Additional Study Information: The purpose of this study is to test for any good and bad effects of the study drug called isatuximab. Isatuximab may or may not improve your AL amyloidosis, but it could also cause side effects. Isatuximab is not approved by the Food and Drug Administration (FDA). Isatuximab has been shown to have good effects in some patients with recurring multiple myeloma. For this reason, the researchers think that isatuximab may also help patients whose amyloidosis has recurred or gotten worse. To decide if the study treatment is better than the usual approach, the study doctors will be looking to see if the study treatment increases the number of patients whose cancer responds to treatment by at least 30 percent.