How is A amyloidosis (AA) treated?

Updated: Nov 12, 2018
  • Author: Robert O Holmes, Jr, DO; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Answer

Therapy has traditionally been aimed at the underlying inflammatory condition to reduce the production of the precursor amyloid protein, SAA. Disease-modifying antirheumatic drugs (DMARDs) such as colchicine, a microtubule inhibitor and weak immunosuppressant, can prevent secondary renal failure due to amyloid deposition specifically in familial Mediterranean fever.

Newer therapies have become more targeted to avoid the cytotoxicity of older agents (eg, chlorambucil, cyclophosphamide). The SAA amyloid seen in CAPS was reduced with a biologic interleukin (IL)–1β trap called rilonacept.

Tumor necrosis factor–alpha (TNF-alpha) is also thought to be involved in amyloid deposition. [29] Aggressive use of newer biologic therapies for RA, such as etanercept (a TNF-alpha blocker), and tocilizumab [30] have been used to decrease the concentration of SAA, serum creatinine, creatinine clearance, and proteinuria in renal AA associated with RA. [31] One study compared etanercept with tocilizumab and showed that IL-6 inhibition may be a more effective therapy. [32]

Additionally, SAA isoforms have been studied using high-resolution 2-dimensional gel electrophoresis and peptide mapping by reverse-phase chromatography, electrospray ionization tandem mass spectrometry, and genetic analysis down to the post-translational modification level. [33] SAA is coded by 4 genes: SAA1, AAA2, SAA3, and SAA4. The SAA1 gene contributes to most of the deposits and contains a single nucleotide polymorphism that defines at least 3 haplotypes. The saa1.3 allele was found to be a risk factor and a poor prognostic indicator in Japanese RA patients. Genetic analysis has proved useful in selecting patients for biologic therapy and for predicting outcome. [34] Early treatment is essential to prevent the long-term sequelae of AA. [35]


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