This study is to understand how well elranatamab (PF-06863135) may be used for relapsed refractory multiple myeloma (RRMM). Sometimes MM might improve at first, but then gets resistant to the treatment and starts growing again (known as relapsed refractory). This study medicine will be compared with standard-of-care (SOC) therapies used in real-world clinical practice. For people receiving elranatamab, the investigators will use data from the phase 2 clinical trial (MagnetisMM-3). The investigators will also use data from multiple real-world sources, representing the SOC in clinical practice. This study does not seek any participants for enrollment. The investigators will compare the experiences of people receiving elranatamab to people receiving SOC therapies. This way, it will help the investigators to know how well elranatamab can be used for RRMM treatment.