PASI-75 response is the percentage of participants who achieved at least a 75% reduction (improvement) from baseline in PASI score at Week 16. The improvement in PASI score was used as a measure of efficacy. The PASI was a measure of psoriatic disease severity taking into account qualitative lesion characteristics (erythema, thickness and scaling) and degree of skin surface area involvement on defined anatomical regions. PASI scores range from 0 to 72, with higher scores reflecting greater disease severity. Erythema, thickness, and scaling are scored on a scale of 0 (none) to 4 (very severe) on 4 anatomic regions of the body: head, trunk, upper limbs, and lower limbs. Degree of involvement on each of the 4 anatomic regions is scored on a scale of 0 (no involvement) to 6 (90% to 100% involvement). The PASI score was set to missing if any severity score or degree of involvement was missing.

mITT consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the Last observation carried forward (LOCF) method.

The sPGA is a measure of psoriasis disease severity at the time of evaluation by the Investigator. It does not compare assessments across visits or rely on investigator recall or prior disease. The sPGA is a 6-point scale ranging from 0 (clear, except for residual discoloration) to 5 (severe; majority of plaques have severe thickness, erythema, and scaling). The investigator examines all of the lesions on the participant and assigns a score ranging from 0 to 5 for thickness, erythema and degree of scaling. Scores for thickness, erythema and scaling are then summed and the mean of these 3 scores equals the overall sPGA score.

mITT population with a sPGA greater than 2 at baseline. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

BSA is a measurement of involved skin. The overall BSA affected by psoriasis is estimated based on the palm area of the subject's hand (entire palmar surface or "handprint" including the fingers), which equates to approximately 1% of total body surface area.

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

The PASI is a measure of psoriatic disease severity taking into account qualitative lesion characteristics (erythema, thickness, and scaling) and degree of skin surface area involvement on defined anatomical regions. The PASI is a validated instrument that has become standard in clinical trials for psoriasis. The PASI scores range from 0 to 72, with higher scores reflecting a greater disease severity.

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

PASI-50 response is the percentage of participants who achieved at least a 50% reduction (improvement) from baseline in PASI score at Week 16. The improvement in PASI score was used as a measure of efficacy. The PASI was a measure of psoriatic disease severity taking into account qualitative lesion characteristics (erythema, thickness and scaling) and degree of skin surface area involvement on defined anatomical regions. PASI scores range from 0 to 72, with higher scores reflecting greater disease severity. Erythema, thickness, and scaling are scored on a scale of 0 (none) to 4 (very severe) on 4 anatomic regions of the body: head, trunk, upper limbs, and lower limbs. Degree of involvement on each of the 4 anatomic regions is scored on a scale of 0 (no involvement) to 6 (90% to 100% involvement). The PASI score was set to missing if any severity score or degree of involvement is missing.

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

The pruritus visual analog scale (VAS) was used to measure the amount of itching and discomfort a participant experiences. Participant's assessment of pruritus (Itch) asked: On average, how much itch have you had because of your condition in the past week? Higher scores correspond to more severe symptom or disease. The participant places a vertical line on a 100-mm VAS on which the left-hand boundary represents no itch at all and the right-hand boundary represents the worst itch imaginable. The distance from the vertical line to the left-hand boundary is recorded. VAS scores range from 0 to 100 mm, where higher scores correspond to worse pruritis (itch).

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

Dermatology Life Quality Index (DLQI) was developed as a practical questionnaire for use in a dermatology clinical setting to assess limitations related to the impact of skin disease. The instrument contains 10 items dealing with the participants skin. With the exception of Item Number 7, the participant responds on a four-point scale, ranging from "Very Much" (score 3) to "Not at All" or "Not relevant" (score 0). Item Number 7 is a multi-part item, the first part of which ascertains whether the participant's skin prevented them from working or studying (Yes or No, scores 3 or 0 respectively), and if "No," then the participant is asked how much of a problem the skin has been at work or study over the past week, with response alternatives being "A lot," "A little," or "Not at all" (scores 2, 1, or 0 respectively). The DLQI total score has a possible range from 0 to 30, with 30 corresponding to the worst quality of life, and 0 corresponding to the best.

