BACKGROUNDDeposition of amyloid fibrils derived from circulating acute-phase reactant serum amyloid A protein (SAA) causes systemic AA amyloidosis, a serious complication of many chronic inflammatory disorders. Little is known about the natural history of AA amyloidosis or its response to treatment.
METHODSWe evaluated clinical features, organ function, and survival among 374 patients with AA amyloidosis who were followed for a median of 86 months. The SAA concentration was measured serially, and the amyloid burden was estimated with the use of whole-body serum amyloid P component scintigraphy. Therapy for inflammatory diseases was administered to suppress the production of SAA.
RESULTSMedian survival after diagnosis was 133 months; renal dysfunction was the predominant disease manifestation. Mortality, amyloid burden, and renal prognosis all significantly correlated with the SAA concentration during follow-up. The risk of death was 17.7 times as high among patients with SAA concentrations in the highest eighth, or octile, (≥155 mg per liter) as among those with concentrations in the lowest octile (<4 mg per liter); and the risk of death was four times as high in the next-to-lowest octile (4 to 9 mg per liter). The median SAA concentration during follow-up was 6 mg per liter in patients in whom renal function improved and 28 mg per liter in those in whom it deteriorated (P<0.001). Amyloid deposits regressed in 60% of patients who had a median SAA concentration of less than 10 mg per liter, and survival among these patients was superior to survival among those in whom amyloid deposits did not regress (P = 0.04).
CONCLUSIONSThe effects of renal dysfunction dominate the course of AA amyloidosis, which is associated with a relatively favorable outcome in patients with SAA concentrations that remain in the low-normal range (<4 mg per liter).
High-dose melphalan with stem-cell transplantation is believed to be the most effective treatment for systemic lightchain (AL) amyloidosis, but many patients are ineligible because of the extent of their disease, and treatment-related mortality (TRM) remains substantial. We report the use of a risk-adapted oral regimen of cyclophosphamide, thalidomide, and dexamethasone (CTD) or attenuated CTD (
SummarySerum amyloid P component (SAP) is a universal constituent of amyloid deposits and contributes to their formation and/or persistence. We therefore developed CPHPC ((R)-1-[6-[(R)-2-carboxy-pyrrolidin-1-yl]-6-oxo-hexanoyl]pyrrolidine-2 carboxylic acid), a novel bis(D-proline) drug, to specifically target SAP and report here a first, exploratory, open label proof of principle study in systemic amyloidosis. CPHPC produced sustained, >95% depletion of circulating SAP in all patients and c. 90% reduction in the SAP content of the two amyloidotic organs that became available. There were no significant adverse effects of either SAP depletion or CPHPC itself. No accumulation of amyloid was demonstrable by SAP scintigraphy in any patient on the drug. In hereditary fibrinogen amyloidosis, which is inexorably progressive, proteinuria was reduced in four of five patients receiving CPHPC and renal survival was prolonged compared to a historical control group. These promising clinical observations merit further study.
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