This randomized, open-label study aim to compare the efficacy and safety of rituximab combining anti-CD38 monoclonal antibody with rituximab in ITP patients.This study will be conducted in ITP patients who had not responded to or had relapsed after previous glucocorticoid treatment.

Immune thrombocytopenia (ITP) is an organ-specific autoimmune disease, which is characterized by decreased platelet count and skin and mucosal bleeding. ITP is a kind of disease with increased platelet destruction and impaired platelet production caused by autoimmunity. Conventional treatment of adult ITP includes first-line glucocorticoid and immunoglobulin therapy, second line TPO and TPO receptor agonist, splenectomy and other immunosuppressive treatments (such as rituximab, vincristine, azathioprine, etc.). ITP is one of the most common hemorrhagic diseases. At present, the treatment response of ITP is not good, and a considerable number of patients need drug maintenance treatment, which seriously affects the quality of life of patients and increases the economic burden of patients. Therefore, there is still a lack of effective treatment for adult ITP, especially for recurrent and refractory ITP patients, which is one of the problems that have attracted more attention and need to be solved urgently.

The main pathogenesis of ITP is the loss of platelet autoantigen immune tolerance, which leads to abnormal activation of humoral and cellular immunity. It is characterized by antibody mediated platelet destruction and insufficient platelet production by megakaryocytes. The residual long-term autoreactive plasma cells may be a source of therapeutic resistance to autoimmune cytopenia. Antiplatelet specific plasma cells have been detected in the spleen of patients with rituximab refractory ITP. Therefore, the strategy of simply eliminating B cells may not work, because LLPC will continue to produce pathogenic antibodies. In view of this, the investigators expected that the combination of rituximab and anti-CD38 monoclonal antibody could simultaneously eliminate CD20 positive B cells and LLPC, thereby profoundly reducing the production of pathogenic antibodies and increasing the efficacy of ITP treatment. Some patients have been treated with this regimen in the past, with good efficacy and safety. Therefore, the investigators planned to conduct a clinical study to evaluate the safety and efficacy of rituximab combined with Daratumumab（anti-CD38 monoclonal antibody）versus rituximab in relapsed adult patients with primary immune thrombocytopenia, in order to provide more treatment options for patients with ITP.

Inclusion Criteria:

• Age ≥18 years, male or female.
• Before enrollment, the subjects have been clinically diagnosed with primary immune thrombocytopenia for no less than three months according to the American Society of Hematology guidelines 2011 Evidence-Based Practice Guideline (Neunert et al. 2011) or the International Consensus Report for the Investigation and Management of Primary Immune Thrombocytopenia (Provan et al. 2010), as applicable locally.
• Subjects with a platelet count of <30×10^9/L within the 48 hours prior to the first dose of the study drug;The platelet count of at least two separate assessments (at least 1 week apart) <30×10^9/L during the screening visit.
• Patients have failed glucocorticoid therapy (either due to inefficacy, efficacy could not be maintained, or relapse).
• Previous emergency treatment for ITP (e.g., methylprednisolone, platelet, gamma globulin infusion) must have been completed at least 2 weeks before the first dose.
• Hepatic and renal function (e.g., alanine aminotransferase, aspartate aminotransferase, total bilirubin, serum creatinine) <1.5 times the upper limit of normal (ULN).
• ECOG performance status score of ≤2.
• Cardiac function: New York Heart Association (NYHA) class ≤2.
• Enrollment of subjects receiving maintenance therapy is permitted, including glucocorticoids (≤0.5 mg/kg of prednisone or equivalent) or TPO receptor agonists, but the concomitant medication must have been stable for a minimum of 4 weeks prior to the initial infusion of the study drug; Azathioprine, danazol, cyclosporine A, tacrolimus, sirolimus, etc. must be stopped at least 4 weeks before the first dose; CD20 monoclonal antibody such as rituximab must have been stopped for more than 6 months; the interval between splenectomy and first administration need to be more than 6 months.
• For fertile female patients, a negative pregnancy test result is required. Fertile female and male patients must use effective contraception separately during the study and for 90 days after the cessation of study drug treatment.
• Subjects comprehensively understand and can adhere to the study protocol requirements and willingly signed the informed consent form.

Exclusion Criteria:

• Uncontrollable primary diseases of important organs, such as malignant tumors, liver failure, heart failure, renal failure and other diseases.
• HIV positive.
• Accompanied by uncontrollable active infection, including hepatitis B, hepatitis C, cytomegalovirus, EB virus and syphilis positive.
• Accompanied by extensive and severe bleeding, such as hemoptysis, upper gastrointestinal hemorrhage, intracranial hemorrhage, etc..
• At present, there are heart diseases, arrhythmias that need treatment or hypertension that researchers judge is poorly controlled.
• Patients with thrombotic diseases such as pulmonary embolism, thrombosis and atherosclerosis.
• Those who have received allogeneic stem cell transplantation or organ transplantation in the past.
• atients with mental disorders who cannot normally obtain informed consent and conduct trials and follow-up.
• Patients whose toxic symptoms caused by pre-trial treatment have not disappeared.
• Other serious diseases that may limit the subject's participation in this test (such as diabetes; Severe cardiac insufficiency; Myocardial obstruction or unstable arrhythmia or unstable angina pectoris in recent 6 months; Gastric ulcer, etc.).
• Patients with septicemia or other irregular severe bleeding.
• Patients taking antiplatelet drugs at the same time.
• Pregnant women, suspected pregnancies (positive pregnancy test for human chorionic gonadotropin in urine at screening) and lactating patients.
• Subjects with a known allergy to medications were used in the trial or excipients.
• Any other conditions unsuitable for participation in this study, as assessed by the investigator.

Researchers qualified can request the dataset, including de-identified individual subject data. Data may be requested from PI from 12 months 36 months after study completion.

12 months to 36 months after study completion

Upon request to PI