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized. Missing values were imputed using the LOCF method.

SF-36 is a 36-item general health status instrument often used in clinical trials and health services research. It consists of 8 scales: physical function (PF), role limitations-physical (RP), vitality (VT), general health perceptions (GH), bodily pain (BP), social function (SF), role limitations-emotional (RE), and mental health (MH). Scale scores range from 0 to 100, with higher scores indicating better quality of life (better functioning)

mITT population consisted of all participants who were randomized and received at least one dose of IP. Participants were included in the treatment group in which they were randomized.

The ACR 20 is defined as a 20% improvement in joint tenderness (78 joint count) and joint swelling scores (76 joint count) compared to baseline plus 20% improvements in 3 of the following 5 assessments (compared to baseline): subject global assessment of disease activity (measured on a 100-mm visual analog scale [VAS]); physician global assessment of disease activity (measured on a 100-mm VAS); subject self-assessment of physical function (Health Assessment Questionnaire - Disability Index [HAQ-DI] score); subject assessment of pain (measured on a 100-mm VAS); and CRP level.

Due to the small sample size in the study for the ACR 20 % improvement, the analysis was not conducted. The decision not to perform the analysis was authorized by the lead therapeutic executive and there is no data available to analyze. No resources are available to conduct the ACR 20% improvement endpoint for this population.

Change from baseline in psoriatic arthritis pain 100-mm VAS; The participant places a vertical line on a 100-mm VAS on which the left-hand boundary represents no pain at all and the right-hand boundary represents the worst possible pain. The distance from the vertical line to the left-hand boundary is recorded.

Due to the small sample size in the study for change from baseline in psoriatic arthritis pain VAS, the analysis was not conducted. The decision not to perform the analysis was authorized by the lead therapeutic executive and there is no data to analyze. No resources are available to conduct the analysis for the end point.

Change from baseline in physical function assessment using HAQ-DI; The HAQ-DI is a 20-question, self-administered instrument that measures the subject's functional ability on a 4-level difficulty scale (0-3, with 0 representing normal or no difficulty; and 3 representing inability to perform). Eight categories of functioning are included: dressing, rising, eating, walking, hygiene, reach, grip, and usual activities.

Due to the small sample size for the change from baseline in physical function assessment using the HAQ-DI, the analysis was not conducted. The decision not to perform the analysis was authorized by the lead therapeutic executive and there is no data available to analyze. No resources are available to conduct the analysis for the end point.

An AE was any noxious, unintended, or untoward medical occurrence, that may appear or worsen in a participant during the course of study. It may be a new intercurrent illness, a worsening concomitant illness, an injury, or any concomitant impairment of the participant's health, including laboratory test values regardless of etiology. Any worsening (ie, any clinically significant adverse change in the frequency or intensity of a preexisting condition) was considered an AE. A serious AE (SAE) is any untoward adverse event that is fatal, life-threatening, results in persistent or significant disability or incapacity, requires or prolongs existing in-patient hospitalization, is a congenital anomaly or birth defect, or a condition that may jeopardize the patient or may require intervention to prevent one of the outcomes listed above. An AE is a treatment emergent AE if the AE start date is on or after the date of the first dose of study drug and no later than 28 days after the last dose.

Safety population consisted of all participants who were randomized and received at least one dose of IP

An AE was any noxious, unintended, or untoward medical occurrence that may appear or worsen in a participant during the course of study. It may be a new intercurrent illness, a worsening concomitant illness, an injury, or any concomitant impairment of the participant's health, including laboratory test values regardless of etiology. Any worsening (ie, any clinically significant adverse change in the frequency or intensity of a preexisting condition) was considered an AE. A serious AE (SAE) is any untoward adverse event that is fatal, life-threatening, results in persistent or significant disability or incapacity, requires or prolongs existing in-patient hospitalization, is a congenital anomaly or birth defect, or a condition that may jeopardize the patient or may require intervention to prevent one of the outcomes listed above. An AE is a treatment emergent AE if the AE start date is on or after the date of the first dose of study drug and no later than 28 days after the last dose.

All participants who received apremilast at any time during the trial.