Tafamidis delays neurological progression comparably across Val30Met and non-Val30Met genotypes in transthyretin familial amyloid polyneuropathy

Background and purpose: To better characterize the effects of tafamidis in non-Val30Met patients with transthyretin familial amyloid polyneuropathy, this post hoc analysis compared the neurological results from a 12-month, open-label study of non-Val30Met versus Val30Met patients at month 12 from the 18-month, double-blind, placebo-controlled registration study. A baseline covariate adjusted analysis was used to control for differences in baseline neurological severity.

Methods: Neurological function was assessed using the Neuropathy Impairment Score - Lower Limbs (NIS-LL) in three cohorts: Val30Met tafamidis (n = 64), Val30Met placebo (n = 61) and non-Val30Met tafamidis (n = 21). The change in NIS-LL from baseline to month 12 for Val30Met and non-Val30Met tafamidis-treated patients was compared with the change from baseline at month 12 for Val30Met placebo-treated patients using a mixed-effects model for repeated measures (MMRM).

Results: The baseline adjusted mean (standard error) change in NIS-LL values at month 12 was similar for Val30Met [1.60 (0.78)] and non-Val30Met [1.62 (1.43)] tafamidis-treated patients and less than that observed in the Val30Met placebo-treated group [4.72 (0.77); P = 0.0055 for Val30Met and P = 0.0592 for non-Val30Met]. Based on the MMRM, the magnitude of change in both tafamidis-treated cohorts was similar across the range of observed baseline NIS-LL values, and was consistently less than that observed in the Val30Met placebo-treated group at month 12.

Conclusions: This baseline-adjusted analysis demonstrated that tafamidis treatment delayed neurological progression comparably in Val30Met and non-Val30Met patients across a range of baseline NIS-LL values. Neurological progression in these two genotype groups may be more similar than previously considered.