Belantamab Mafodotin Combination Therapy

The purpose of this study is to find out whether combination treatment with the study drugs belantamab mafodotin, nirogacestat, and pomalidomide is a safe treatment for people who have relapsed or refractory multiple myeloma. The researchers will test different doses of belantamab mafodotin to find the safest dose to give with nirogacestat and pomalidomide. The researchers also want to find out whether belantamab mafodotin plus nirogacestat and pomalidomide is an effective treatment for this type of bone marrow cancer, and the researchers will do tests that show whether the study treatment slows or stops the growth of cancer.