Inclusion Criteria:

          -  Prior diagnosis of multiple myeloma according to IMWG diagnostic criteria.

          -  Measurable disease at screening.

          -  Has received at least 3 but not more than 5 prior lines of multiple myeloma treatment,
             including proteasome inhibitor, immunomodulatory drug, and anti-CD38 therapies.

          -  Eastern Cooperative Oncology Group performance status of 0 or 1.

          -  Willing to avoid pregnancy or fathering children.

          -  Willing to provide fresh and archival bone marrow aspiration and biopsy tissue.

        Exclusion Criteria:

          -  Receipt of any of the following treatment within the indicated interval before the
             first administration of study drug:

               -  Anti-myeloma treatment within 2 weeks or 5 half-lives (whichever is longer).

               -  Investigational drug (including investigational vaccines) or invasive
                  investigational medical device within 4 weeks.

               -  Autologous stem cell transplant within 12 weeks, or allogeneic stem cell
                  transplant at any time.

               -  Plasmapheresis within 4 weeks.

               -  Radiation therapy within 2 weeks.

               -  Major surgery within 2 weeks, or inadequate recovery from an earlier surgery, or
                  surgery planned during the time the participant is expected to participate in the
                  study or within 2 weeks after the last dose of study treatment.

          -  Toxicity ≥ Grade 2 from previous anti-myeloma therapy except for stable chronic
             toxicities (≤ Grade 2) not expected to resolve, such as stable Grade 2 peripheral
             neuropathy.

          -  Known additional malignancy (other than multiple myeloma) that is progressing or
             requires active treatment, or history of other malignancy within 2 years of study
             entry.

          -  Laboratory values at screening outside the protocol-defined range.

          -  Significant concurrent, uncontrolled medical condition including but not limited to
             known chronic obstructive pulmonary disease (COPD), persistent asthma, or history of
             asthma within the past 2 years; chronic or current active infectious disease requiring
             systemic antibiotics, antifungal, or antiviral treatment; acute diffuse infiltrative
             pulmonary disease; clinically significant or uncontrolled cardiac disease.

          -  Plasma cell leukemia, Waldenström's macroglobulinemia, POEMS syndrome, or amyloidosis.