A Phase 2 Study of Efficacy and Safety of AK111 in Subjects With Moderate-to-Severe Psoriasis

This is a randomized, double-blind, placebo-controlled, multi-center Phase II clinical study to evaluate the efficacy and safety of AK111 in subjects with moderate to severe plaque psoriasis. The study will consist of 4 periods: up to 4 weeks screening period, 12 weeks placebo-controlled period,12 weeks crossover treatment period,44 weeks long-term treatment period.

Key Inclusion Criteria:

• Male or female, 18 to 75 years of age
• Moderate to severe plaque-type psoriasis diagnosed for at least 6 months
• Moderate-to-severe plaque psoriasis as defined at baseline by meeting all three criteria:

• Clinical diagnosis of stable plaque psoriasis with involvement of ≥ 10% body surface area.
• Psoriasis area and severity index(PASI) ≥12.
• Static Physicians Global Assessment score ≥3.
• Subjects with a history of an inadequate response, intolerable or medically inappropriate use of systemic therapy and/or phototherapy.
• Subjects who are women of childbearing potential must have a negative urine pregnancy test at screening and must be practicing an adequate, medically acceptable method of birth control for at least 8 months after the last study drug administration.

Key Exclusion Criteria:

• Forms of psoriasis other than chronic plaque-type psoriasis.
• History or evidence of active TB, Patients with evidence of latent tuberculosis may enter the trial after sufficient treatment according to protocol.
• Positive results of confirmatory serology test for hepatitis B, hepatitis C, HIV or syphilis at screening.
• History of a serious or systemic infection within 2 months before screening.
• History of malignancy of any organ system within the past 5 years.
• Inadequate washout period for prior drug therapy.
• Previous use of secukinumab, ixekizumab or any other drug that targets IL-17 or IL-17 receptor.
• Any medical conditions, in the opinion of the Investigator or the Sponsor's medical monitor, would place the subject at risk, interfere with study participation or study results interpretation.