Jiangsu Purijin Biopharmaceutical Co., Ltd.

Primary objective: To evaluate the 3-month ORR (at least PR or better at the 3-month time point) of CART-BCMA in the treatment of relapsed/refractory multiple myeloma;

Main purpose 1. To evaluate the safety and tolerability of CART-BCMA in patients with relapsed/refractory multiple myeloma after infusion; 2. To determine the maximum tolerated dose (MTD) and/or subsequent recommended dose (RD) of CART-BCMA in patients with relapsed/refractory multiple myeloma. Secondary purpose 1. To preliminarily evaluate the effectiveness of CART-BCMA in patients with relapsed/refractory multiple myeloma. 2. To preliminarily evaluate the pharmacokinetic parameters of CART-BCMA cells and CAR copy number in patients with relapsed/refractory multiple myeloma. 3. To preliminarily evaluate the immunogenicity of CART-BCMA. Exploratory purpose 1. To explore and evaluate the overall survival (OS) of patients with relapsed/refractory multiple myeloma after CART-BCMA infusion therapy; 2. To explore and evaluate the expansion of CART-BCMA in the blood of subjects and its relationship with efficacy, adverse reactions, and related biomarker levels; 3. To explore and evaluate the expression of BCMA in bone marrow plasma cells and myeloma cells at baseline and its relationship with the efficacy of CART-BCMA; 4. To explore and evaluate the negative rate of BCMA expression in bone marrow plasma cells and myeloma cells during disease progression/relapse.