Phase II Study of Apremilast (CC-10004) in Adults With in Psoriatic Arthritis

A modified American College of Rheumatology 20% (ACR 20) response was defined as a participant who met the following 3 criteria for improvement from Baseline: • ≥ 20% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 20% improvement in 76 swollen joint count; and • ≥ 20% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm visual analog scale \[VAS\]); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline and Week 12

Population: The intent-to-treat (ITT) population which consisted of all randomized participants with at least one of the ACR components assessed at baseline. Last observation carried forward (LOCF) imputation was used.

Dactylitis is characterized by swelling of the entire finger or toe. Each digit on the hands and feet was rated on a scale from 0 (no dactylitis) to 3 (severe dactylitis). The dactylitis severity score is the sum of the individual scores for each digit and ranges from 0 to 60. Change in the dactylitis severity score was assessed from Baseline (Day 1) and from Week 12 (Day 85).

Time frame: Baseline, Week 12 and Week 24

Population: Participants enrolled in the Extension Phase with a baseline/Week 12 value and at least 1 post-baseline value in the extension period; LOCF imputation was used.

The DLQI is a validated, self-administered, 10-item questionnaire that measures the impact of skin disease on participants' quality of life, based on recall over the past week. Domains include symptoms, feelings, daily activities, leisure, work, personal relationships, and treatment. Each question is answered on a scale from 0 (not at all) to 3 (very much) The total score ranges from 0 to 30 where a higher score indicates that a participant's dermatological condition has a greater impact on their daily life.

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase with a Baseline/Week 12 value and at least 1 post-baseline value in the extension period; LOCF imputation was used.

The Medical Outcome SF 36-Item Health Survey, Version 2 is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). The summary physical health score included the following subscales: physical functioning, role-physical, bodily pain, and general health. The summary mental health score included other subscales: vitality, social functioning, role-emotional, and mental health. Norm-based scores were used in analyses, calibrated so that 50 is the average score and the standard deviation equals 10, where higher scores are associated with better functioning/quality of life. Each domain is scored by summing the individual items and transforming the scores into a 0 to 100 scale. A higher change from baseline indicates an improvement in better health results or functioning.

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase with a Baseline/Week 12 value and at least 1 post-baseline value in the extension period; LOCF imputation was used.

The HAQ-DI is a self-administered instrument consisting of 20 questions in eight categories of functioning which represent a comprehensive set of functional activities - dressing, rising, eating, walking, hygiene, reach, grip, and usual activities. Each item asks over the past week whether a particular task can be performed. For each item, there is a four-level difficulty scale that is scored from 0 to 3, representing normal (no difficulty) (0), some difficulty (1), much difficulty (2), and unable to do (3). The eight category scores are averaged into an overall HAQ-DI score on a scale from zero (no disability) to three (completely disabled).

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase with a Baseline/Week 12 value and at least 1 post-baseline value in the extension period; LOCF imputation was used.

Dactylitis is characterized by swelling of the entire finger or toe. Each digit on the hands and feet was rated on a scale from 0 (no dactylitis) to 3 (severe dactylitis). The dactylitis severity score is the sum of the individual scores for each digit and ranges from 0 to 60.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; participants with a baseline value and at least 1 post-baseline value in the treatment period are included; LOCF imputation was used.

The DLQI is a validated, self-administered, 10-item questionnaire that measures the impact of skin disease on participants' quality of life, based on recall over the past week. Domains include symptoms, feelings, daily activities, leisure, work, personal relationships, and treatment. Each question is answered on a scale from 0 (not at all) to 3 (very much). The total score ranges from 0 to 30 where a higher score indicates that a participant's dermatological condition has a greater impact on their daily life.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; participants with a baseline value and at least 1 post-baseline value in the treatment period are included; LOCF imputation was used.

