Multi-Dose Study of SHR-1314 in Subjects With Moderate-to-severe Plaque Psoriasis

Major Inclusion Criteria: 1. Provide written informed consent before any study assessment is performed. 2. Male or female at least 18 years of age at screening. 3. At the time of randomization, moderate to severe plaque psoriasis, defined by: * PASI score of 12 or greater and * PGA score of 3 or greater and * BSA affected by plaque-type psoriasis of 10% or greater. 4. Subject is a candidate for systemic psoriasis therapy and/or phototherapy and/or chemo phototherapy. Major Exclusion Criteria: 1. Forms of psoriasis other than chronic plaque-type (e.g., pustular, erythrodermic, and guttate psoriasis) at screening. 2. Drug-induced psoriasis (i.e. new onset or current exacerbation from beta-blockers, calcium channel inhibitors or lithium) at randomization. 3. Active systemic infections (other than common cold) during the two weeks before randomization (e.g., hepatitis), or serious infections requiring hospitalization and/or intravenous injection of antibiotic treatment within eight weeks from randomization. 4. Presence of other skin conditions (e.g. skin infections, seborrheic dermatitis) that in the judgement of the Investigator could interfere with assessment of psoriasis. 5. History of inflammatory bowel disease or have other ongoing active autoimmune diseases. 6. At screening, history or symptoms of malignancy of any organ system, treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases. 7. History of depression and/or suicidal ideation or behavior which in the opinion of the Investigator, makes the subject unsuitable for clinical study participation. 8. Any severe, progressive or uncontrolled medical condition at randomization that in the judgement of the Investigator prevents the subject from participating in the study. 9. Have a known allergy or hypersensitivity to any biologic therapy at screening that would pose an unacceptable risk to the subject if participating in this study. 10. Concurrent or recent use of psoriasis treatments/ medications. 11. Are currently enrolled in, or discontinued from a clinical trial involving an Investigational product (IP) within the last 4 weeks or at least 5 half-lives of the last dosing prior to randomization, whichever is longer; or concurrently enrolled (at randomization) in any other trials. 12. Have had a live attenuated vaccination within 12 weeks before randomization, or intend to have a live attenuated vaccination during the course of the study, or have participated in a vaccine clinical trial within 12 weeks prior to randomization. 13. Have evidence of positive test for hepatitis B, hepatitis C antibody, or human immunodeficiency virus (HIV) antibodies. A positive test for hepatitis B is defined as 1) positive for hepatitis B surface antigen \[HBsAg\], or 2) positive for anti-hepatitis B core antibody \[HBcAb+\] but negative for hepatitis B surface antibody \[HBsAb-\]. 14. History or evidence of active or latent tuberculosis at screening. 15. Have laboratory test values that are considered clinically significant at screening that, in the opinion of the Investigator, pose an unacceptable risk to the subject if participating in the study or of interfering with the interpretation of data. 16. Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive human chorionic gonadotropin laboratory test at screening or Day 0. 17. Females of child bearing potential (defined as all females physiologically capable of becoming pregnant) and males who are unwilling or unable to use highly effective contraception during the study and 20 weeks after the last administration of investigational product (anticipated 5 half-lives). 18. History of alcohol or illicit drug abuse within the year prior to screening. 19. Are unwilling or unable to maintain their normal pattern of alcohol, caffeine, smoking, and exercise from the start to the end of the study. 20. Have any other condition that precludes the subject from following and completing the protocol, in the opinion of the Investigator.