This is a phase II, randomised, double-blind, placebo-controlled, multiple-dose, multi-center study of AbGn-168H in subjects with moderate to severe chronic plaque psoriasis. The objectives of this study is to investigate efficacy, safety, tolerability, and pharmacokinetics (PK) of multiple doses of AbGn-168H administered intravenously to patients with moderate to severe chronic plaque psoriasis.

Inclusion Criteria:

1. Age 18 to 75 (inclusive), males or females
2. Body weight < 140 kg
3. Patients with stable moderate to severe plaque-type psoriasis, no significant changes within the past 6 months, involving ≥ 10% body surface area, with disease severity PASI ≥ 10 at screening visit and visit 2.
4. Psoriasis disease duration of at least 6 months prior to screening
5. Patients must be candidates for systemic psoriasis treatment or phototherapy
6. Patient must give informed consent and sign an approved consent form prior to any study procedures
7. Females of childbearing potential must have a negative pregnancy test result prior to enrollment and agree to use a highly effective method of birth control during the study. A highly effective method of birth control is defined as one which results in a low failure rate (less than 1% per year).

Exclusion Criteria:

1. Patients with primary guttatae, erythrodermic, or pustular psoriasis and patients with drug-induced psoriasis

2. Evidence of current or previous clinically significant disease, medical condition other than psoriasis, or finding of the medical examination (including vital signs and ECG), that in the opinion of the Investigator, would compromise the safety of the patient or the quality of the data. This criterion provides an opportunity for the investigator to exclude patients based on clinical judgment, even if other eligibility criteria are satisfied. (Psoriatic arthritis is not considered an exclusion)

3. HIV infection or a known HIV-related Malignancy.

4. Chronic or acute hepatitis B and C, or carrier status. Patient with anti-HBc Ab and undetectable anti-HBs Ab should also be excluded.

5. Tuberculosis or a positive Tuberculin Skin Test (TST) for tuberculosis. Subjects previously received BCG vaccination or cannot receive TST can participate in the study after showing negative responses in Interferon-Gamma Release Assays (IGRA).

6. History of malignancy in the past 5 years or suspicion of active malignant disease except treated cutaneous squamous cell or basal cell carcinoma and carcinoma in situ of the cervix uteri.

7. History of allergy/hypersensitivity to a systemically administered biologic agent or its excipients

8. Use of biologic agents or investigational drug within 8-12 weeks prior to treatment, systemic anti-psoriatic medications or phototherapy within 4 weeks prior to treatment, or topical anti-psoriasis medications (except emollients) within 2 weeks prior to treatment

9. Intake of restricted medications or other drugs considered likely to interfere with the safe conduct of the study

10. Current alcohol abuse

11. Current drug abuse or positive drug screen at screening visit. Subjects with legitimate medically supervised uses of the drugs which are not excluded for other reasons can be enrolled.

12. Any blood donation or significant blood loss within 4 weeks prior to Visit 2

13. Excessive (e.g. competitive) physical activities (within 1 week prior to administration or during the trial)

14. Patients with any of the following laboratory values at screening and are considered clinically significant by the investigators:

    • Haemoglobin, hematocrit, white blood cell count, absolute lymphocyte or neutrophil count, or platelet count < LLN (below the lower limit of the reference normal range)
    • ALT, AST and/or total bilirubin > 2.5xULN
    • Serum creatinine > 1.5x ULN

15. Any clinically significant laboratory abnormalities other than those listed on Exclusion Criteria 14, based on the investigator's medical assessment at screening