A Clinical Study Evaluating the Safety and Preliminary Efficacy of Universal Allogeneic CAR T-cell Therapy Targeting CD19 and BCMA(QT-019C)in Patients With Refractory Primary Immune Thrombocytopenia

This study is a single-arm, open-label clinical trial aimed at evaluating the safety, tolerability, and efficacy of QT-019C in patients with refractory primary ITP, and obtaining pharmacokinetic(PK) and pharmacodynamic(PD) data. The study comprises two phases: dose escalation and dose expansion， and plans to recruit 10 to 27 participants. Dose escalation will follow a 3 + 3 design, and 10 to 21 participants will be included in this phase. Four dose groups (Group A, Group B, Group C, and Group D) will be set up. Participants who sign the informed consent forms and have been screened by inclusion/exclusion criteria will undergo leukapheresis, lymphodepletion pre-treatment, and a single infusion of QT-019C. Participants will undergo regular checks to evaluate the safety and tolerability of the treatment, along with data on PK, PD, and preliminary efficacy. After the last subject in each dose group has completed the dose-limiting toxicity (DLT) assessment window of 28 days after a single dose, enrollment and treatment for the next dose group may be initiated after the Safety Review Committee (SRC) agrees to enter the next dose group based on clinical safety data assessment. After the dose escalation is completed, the SRC will determine whether to conclude the study or select a dose level or dose range as the recommended dose (RD) for a dose expansion study based on the conditions of the dose escalation phase. 6 participants will be included in this phase for further assessment of QT-019C's safety and early efficacy. All participants will complete a follow-up up to 24 months.