The Medical Outcome SF 36-Item Health Survey, Version 2 is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). The summary physical health score included the following subscales: physical functioning, role-physical, bodily pain, and general health. The summary mental health score included other subscales: vitality, social functioning, role-emotional, and mental health. Norm-based scores were used in analyses, calibrated so that 50 is the average score and the standard deviation equals 10, where higher scores are associated with better functioning/quality of life. Each domain is scored by summing the individual items and transforming the scores into a 0 to 100 scale. A higher change from baseline indicates an improvement in better health results or functioning.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; participants with a baseline value and at least 1 post-baseline value in the treatment period are included; LOCF imputation was used.

The FACIT-Fatigue is a 13 item self-administered questionnaire that assesses both the physical and functional consequences of fatigue based on recall during the past 7 days. Each question is answered on a 5-point scale, where 0 means not at all, and 4 means very much. The total score ranges from 0 to 52 with higher scores representing less fatigue.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; participants with a baseline value and at least 1 post-baseline value in the treatment period are included; LOCF imputation was used.

The FACIT-Fatigue is a 13 item self-administered questionnaire that assesses both the physical and functional consequences of fatigue based on recall during the past 7 days. Each question is answered on a 5-point scale, where 0 means not at all, and 4 means very much. The total score ranges from 0 to 52 with higher scores representing less fatigue.

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase with a Baseline/Week 12 value and at least 1 post-baseline value in the extension period; LOCF imputation was used.

The HAQ-DI is a self-administered instrument consisting of 20 questions in eight categories of functioning which represent a comprehensive set of functional activities - dressing, rising, eating, walking, hygiene, reach, grip, and usual activities. Each item asks over the past week whether a particular task can be performed. For each item, there is a four-level difficulty scale that is scored from 0 to 3, representing normal (no difficulty) (0), some difficulty (1), much difficulty (2), and unable to do (3). The eight category scores are averaged into an overall HAQ-DI score on a scale from zero (no disability) to three (completely disabled).

Time frame: Baseline and Week 12

Population: Intent-to-treat population; participants with a baseline value and at least 1 post-baseline value in the treatment period are included; LOCF imputation was used.

The ACR-N index score was calculated for each participant at each time point in the study according to the following definition: ACR-N = the lowest of the following 3 values: • percent improvement from Baseline in the 76 swollen joint count, • percent improvement from Baseline in the 78 tender joint count • median percent improvement from Baseline in the following 5 measures ◦ Patient's assessment of pain (measured on a 100 mm visual analog scale \[VAS\]); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. The maximal ACR-N for each participant during the 12-week extension period was calculated, and represents the maximal ACR response achieved.

Time frame: ACR was measured at Baseline and Weeks 16, 20 and 24

Population: Participants enrolled in the Extension Phase with non-missing ACR data

The ACR-N index score was calculated for each participant at each time point in the study according to the following definition: ACR-N = the lowest of the following 3 values: - percent improvement from Baseline in the 76 swollen joint count, - percent improvement from Baseline in the 78 tender joint count - median percent improvement from Baseline in the following 5 measures ◦ Patient's assessment of pain (measured on a 100 mm visual analog scale \[VAS\]); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. The maximal ACR-N for each participant during the 12-week treatment period was calculated, and represents the maximal ACR response achieved.

Time frame: ACR was measured at Baseline and Weeks 2, 4, 6, 8, 10, and 12

Population: Intent-to-treat population with non-missing ACR data

Relapse of psoriatic arthritis was defined as a 50% loss of the maximal ACR improvement during the Follow-up Phase in participants who achieved at least an ACR 20 at their Final Extension Phase/Early Termination Visit.

Time frame: Week 24 to Week 28 (28-day follow-up period)

Population: Participants with an ACR 20 response at the Week 24 (or Early Termination) visit and entered the Follow-up Phase after the Extension Phase

Relapse of psoriatic arthritis was defined as a 50% loss of the maximal ACR improvement during the Observation Phase in participants who received apremilast and achieved at least an ACR 20 at their Final Treatment Phase/Early Termination Visit.

Time frame: 28-day observational follow-up period following Week 12

Population: Participants who received apremilast with an ACR 20 response at the Week 12 (or Early Termination) visit who did not enroll in the Extension Phase.

