The study is a Phase II, multicenter, randomized, double-blind study to evaluatethe efficacy and safety of LP-003 administered subcutaneously as an add-on therapy for the treatment of adult patients aged 18-75 who have been diagnosed with refractory CSU and who remain symptomatic despitestandard-dose H1 antihistamine treatment.

Inclusion Criteria:

1. Aged 18 to 75 years at the screening period.
2. Presence of wheals with itching for ≥ 6 weeks prior to randomization. At the screening visit, subjects had taken double or more than the approved dose, or a combination of two or more H1 antihistamines for the treatment of chronic spontaneous urticaria for at least 2 weeks. Within the 7 days preceding randomization, the Urticaria Activity Score 7 (UAS7) was ≥16 (range 0-42), Itch Severity Score 7 (ISS7) was ≥8 (range 0-21), at least one UAS (range 0-6) was ≥4 on any screening visit day, and there must be a current record of medication use.
3. Subjects must not miss more than one diary record (morning or night) within 7 days prior to randomization (day 1), and are willing and able to complete daily symptom electronic diary records during the study period;
4. Male participants and their partners or female participants must agree to take one or more non pharmacological contraceptive measures (such as complete abstinence, contraceptive ring, partner ligation, etc.) during the trial period and within 6 months after the end of the trial and have no plans for sperm or egg donation.
5. Agree to participate in this clinical trial and voluntarily sign an informed consent form.

Exclusion Criteria:

1. The subject has a primary or sole trigger for chronic urticaria (chronic Induced urticaria), including artificial urticaria (symptomatic skin scratch disease), cold, heat, sun, pressure, delayed pressure, water, cholinergic, or contact urticaria;
2. Other medical conditions accompanied by symptoms of urticaria or angioedema including, but not limited to, urticarial vasculitis, pigmented urticaria, erythema multiforme, mastocytosis, hereditary urticaria, or drug-induced urticaria;
3. Any other dermatologic condition with chronic itching, such as atopic dermatitis, herpetic pemphigoid, herpetic dermatitis, senile itching, or psoriasis, which in the judgment of the Investigator may affect the evaluation of the study and the results of the study;
4. Subjects with clinically significant conditions such as (but not limited to) unstable ischemic heart disease, NYHA Class III/IV left ventricular failure, cardiac arrhythmias, uncontrolled hypertension, cerebrovascular disease, neurodegenerative, or other neurological disorders, uncontrolled hypothyroidism and hyperthyroidism and other autoimmune disorders, hypokalemia, hyper adrenergic state; past diagnosis of malignancy (other than basal cell carcinoma or squamous cell skin cancer); history of myocardial infarction within 12 months prior to screening;
5. Acute active infections requiring treatment at screening, including but not limited to, pulmonary infections, tuberculosis;
6. Positive hepatitis B surface antigen or hepatitis B core antibody (except for HBV-DNA testing below the lower limit of the research center's test) at screening; positive hepatitis C virus antibody, human immunodeficiency virus (HIV) antibody, and anti-syphilis helical antibody (TP-Ab) (except for those who are negative for RPR or TRUST);
7. Clinically significant cardiovascular, neurological, psychiatric, metabolic, hepatic, or other abnormalities identified during the Screening Period that may affect the interpretation of the study results and/or the safety of the subject;
8. Comorbid neurological or psychiatric disorders that prevent or prevent cooperation; patients with disabilities as defined by law (blindness, deafness, mute, mental retardation, psychiatric disorders, etc.);
9. Major surgery within 8 weeks prior to screening or surgery planned during the study period;
10. Evidence of historical or ongoing alcohol or substance abuse in the 6 months prior to screening;
11. Poor compliance, such as low medication adherence, inability to accurately complete a diary card, or use of prohibited medications;
12. Pregnant women, nursing mothers, or those with recent birth plans;
13. Patients who have participated in clinical trials of other drugs within the last 3 months;
14. Those who are considered by the investigator to be unfit to participate in the clinical trial.