Phase I Study of SHR-2173 Injection in Patients With Primary Immune Thrombocytopenia

Inclusion criteria

• Participants must fully understand the trial content, procedures, and potential adverse reactions, and voluntarily sign a written informed consent form (ICF).
• Age at signing the ICF must be ≥ 18 years (including the boundary value), regardless of gender.
• Confirmed diagnosis of primary ITP for at least 3 months at screening.
• Previous treatment with corticosteroids.
• At the last ITP treatment, participants experienced loss of remission, no remission, relapse after remission, or intolerance.
• Platelet count <30×10⁹/L at screening with clinical assessment indicating treatment necessity
• Participants must have adequate organ function
• Clinically stable condition with World Health Organization (WHO) bleeding scale grade 0-1
• Female participants of childbearing potential or male participants with fertile partners must refrain from sperm/ova donation from ICF signing until 12 weeks after last dose and agree to protocol-specified contraceptive measures

Exclusion criteria

• Diagnosis of secondary thrombocytopenia or concomitant autoimmune hemolytic anemia
• Received platelet transfusion, whole blood transfusion, plasma exchange, or any other emergency treatment drugs within 14 days prior to the first infusion of SHR-2173
• Received immunosuppressants (other than corticosteroids) such as Janus kinase [JAK] inhibitors or Bruton tyrosine kinase [BTK] inhibitors within either 5 times the drug elimination half-life or 14 days prior to the first infusion of SHR-2173 (whichever is longer)
• Previous treatment with SHR-2173
• Screening prothrombin time or activated partial thromboplastin time outside the normal range; concurrent coagulation disorders and/or receiving antiplatelet or anticoagulant medications (e.g., warfarin, clopidogrel, novel oral anticoagulants), except for low-dose acetylsalicylic acid
• History of any thrombotic or embolic events within 12 months prior to the first administration, or clinical symptoms and history suggesting thrombophilia
• Current life-threatening bleeding (related to thrombocytopenia) or expected to require emergency treatment within one week after randomization
• Active viral, bacterial, or other infections (including tuberculosis [TB]) requiring systemic treatment at screening, or SARS-CoV-2 infection during screening, or history of clinically significant recurrent infections
• Received live or attenuated live vaccines within 8 weeks prior to the first administration of SHR-2173, or planned to receive live/attenuated vaccinations during the trial
• Received live or attenuated live vaccines within 8 weeks prior to the first administration of SHR-2173, or planned to receive live/attenuated vaccinations during the trial
• Diagnosis of myelodysplastic syndrome; history of or current malignancy within 5 years prior to screening (except for cured non-melanoma skin cancer, in situ carcinoma [e.g., cervical, breast, bladder, prostate cancer], and cancers in complete remission for at least 5 years with no evidence of recurrence)
• Previous splenectomy
• Previous allogeneic stem cell or organ transplantation (except for corneal transplantation ≥ 3 months prior to screening); known or suspected history of immunosuppression
• Planned surgery during the dosing period
• Any severe and/or unstable pre-existing medical, psychiatric, or other conditions that the investigator judges may interfere with patient safety, obtaining informed consent, or compliance with study procedures
• Allergic constitution (e.g., allergies to two or more drugs, foods, or pollens) or known hypersensitivity (immediate or delayed) or atopic reactions to the study drug (including excipients, monoclonal antibodies)
• Concurrent participation in other investigational studies within either 30 days prior to enrollment or 5 half-lives of the investigational drug (whichever is longer)
• Females who are lactating or pregnant (positive serum or urine β-human chorionic gonadotropin [hCG]) at screening or on Day 1 of Week 1 prior to administration