The number of participants who withdrew prematurely from the treatment phase due to lack of efficacy, including flare of psoriasis, flare of psoriatic arthritis or worsening or not responding to study treatment.

Time frame: Baseline to Week 12

Population: Intent-to-treat population

The severity of each adverse event (AE) was graded based upon the participant's symptoms according to National Cancer Institute (NCI) Common Toxicity Criteria (CTCAE, Version 3.0), on a scale from 1 (Mild AE) to 5 (Death due to AE). Severe AEs are defined as NCI CTCAE grade 3 or higher. AEs related to study drug are those determined by the investigator as suspected to be related to study drug where a temporal relationship of the adverse event to study drug administration made a causal relationship possible, and other medications, therapeutic interventions, or underlying conditions did not provide a sufficient explanation for the observed event. A serious adverse event (SAE) is any AE which: - Resulted in death - Was life-threatening - Required inpatient hospitalization or prolongation of existing hospitalization - Resulted in persistent or significant disability/incapacity - Was a congenital anomaly/birth defect - Constituted an important medical event.

Time frame: Weeks 12 to 24 (Extension Phase)

Population: The safety population; participants who entered the Extension Phase.

The severity of each adverse event (AE) was graded based upon the participant's symptoms according to National Cancer Institute (NCI) Common Toxicity Criteria (CTCAE, Version 3.0), on a scale from 1 (Mild AE) to 5 (Death due to AE). Severe AEs are defined as NCI CTCAE grade 3 or higher. AEs related to study drug are those determined by the investigator as suspected to be related to study drug where a temporal relationship of the adverse event to study drug administration made a causal relationship possible, and other medications, therapeutic interventions, or underlying conditions did not provide a sufficient explanation for the observed event. A serious adverse event (SAE) is any AE which: - Resulted in death - Was life-threatening - Required inpatient hospitalization or prolongation of existing hospitalization - Resulted in persistent or significant disability/incapacity - Was a congenital anomaly/birth defect - Constituted an important medical event.

Time frame: 12 weeks

Population: The safety population which consisted of all enrolled participants who received at least 1 dose of study medication.

The number of participants who were dose reduced during the treatment phase due to adverse events.

Time frame: Baseline to Week 12

Population: Safety population

A modified ACR 20 response was defined as a participant who met the following 3 criteria for improvement: • ≥ 20% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 20% improvement in 76 swollen joint count; and • ≥ 20% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm VAS); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. Response at Week 24 was measured as improvement from Baseline (Day 1) and from Week 12 (Day 85). Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used. For the analysis of response from Week 12 (Day 85), participants with a tender or swollen joint count of 0 at Day 85 were excluded.

A modified American College of Rheumatology 50% (ACR 50) response was defined as a participant who met the following 3 criteria for improvement from Baseline: • ≥ 50% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 50% improvement in 76 swollen joint count; and • ≥ 50% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm visual analog scale \[VAS\]); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; LOCF imputation was used.

A modified ACR 50 response was defined as a participant who met the following 3 criteria for improvement: • ≥ 50% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 50% improvement in 76 swollen joint count; and • ≥ 50% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm VAS); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. Response at Week 24 was measured as improvement from Baseline (Day 1) and from Week 12 (Day 85). Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline (Day 1), Week 12 (Day 85) and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used. For the analysis of response from Week 12 (Day 85), participants with a tender or swollen joint count of 0 at Day 85 were excluded.

A modified American College of Rheumatology 70% (ACR 70) response was defined as a participant who met the following 3 criteria for improvement from Baseline: • ≥ 70% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 70% improvement in 76 swollen joint count; and • ≥ 70% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm visual analog scale \[VAS\]); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index (HAQ-DI)); ◦ C-reactive protein. Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; LOCF imputation was used.

