Participants who have have relapsed (returning) and refractory (stopped responding to treatment) multiple myeloma (RRMM) will be invited to take part in this study. This study is being done to learn more about the drug AMG 701 in people with RRMM. This study will see how the AMG 701 moves throughout the systems in your body (pharmacokinetics), how you feel while taking the AMG 701 (tolerability), how well it is working on you (efficacy), and whether it causes any side effects (safety). AMG 701 is still experimental and is not approved by any regulatory health agency, such as the U.S. Food and Drug Administration (FDA), for use in people with your condition, RRMM. AMG 701 will be
administered as an injection under the skin (subcutaneously) and some participants in the study will additionally receive AMG 701 as an intravenous (into a vein) infusion.