Phase 3b Safety and Efficacy Study of Apremilast to Treat Moderate to Severe Plaque-plaque Psoriasis

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.

The sPGA is an assessment by the Investigator of the overall disease severity at the time of evaluation. The sPGA is a 5-point scale ranging from 0 (clear) to 4 (severe), incorporating an assessment of the severity of the three primary signs of the disease: erythema, scaling and plaque elevation. When making the assessment of overall severity, the Investigator should factor in areas that have already been cleared (ie, have scores of 0) and not just evaluate remaining lesions for severity, ie, the severity of each sign is averaged across all areas of involvement, including cleared lesions. In the event of different severities across disease signs, the sign that is the predominant feature of the disease should be used to help determine the sPGA score.

BSA is a measurement of involved skin. The overall BSA affected by psoriasis was estimated based on the palm area of the participant's hand (entire palmar surface or "handprint" including the fingers), which equates to approximately 1% of total body surface area. BSA percent change from baseline was determined at each visit of the study, and is calculated as 100*(post-baseline BSA - baseline BSA) / baseline BSA.

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 PASI score 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.

DLQI is a simple, compact, and practical questionnaire for use in a dermatology clinical setting to assess limitations related to the impact of skin disease. The instrument contains ten items dealing with the participant's 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 is derived by summing all item scores, which has a possible range of 0 to 30, with 30 corresponding to the worst quality of life, and 0 corresponding to the best.

The SF-36 is a 36-item general health status instrument and 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 health. Scores from the 8 scales were transformed to the norm-based scores using weights from U.S. general population to have a mean of 50 and variance = 10, with higher scores indicating better health. From these 8 scale, two overall summary scores were obtained - a Physical Component Summary score (PCS) and a Mental Component Summary score (MCS), both having the same mean of 50 and variance = 10 as noted for the individual scales for the U.S. general population, and with higher scores indicating better health. For MCS, change from baseline was calculated, where change = visit value - baseline value.

The Lattice System Physician's Global Assessment is a global assessment performed by the investigator of psoriasis severity. Integrating ranges of BSA involvement with assessments of overall plaque severity (using a 4 point scale from none to marked for the signs of plaque elevation, erythema and scale), the LS-PGA produces an overall assessment of psoriasis severity on an 8-point scale, ranging from clear to very severe. To determine the final score, the lattice portion is governed by the BSA and among the plaque qualities, weights plaque elevation as most important, erythema next, and scale least.

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

A TEAE in the apremilast-exposure phase is an AE with a start date on or after the date of the first dose of study drug and no later than 28 days after the last dose of study drug. An AE is any noxious, unintended, or untoward medical occurrence that may appear or worsen during the study. It may be a new intercurrent illness, a worsening concomitant illness, an injury, or any concomitant impairment of the subject'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) should be considered an AE. A serious AE (SAE) is any untoward AE that is fatal, life-threatening, results in persistent or significant disability or incapacity, requires or prolongs existing in-patient hospitalization, is a congenital anomaly/birth defect, or is a condition that may jeopardize or may require intervention to prevent one of the outcomes listed above.

Psoriasis flare is an AE and represents an atypical or unusual worsening of disease during treatment. It is defined as a sudden intensification of psoriasis requiring medical intervention or a diagnosis of new generalized erythrodermic, inflammatory, or pustular psoriasis. Rebound is an AE and is defined as a severe and sudden worsening of disease that occurs after treatment has been discontinued. This exacerbation is characterized by a PASI ≥125% of baseline or a new generalized pustular, erythrodermic, or more inflammatory psoriasis after stopping therapy.

Psoriasis flare is an AE and represents an atypical or unusual worsening of disease during treatment. It is defined as a sudden intensification of psoriasis requiring medical intervention or a diagnosis of new generalized erythrodermic, inflammatory, or pustular psoriasis. Rebound is an AE and is defined as a severe and sudden worsening of disease that occurs after treatment has been discontinued. This exacerbation is characterized by a PASI ≥125% of baseline or a new generalized pustular, erythrodermic, or more inflammatory psoriasis after stopping therapy. PASI ≥125% of baseline score at any visit after the last dose date for those who discontinued within the phase.