Tafamidis polyneuropathy amelioration requires modest increases in transthyretin stability even though increases in plasma native TTR and decreases in non-native TTR do not predict response.

Abstract

BACKGROUND:

TTR aggregation causes hereditary transthyretin (TTR) polyneuropathy (ATTRv-PN) in individuals with destabilised TTR variants. ATTRv-PN can be treated with ligands that bind TTR and prevent aggregation. One such ligand, tafamidis, is widely approved to treat ATTRv-PN. We explore how TTR stabilisation markers relate to clinical efficacy in 210 ATTRv-PN patients taking tafamidis.

METHODS:

TTR concentration in patient plasma was measured before and after tafamidis treatment using assays for native or combined native + non-native TTR. TTR tetramer dissociation kinetics, which are slowed by tafamidis binding, were also measured.

RESULTS:

Native TTR levels increased by 56.8% while combined native + non-native TTR levels increased by 3.1% after 24 months of tafamidis treatment, implying that non-native TTR decreased. Accordingly, the fraction of native TTR increased from 0.54 to 0.71 with tafamidis administration. Changes in native and non-native TTR levels were uncorrelated with clinical response to tafamidis. TTR tetramer dissociation generally slowed to an extent consistent with ∼40% of TTR being tafamidis-bound. Male non-responders had a lower extent of binding.

CONCLUSIONS:

Native and non-native TTR concentration changes cannot be used as surrogate measures for therapeutic efficacy. Also, successful tafamidis therapy requires only moderate TTR stabilisation. Male patients may benefit from higher tafamidis doses.

• Authors: Cecília Monteiro, Jaleh S Mesgarzadeh, João Anselmo, Joana Fernandes, Marta Novais, Carla Rodrigues, David L Powers, Evan T Powers, Teresa Coelho, Jeffery W Kelly
• Journal: Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis (Amyloid) Vol. 30 Issue 1 Pg. 81-95 (Mar 2023) ISSN: 1744-2818 [Electronic] England
• PMID: 36178172 (Publication Type: Journal Article)

Chemical References

• tafamidis
• Prealbumin
• Benzoxazoles

Topics

• Humans
• Male
• Amyloid Neuropathies, Familial (drug therapy, genetics)
• Prealbumin (genetics, metabolism)
• Polyneuropathies (drug therapy, genetics)
• Benzoxazoles (pharmacology, therapeutic use)