A Study of YKST02 in Participants With Relapsed or Refractory Multiple Myeloma

This study tests a new drug called YKST02 in people with multiple myeloma (a blood cancer) that has relapsed (come back) or become refractory (stopped responding to treatment). It is an early-phase study looking at safety and the right dose. **You may be eligible if...** - You have been diagnosed with multiple myeloma per standard criteria - You have received at least two prior classes of treatment, including an immunomodulatory drug (e.g., lenalidomide), a proteasome inhibitor (e.g., bortezomib), and an anti-CD38 drug (e.g., daratumumab) - You have measurable disease in your blood, urine, or free light chains - Your performance status and organ function are adequate **You may NOT be eligible if...** - You have not had enough prior lines of therapy - You have serious organ problems or active infections - You are pregnant Talk to your doctor to see if this trial is right for you.