This trial was designed to evaluate the efficacy and safety of SHR-1819 injection in patients with Prurigo Nodularis.

Inclusion Criteria:

1. Subjects voluntarily sign informed consent forms prior to the commencement of any proceedings related to the study, are able to communicate smoothly with the investigator, understand and are willing to complete the study in strict compliance with the requirements of this clinical research protocol.
2. The age was ≥18 at the time of signing the informed consent and gender is unlimited.
3. Has prurigo nodularis at screening.

Exclusion Criteria:

1. Pregnant or lactating women.
2. Screening for people with a history of heavy alcohol consumption or substance abuse in the 6 months prior to screening.
3. Has an active skin disease or skin complications due to other diseases that may affect the evaluation of PN.
4. PN secondary to medical conditions such as neurological or psychiatric disorders.
5. Diagnosis of moderate to severe AD during the screening/lead-in period or prior to randomization.
6. History of clinically significant diseases (e.g., circulatory system abnormalities, endocrine system abnormalities, neurological disorders, hematologic disorders, immune system disorders, psychiatric disorders, and metabolic instability) that the researcher believes that participation in the study poses a risk to the safety of the subject or that the disease/illness worsens during the study period will affect the effectiveness or safety analysis.
7. Phase II: Treated with biologics targeting IL-4Rα, or participated in previous clinical studies of biologics targeting IL-4Rα, including SHR-1819 injection. Phase III: Subjects who have previously received anti-IL-4Rα biologics for any indication including atopic dermatitis (AD), asthma, sinusitis, etc., and were judged by the investigator to have an inadequate response or intolerance (e.g., experienced drug-related adverse reactions requiring treatment discontinuation) must be excluded even if the washout requirement is met.
8. Subjects with malignancy prior to screening (except for squamous cell carcinoma of the skin, basal cell carcinoma, or carcinoma in situ of the cervix that are completely resected and have no evidence of recurrence).
9. Major surgeries are planned for the duration of the study.
10. Other conditions that, in the opinion of the investigator, are not suitable for participation in this study.