Completion of study in orig timeframe not feasible considering evolving treatments for MM in US.

The purpose of this study is to document the participants characteristics, disease burden, and clinical management of participants in the United States who are treated for relapsed multiple myeloma in routine medical practice with a treatment strategies that include a proteasome inhibitor (PI) and/or immunomodulatory drug (IMiD) used either as monotherapy or combination therapy with other treatments.

Inclusion Criteria:

• Must sign, and/or their legally acceptable representative where applicable must sign, a participation agreement/informed consent form (ICF) allowing data collection and source data verification in accordance with local requirements
• Have a diagnosis of relapsed MM [according to 2014 International Myeloma Working Group (IMWG) criteria] with 1 to 3 prior lines of therapy. (An induction regimen followed by autologous stem cell transplantation and single-agent maintenance therapy will be considered a single line of therapy.)
• Participants must have initiated a new line of induction therapy that includes a proteasome inhibitor (PI) and/or immunomodulatory drug (IMiD) within 90 days prior to enrollment. A short course of corticosteroids is allowed prior to initiating the new line of induction therapy
• Must be willing and able to complete the protocol-required patient-reported outcome (PROs)

Exclusion Criteria:

• Participant has plasma cell leukemia [greater than (>) 2.0 * 10^9 per liter] circulating plasma cells by standard differential), Waldenstrom's macroglobulinemia, POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, and/or skin changes), or amyloid light-chain amyloidosis
• Participant has a life expectancy of less than 6 months
• At the time of screening, participant is enrolled in an interventional clinical trial for MM using an anti-neoplastic agent that is not currently approved by the United States (US) Food and Drug Administration (FDA)

The participants to be enrolled in this registry will be participants whose multiple myeloma (MM) has relapsed after the administration of 1 to 3 prior lines of therapy and who initiate treatment with a proteasome inhibitor (PI) and/or immunomodulatory drug (IMiD) used either as monotherapy or combination therapy with other treatments within 90 days prior to study enrollment. Participants are to be recruited from medical centers in the United States.