Inclusion Criteria:

          -  Patients with confirmed diagnosis of active multiple myeloma (as defined by
             International Myeloma Working Group [IMWG] criteria) who have relapsed/refractory
             disease after and have received at least 3 prior lines of prior therapy.

          -  Eastern Cooperative Oncology Group Performance Status of 0 or 1;

          -  No previous treatment with investigational gene targeting CS1 or chimeric antigen
             receptor therapy targeting CS1

          -  Adequate organ function, including bone marrow, renal, hepatic, pulmonary, and cardiac
             function based on the last assessment performed within the screening period.

          -  Other criteria may apply.

        Exclusion Criteria:

          -  Previous treatment with investigational gene therapy targeting CS1 or chimeric antigen
             receptor therapy targeting CS1;

          -  Any cellular therapy (other than autologous or allogenic HSCT) within 60 days prior to
             enrollment;

          -  Prior treatment with rituximab or other anti-CD20 therapy within 3 months

          -  Any known active or uncontrolled infection

          -  Autologous hematopoietic stem cell transplantation (HSCT) within 12 weeks prior to
             enrollment; any cellular therapy (other than autologous) within 60 days prior to
             enrollment; prior allogeneic HSCT.

          -  Seropositive for Hepatitis C virus or positive for Hepatitis B surface antigen or core
             antibody.

          -  Presence of active and clinically relevant central nervous system disorder, such as
             epilepsy, generalized seizure disorder, paresis, aphasia, stroke, severe brain injury,
             dementia, Parkinson's disease, cerebellar disease, or organic brain syndrome.