This study aims to test a new treatment for people with relapsed or refractory multiple myeloma (RR/MM). Multiple myeloma is a type of blood cancer. The treatment being studied is called OriCAR-017, which is a special kind of cell product designed to target a protein called GPRC5D. This is a Phase I/II study, meaning it's in the early stages of testing. It will check how safe the treatment is, how it moves and acts in the body (pharmacokinetics and pharmacodynamics), and if it seems to be working.

The study involves different stages. The first stage will test three different doses in 18 people. The next stages will include more people to further check the treatment's effects. Participants need to be 18 to 75 years old and meet specific health criteria. The study will not accept pregnant women, people with certain infections, or those who have had recent stem cell treatments.

• The study involves multiple stages and will require several visits.
• Participants need to have had certain previous treatments.
• Effective contraceptive measures are required for two years after treatment.