Primary Objective:~To determine the safety and tolerability of belantamab maintenance therapy after auto-HCT.~Secondary Objectives:~To estimate the complete remission rate (CRR) as defined by the International Myeloma Working Group (IMWG) criteria (Appendix A.) within 9 months post salvage autotransplant with single agent belantamab mafodotin maintenance therapy starting approximately 3 months post salvage auto-transplant in patients with relapsed myeloma.~To evaluate progression-free survival (PFS) and overall survival (OS) (from the data of initiation of maintenance therapy assessed up to 2 years)~To discover the impact of belantamab mafodotin on graft function and immune reconstitution.~To assess minimal residual disease status (FDA approved ClonoSeq NGS assay - MRD measured down to 1 in 1 million cells, <106 ) after at 3 months, 6 months and 1 year after initiation of maintenance therapy
The goal of this clinical research study is to learn if belantamab mafodotin (Blenrep) can help to prevent multiple myeloma (MM) from coming back after patients have had an autologous stem cell transplant (AutoSCT). The safety of this drug after transplant will also be studied