Inclusion Criteria:
* Age 18 and above, male or female;
* Conform to the diagnostic criteria of persistent or chronic immune thrombocytopenia (ITP);
* Failure of previous glucocorticoid therapy;
* In the second-line treatment phase, eligible subjects must meet any of the following criteria: (1) Demonstrate no response to treatment with at least one thrombopoietin receptor agonist (including but not limited to recombinant human thrombopoietin \[rhTPO\], eltrombopag, hetrombopag, avatrombopag, or romiplostim); Fail to achieve sustained response (manifested as non-response, loss of response, or disease relapse) following anti-CD20 monoclonal antibody therapy (e.g., rituximab) or anti-CD38 monoclonal antibody therapy; (2) Exhibit no therapeutic response or experience disease relapse after splenectomy.
* The platelet count was \<30×109/L within 48 hours before the first administration;
* ECOG physical state score ≤ 2 points;
* Patients receiving maintenance treatment (including corticosteroids (less than or equal to 20mg prednisone), TPO receptor agonists, etc.) must have a stable dose at least 4 weeks before the first administration;
* Signed and dated written informed consent;
Exclusion Criteria:
* Received any treatment of anti-BCMA antibody drug;
* Accompanied by autoimmune hemolytic anemia, or various secondary and hereditary thrombocytopenia;
* History of any thrombotic or embolic events in the 12 months prior to the first dose or accompanied by extensive and severe bleeding, such as hemoptysis, upper gastrointestinal hemorrhage, intracranial hemorrhage, etc;
* Participated in any other study drug or exposure to other study drugs within 4 weeks or 5 half-lives before the first dose (whichever is longer);
* Use of anticoagulants or any drug with antiplatelet effects (such as aspirin) within 3 weeks before the first dose;
* Treatment with ITP (methylprednisolone, platelet, gamma-globulin infusion or TPO receptor agonist therapy) within 2 weeks before the first dose;
* Splenectomy was performed within 6 months before the first dose;
* Patients who received azathioprine, danazol, cyclosporine A, tacrolimus, sirolimus, etc., within 4 weeks prior to the first dose; or received treatments such as CD20 monoclonal antibodies (e.g., rituximab), CD38 monoclonal antibodies, cyclophosphamide, or vindesine within 3 months prior to the first dose；
* Received a live vaccine within 4 weeks before the first dose, or planned to receive any live vaccine during the clinical trial;
* Those who have received allogeneic stem cell transplantation or organ transplantation in the past;
* Other serious diseases that may limit the subject's participation in this trial (such as diabetes; Hepatic and renal insufficiency; Severe cardiac insufficiency; Myocardial obstruction or unstable arrhythmia or unstable angina pectoris in recent 6 months; Gastric ulcer, etc.);
* Patients with malignant tumors within 5 years before the screening;
* A history of severe recurrent or chronic infection;
* A known or suspected history of immunosuppression, including a history of invasive opportunistic infections;
* Clinically significant laboratory abnormalities at the time of screening;
* HIV antibody or syphilis antibody positive;
* Accompanied by uncontrollable active infection, including hepatitis B, hepatitis C; Pregnant women, suspected pregnancies (positive pregnancy test for human chorionic gonadotropin in urine at screening) and lactating patients;
* Patients with mental disorders who cannot normally obtain informed consent and conduct trials and follow-up;
* Patients whose symptoms of toxicity from pre-trial treatment have not resolved;
* Any other ineligibility for subjects in the study was assessed by the investigator.
