To determine whether secukinumab can alter the activity of cytochrome P450 (CYP) 3A4 using midazolam as probe substrate in patients with moderate-to-severe plaque psoriasis.

This will be an open-label, confirmatory study investigating potential disease-drug-drug interaction of secukinumab and midazolam in male and female patients with moderate-to-severe plaque psoriasis. A total of approximately 25 patients are required to obtain at least 20 completers in the study Patients who meet the eligibility criteria at screening, will have a baseline assessment day (within 1 week prior to the start of secukinumab) during which a full midazolam PK profile after a single oral dose of 5 mg will be assessed by collecting blood over the 12 hour postdose period.

On Day 1 (Week 0), Day 8 (Week 1), Day 15 (Week 2), Day 22 (Week 3) and Day 29 (Week 4) patients will receive 300 mg s.c. secukinumab (2 injections of 150 mg s.c.). On Day 8 and on Day 36 (Week 5), patients will receive additional single doses of 5 mg oral midazolam (total of 3 single doses). The midazolam PK profile will be assessed over the 12 hour postdose period.

On those days when midazolam PK profiles are assessed, samples will be collected and analyzed for circulating IL-6, inflammatory panel (collected at screening, baseline and pre-dose Day 1 only), total IL-17A (after following initiation of secukinumab treatment), hsCRP and for 4-beta-hydroxycholesterol (exploratory endogenous phenotyping marker of CYP3A activity).

There will be an extended treatment period during which patients will receive secukinumab 300 mg s.c. at Weeks 8, 12, 16, 20 and 24.

Then there will be a follow-up period of 12 weeks following the last dose administered at Week 24. Visits will be at Weeks 28, 32 and 36.

Inclusion Criteria:

• Moderate to severe plaque psoriasis as defined at baseline by: PASI score of 12 or greater and IGA mod 2011 score of 3 or greater (based on a scale of 0 - 4) and Body Surface Area (BSA) affected by plaque-type psoriasis of 10% or greater.
• Chronic plaque-type psoriasis considered inadequately controlled by: topical treatment and/or; phototherapy and/or previous systemic therapy
• Men or women at least 18 years of age or older at time of screening.

Exclusion Criteria:

• Forms of psoriasis other than chronic plaque-type
• Pregnant or nursing (lactating) women,
• History of an ongoing, chronic or recurrent infectious disease, or evidence of tuberculosis infection.
• Subjects with known history of hypersensitivity to midazolam