Inclusion Criteria:

• Participant must be 18 years of age inclusive or older
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1.
• Participants with relapsed or refractory MM who have received at least 3 prior lines of therapy for MM, including PIs and IMiDs or at least 2 prior lines if at least one of these lines consisted of 2 or more multiagent regimens (eg, Induction regimen with autologous stem cell transplant followed by maintenance).
• RRMM with measurable disease:
• Serum M protein ≥0.5 g/dL measured using serum protein immunoelectrophoresis and/or
  • Urine M protein ≥200 mg/24 hours measured using urine protein immunoelectrophoresis and/or
  • Serum free light chain (sFLC) MM without measurable M protein in serum or urine per previous criteria (serum Ig free light chain ≥10 mg/dL and abnormal serum Ig kappa lambda free light chain ratio <0.26 or >1.65).
• Men or woman or childbearing potential should agree to use contraception.
• Substudy 01, 02 (Terminated), 03 (Terminated): Anti-CD38 therapy naïve or prior exposure to such drugs without being refractory but with a wash out of at least 6 months after the last dose. "Refractory" is defined as progressing within 60 days of last dose of anti-CD38 targeting therapy.
• Substudy 04: Participants must be exposed to anti-CD38 and anti-BCMA therapy

Exclusion Criteria:

• Primary systemic amyloid light chain amyloidosis, plasma cell leukemia, monoclonal gammopathy of undetermined significance, or smoldering myeloma.
• Uncontrolled infection within 14 days prior to first study intervention administration.
• Clinically significant cardiac (including valvular) or vascular disease within 3 months prior to first study intervention administration, eg, myocardial infarction, unstable angina, coronary (eg, coronary artery bypass graft, percutaneous coronary intervention) or peripheral artery revascularization, left ventricular ejection fraction <40%, heart failure New York Heart Association Classes III and IV, stroke, transient ischemic attack, pulmonary embolism, other thromboembolic event, or cardiac arrhythmia (Grade 3 or higher by NCI CTCAE Version 5.0).
• Known acquired immunodeficiency syndrome-related illness or known human immunodeficiency virus (HIV) disease requiring antiviral treatment or active hepatitis A.
• Uncontrolled or active hepatitis B virus (HBV) infection.
• Active hepatitis C virus (HCV) infection.
• Any of the following within 3 months prior to first study intervention administration: treatment resistant peptic ulcer disease, erosive esophagitis or gastritis, infectious or inflammatory bowel disease.
• Second malignancy other than basal cell or squamous cell carcinoma of the skin or in situ carcinoma, unless they are successfully treated with curative intent for more than 3 years before first study intervention administration.
• Any anti-MM drug treatment within 14 days before first study intervention administration, including dexamethasone.
• Participants with a contraindication to treatment.
• Vaccination with a live vaccine 4 weeks before the start of the study.
• Hemoglobin <8 g/dL.
• Platelets <50 x 10^9/L.
• Absolute neutrophil count <1.5 x 10^9/L.
• Creatinine clearance <30 mL/min.
• Total bilirubin >1.5 x ULN, except for known Gilbert syndrome in which direct bilirubin should be ≤2.5 x ULN.
• Aspartate aminotransferase and/or alanine aminotransferase >3 x ULN.
• Patients with grade 3 or 4 hypercalcemia.
• Substudy 01:
  • Malabsorption syndrome or any condition that can significantly impact the absorption of pomalidomide.
  • For the first 10 participants: Body weight ≤70 kg
• Substudy 02 (terminated):
  • History of resected/ablated basal or squamous cell carcinoma (SCC) of the skin or carcinoma in situ of the cervix, or other local tumors, even if considered cured by local treatment.
  • Therapeutic doses of anticoagulants or antiplatelet agents within 7 days prior to the first dose of SAR439459.
  • Prothrombin time or INR >1.5 × upper limit of normal (ULN).
• Substudy 03 (terminated):
  • Current corneal epithelial disease except mild punctate keratopathy
  • Patients who have received prior therapy with belantamab mafodotin
• Substudy 04:
  • Central nervous system or leptomeningeal disease.
  • Medical history of seizure.
  • Participants currently receiving hepatically metabolized narrow therapeutic index drugs (eg, digoxin, warfarin) if cannot be closely monitored.

        The above information is not intended to contain all considerations relevant to a patient's
        potential participation in a clinical trial.