This study is for patients with a specific type of blood cancer called Multiple Myeloma. Some patients' cancer has returned after treatment (relapsed) or stopped responding to treatment (refractory). The study uses TGFbi natural killer (NK) cells, which are special white blood cells that fight cancer, and a drug called isatuximab, which helps the immune system attack cancer. Patients also receive cyclophosphamide and dexamethasone to further support treatment. The goal is to see if this combination is safe and effective.

• The study lasts up to 6 cycles of 28 days each, with regular monitoring.
• Participants must be 18 or older and have tried at least 3 other treatments.
• Regular blood tests and heart checks are required throughout the study.

If you join, you will have check-ups after the study at 30 and 60 days, and every 12 weeks for up to 2 years if you stop treatment for other reasons than disease progression. Participants need to follow specific health guidelines to ensure safety and accurate results.