The aim of the study is to assess the efficacy and safety of the BCD-248 in combination with daratumumab versus the combination of daratumumab, pomalidomide, and dexamethasone in the treatment of relapsed or refractory multiple myeloma. The study will be conducted in a population of male and female subjects aged 18 years and older, with confirmed symptomatic multiple myeloma with measurable disease, who have received one prior line of therapy that included a proteasome inhibitor and lenalidomide and were refractory to lenalidomide, or who have received two or three prior lines of therapy that included a proteasome inhibitor and lenalidomide, with disease progression during or after the last line of therapy.