Clinical Study to Evaluate the Safety and Efficacy of IM21 CAR-T Cells in the Treatment of Elderly Patients With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria:

1. Patients with relapsed or refractory multiple myeloma who had received at least second line regular treatment failure;
2. Age ≥60 years old;
3. The expected survival time is more than 3 months;
4. ECOG score is 0-2;
5. Those who voluntarily participate in the study and sign the informed consent;
6. Hemoglobin (Hb)≥80g/L; Absolute count of neutrophils (ANC) \>1×10\^9/L Total platelet count (PLT)≥35×10\^9/L;
7. left ventricular ejection fraction \> 45%.

Exclusion Criteria:

1. High-risk viscera-involved patients: the tumor invaded the gastrointestinal tract, lung, pericardium and one of the great vessels;
2. Those who have graft versus host disease and need to use immunosuppressive agents;
3. Use of systemic steroids in combination within 5 days prior to the blood collection period (except for recent or current use of inhaled steroids);
4. Active hepatitis B or C virus, HIV or other untreated active infected persons;
5. Any circumstance that, in the opinion of the investigator, may increase the risk to the subject or interfere with test results;
6. Patients who use chemotherapy or radiotherapy within 3 days before the blood collection stage.