A Study to Investigate the Safety and Efficacy of Belantamab for the Treatment of Multiple Myeloma When Used as Monotherapy and in Combination Treatments

The study consists of three parts: * Part 1: The primary purpose of this part aims to evaluate the safety, tolerability, and clinical activity of escalating doses of single agent belantamab in participants with refractory multiple myeloma (RRMM) who have received at least 3 prior therapies (4L+). * Part 2: The primary purpose of this part is to evaluate the safety, tolerability, and clinical activity of different doses of belantamab in combination with a fixed dose of Belantamab mafodotin (delivered as separate drugs) in participants with RRMM who have received at least 3 prior therapies (4L+). * Part 3: The Primary purpose of this part will evaluate the clinical activity of a selected dose of the belantamab in combination with the pomalidomide-dexamethasone (Pd) standard of care (SoC) backbone. The study will focus on participants with multiple myeloma who have undergone at least one prior line of therapy, including treatment with lenalidomide.

Inclusion criteria * Participants at the time of signing the Informed Consent Form (ICF) are at least 18 years old or are of the legal age of consent in the jurisdiction in which the study is taking place. * Participants who have histologically or cytologically confirmed diagnosis of Multiple Myeloma (MM), as defined by the international myeloma working group (IMWG) and have progressed on or following the last line of treatment * Part 1 and Part 2: Participants who have received at least 3 prior lines of anti-myeloma treatments, including any immunomodulatory drug (IMiDs lenalidomide, pomalidomide or thalidomide), a proteasome inhibitor, and an anti-CD38 monoclonal antibodies (mAb) (either in combination or separately). * Part 3: Have received at least 1 prior line of treatment anti-myeloma treatments, including lenalidomide. Prior anti-CD38-containing regimen is not mandated, however no more than 70% of participants recruited may be anti-CD38 naïve. * Participants with a history of Autologous stem cell transplant (ASCT) are eligible for study participation provided the following eligibility criteria are met: * transplant was greater than (\>)100 days prior to screening. * No active bacterial, viral, or fungal infection(s) present * Eastern cooperative oncology group-performance status (ECOG-PS) of 0 to 2. * Measurable disease defined as at least ONE of the following: * Serum M-protein concentration greater than or equal to (\>=) 0.5 gram (g)/ deciliter (dL) (\>=5 gram/liter \[g/L\]) * Urine M-protein excretion \>=200 milligram (mg)/24 hours (\>=0.2 g/24 hours) * Serum free light chain (FLC) assay: involved FLC level \>=10 mg/dL (\>=100 milligrams per liter \[mg/L\]) and an abnormal serum FLC ratio (less than \[\1.65) * Have adequate organ system function as defined by the laboratory assessments * All prior treatment-related toxicities (defined by National Cancer Institute-Common Toxicity Criteria for Adverse Events \[NCI-CTCAE\], v5.0, 2017) must be Grade less than or equal to (\