• Previously diagnosed with MM based on standard IMWG criteria

• Patient has given voluntary written informed consent before any study-related procedures not part of normal medical care are performed, with the understanding that consent may be withdrawn by the patient at any time without prejudice to their future medical care.

• Patient who has been treated with at least 4 prior lines of anti-myeloma treatment including immunomodulating agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody.

• In addition, to at least 4 prior lines of anti-myeloma treatment, patient has received ide-cel in accordance with the FDA approved US Prescribing Information and has achieved at least a partial response, and is within 90 days of infusion

• ECOG performance status ≤2 (Karnofsky ≥60%, see Appendix A)

• Screening Laboratory evaluations within the following parameters

‣ Absolute neutrophil count (ANC) ≥ 1,000 cells/dL (1.0 x 109/L) (Growth factors cannot be used more recently than 7 days prior to initiation of therapy)

⁃ Platelet count ≥ 75,000 cells/dL (75 x 109/L) (without transfusions during the 7 days prior to initiation of therapy)

⁃ Hemoglobin ≥ 8.0 g/dL (RBC transfusions are permitted)

⁃ Total Bilirubin ≤ 1.5 X upper limit of normal (ULN) (except subjects with Gilbert Syndrome, who can have total bilirubin \< 3.0 mg/dL)

⁃ AST or ALT ≤ 3x ULN

⁃ Creatinine clearance ≥ 30 ml/min according to the Cockroft-Gault formula:

• Female CrCl = \[(140 - age in years) x weight in kg x 0.85\] / \[72 x serum creatinine in mg/dL\]

∙ Male CrCl = \[(140 - age in years) x weight in kg x 1.00\] / \[72 x serum creatinine in mg/dL\]

• Age ≥18 years.

• Ability to understand and the willingness to sign a written informed consent document.

• A Female of childbearing potential (FCBP) must:

‣ Have two negative pregnancy tests before enrollment and randomization into the clinical studies and prior to each re-supply of study drug during the clinical studies based on the frequency outlined in the Pregnancy Prevention Plan (PPP, Appendix D).

⁃ Sexually active FCBP must agree to use protocol-specified contraceptive methods during participation in the clinical studies and for at least 28 days after the last dose of study drug.

• Sexually active males (including those who have had a vasectomy) must agree to use protocol specified contraceptive methods during participation in the clinical studies and for at least 28 days after the last dose of study drug.

• All participants (male and female with or without childbearing potential) must agree to abstain from donating blood products for at least 28 days after the last dose of study drug and semen or sperm while taking study drug and for at least 28 days after the last dose of study drug.