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 a real-world data source, 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.

Inclusion Criteria:

• Aged 18 years and older at index date
• Diagnosis of MM
• Measurable disease according to IMWG criteria
• ECOG performance status ≤2
• Refractory to at least 1 proteasome inhibitor, 1 immunomodulatory drug, and 1 anti-CD38 treatment (ie, triple-class refractory [TCR])
• At least 1 treatment following their TCR eligibility

Exclusion Criteria:

• Acute plasma cell leukemia
• Amyloidosis
• Smoldering MM
• Stem cell transplant within 12 weeks of index or active graft versus host disease (GVHD)
• Active malignancy within 3 years before index, except for basal cell or squamous cell skin cancer or carcinoma in situ
• Administration with an investigational drug within 30 days prior to index

Patients treated with elranatamab will come from the MagnetisMM-3 trial. Patients treated with the standard-of-care therapies will come from real-world data sources.

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.