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.
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.
Diagnosis of primary Amyloid Light chain (AL) Amyloidosis, active Polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome, primary plasma cell leukemia.
Part 3: Active or history of venous or arterial thromboembolism within the past 3 months. Contraindications to or unwilling to undergo protocol-required anti-thrombotic prophylaxis
Any serious and/or unstable pre-existing medical, psychiatric disorder, or other conditions (including lab abnormalities) that could interfere with participant's safety, obtaining informed consent, or compliance with study procedures.
Participant is exhibiting signs of meningeal or central nervous system involvement with MM.