Known meningeal involvement of multiple myeloma. Myeloma-related central nervous system involvement Exhibiting clinical signs of meningeal involvement of multiple myeloma Documented history of central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of multiple myeloma. If either is suspected, whole body magnetic resonance imaging (MRI) and lumbar cytology are required Patients who have known central nervous system involvement with multiple myeloma will be excluded from this clinical trial Known active central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of multiple myeloma History of plasma cell leukemia or multiple myeloma (MM) central nervous system (CNS) involvement History of central nervous system multiple myeloma involvement Subjects with known central nervous system involvement with multiple myeloma Known central nervous system involvement by multiple myeloma Documented current central nervous system involvement by multiple myeloma Exhibiting clinical signs of or has a known history of meningeal or central nervous system involvement by multiple myeloma Exhibiting clinical signs of meningeal involvement of multiple myeloma Subjects with Central Nervous System involvement with multiple myeloma Participant is exhibiting clinical signs of meningeal involvement of multiple myeloma Clinical signs of meningeal involvement of multiple myeloma Myeloma-related central nervous system involvement No known central nervous system involvement by myeloma. History of central nervous system involvement or symptoms suggestive of central nervous system involvement by multiple myeloma Known central nervous system involvement by multiple myeloma