Effects of Acoramidis on Kidney Function in Transthyretin Amyloid Cardiomyopathy

BACKGROUND: Acoramidis achieves near-complete (≥90%) transthyretin stabilization and is approved to reduce cardiovascular-related hospitalization in transthyretin amyloid cardiomyopathy. Its effects on kidney function are not well characterized. METHODS: Data from randomized phase 2 (N=49) and phase 3 (N=632) studies in transthyretin amyloid cardiomyopathy were included. The estimated glomerular filtration rate (eGFR) slope was generated using a linear spline mixed-effects model. The urinary albumin-to-creatinine ratio was measured longitudinally. Relationships between changes in kidney function and clinical outcomes were explored using Cox proportional hazards models. RESULTS: Acoramidis initiation resulted in a modest acute dip in eGFR that was dose-dependent, reversible, and not associated with adverse kidney-related events. At Day 28, the mean (±SE) dip in eGFR from baseline with acoramidis was 8.5±0.48 mL/min per 1.73 m 2 ; the placebo-corrected reduction in the urinary albumin-to-creatinine ratio was 15.5% (95% CI, 0.4%–28.4%; P =0.044). The rate of decline in kidney function (chronic eGFR slope) was significantly improved with acoramidis versus placebo (−1.01 versus −3.48 mL/min per 1.73 m 2 per year; P <0.001), and the reduction in the urinary albumin-to-creatinine ratio was sustained (13.7% [95% CI, 1.7%–24.2%]; P =0.026) over time. Concomitant tafamidis use did not influence the chronic eGFR slope in either arm. Comparing acoramidis versus placebo subgroups with acute eGFR dips ≥ the median (4.89 mL/min per 1.73 m 2 ) favored acoramidis for all-cause mortality or cardiovascular-related hospitalization (hazard ratio, 0.42 [95% CI, 0.22–0.78]; P =0.006; P interaction=0.043) and cardiovascular-related hospitalization (hazard ratio, 0.34 [95% CI, 0.17–0.66]; P =0.002, P interaction=0.025). Within the placebo arm, eGFR dips portended worse outcomes. CONCLUSIONS: Acoramidis initiation resulted in an acute dip in eGFR and reductions in both the chronic eGFR slope and urinary albumin-to-creatinine ratio versus placebo without adverse kidney-related events. Acoramidis effects on kidney function may be mediated through direct kidney-protective hemodynamic effects. Importantly, the acute dip in eGFR was associated with a reduced risk of adverse clinical outcomes within the first year. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03458130. URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03536767. URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03860935. URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04988386.