A Phase III, Open-label, Randomised, Multicentre Study to Evaluate AZD0120 in Participants With Relapsed Refractory Multiple Myeloma.

Inclusion Criteria: * Age ≥ 18 years * Documented diagnosis of multiple myeloma according to the IMWG diagnostic criteria * Documented evidence of measurable disease: 1. Serum M-protein level ≥ 1 g/dL 2. Urine M-protein level ≥ 200 mg/24h 3. Serum immunoglobulin free light chain ≥ 10 mg/dL (100 mg/L) and abnormal serum immunoglobulin kappa lambda free light chain ratio * Documented evidence of PD by IMWG 2016 criteria based on investigator's determination during or after the most recent line of therapy. Participants with only 1 prior line of therapy must have progressed within 47 months of a stem cell transplant, or if not transplanted, then within 42 months of starting initial therapy * Received 1 to 3 lines of prior therapy including an IMiD and either a PI or a CD38 antibody. Participant must have undergone at least 2 complete cycles of treatment for each line of therapy, unless PD was the best response to the line of therapy * Eligible to receive at least one of the standard regimens (DKd, PVd, DPd, or Kd) as determined by the Investigator. * ECOG performance status score of 0 to 1 * Adequate hematology and chemistry laboratory values: 1. Haemoglobin ≥ 8.0 g/dL 2. Absolute neutrophil count ≥ 1 × 10\^9/L (1000 per mm3) 3. Platelet count ≥ 75 × 10\^9/L (75000 per mm3) in participants with \< 50% of bone marrow nucleated cells are plasma cells or ≥ 50 × 10\^9/L (50000 per mm3) in participants with ≥ 50% of bone marrow nucleated cells are plasma cells 4. Absolute lymphocyte count ≥ 300/µL (0.3 × 109/L) 5. Total bilirubin ≤ 1.5 × ULN in the absence of Gilbert's syndrome or ≤ 3 × ULN if the participant has Gilbert's syndrome. AST and ALT≤ 3.0 × ULN. CrCl by Cockcroft and Gault method ≥ 30 mL/minute Exclusion Criteria: * Known active, or prior history of CNS involvement or exhibits clinical signs of meningeal involvement of MM. * Primary amyloidosis, active plasma cell leukaemia, Waldenstrom macroglobulinemia or Polyneuropathy Organomegaly Endocrinopathy M-protein and Skin (POEMS) syndrome. * Participants with primary refractory MM (failed to generate at least a minimal response to any prior therapy) * Significant neurological or psychiatric condition * Significant medical condition that places the participant at an unacceptable risk for treatment-related complications * Previously received any prior BCMA-targeted treatment * Previously received CAR-T or CAR-NK therapy directed at any target * Previously received T-cell engager therapy directed at any target * Previously received allogeneic stem cell transplantation at any time during prior therapy or received autologous stem cell transplantation within 12 weeks of randomization