A Study to Learn About the Effects of the Combination of Elranatamab (PF-06863135) and Iberdomide in Patients With Relapsed or Refractory Multiple Myeloma (MagnetisMM-30)

Inclusion Criteria:

• Prior diagnosis of multiple myeloma as defined by IMWG criteria

• Measurable disease based on IMWG criteria as defined by at least 1 of the following:

• Serum M-protein ≥0.5 g/dL by SPEP

• Urinary M-protein excretion ≥200 mg/24 hour by UPEP

• Serum immunoglobulin FLC ≥10 mg/dL (≥100 mg/L) AND abnormal serum immunoglobulinkappa to lambda FL ratio (<0.26 or >1.65)

• Part 1: Received 2-4 prior lines of therapy for multiple myeloma, consisting of atleast 1 immunomodulatory drug and 1 proteasome inhibitor.

• Part 2: Received 1-3 prior lines of therapy for multiple myeloma, consisting of atleast 1 immunomodulatory drug and 1 proteasome inhibitor.

• ECOG performance status 0-1

• Resolved acute effects of any prior therapy to baseline severity or CTCAE Grade ≤1

Exclusion Criteria:

• Plasma cell leukemia, Smoldering multiple myeloma, Waldenström's macroglobulinemia,Amyloidosis, POEMS Syndrome

• Impaired cardiovascular function or clinically significant cardiovascular diseases

• Stem cell transplant within 12 weeks prior to enrollment or active graft vs hostdisease

• Participants with any active, uncontrolled bacterial, fungal, or viral infection

• Any other active malignancy within 3 years prior to enrollment, except foradequately treated basal cell or squamous cell skin cancer, or carcinoma in situ

• Previous treatment with:

• BCMA-directed or CD3 redirecting therapy

• Iberdomide (CC-220) or Mezigdomide

• Administration of strong inhibitor or inducer of CYP3A4/5 within 2 weeks prior todosing and during the study

• Administration with an investigational product within 30 days preceding the firstdose of study intervention

• Participant is unable or unwilling to undergo protocol required thromboembolismprophylaxis