Be at least 18 years of age. 2. Have a documented diagnosis of multiple myeloma according to IMWG diagnostic criteria. 3. Measurable disease at screening as defined by any of the following: ·ð Serum monoclonal paraprotein (M-protein) level ³ð1.0 g/dL or urine M-protein level ³ð200 mg/24 hours, or ·ð Light chain multiple myeloma without measurable disease in the serum or the urine: Serum immunoglobulin free light chain ³ð10 mg/dL and abnormal serum immunoglobulin kappa lambda free light chain ratio. 4. Received at least 3 prior lines of therapy or are double refractory to a proteasome inhibitor (PI) and an immunomodulatory agent (IMiD) (induction with or without hematopoietic stem cell transplant and with or without maintenance therapy is considered a single regimen). Participants will have undergone at least 1 complete cycle of treatment for each regimen (unless progressive disease was the best response). 5. Received as part of previous therapy a PI, an IMiD, and an anti-CD38 antibody (prior exposure can be from different monotherapy or combination regimens). 6. Must have documented evidence of progressive disease based on study physician s determination of response by the IMWG response criteria on or after the last regimen. Participants with documented evidence of progressive disease within the previous 6 months and who are refractory or non-responsive to their most recent line of treatment afterwards are also eligible. 7. Have an Eastern Cooperative Oncology Group (ECOG) Performance Status grade of 0 or 1. 8. Must not be pregnant or must not plan to become pregnant within the study period. 9. Participants must sign an informed consent form (ICF) indicating that he or she understands the purpose and observational nature of the study and is willing to participate. Consent is to be obtained prior to the initiation of any study-related data collection. Prior to data collection, all patients (and/or a legally acceptable representative where applicable) must