Key Inclusion Criteria:

          1. Age ≥18 years.

          2. Relapsed or refractory multiple myeloma, as defined by IMWG response criteria and
             treatment with at least 2 prior lines of therapy.

          3. Eastern Cooperative Oncology Group performance status 0 or 1.

          4. Adequate renal, liver, cardiac and pulmonary organ function

          5. Female subjects of childbearing potential and male subjects must agree to use
             acceptable method(s) of contraception from enrollment through at least 12 months after
             CTX120 infusion.

        Key Exclusion Criteria:

          1. Prior allogeneic stem cell transplant (SCT).

          2. Less than 60 days from autologous SCT at time of screening and with unresolved serious
             complications.

          3. Prior treatment with any gene therapy or genetically modified cell therapy, including
             CAR T cells or natural killer cells, or BCMA-directed therapy.

          4. Evidence of direct central nervous system (CNS) involvement by multiple myeloma.

          5. History or presence of clinically relevant CNS pathology such as a seizure disorder,
             cerebrovascular ischemia/hemorrhage, dementia, cerebellar disease, any autoimmune
             disease with CNS involvement.

          6. Unstable angina, clinically significant arrhythmia, or myocardial infarction within 6
             months of enrollment.

          7. Active HIV, hepatitis B virus or hepatitis C virus infection.

          8. Previous or concurrent malignancy, except basal cell or squamous cell skin carcinoma,
             adequately resected and in situ carcinoma of cervix, or a previous malignancy that was
             completely resected and has been in remission for ≥5 years.

          9. Use of systemic anti-tumor therapy or investigational agent within 14 days prior to
             enrollment.

         10. Primary immunodeficiency disorder or active autoimmune disease requiring steroids
             and/or other immunosuppressive therapy.

         11. Women who are pregnant or breastfeeding.