A key feature of a number of diseasesmost noticeably Alzheimer'sis the presence of so-called amyloid deposits comprised of insoluble clumps of proteins that kill surrounding cells. A naturally occurring protein present in the bloodstream known as serum amyloid P component (SAP) aids these plaques in destroying healthy tissue by binding to the amyloid fibers and preventing the body from breaking them down. Findings published today in the journal Nature suggest that a drug designed to thwart the action of SAP holds promise for treating human amyloid diseases.
Mark Pepys of the Royal Free and University College Medical School in London and his colleagues targeted SAP with a new drug called CPHPC. The molecule blocks the binding of SAP to amyloid fibers and instead causes SAP molecules to bind to one another. These SAP protein packs are then removed from the bloodstream and metabolized by the liver. In mice, administering the drug removed SAP from plaques and led to a gradual reduction in the size of the deposits. The researchers also tested CPHPC on 19 patients suffering from systemic amyloidosis, a disease in which protein clumps form throughout the body. They found that SAP levels in the blood were reduced without adverse side effects. According to the report, continued treatment with CPHPC is most likely required to completely clear SAP from major amyloid deposits and maximize the reduction in the plaques.
Exactly what the results will mean for treatment of Alzheimer's disease so far remains unclear. Says Pepys, "Although amyloid deposits are closely related with Alzheimer's disease and maturity onset diabetes, it is not known whether they actually cause these diseases." Whether CPHPC can combat the memory-robbing disease is the focus of clinical trials set to start this year.