A Study of Teclistamab and Mezigdomide in People With Multiple Myeloma

The researchers are doing this study to find out whether combining teclistamab and mezigdomide is a safe and effective treatment approach in people with relapsed/refractory multiple myeloma (MM).

Inclusion Criteria: 1. Patients with relapsed or refractory multiple myeloma who have been treated with a proteasome inhibitor, an IMiD, and an anti-CD38 antibody. Patients who have been treated with at least 2 prior lines of therapy are eligible. Multiple myeloma is defined by the International Myeloma Working Group (IMWG) updated criteria. 2. Patients need to have measurable disease defined by one or more of the following: 1. Serum myeloma (M)-protein greater than or equal to 0.5 g/dL (5 g/L). 2. Urine M-protein greater or equal to 200 mg/24 h. 3. Involved light chain (either kappa or lambda) \>10 mg/dL with an abnormal kappa: lambda ratio 4. Plasmacytoma(s) that is new or definitely increased verified by imaging or biopsy. Increase is defined as a 50% and at least 1 cm increase as measured serially by the sum of the products of the cross-diameters of the measurable lesion. 5. A bone marrow biopsy demonstrating \>30% infiltration of clonal plasma cells. 3. Patients who have received prior BCMA-directed therapy \> 90 days prior including antibody drug conjugates or chimeric antigen receptor T-cell \[CAR T\] are eligible. BCMA presence on the cell surface should be confirmed in patients who have been treated with prior BCMA targeted therapies. Prior treatment with BCMA targeted bispecific antibodies is not allowed. 4. Patients who have received bispecific antibodies \>60 days prior with targets other than BCMA are eligible. 5. Patients who have received allogeneic stem cell transplantation \>6 months prior are eligible. 6. Age ≥18 years. 7. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0-1. PS-2 is permitted if PS is due solely to bone pain. 8. Fulfil the criteria for Adequate Organ System Function Based on Safety Assessments: Hematologic: * Hemoglobin ≥8 g/dL (without prior RBC transfusion within 7 days before the laboratory test; recombinant human erythropoietin use is permitted) * Absolute neutrophil count (ANC) ≥1.0 × 109/L (prior growth factor support is permitted but must be without support for 7 days for G-CSF or GM-CSF and for 14 days for pegylated-G-CSF) before the screening and laboratory test * Platelets ≥75 × 10\^9/L in participants in whom \2×ULN, then direct bilirubin ≤1.5×ULN is required) * AST and ALT ≤2.5 × ULN * eGFR ≥30 mL/min Calculated by CKD-EPI formula adjusted for body surface area (BSA): (mL/min/1.73 m2) x BSA/1.73) * Serum calcium corrected for albumin ≤14 mg/dL (≤3.5 mmol/L) or free ionized calcium ≤6. mg/dL (≤1.6 mmol/L) 9. Resolved acute effects of any prior therapy to baseline severity or CTCAE Grade ≤ 1, with the exception of peripheral neuropathy attributable to bortezomib. 10. Female participants: A female participant is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies: ° Is not a woman of childbearing potential (WOCBP) Nonchildbearing potential is defined as follows (by other than medical reasons): * ≥45 years of age and has not had menses for \>1 year * Patients who have been amenorrhoeic for \