Inclusion Criteria:
1. Participant must be able and willing to comply with the clinical trial protocol requirements and must sign and date the informed consent form(s) as approved by the IEC/IRB prior to any screening evaluation and, if applicable, prior to participating in the optional skin biopsy subtrial.
2. Diagnosed with plaque psoriasis, with stable psoriatic arthritis or without psoriatic arthritis, ≥6 months prior to screening.
3. Participant has had stable plaque psoriasis ≥3 months before screening
4. Screening and baseline PASI score ≥12 (moderate to severe) with affected BSA ≥10% and sPGA score ≥3.
5. Candidate for phototherapy or systemic treatment for plaque psoriasis.
6. Participant must have a Body Mass Index of ≥18 and ≤39 kg/m\^2.
7. Participant must be able and willing to comply with restrictions on prior and concomitant medication.
8. Participant must be able and willing to adhere to the lifestyle restrictions as described in the protocol.
9. Participant with plaque psoriasis, that according to the investigator's judgement is not adequately controlled with his/her current therapy.
10. Participant must be otherwise stable on the basis of medical history, physical examination, vital signs, and 12-lead Electrocardiogram (ECG) performed at screening.
Exclusion Criteria:
1. Candidate has non-plaque form of psoriasis (e.g. erythrodermic, guttate, or pustular psoriasis).
2. Candidate has current drug-induced psoriasis (e.g. a new onset of psoriasis or an exacerbation of psoriasis from beta blockers, calcium channel blockers, or lithium).
3. Participant has a positive result for hepatitis B virus (HBV) (positive for hepatitis B surface antigen \[HBsAg\] or detectable hepatitis B virus core antibody (HBcAb\]; participants having a negative HBsAg and a positive HBcAb result may enroll if they have a positive hepatitis B virus surface antibody \[HBsAb\] demonstrating natural immunity), or for hepatitis C virus (HCV) (positive for HCV antibody \[Ab\] and positive confirmatory polymerase chain reaction test for HCV; however, a participant with documented proof of cure from HCV may be enrolled).
4. Participant has a history of human immunodeficiency virus (HIV) Ab positivity, or tests positive for HIV at screening.
5. Participant has a history of or current immunosuppressive condition.
6. Participant meets 1 of the following tuberculosis (TB) criteria at screening:
1. A history of active or currently active TB (regardless of treatment).
2. A positive QuantiFERON®-TB Gold Plus In-tube test at screening unless the investigator assesses this is due to a documented history of adequately treated latent TB infection (LTBI).
7. Participant has evidence of skin conditions other than psoriasis (e.g. eczema) at the time of screening or baseline visit that would interfere with the evaluation of psoriasis, per investigator judgement.
8. Participant has a history or presence of clinically significant abnormalities detected on 12-lead ECG at screening or either rhythm or conduction, e.g. known long QT syndrome, or a QT interval corrected for heart rate using Fridericia's formula (QTcF) \>450 ms for male participants or \>470 ms for female participants detected on the 12-lead ECG.
9. Participant has a history of malignancy within the past 5 years prior to screening with the exception of excised and curatively treated non-metastatic basal cell carcinoma or squamous cell carcinoma of the skin or in situ uterine cervical carcinoma which is considered cured with minimal risk of recurrence.
10. Participant had a major surgery within 8 weeks prior to the first dose or has a major surgery planned during the trial.