A modified ACR 70 response was defined as a participant who met the following 3 criteria for improvement: • ≥ 70% improvement in 78 tender joint count (includes 10 additional joints often involved in psoriatic arthritis: the first carpometacarpal \[CMC\] and the distal interphalangeal \[DIP\] joints of the fingers); • ≥ 70% improvement in 76 swollen joint count; and • ≥ 70% improvement in at least 3 of the 5 following parameters: ◦ Patient's assessment of pain (measured on a 100 mm VAS); ◦ Patient's global assessment of disease activity (measured on a 100 mm VAS); ◦ Physician's global assessment of disease activity (measured on a 100 mm VAS); ◦ Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index \[HAQ-DI\]); ◦ C-reactive protein. Response at Week 24 was measured as improvement from Baseline (Day 1). Participants with no post-baseline ACR scores were considered non-responders.

Time frame: Baseline (Day 1) and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used.

A PsARC response is defined as improvement from Baseline in at least 2 of the following 4 measures, at least 1 of which must be tender joint count or swollen joint count, and no worsening in any of the 4 measures, according to the following: • At least 30% improvement in the 78 tender joint count, • At least 30% improvement in the 76 swollen joint count, • At least 20% improvement in the patient global assessment of disease activity, measured on a 100 mm visual analog scale (VAS), where 0 mm = lowest disease activity and 100 mm = highest; • At least 20% improvement in the physician global assessment of disease activity, measured on a 100 mm VAS, where 0 mm = lowest disease activity and 100 mm = highest. Participants with no post-baseline PsARC scores were considered non-responders.

Time frame: Baseline and Week 12

Population: Intent-to-treat population; LOCF imputation was used.

A PsARC response is defined as improvement from Baseline in at least 2 of the following 4 measures, at least 1 of which must be tender joint count or swollen joint count, and no worsening in any of the 4 measures: • At least 30% improvement in the 78 tender joint count, • At least 30% improvement in the 76 swollen joint count, • At least 20% improvement in the patient global assessment of disease activity, measured on a 100 mm visual Analog scale (VAS), where 0 mm = lowest disease activity and 100 mm = highest; • At least 20% improvement in the physician global assessment of disease activity, measured on a 100 mm VAS, where 0 mm = lowest disease activity and 100 mm = highest. Participants with missing data were considered non-responders.

Time frame: Baseline and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used.

The DAS28-CRP(3) measures the severity of disease derived from the following 3 variables: • 28 tender joint count (does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count • C-reactive protein (CRP) DAS28-CRP(3) scores range from 0 to 9.4, where higher scores indicate more disease activity. Mild disease severity is defined as a DAS28-CRP(3) score of ≤ 3.2. In remission is defined as a DAS28-CRP(3) score of ≤ 2.6.

Time frame: Week 12

Population: Intent-to-treat population; LOCF imputation was used. Participants with no post-baseline DAS28-CRP(3) scores were considered non-responders.

The DAS28-CRP(4) measures the severity of disease derived from the following 4 variables: • 28 tender joint count, (does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count • C-reactive protein (CRP) • Patient's global assessment of disease activity. DAS28-CRP(4) scores range from 0 to 9.4, where higher scores indicate more disease activity. Mild disease severity is defined as a DAS28-CRP(4) score of ≤ 3.2. In remission is defined as a DAS28-CRP(4) score of ≤ 2.6.

Time frame: Week 12

Population: Intent-to-treat population; LOCF imputation was used. Participants with no post-baseline DAS28-CRP(4) scores were considered non-responders.

Enthesitis is inflammation of the entheses, the sites where tendons or ligaments insert into the bone. Enthesitis is characterized by swelling, pain, and tenderness around the calcaneous, and occasionally by effusion in the bursa associated with this joint. The enthesitis assessment is an evaluation of inflammation at the insertions of the Achilles tendon into the calcaneous and of the plantar fascia into the calcaneous. Inflammation at 1 or more insertions on either the right or left side constituted a positive assessment.

Time frame: Baseline and Week 12

Population: Intent-to-treat population

Enthesitis is inflammation of the entheses, the sites where tendons or ligaments insert into the bone. Enthesitis is characterized by swelling, pain, and tenderness around the calcaneous, and occasionally by effusion in the bursa associated with this joint. The enthesitis assessment is an evaluation of inflammation at the insertions of the Achilles tendon into the calcaneous and of the plantar fascia into the calcaneous. Inflammation at 1 or more insertions on either the right or left side constituted a positive assessment.

