A Safety and Efficacy Study Evaluating CTX120 in Subjects With Relapsed or Refractory Multiple Myeloma

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.