The present invention relates to the use of substituted quinoline compounds for treating immunoglobulin light chain (LC) amyloidosis (AL), especially cardiotoxicity associated with immunoglobulin LC AL. In particular, the substituted quinoline compounds useful in the treatment of cardiac LC amyloidosis are 5,7-dihalo-8-hydroxyquinoline derivatives, especially 5,7-dichloro-8-hydroxyquinoline derivatives.