A Open-Label Phase in Participants With Multiple Myeloma

1. Aged at least 18 years old;

2. Initial diagnosis of multiple myeloma documented according to International Myeloma Working Group (IMWG) diagnostic criteria.Multiple myeloma is defined as clonal bone marrow plasma cells ≥ 10% or biopsy-proven bony or extramedullary plasmacytoma, and any one or more of the following myeloma-defining events: • Evidence of end-organ damage attributable to the underlying plasma cell proliferative disorder, including the following: Hypercalcemia: serum calcium > 0.25 mmol/L (> 1 mg/dL) above the upper limit of normal or corrected serum calcium > 2.75 mmol/L (> 11 mg/dL); renal insufficiency: creatinine clearance < 40 mL/min or serum creatinine > 177 μmol/L (> 2 mg/dL); anemia: hemoglobin value > 2 g/dL below the lower limit of normal or hemoglobin value < 10 g/dL; bone lesions: one or more osteolytic lesions on skeletal radiographs, computed tomography (CT), or positron emission tomography (PET)-CT.

3.Safety run-in stage: Relapsed or refractory measurable multiple myeloma who have previously received ≥ 1 line of anti-myeloma therapy (including treatment with at least one proteasome inhibitor and one immunomodulatory drug), and the participant must be relapsed or refractory to the most recent treatment.Participants previously exposed to anti-CD38 monoclonal antibodies may also be enrolled (a 90-day washout period is required).

4. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.