This study is for people with a type of blood cancer called multiple myeloma (MM), which has returned after treatment or didn't respond to treatment. The study will compare a new drug, anitocabtagene autoleucel, to standard treatments. The main goal is to see which treatment helps people live longer without the cancer getting worse. People in the study will be followed up for 15 years to check long-term effects.

• The study is open to those who've had 1-3 treatments before, including specific medicines like immunomodulatory drugs (IMiDs) and anti-CD38 antibodies.
• Participants cannot join if they've had certain types of treatments before or have other serious health conditions.
• The study requires regular visits and tests, and participants must be able to receive one of the standard treatment options.

Participants must have a good overall health status (ECOG performance status of 0 or 1), and women who can have children need a negative pregnancy test. This study may help improve future treatments for MM, but there are specific criteria to meet before joining.