Administered by subcutaneous injection

A PASI 75 response is a 75% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

A PASI 75 response is a 75% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Percent improvement from baseline is calculated as (value at baseline - value at post-baseline visit) × 100 / (value at baseline).

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Percent improvement from baseline is calculated as (value at baseline - value at post-baseline visit) × 100 / (value at baseline).

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from baseline (negative value) indicates improvement.

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from Baseline (negative value) indicates improvement.

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from Baseline (negative value) indicates improvement.

The Investigator assessed whether each adverse event (AE) was possibly related to the investigational product. AEs were graded for severity according to the Common Toxicity Criteria for Adverse Events (CTCAE) version 4.03.

A serious AE is defined as an AE that meets at least 1 of the following serious criteria:

• fatal
• life threatening
• requires inpatient hospitalization or prolongation of existing hospitalization
• results in persistent or significant disability/incapacity
• congenital anomaly/birth defect
• other medically important serious event. Results are reported from Day 1 to week 16 for the Part 1 ABP 501 and Adalimumab groups, and from post week 16 to the end of study (week 52) for the Part 2 ABP 501/ABP 501, Adalimumab/Adalimumab and Adalimumab/ABP 501 groups.

Two validated assays were used to detect the presence of anti-drug antibodies. Samples were first tested in an electrochemiluminescence (ECL)-based bridging immunoassay to detect anti-drug antibodies (ADA) against ABP 501 and adalimumab (Binding Antibody Assay). Samples confirmed to be positive for binding antibodies were subsequently tested in a non-cell based bioassay to determine neutralizing activity against ABP 501 or adalimumab (Neutralizing Antibody Assay).

Developing antibody incidence is defined as a negative or no antibody result at baseline and a positive antibody result at a post-baseline time point.

Total of all reporting groups

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema).

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement. The total PASI score ranges from 0 to 72. The higher the total score, the more severe the disease.

Data are reported for 174 and 173 participants in each reporting group respectively.

Data are reported for 174 and 173 participants in each reporting group respectively.

Participants received 80 mg adalimumab subcutaneously on week 1/day 1 (initial loading dose) and 40 mg at week 2 and every 2 weeks thereafter for 16 weeks.

A PASI 75 response is a 75% or greater improvement (reduction) from baseline in PASI score. The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Full analysis set; LOCF imputation was used for participants with at least 1 postbaseline value.

A PASI 75 response is a 75% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set which includes all participants who were re-randomized at Week 16 in the study. Only participants with available data at week 32 are included.

A PASI 75 response is a 75% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set which includes all participants who were re-randomized at Week 16 in the study. Only participants with available data at week 50 are included.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Percent improvement from baseline is calculated as (value at baseline - value at post-baseline visit) × 100 / (value at baseline).

This analysis was performed in the re-randomized analysis set with available data

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Percent improvement from baseline is calculated as (value at baseline - value at post-baseline visit) × 100 / (value at baseline).

This analysis was performed in the re-randomized analysis set with available data

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

Full analysis set; LOCF imputation was used for participants with at least 1 postbaseline value.

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

This analysis was performed in the re-randomized analysis set with available data

The sPGA is a 6-point scale ranging from 0 (clear) to 5 (very severe) used to measure the severity of disease (induration, scaling, and erythema). A sPGA response is defined as a sPGA value of clear (score 0) or almost clear (score 1).

This analysis was performed in the re-randomized analysis set with available data.

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from baseline (negative value) indicates improvement.

Full analysis set; LOCF imputation was used for participants with at least 1 postbaseline value.

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from Baseline (negative value) indicates improvement.

This analysis was performed in the re-randomized analysis set with available data

A measurement of psoriasis involvement, given as the physician's assessment of the percentage of the participant's total body surface area (BSA) involved with psoriasis. The percent of BSA affected was estimated by assuming that the subject's palm, excluding the fingers and thumb, represented roughly 1% of the body's surface.

Change from baseline is calculated as (value at post-baseline visit - value at baseline).

A decrease from Baseline (negative value) indicates improvement.

This analysis was performed in the re-randomized analysis set with available data

The Investigator assessed whether each adverse event (AE) was possibly related to the investigational product. AEs were graded for severity according to the Common Toxicity Criteria for Adverse Events (CTCAE) version 4.03.

A serious AE is defined as an AE that meets at least 1 of the following serious criteria:

• fatal
• life threatening
• requires inpatient hospitalization or prolongation of existing hospitalization
• results in persistent or significant disability/incapacity
• congenital anomaly/birth defect
• other medically important serious event. Results are reported from Day 1 to week 16 for the Part 1 ABP 501 and Adalimumab groups, and from post week 16 to the end of study (week 52) for the Part 2 ABP 501/ABP 501, Adalimumab/Adalimumab and Adalimumab/ABP 501 groups.

The safety analysis set includes all randomized participants who received at least 1 dose of study drug, based on actual treatment received.

Two validated assays were used to detect the presence of anti-drug antibodies. Samples were first tested in an electrochemiluminescence (ECL)-based bridging immunoassay to detect anti-drug antibodies (ADA) against ABP 501 and adalimumab (Binding Antibody Assay). Samples confirmed to be positive for binding antibodies were subsequently tested in a non-cell based bioassay to determine neutralizing activity against ABP 501 or adalimumab (Neutralizing Antibody Assay).

Developing antibody incidence is defined as a negative or no antibody result at baseline and a positive antibody result at a post-baseline time point.

Results are reported for the anti-drug antibody analysis set (defined as the subset of participants in the Safety Analysis Set who had at least 1 evaluable antibody test) from Baseline to Week 16 for all randomized participants, and from baseline to Week 52 for participants who were re-randomized.

A PASI 90 response is a 90% or greater improvement (reduction) from baseline in PASI score. The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Full analysis set; LOCF imputation was used for participants with at least 1 postbaseline value.

A PASI 90 response is a 90% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set with available data

A PASI 90 response is a 90% or greater improvement (reduction) from baseline in PASI score.

The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set with available data.

A PASI 100 response is a 100% improvement (reduction) from baseline in PASI score. The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

Full analysis set; LOCF imputation was used for participants with at least 1 postbaseline value.

A PASI 100 response is a 100% improvement (reduction) from baseline in PASI score. The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set with available data

A PASI 100 response is a 100% improvement (reduction) from baseline in PASI score. The PASI measures the average redness (erythema), thickness (induration), and scaliness (each graded on a 0 to 4 scale) of psoriasis lesions, weighted by the area of involvement in the four main body areas (i.e., head and neck, trunk, upper extremities, and lower extremities). PASI scores can range from 0.0 to 72.0, with higher scores indicating greater severity and/or more extensive psoriasis.

This analysis was performed in the re-randomized analysis set with available data.

Participants received 80 mg adalimumab subcutaneously on week 1/day 1 (initial loading dose) and 40 mg at week 2 and every 2 weeks thereafter for 16 weeks.

Participants who received ABP 501 in Part 1 with a PASI 50 response at week 16 continued to receive 40 mg ABP 501 every 2 weeks until week 48.

Participants who received adalimumab in Part 1 with a PASI 50 response at week 16 continued to receive 40 mg adalimumab every 2 weeks until week 48.

Participants who received adalimumab in Part 1 with a PASI 50 response at week 16 were transitioned to receive 40 mg ABP 501 every 2 weeks until week 48.