Time frame: Week 12 and Week 24

Population: Participants enrolled in the Extension Phase

The DAS28 measures the severity of disease at a specific time. DAS28-CRP(3) is derived from the following 3 variables: • 28 tender joint count, (does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count • C-reactive protein (CRP) according to the formula: DAS28-CRP(3) = \[0.56\*√(TJC28) + 0.28\*√(SJC28) + 0.36\*ln(CRP+1)\] \* 1.10 + 1.15. DAS28 scores range from 0 to 9.4, where higher scores indicate more disease activity. A EULAR response reflects an improvement in disease activity based on the DAS-28 score. A Good Response is defined as an improvement (decrease) in the DAS28 \> 1.2 from Baseline and attainment of a DAS28 score ≤ 3.2. A Moderate Response is defined as either: • an improvement (decrease) in the DAS28 \> 0.6 and ≤ 1.2 and a DAS28 score ≤ to 5.1 or, • an improvement (decrease) in the DAS28 \> 1.2 and a DAS28 score \> 3.2

Time frame: Baseline and Week 12

Population: Intent-to-treat population; LOCF imputation was used. Participants with no baseline or post-baseline DAS28-CRP(3) scores were considered non-responders.

The DAS28 measures the severity of disease at a specific time. DAS28-CRP(3) is derived from the following 3 variables: • 28 tender joint count, (does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count • C-reactive protein (CRP) according to the formula: DAS28-CRP(3) = \[0.56\*√(TJC28) + 0.28\*√(SJC28) + 0.36\*ln(CRP+1)\] \* 1.10 + 1.15. DAS28 scores range from 0 to 9.4, where higher scores indicate more disease activity. A EULAR response reflects an improvement in disease activity based on the DAS-28 score. A Good Response is defined as an improvement (decrease) in the DAS28 \> 1.2 from Baseline and attainment of a DAS28 score ≤ 3.2. A Moderate Response is defined as either: • an improvement (decrease) in the DAS28 \> 0.6 and ≤ 1.2 and a DAS28 score ≤ to 5.1 or, • an improvement (decrease) in the DAS28 \> 1.2 and a DAS28 score \> 3.2

Time frame: Baseline and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used.

The DAS28 measures the severity of disease at a specific time. DAS28-CRP(4) is derived from the following 4 variables: • 28 tender joint count, (does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count • C-reactive protein • Patient's global assessment of disease activity according to the formula: DAS28-CRP(4) = 0.56\*√(TJC28) + 0.28\*(SJC28) + 0.36\*ln(CRP+1) + 0.014\*GH + 0.96. DAS28 scores range from 0 to 9.4, where higher scores indicate more disease activity. A EULAR response reflects an improvement in disease activity based on the DAS-28 score. A Good Response is defined as an improvement (decrease) in the DAS28 \> 1.2 from Baseline and attainment of a DAS28 score ≤ 3.2. A Moderate Response is defined as either: • an improvement (decrease) in the DAS28 \> 0.6 and ≤ 1.2 and a DAS28 score ≤ to 5.1 or, • an improvement (decrease) in the DAS28 \> 1.2 and a DAS28 score \> 3.2

Time frame: Baseline and Week 24

Population: Participants enrolled in the Extension Phase; LOCF imputation was used.

