**Study Overview**: This clinical trial is testing a new treatment called **NXC-201 CAR-T** for patients diagnosed with a type of disease called **light chain (AL) amyloidosis**. This condition occurs when abnormal proteins called light chains build up in the body's organs, causing problems. **CAR-T therapy** is a type of treatment that uses a patient's own immune cells to fight the disease. **Study Process**: Participants will first undergo **leukapheresis**, a procedure where blood is taken from the body to collect white blood cells. After a month, they will receive medications called **Cyclophosphamide** and **Fludarabine** to prepare their bodies for the infusion of **NXC-201 CAR-T cells**. These cells are administered on **Day 0**. **Key Points**: - **Study Duration**: The study involves multiple steps and may require hospital visits. - **Eligibility**: Participants need to be at least 18 years old, have had certain treatments previously, and meet specific health criteria. - **Risks/Benefits**: While the study aims to find a new treatment, there could be potential risks or side effects. Compensation details are not mentioned. Participants must be willing to follow strict guidelines, including using birth control and attending all required visits.