• Patients or their guardians understand and voluntarily sign the informed consent form, and are expected to complete the follow-up examination and treatment of study procedures;

• Aged 18-75 years, male or female;

• According to IMWG diagnostic criteria, diagnosed with multiple myeloma;

• Patients with documented multiple myeloma disease as relapsed refractory or primary refractory, defined as: a) relapsed refractory: no response to salvage therapy (no response defined as failure to achieve minimal response \[MR\] or disease progression on treatment), or disease progression within 60 days of the last treatment, or disease progression in patients who have achieved MR or above remission; b) primary refractory: never achieved MR or above response to any treatment, including never achieved MR or above remission, but M protein changes are not large, patients without evidence of clinical progression and patients who have primary refractory, progressed, and met the definition of progression.

• the presence of measurable disease at screening as determined by any of the following criteria: serum monoclonal paraprotein (M-protein) level ≥ 1.0 g/dL or urine M-protein level ≥ 200 mg/24 hours; or diagnosis of light chain multiple myeloma without measurable disease in serum or urine: serum immunoglobulin free light chain ≥ 10 mg/dL and abnormal serum immunoglobulin κ/γ free light chain ratio; extramedullary measurable disease; the presence of tumor cells in the bone marrow as detected;

• the patient has recovered from the toxicity of previous treatment, that is, CTCAE toxicity grade \< 2 (unless the abnormality is tumor-related or judged by the investigator to be stable, it has little effect on safety or efficacy);

• ECOG performance status score 0 to 2 and expected survival greater than 3 months;

• Appropriate organ function:

⁃ alanine aminotransferase (ALT) ≤ 3 times the upper limit of normal (ULN); aspartate aminotransferase (AST) ≤ 3 times the ULN; total bilirubin ≤ 1.5 times the ULN; Serum creatinine ≤ 1.5 times ULN, or creatinine clearance ≥ 30 mL/min (calculated by Cockcroft-Gault formula); Intraventricular oxygen saturation ≥ 92%; Left ventricular ejection fraction (LVEF) ≥ 45%, no pericardial effusion confirmed by echocardiography, no clinically significant electrocardiographic findings; no clinically significant pleural effusion; 9. venous access for collection can be established, no contraindications for leukocyte collection.