This clinical trial is focused on studying a condition known as Immunoglobulin Light-Chain (AL) Amyloidosis. This is a disease where abnormal proteins, called amyloids, build up in organs and tissues, affecting their normal function. The trial will use a treatment called teclistamab, which is a solution for injection. Teclistamab is a type of medication known as a BiTE, or bispecific T-cell engager, which is designed to help the immune system target and destroy abnormal cells.

The purpose of the study is to evaluate how well teclistamab works in patients who have previously been treated for AL amyloidosis. Participants will receive teclistamab injections under the skin over a period of time. The study will monitor the response of the disease to the treatment after three cycles, which are periods of treatment followed by rest. The study will also look at how long the response lasts, how the organs affected by the disease respond, and the overall safety and tolerability of the treatment.

Throughout the study, participants will be regularly assessed to see how their condition is responding to the treatment. This includes checking for any changes in their health and any side effects they might experience. The study aims to provide valuable information on the effectiveness and safety of teclistamab for people with AL amyloidosis, potentially leading to better treatment options in the future.