Placebo subcutaneous (sc) injection every two weeks (Q2W).

The treatment received from Week 16 to Week 48 is based on initial treatment and response to treatment at Week 16:

• Subjects with a PASI75 response at Week 16 continue to receive blinded Placebo.
• Subjects who do not achieve a PASI75 response at Week 16 will be removed from blinded study medication and escape to CZP 400 mg Q2W. Subjects who receive unblinded CZP 400 mg Q2W for 16 weeks and do not achieve a PASI50 response will be withdrawn from the study.

Subjects can enter a 96-week open-label extension period after completing the Maintenance Period and receive CZP under certain conditions.

• Active Substance: Etanercept
• Pharmaceutical Form: Solution for injection in pre-filled syringe
• Concentration: 50 mg / mL
• Route of Administration: Subcutaneous use

• Active Substance: Placebo
• Pharmaceutical Form: Solution for injection in pre-filled syringe
• Concentration: 0.9 % saline
• Route of Administration: Subcutaneous use

The PASI75 response assessments are based on at least 75% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

The Investigator assessed the overall severity of Psoriasis (PSO) using the following 5-point scale: 0=clear, 1=almost clear, 2=mild, 3=moderate, 4=severe.

The PASI90 response assessments are based on at least 90% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

The PASI75 response assessments are based on at least 75% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

Etanercept (ETN) 50 mg subcutaneous (sc) injections twice per week throughout Week 11.5.

•PASI75 responders at Week 16 were re-randomized to either CZP (loading dose of 400 mg at Weeks 16, 18, and 20 followed by 200 mg Q2W) or Placebo Q2W. Participants who did not achieve a PASI75 response at Week 16 escaped to CZP 400 mg Q2W.

Participants who received unblinded CZP 400 mg Q2W for 16 weeks and did not achieve a PASI50 response were withdrawn from the study. Participants could enter a 96-week open-label extension period after completing the Maintenance Period and receive CZP under certain conditions.

CZP 400 mg injections at Weeks 0, 2, 4, followed by CZP 200 mg every 2 weeks (Q2W) from Week 6 to Week 14. Treatment received from Week 16-48 is based on initial treatment and response to treatment:

•PASI75 responders at Week 16 were re-randomized to receive either CZP 200 mg Q2W or CZP 400 mg every 4 weeks (Q4W); with Placebo administered on alternate dosing weeks to maintain the blind) Or Placebo Q2W. Participants who did not achieve a PASI75 response at Week 16 were removed from blinded study medication and escaped to CZP 400 mg Q2W.

Participants who received unblinded CZP 400 mg Q2W for 16 weeks and did not achieve a PASI50 response were withdrawn from the study. Participants could enter a 96-week open-label extension period after completing the Maintenance Period and receive CZP under certain conditions.

CZP 400 mg injections every 2 weeks (Q2W) through Week 14. Treatment received from Week 16-48 is based on initial treatment and response to treatment:

•PASI75 responders at Week 16 were re-randomized to CZP 200 mg Q2W or CZP 400 mg Q2W or Placebo Q2W. Participants who did not achieve a PASI75 response at Week 16 were removed from blinded study medication and escaped to CZP 400 mg Q2W.

Participants who received unblinded CZP 400 mg Q2W for 16 weeks and did not achieve a PASI50 response were withdrawn from the study. Participants could enter a 96-week open-label extension period after completing the Maintenance Period and receive CZP under certain conditions.

This arm consisted of participants initially randomized in the Placebo arm, who achieved a PASI75 response at Week 16 and continued to receive blinded Placebo in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the Etanercept arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded Placebo in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the Etanercept arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded CZP 200 mg Q2W in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 200 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded Placebo in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 200 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded CZP 200 mg Q2W in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 200 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded CZP 400 mg Q4W in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 400 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded Placebo in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 400 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded CZP 200 mg Q2W in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the CZP 400 mg arm, who achieved a PASI75 response at Week 16 and were re-randomized to receive blinded CZP 400 mg Q2W in the Maintenance Period (Week 16 to Week 48).

This arm consisted of participants initially randomized in the Placebo arm, who did not achieve a PASI75 response at Week 16 escaped from the blinded treatment and received CZP 400 mg every two weeks. Participants who did not achieve PASI50 after 16 weeks of unblinded treatment were withdrawn from the study.

This arm consisted of participants initially randomized in the Etanercept arm, who did not achieve a PASI75 response at Week 16 escaped from the treatment and received CZP 400 mg every two weeks. Participants who did not achieve PASI50 after 16 weeks of unblinded treatment were withdrawn from the study.

This arm consisted of participants initially randomized in the CZP 200 mg arm, who did not achieve a PASI75 response at Week 16 escaped from the blinded treatment and received CZP 400 mg every two weeks. Participants who did not achieve PASI50 after 16 weeks of unblinded treatment were withdrawn from the study.

This arm consisted of participants initially randomized in the CZP 400 mg arm, who did not achieve a PASI75 response at Week 16 escaped from the blinded treatment and received CZP 400 mg every two weeks. Participants who did not achieve PASI50 after 16 weeks of unblinded treatment were withdrawn from the study.

This arm consisted of participants from the Placebo-controlled Maintenance Period, who achieved PASI50 response (had no relapse) at Week 48 and entered the 96-Weeks OLE Period receiving CZP 200 mg Q2W.

This arm consisted of participants who received CZP 200 mg Q2W in the Maintenance Period, who achieved a PASI50 response (had no relapse) at Week 48 and entered OLE.

This arm consisted of participants who received CZP 400 mg Q4W in the Maintenance Period, who achieved a PASI50 response (had no relapse) at Week 48 and entered OLE on the CZP 200mg Q2W dose.

This arm consisted of participants who received CZP 400 mg Q2W in the Maintenance Period, who achieved a PASI50 response (had no relapse) at Week 48 and entered OLE on the CZP 200mg Q2W dose.

This arm consisted of participants who received open-label CZP 400mg Q2W in the Maintenance Period and entered OLE.

This arm consisted of participants from the Placebo-controlled Maintenance Period, who did not achieve PASI50 response (had relapse) and entered the 96-weeks OLE Period receiving CZP 400 mg Q2W.

This arm consisted of participants who relapsed on CZP 200 mg Q2W, CZP 400 mg Q4W and 400 mg Q2W.