• Age 19 to 75 years old, male or female. The subject or his/her guardian voluntarily signed the informed consent;

• Subjects with relapsed or refractory Plasma Cell Neoplasms（including Multiple Myeloma, Plasma Cell Leukemia, AL Amyloidosis）according to IMWG criteria and have had at least 3 prior lines of therapy (including chemotherapy based on proteasome inhibitors and immunomodulatory agents). Disease progression must be documented during or within 12 months following the most recent anti-myeloma treatment (for subject whose last-line treatment was CAR-T, disease progression was not limited to occurring within 12 months after treatment).

• Evidence of cell membrane BCMA expression, as determined by a validated immunohistochemistry (IHC) or flow cytometry of tumor tissue.

• The subjects were unable to receive autologous hematopoietic stem cell transplantation treatment, or relapsed after autologous hematopoietic stem cell transplantation, and the researchers determined that treatment was needed.

• ECOG performance score 0-2 (except for subjects with central nervous system invasion, which needs to be confirmed by the investigator).

• Estimated life expectancy≥12 weeks.

• Subjects should have adequate organ function:

‣ Complete blood count (CBC) test \[the following criteria should be met within 24 hours prior to apheresis, and supportive treatment such as transfusion, platelet transfusion, cell growth factor (except recombinant erythropoietin) should be avoided within 7 days prior to detection\]: Absolute neutrophil count (ANC) ≥1×10\^9 /L; hemoglobin ≥70 g/L.; platelets ≥50×10\^9 /L; absolute lymphocyte count (ALC) ≥0.3×10\^9 /L;

⁃ Liver function: Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5×upper limit of normal (ULN); total serum bilirubin ≤ 1.5×ULN.

⁃ Kidney function: Serum creatinine ≤2.5×upper limit of normal (ULN), or； Creatinine clearance rate (CrCl) calculated according to Cockcroft-Gault formula ≥ 60 ml/min.

⁃ Electrolytes: Serum potassium ≥ 3.0 mmol/L; Serum calcium ≥ 2.0 mmol/L; Serum magnesium ≥ 0.5 mmol/L.

⁃ Coagulation function: Fibrinogen ≥ 1.0 g/L; activated partial thromboplastin time (APTT) ≤ ULN+10s, prothrombin time (PT) ≤ ULN+3s.

⁃ Cardiac function: Left ventricular ejection fraction (LVEF) ≥ 50%.

• The subjects must be willing to provide valid initial diagnostic evidence and undergo bone marrow examinations before and after treatment.

• Women of childbearing age and all male patients must consent to use a effective contraception for at least 12 months after Meta10-BCMA infusion and until two consecutive PCR tests show no more CAR T cells in vivo；

• The subjects should have measurable disease based on at least one of the following parameters:

‣ The proportion of primitive naive or monoclonal plasma cells ≥ 5% by bone marrow cytology, bone marrow biopsy histology or flow cytometry;

⁃ Serum monoclonal protein (M-protein) level: M protein ≥10 g/L for IgG type, M protein ≥5g/L for IgA, IgD, IgM, and IgE type;

⁃ Urine M protein level ≥200 mg/24 hours;

⁃ Light chain multiple myeloma without measurable lesions in serum or urine: the affected serum free light chain ≥100 mg/L with abnormal serum κ/λ free light chain ratio;

⁃ There are measurable extramedullary plasmacytoma lesions.