To Evaluate the Efficacy and Safety of QL2109 and DARZALEX FASPRO® in Multiple Myeloma

Inclusion Criteria: * Males and females at least 18 years of age. * Subject must have measurable disease of MM as defined by the criteria below:Serum M-protein level ≥0.5 g/dL or urine M-protein level ≥200 mg/24 hours; or Light chain multiple myeloma, for subjects without measurable disease in the serum or urine: Serum immunoglobulin free light chain (FLC) ≥10 mg/dL and abnormal serum immunoglobulin kappa lambda FLC ratio. * Subjects must have received prior antimyeloma treatment. The prior treatment must have included both a PI- and lenalidomide-containing regimens. Subjects who received only 1 line of prior treatment must have demonstrated PD on or within 60 days of completion of the lenalidomide containing regimen (ie, lenalidomide refractory). * Subjects must have documented evidence of PD based on the investigator's determination of response as defined by the modified IMWG criteria on or after the last regimen. * Eastern Cooperative Oncology Group (ECOG) performance status score of ≤ 2. * For subjects experiencing toxicities resulting from previous therapy, the toxicities must be resolved or stabilized to ≤Grade 1. * Any of the following laboratory test results during Screening: 1. Absolute neutrophil count ≥1.0 × 109/L; 2. Hemoglobin level ≥75 g/L (≥4.65 mmol/L); (transfusions are not permitted to reach this level); 3. Platelet count ≥75 × 109/L in subjects in whom \<50% of bone marrow nucleated cells are plasma cells and platelet count ≥50 x 109/L in subjects in whom ≥50% of bone marrow nucleated cells are plasma cells; 4. Alanine aminotransferase (ALT) level ≤2.5 times the upper limit of normal (ULN);Aspartate aminotransferase (AST) level ≤2.5 x ULN; 5. Total bilirubin level ≤1.5 x ULN, (except for Gilbert Syndrome: direct bilirubin ≤1.5 × ULN); 6. Creatinine clearance ≥30 mL/min 7. Serum calcium corrected for albumin ≤14.0 mg/dL (≤3.5 mmol/L), or free ionized calcium ≤ 6.5 mg/dL (≤1.6 mmol/L). Exclusion Criteria: * Subject has plasma cell leukemia (\>2.0 × 109/L circulating plasma cells by standard differential) or Waldenström's macroglobulinemia or POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) or amyloidosis. * History of malignancy (other than MM) within 3 years before the date of randomization (exceptions are squamous and basal cell carcinomas of the skin, carcinoma in situ of the cervix or breast, or other non-invasive lesion that in the opinion of the investigator, with concurrence with the sponsor's medical monitor, is considered cured with minimal risk of recurrence within 3 years). * Clinical signs of meningeal involvement of MM. * Previous therapy with any anti-CD38 monoclonal antibody. * Previous exposure to pomalidomide. * Subject has received antimyeloma treatment within 2 weeks or 5 pharmacokinetic half-lives of the treatment, whichever is longer, before the date of randomization. The only exception is emergency use of a short course of corticosteroids (equivalent of dexamethasone 40 mg/day for a maximum of 4 days) for palliative treatment before Cycle 1, Day 1 (C1D1). * Previous allogenic stem cell transplant; or autologous stem cell transplantation (ASCT) within 12 weeks before C1D1. * Subject has had major surgery within 2 weeks before randomization, or has not fully recovered from an earlier surgery, or has surgery planned during the time the subject is expected to participate in the study or within 2 weeks after the last dose of study drug administration. * Ongoing ≥ Grade 2 peripheral neuropathy. * Subject had ≥Grade 3 rash during prior therapy. * Pregnant or nursing women.