Research Purpose: This study tests how safe and effective TriPRIL CAR T Cells are for adults with multiple myeloma that has returned or not responded to treatment. Multiple myeloma is a type of cancer that affects your blood cells.

Eligibility: Participants must be 18 or older with multiple myeloma that hasn’t improved with at least three treatments. You must be able to understand the study and agree to its terms. Your body must handle the study’s procedures, and you must use birth control if you can have children.

Study Details: You will receive TriPRIL CAR T Cells once and have follow-up visits for up to 2 years to monitor your health. About 18 people will join this study. It's important to know that this is the first time TriPRIL CAR T Cells will be tested in people, and they have not been approved by the FDA.

• Time Commitment: The study lasts up to 2 years with regular follow-ups.
• Participation: You will receive one infusion of investigational treatment.
• Important: You need to meet specific health criteria and not have certain conditions or treatments that could interfere with the study.