HPP737 in Adult Patients With Plaque Psoriasis

Inclusion Criteria: * Subjects must voluntarily sign the informed consent form prior to the initiation of any trial-related procedures, be able to communicate effectively with the investigators, and understand and comply with the requirements of this trial; * Age at the time of signing the informed consent form: age ≥18 years, regardless of sex; * Clinically diagnosed patients with stable plaque psoriasis (Zhendingxing Banquzhuang Yinxie Bing), with a psoriasis history of ≥6 months before randomization; * Diagnosed with moderate to severe plaque psoriasis and meeting the following criteria at screening: 1) PASI (Psoriasis Area and Severity Index), score ≥10; and sPGA (Static Physician's Global Assessment) score ≥3; and BSA (Body Surface Area) score ≥10% * Body Mass Index (BMI): 18 kg/m2 ≤ BMI ≤ 35 kg/m2. Exclusion Criteria: * Presence of other forms of psoriasis (e.g., guttate psoriasis, pustular psoriasis, erythrodermic psoriasis) diagnosed at screening, in addition to chronic plaque psoriasis; * Patients with drug-induced psoriasis (including but not limited to newly onset or exacerbated psoriasis caused by β-blockers \[beta-receptor blockers\], calcium channel blockers, or lithium preparations) * Subjects with other skin diseases that may interfere with clinical assessment (such as severe bacterial, fungal, or viral skin infections), chronic diarrhea, severe gastrointestinal diseases (such as active peptic ulcer, gastrointestinal tract disorders, etc.), or a history of inflammatory bowel disease (Crohn's disease, ulcerative colitis, etc.), or other active autoimmune inflammatory diseases (mixed connective tissue disease, idiopathic inflammatory myopathy, etc.); * History of congenital or acquired immunodeficiency; * Severe infection or systemic infection within 4 weeks prior to randomization, requiring oral and/or intravenous anti-infective therapy; or hospitalization due to infection; * Medical history, symptoms, and examination results during screening indicating that the subject has active tuberculosis (TB); Note: Subjects with a negative T-cell test for Mycobacterium tuberculosis infection (T-SPOT test) during the screening period are eligible for inclusion in this study. Subjects with a positive T-SPOT result during the screening period are required to undergo TB-related clinical evaluation (TB-related clinical evaluations conducted within 12 weeks prior to randomization may be directly utilized for assessment). If the TB-related clinical evaluation confirms active tuberculosis, the subject shall not be enrolled in this study; if the evaluation confirms non-active tuberculosis, the subject may be included. If the study center is unable to perform the T-SPOT test, an interferon-gamma release assay (IGRA) may also be used for TB screening, and the handling of IGRA results should follow the same procedures as for the T-SPOT test. * History of moderate to severe heart failure (New York Heart Association \[NYHA\] functional classification ≥ Class III), or occurrence of cardiovascular or cerebrovascular events or other serious events within 3 months prior to randomization, as judged by the investigator to be unsuitable for participation in this clinical trial; * History of malignancy in any organ system within 5 years prior to randomization, except for malignancies with low risk of metastasis and death, such as adequately treated carcinoma in situ, basal cell carcinoma, or squamous cell carcinoma of the skin, etc.; * History of depression and/or suicidal ideation or any suicidal behavior at screening or baseline based on Columbia-Suicide Severity Rating Scale (C-SSRS) assessment (Appendix 6). If the subject answers "Yes" to any question on the C-SSRS questionnaire, or if the investigator assesses clinical risk, these subjects will be excluded; * Presence of clinically severe, progressive, or uncontrolled diseases during the screening period, including but not limited to the respiratory system, cardiovascular system, endocrine system, hematological system, skeletal system, and nervous system, where participation in the trial may pose unacceptable risk to the subject or interfere with interpretation of data, as assessed by the investigator; * Use of the following psoriasis (Yinxie Bing) treatments/medications prior to randomization: 1) Within 2 weeks prior to randomization, the subject has received topical treatment for psoriasis, such as glucocorticoids, vitamin D3 derivatives, or retinoids. However, subjects are permitted to use the following topical treatments: non-medicated shampoos and emollients (i.e., those not containing glucocorticoids or vitamin D3 derivatives). Within 4 weeks prior to randomization, the subject has received phototherapy/photochemotherapy (including but not limited to psoralen and ultraviolet A (PUVA) phototherapy, ultraviolet B (UVB)) or non-biologic systemic therapies (including but not limited to systemic glucocorticoids, leflunomide, cyclophosphamide, azathioprine, methotrexate, cyclosporin, retinoids, mycophenolate mofetil, traditional Chinese medicines for the treatment of psoriasis, or other small-molecule targeted agents for the treatment of psoriasis). Tumor necrosis factor-α (TNF-α) antagonists: (1) Use of a TNF-α antagonist (e.g., adalimumab, infliximab, golimumab, etanercept, certolizumab pegol) within a specified period prior to randomization (such as within 12 weeks before randomization); (2) or history of prior use of two or more TNF-α antagonists before randomization; 4) Within 24 weeks prior to randomization, the subject has used other biologic agents, including but not limited to IL-17 inhibitors, IL-23 inhibitors, or IL-12/IL-23 inhibitor class drugs. * Receipt of a live attenuated vaccine within 12 weeks prior to randomization, or planned receipt of a live attenuated vaccine during the trial period; * Subjects who previously had poor efficacy with other PDE4 (phosphodiesterase-4) inhibitors (such as apremilast, Hemay005, etc.) * Participation in and receipt of any interventional clinical trial treatment within 1 month prior to randomization;