A Study of the Efficacy and Safety of Monotherapy With BCD-264 and Darzalex in Subjects With Relapsed and Refractory Multiple Myeloma

This study compares two treatments for multiple myeloma (a blood cancer) that has come back or stopped responding: BCD-264 (a new drug) versus daratumumab (Darzalex), a well-known approved treatment. Both target a protein on myeloma cells called CD38. **You may be eligible if...** - You are 18 or older with a confirmed diagnosis of multiple myeloma - Your disease has come back or is no longer responding to treatment - You have previously been treated with both a proteasome inhibitor and an immunomodulatory drug - Your disease is measurable on lab tests - You are generally functional (ECOG score 0–2) - You are willing to have a bone marrow biopsy **You may NOT be eligible if...** - You have previously been treated with daratumumab or any other anti-CD38 therapy - You had a stem cell transplant (your own cells) within the last 12 weeks, or ever had a donor transplant - You have plasma cell leukemia, POEMS syndrome, or amyloidosis - You are pregnant or not willing to use contraception Talk to your doctor to see if this trial is right for you.