Subjects will receive secukinumab at pre-specified time-points.

Subjects will receive placebo at pre-specified time-points to maintain the blinding in the double-blind Treatment Period.

The PASI90 response assessments are based on at least 90% improvement in PASI score from Baseline. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for redness, thickness, and scaling for each of the 4 body areas with 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 respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

The PASI100 response assessments are based on 100% improvement in PASI score from Baseline. 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 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 IGA measures the overall psoriasis severity following a 5-point scale (0-4), where scale 0= clear, no signs of psoriasis; presence of post-inflammatory hyperpigmentation, scale 1= almost clear, no thickening; normal to pink coloration; no to minimal focal scaling, scale 2= mild thickening, pink to light red coloration and predominately fine scaling, 3= moderate, clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling and 4= severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. IGA response was defined as Clear (0) or Almost Clear (1) with at least a two-category improvement from Baseline at Week 16.

The number of TEAEs adjusted by duration of exposure to study treatment was scaled such that provided an incidence rate per 100 patient-years. If a participant had multiple events, the time of exposure was calculated to the first occurrence of the AE being considered. If a participant had no events, the total time at risk was used.

The number of SAEs adjusted by duration of exposure to study treatment was scaled such that it provided an incidence rate per 100 patient-years. If a participant had multiple events, the time of exposure was calculated to the first occurrence of the AE being considered. If a participant had no events, the total time at risk was used.

The number of TEAEs leading to discontinuation adjusted by duration of exposure to study treatment was scaled such that it provided an incidence rate per 100 patient-years. If a participant had multiple events, the time of exposure was calculated to the first occurrence of the AE being considered. If a participant had no events, the total time at risk was used.

Participants randomized to this arm received BKZ 320 mg sc Q4W for 16 weeks in the Initial Treatment Period. At Week 16, participants were re-randomized to receive BKZ 320 mg sc Q8W until Week 48 in the Maintenance Treatment Period (MTP). Placebo was administered at pre-specified time-points to maintain the blinding.

Participants randomized to this arm received BKZ 320 mg sc Q4W for 16 weeks in the Initial Treatment Period. At Week 16, participants continued to receive BKZ 320 mg sc every 4 Weeks (Q4W/Q4W) until Week 48 in the Maintenance Treatment Period.

Participants in secukinumab arm continued to receive secukinumab 300 mg sc Q4W until Week 48 in the Maintenance Treatment Period.

Participants randomized to this arm received BKZ 320 mg sc Q4W for the first 16 weeks and then re-randomized to receive BKZ 320 mg sc Q4W or Q8W until Week 48 of the double-blind Treatment Period. Based on the PASI90 response and the dose the participant was receiving at Week 48, participants were randomized to receive BKZ 320 mg sc Q8W until Week 136 in the Open-Label Extension (OLE) Period.

Participants randomized to this arm received BKZ 320 mg sc Q4W for the first 16 weeks and then re-randomized to receive BKZ 320 mg sc Q4W or Q8W until Week 48 of the double-blind Treatment Period. Based on the PASI90 response and the dose the participant was receiving at Week 48, participants were randomized to receive BKZ 320 mg sc Q4W starting in OLE Period. The participant's dosing interval was changed from BKZ 320mg Q4W to BKZ 320mg Q8W at Week 64, or at the next scheduled clinic visit if the participant has already completed the Week 64 after protocol amendment 5.

Participants randomized to this arm received Secukinumab 300 mg sc Q4W until Week 48 of the double-blind Treatment Period. Based on the PASI90 response in double-blind Treatment Period, participants randomized to receive BKZ 320 mg sc Q8W until Week 136 of the OLE Period.

Participants randomized to this arm received Secukinumab 300 mg sc Q4W until Week 48 of the double-blind Treatment Period. Based on the PASI90 response in double-blind Treatment Period, participants randomized to receive BKZ 320 mg sc Q4W starting in OLE Period. The participant's dosing interval was changed from BKZ 320mg Q4W to BKZ 320mg Q8W at Week 64, or at the next scheduled clinic visit if the participant has already completed the Week 64 after protocol amendment 5.

Participants who were still receiving treatment in the OLE Period and attended the Week 144 visit were directly rolled over to the OLE2 Period. In OLE2 Period, participants continued receiving BKZ 320 mg sc Q8W for 40 additional weeks until OLE2 Week 48.

Participants who completed the Week 144 and were participating in the Safety Follow-Up (SFU) or had completed the SFU visit reinitiated their treatment in the OLE2 Period after having undergone Screening assessments during a 4-week OLE2 Screening Period. Participants with an IGA score less than (<) 3 at the Week 144/OLE2 Baseline Visit continued receiving BKZ 320 mg sc Q8W for 40 additional weeks until OLE2 Week 48 in OLE2 Period.

Participants who completed the Week 144 visit and were participating in the SFU or had completed the SFU visit reinitiated their treatment in the OLE2 Period after having undergone Screening assessments during a 4-week OLE2 Screening Period. Participants with an IGA score greater than or equal to (>=) 3 at the Week 144/OLE2 Baseline Visit received BKZ 320 mg sc Q4W for the first 16 weeks, and then switched to BKZ 320 mg sc Q8W for 24 weeks until OLE2 Week 48 in OLE2 Period.