A Study to Evaluate ABY-035 in Subjects With Moderate-to-severe Plaque Psoriasis

This randomized, double-blinded dose-finding study evaluates four dose levels of ABY-035, in comparison to placebo, in subjects with moderate to severe plaque psoriasis.

The study consists of 52-week Core study and two optional 52-week periods, Extension and Prolongation of Extension.

The Core study consists of three periods: Induction (placebo-controlled, Week 0-12), Optimization (Week 12-24), and Individualization (Week 24-52).

The Core study evaluates four doses of ABY-035, in comparison to placebo, in subjects with moderate to severe plaque psoriasis. The treatment periods in the Core study are:

* Induction (Week 0-12) - four dose levels and placebo (Q2W)
* Optimization (Week 12-24) - starting with a possible dose adjustment (all subjects on Q2W) depending on PASI score. Subjects on placebo switch to active drug (Q4W).
* Individualization (Week 24-52) - starting with a switch to Q4W for all subjects. From week 32 dosing interval alters depending on PASI score.

The study is unblinded after completion of the Core study. During the optional Extension and Prolongation of Extension periods, dose levels and intervals alter depending on PASI score.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosed with plaque psoriasis of at least 6 months prior to Screening, without clinically significant flares during the 12 weeks before randomization, with or without psoriatic arthritis
* Having precedent failure, intolerance and/or contraindication to at least two standard therapies for moderate to-severe plaque psoriasis (systemic therapy and/or phototherapy), and previousinsufficient disease control of topical therapy (e.g. corticosteroids, vitamin D derivatives, cignolin/dithranol).
* Moderate-to-severe plaque psoriasis at Screening and at Baseline as defined by:

  i. Psoriasis involving ≥10% BSA ii. PASI score of ≥ 12 iii. sPGA score of ≥ 3
* Use of highly effective method of contraception or female of non-childbearing potential

Exclusion Criteria:

* Current forms of psoriasis other than chronic plaque-type
* Current drug induced psoriasis
* History of hypersensitivity or allergy to the IMP or its excipients
* History of recurrent or medically important infections requiring intervention and/or systemic treatment in the last 12 months, including infections with e.g. candida and Staphylococcus aureus
* History of or any signs of lymphoproliferative disease, or a known malignancy or a history of malignancy within the previous 5 years (with the exception of basal cell or squamous cell carcinoma of the skin that had been fully excised with no evidence of recurrence)
* Autoimmune disease of relevance
* Inflammatory Bowel Disease requiring treatment within the past 12 months
* Clinically significant heart condition which is not well controlled by current therapy, as assessed by the Investigator
* Significantly immunocompromised subject
* Blood pressure out of range
* Laboratory values out of range, including ALT, AST, eGFR
* Positive to HIV, hepatitis B, hepatitis C or tuberculosis
* Recent previous psoriasis treatments, within defined wash-out periods
* Prior exposure to systemic psoriasis treatments with anti-IL-17 biological therapies
* Live vaccination within defined time restrictions
* Inability or unwillingness to limit ultraviolet (UV) light exposure during the course of the study
* Pregnancy, breast feeding
* Drug and/or alcohol abuse or dependence