calculated using ANCOVA.

Time frame: Baseline, Week 12

Change From Baseline in Medical Outcomes Study 36-item Short Form Health Survey (SF-36) and Physical Component Summary (PCS) and Mental Component Summary (MCS)

The SF-36 is a self-reported instrument that measures the participant's health status during the previous 7 days. It comprises 36-items covering 8 domains: physical functioning, role physical, role emotional, bodily pain, vitality, social functioning, mental health, and general health. Items are answered on Likert scales of varying lengths. The 8 domains are regrouped in the PCS and MCS scores. Scores range from 0 to 100, with higher scores indicating better levels of function and/or better health. LS mean change from baseline was calculated using ANCOVA.

Time frame: Baseline, Week 12

Change From Baseline in Patient's Global Assessment of Disease Severity (PatGA)

The PatGA is a single-item self-reported instrument asking the participant to rate the severity of their psoriasis "today" by circling a number on the numeric rating scale from 0 (Clear = no psoriasis) to 5 (Severe = the worst their psoriasis has ever been). LS mean change from baseline calculated using MMRM.

Time frame: Baseline, Week 12

Percentage of Participants Achieving Palmoplantar PASI (PPASI) of ≥50% (PPASI50), ≥75% (PPASI75), or 100% (PPASI100) Improvement

The Palmoplantar PASI is a composite score derived from the sum of scores for erythema, induration, and desquamation \[scores range from 0 (none) to 4 (very severe) for each\] multiplied by the score for the extent of palm and sole area involvement \[scores range from 0 (0%) to 6 (90 to100%)\], with a total scores range from 0 to 72. Participants achieving PPASI50, PPASI75 or PASI100 were defined as having an improvement of at least 50%, 90%, or of 100%, respectively, in the PPASI scores compared to baseline.

Time frame: Week 12

Pharmacokinetics (PK): Trough Concentration at Steady State (Ctrough ss)

Time frame: Weeks 12: Day 84 and Week 24: Day 168

Percentage of Participants With Anti-ixekizumab Antibodies

Percentage of participants with treatment-emergent positive anti-ixekizumab antibodies was summarized by treatment group. Percentage was calculated based on the number of evaluable participants and was calculated by number of participants with treatment-emergent positive anti-ixekizumab antibodies / number of evaluable participants \* 100%.

Time frame: Baseline through Week 12