Tafamidis, a potent and selective transthyretin kinetic stabilizer that inhibits the amyloid cascade.

Abstract

The transthyretin amyloidoses (ATTR) are invariably fatal diseases characterized by progressive neuropathy and/or cardiomyopathy. ATTR are caused by aggregation of transthyretin (TTR), a natively tetrameric protein involved in the transport of thyroxine and the vitamin A-retinol-binding protein complex. Mutations within TTR that cause autosomal dominant forms of disease facilitate tetramer dissociation, monomer misfolding, and aggregation, although wild-type TTR can also form amyloid fibrils in elderly patients. Because tetramer dissociation is the rate-limiting step in TTR amyloidogenesis, targeted therapies have focused on small molecules that kinetically stabilize the tetramer, inhibiting TTR amyloid fibril formation. One such compound, tafamidis meglumine (Fx-1006A), has recently completed Phase II/III trials for the treatment of Transthyretin Type Familial Amyloid Polyneuropathy (TTR-FAP) and demonstrated a slowing of disease progression in patients heterozygous for the V30M TTR mutation. Herein we describe the molecular and structural basis of TTR tetramer stabilization by tafamidis. Tafamidis binds selectively and with negative cooperativity (K(d)s ~2 nM and ~200 nM) to the two normally unoccupied thyroxine-binding sites of the tetramer, and kinetically stabilizes TTR. Patient-derived amyloidogenic variants of TTR, including kinetically and thermodynamically less stable mutants, are also stabilized by tafamidis binding. The crystal structure of tafamidis-bound TTR suggests that binding stabilizes the weaker dimer-dimer interface against dissociation, the rate-limiting step of amyloidogenesis.

• Authors: Christine E Bulawa, Stephen Connelly, Michael Devit, Lan Wang, Charlotte Weigel, James A Fleming, Jeff Packman, Evan T Powers, R Luke Wiseman, Theodore R Foss, Ian A Wilson, Jeffery W Kelly, Richard Labaudinière
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 109 Issue 24 Pg. 9629-34 (Jun 12 2012) ISSN: 1091-6490 [Electronic] United States
• PMID: 22645360 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Amyloid
• Benzoxazoles
• Prealbumin
• tafamidis

Topics

• Amyloid (antagonists & inhibitors)
• Benzoxazoles (pharmacology)
• Binding Sites
• Humans
• Kinetics
• Models, Molecular
• Prealbumin (metabolism)