Therapeutic compounds and methods for modulating amyloid deposition in a subject, whatever its clinical setting, are described. Amyloid deposition is modulated by the administration to a subject of an effective amount of a therapeutic compound comprising a phosphonate group and a carboxylate group, a congener thereof, or a pharmaceutically acceptable salt or ester thereof. In preferred embodiments, an interaction between an amyloidogenic protein and a basement membrane constituent is modulated.