Inclusion Criteria:
1. Age ≥ 18
2. Relapsed/Refractory Multiple Myeloma
3. Secretory disease: PP≥5g/L and/or sFLC≥100mg/L of involved light chain with abnormal K:L ratio.
4. ≥3 prior lines of therapies (including proteasome inhibitor, IMiD, anti CD38 antibody)
5. Refractory to last line of therapy (not achieved at least PR and progressed within 60 days of last dose or achieved at least PR but progressed within 6 months of last dose)
6. Has previously received or is not suitable for ASCT
7. Eastern Cooperative Oncology Group (ECOG) performance status 0/1
8. Creatinine Clearance (CrCl)≥40ml/min, Absolute Neutrophil Count (ANC)≥1x10\^9/L, Platelets (plt)≥50x10\^9/L, Haemoglobin (Hb)≥80 /L, lymphocyte count ≥0.3x10\^9/L
9. Patients must weigh \>30 kg
10. Agreement to have a pregnancy test, use adequate contraception (if applicable)
11. Written informed consent
Exclusion Criteria:
1. Previous diagnosis of systemic light chain amyloidosis
2. Prior treatment with investigational or approved gene therapy or cell therapy products
3. Stem cell transplant patients only:
* allogeneic stem cell transplant within 12 months prior to registration into the study
* moderate/ severe chronic GVHD (NIH consensus criteria) requiring immunosuppressive therapy and/or systemic steroids
4. Oxygen saturation ≤ 90% on air
5. Patients with clinically significant, uncontrolled heart disease or a recent (within 6 months) cardiac event
6. Left ventricular ejection fraction \< 50% (ECHO or MUGA)
7. Corrected QT interval (QTc)\>470 ms on ECG
8. Uncontrolled cardiac arrhythmia (patients with rate-controlled atrial fibrillation are not excluded)
9. History or evidence of deep vein thrombosis or pulmonary embolism requiring ongoing therapeutic anticoagulation at preconditioning
10. Chronic renal impairment requiring dialysis
11. Patients with significant liver disease: alanine aminotransferase or aspartate aminotransferase ≥3x upper limit normal (ULN), or total bilirubin ≥25umol/L (1.5mg/dL), except in patients with Gilbert's syndrome, or evidence of end-stage liver disease (e.g. ascites, hepatic encephalopathy)
12. Patients with any major surgical intervention in the last 3 months, cement augmentation for vertebral collapse is permitted
13. Patients with active gastrointestinal bleeding
14. Patients with active infectious bacterial or viral disease requiring treatment
15. Known active central nervous system involvement of MM. History or presence of clinically relevant central nervous system pathology such as epilepsy, paresis, aphasia, stroke within 3 months prior to enrolment, severe brain injuries, dementia, Parkinson's disease, cerebellar disease, organic brain syndrome, uncontrolled mental illness, or psychosis
16. Patients receiving corticosteroids at a dose of \>5 mg prednisolone per day (or equivalent) that cannot be discontinued
17. Active autoimmune disease requiring immunosuppression
18. Past or current history of other neoplasms
19. Received any radiotherapy within the last 7 days prior to lymphodepletion or leukapheresis. Localised radiation to a single site, e.g. for bone pain is permitted at any time
20. Patients with any anti-myeloma therapy within the last 7 days prior to LD or leukapheresis
21. Inability to tolerate leucapheresis
22. Life expectancy \<3 months
23. Women who are pregnant or breastfeeding
24. Known allergy to albumin or DMSO
Exclusion criteria for CAR-T cell infusion:
1. Active infection requiring systemic anti-microbial therapy, or with temperature more or equal to 38 C within 48 hours before scheduled CAR-T cell infusion
2. Requirement for supplementary oxygen at the time of scheduled CAR-T cell infusion
3. Clinical deterioration of organ functions (hepatic or renal function) exceeding criteria set at study entry
