Inclusion Criteria: Participants must satisfy the following criteria to be enrolled in the study: 1. must understand and voluntarily sign an informed consent form (ICF) prior to any study-related assessments/procedures being conducted. 2. willing and able to adhere to the study visit schedule and other protocol requirements. 3. Participant is ≥ 18 years of age the time of signing the ICF. 4. Participant has a history of multiple myeloma (MM) with relapsed and/or refractory disease who have failed or who are ineligible or intolerant to available therapies that may provide clinical benefit. 5. Have documented disease progression on or within 12 months from the last dose of their last myeloma therapy. 6. Participant must have measurable disease. 7. Participant has an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1. 8. Females of childbearing potential (FCBP) must commit to true abstinence from heterosexual contact or agree to use at least one method of highly effective contraception without interruption from screening to at least 9 weeks after the last dose of CC-92328 9. Males must practice true abstinence or agree to use a condom 10. FCBP and males must avoid conceiving from signing the ICF, while participating in the study, during dose interruptions, and for at least 9 weeks after the last dose of CC-92328. Exclusion Criteria: The presence of any of the following will exclude a participant from enrollment: 1. Participant has symptomatic central nervous system involvement of MM. 2. Participant had a prior autologous stem cell transplant ≤ 90 days prior to starting CC-92328. 3. Participant had a prior allogeneic stem cell transplant with either standard or reduced intensity conditioning ≤ 12 months prior to starting CC-92328. 4. Participant had prior systemic cancer-directed treatments or investigational modalities ≤ 5 half-lives or 4 weeks prior to starting CC-92328, whichever is shorter. 5. Participant is a pregnant or lactating female. 6. Participant received live virus vaccines within at least 4 weeks prior to starting study drug. 7. Participant has known active human immunodeficiency virus (HIV) infection. 8. Participant has active hepatitis B or C (HBV/HCV) infection. 9. Participant weight is ≤ 40 kg at screening.