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. (2nd January 2023)

• Record Type: Journal Article
• Authors: Monteiro, Cecília; Mesgarzadeh, Jaleh S.; Anselmo, João; Fernandes, Joana; Novais, Marta; Rodrigues, Carla; Powers, David L.; Powers, Evan T.; Coelho, Teresa; Kelly, Jeffery W.
• Is Part Of: Amyloid. Volume 30:Number 1(2023)
• Page Start: 81
• Page End: 95
• Publication Date: 2023-01-02
• Subjects: Amyloid -- hereditary TTR amyloid polyneurophathy (ATTRv-PN) -- kinetic stabilisation -- tafamidis -- transthyretin (TTR); Amyloidosis -- Periodicals; 616.3995
• DOI: 10.1080/13506129.2022.2126308
• Languages: English
• ISSNs: 1350-6129

Abstract

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.