Inclusion Criteria:  Documented diagnosis of relapsed/refractory multiple myeloma (MM) Subjects must have measurable disease Subjects must have received ≥3 prior MM lines of therapy Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 Adequate hematologic, renal, liver, pulmonary, and cardiac functions Life expectancy of at least 3 months without treatment  Exclusion Criteria:  Subjects with known active or history of central nervous system (CNS) or leptomeningeal involvement of myeloma or plasma cell leukemia Current or history of thyroid disorder (including hyperthyroidism), except for subjects with hypothyroidism controlled on a stable dose of hormone replacement therapy Autologous stem cell transplantation within last 6 weeks prior to the start of lymphodepletion Any prior allogeneic hematopoietic stem cell transplantation Systemic anti-cancer therapy within 2 weeks prior to the start of lymphodepletion