 The study is being conducted to determine the safety, tolerability and maximum tolerated dose of Venetoclax and dexamethasone in relapsed or refractory amyloid light chain AL amyloidosis patients. AL amyloidosis is a disease involving cells called plasma cells that make antibodies as part of your immune system. These cells are not functioning the way they are supposed to and they start to produce abnormal fragments of antibodies that are toxic to your body and can form amyloid. The antibody fragments are called light chains. They can cause damage to organs, especially the kidneys, heart, skin, liver, and lungs. 