The purpose of this study is to learn about the effects of the study drug (PF-06863135, also called “elranatamab”) for treating multiple myeloma. The study drug (PF-06863135) is an investigational drug because it is not approved for use in this country. The study drug is comprised of two antibodies (sometimes called a “bispecific antibody”). The study drug binds to T-cells (a type of immune system cell) and myeloma cells; this causes the T –cells to kill the myeloma cells.

Depending on the participant’s prior therapy, the participants will be placed in either Cohort A or Cohort B. There is no difference in treatment and procedures for the two cohorts.

During the first week, participants will receive 3 injections of elranatamab (each administered at least 2 days apart). After the first week, participants will receive 1 injection of elranatamab once a week. If a participant received elranatamab for at least 6 months and achieved a partial response or better, participants will receive 1 injection of elranatamab once biweekly. At least once a month, participants will have a physical examination and lab draws to assess for safety and response. Some other procedures that participants will have to complete is electrocardiogram, imaging, electrocardiogram, questionnaires, and bone marrow biopsy. Some of these procedures are part of your routine care for multiple myeloma. Participants will be on this study for at least 2 years. Participants may choose to withdraw at any time or if the study doctor thinks this treatment is no longer beneficial.  

Participants will receive a stipend for each completed study visit if deemed eligible for the study.