The DAS28 measures the severity of disease at a specific time. DAS28-CRP(4) is derived from the following 4 variables: • 28 tender joint count, (TJC; does not include the DIP joints, the hip joint, or the joints below the knee) • 28 swollen joint count (SJC) • C-reactive protein (CRP) • Patient's global assessment of disease activity (GH) according to the formula: DAS28-CRP(4) = 0.56\*√(TJC28) + 0.28\*(SJC28) + 0.36\*ln(CRP+1) + 0.014\*GH + 0.96. DAS28 scores range from 0 to 9.4, where higher scores indicate more disease activity. A EULAR response reflects an improvement in disease activity based on the DAS-28 score. A Good Response is defined as an improvement (decrease) in the DAS28 \> 1.2 from Baseline and a DAS28 score ≤ 3.2. A Moderate Response is defined as either: • an improvement (decrease) in the DAS28 \> 0.6 and ≤ 1.2 and a DAS28 score ≤ to 5.1 or, • an improvement (decrease) in the DAS28 \> 1.2 and a DAS28 score \> 3.2

Time frame: Baseline and Week 12

Population: Intent-to-treat population; LOCF imputation was used. Participants with no baseline or post-baseline DAS28-CRP(4) scores were considered non-responders.

Time to ACR 20 was measured from the first dose of apremilast to the first time a participant achieved an ACR 20 response in the treatment or extension phase. The Kaplan-Meier estimates of time to ACR 20 response were calculated for participants who had an ACR 20 response at any time during the study.

Time frame: Baseline to Week 24

Population: Participants enrolled in the Extension Phase with an ACR 20 response at any time during the study

The Kaplan-Meier estimates of time to ACR 20 response was calculated for participants who had an ACR 20 response at any time during the treatment phase.

Time frame: Baseline to Week 12

Population: Intent-to-treat population with an ACR 20 response during the treatment phase.

Time to ACR 50 response was measured from the first dose of apremilast to the first time a participant achieved an ACR 50 response in the treatment or extension phase. The Kaplan-Meier estimates of time to ACR 50 response were calculated for participants who had an ACR 50 response at any time during the study.

Time frame: Baseline to Week 24

Population: Participants enrolled in the Extension Phase with an ACR 50 response at any time during the study

The Kaplan-Meier estimates of time to ACR 50 response was calculated for participants who had an ACR 50 response at any time during the treatment phase.

Time frame: Baseline to Week 12

Population: Intent-to-treat population who had an ACR 50 response during the treatment phase.

Time to ACR 70 response was measured from the first dose of apremilast to the first time a participant achieved an ACR 70 response in the treatment or extension phase. The Kaplan-Meier estimates of time to ACR 70 response were calculated for participants who had an ACR 70 response at any time during the study.

Time frame: Baseline to Week 24

Population: Participants enrolled in the Extension Phase with an ACR 70 response at any time during the study

The Kaplan-Meier estimates of time to ACR 70 response was calculated for participants who had an ACR 70 response at any time during the treatment phase.

Time frame: Baseline to Week 12

Population: Intent-to-treat population with an ACR 70 response during the treatment phase.

Relapse of psoriatic arthritis was defined as a 50% loss of the maximal ACR improvement during the Follow-up Phase in participants who achieved at least an ACR 20 at their Final Extension Phase (Week 24)/Early Termination Visit. The time to relapse during the Follow-up Phase was calculated from the time of maximum ACR reduction and from the date of the Final Extension Phase visit. Participants classified as responders who did not relapse were censored at the day of the last follow-up.

Time frame: From Week 24 to the end of the 28-day follow-up (1) and from the date of maximal ACR until the end of the 28-day follow-up phase (2).

Population: Participants with an ACR 20 response at the Week 24 (or Early Termination) visit and entered the Follow-up Phase after the Extension Phase

Relapse of psoriatic arthritis was defined as a 50% loss of the maximal ACR improvement during the Observation Phase in participants who received apremilast and achieved at least an ACR 20 at their Final Treatment Phase/Early Termination Visit. The time to relapse during the Observational Phase was calculated from the time of maximum ACR reduction and from the date of the Final Treatment Phase visit. Participants classified as responders who did not relapse were censored at the day of the last follow-up.

Time frame: From Week 12 to end of 28-day observational follow-up (1) and from the date of maximal ACR during the 12-week Treatment Phase until the end of the 28-day observational follow-up phase (2).

Population: Participants who received apremilast and with an ACR 20 response at the Week 12 (or Early Termination) visit who did not enroll in the Extension Phase.