BACKGROUND: Acoramidis achieves near-complete (≥90%) transthyretin stabilization and is approved to reduce cardiovascular-related mortality and 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 identifiers: NCT03458130, NCT03536767, NCT03860935, NCT04988386.
Long-Term Efficacy and Safety of Acoramidis in ATTR-CM: Initial Report From the Open-Label Extension of the ATTRibute-CM Trial
BACKGROUND: In the phase 3 randomized controlled study ATTRibute-CM (Efficacy and Safety of AG10 in Subjects With Transthyretin Amyloid Cardiomyopathy), acoramidis, a transthyretin stabilizer, demonstrated significant efficacy on the primary end point. Participants with transthyretin amyloid cardiomyopathy who completed ATTRibute-CM were invited to enroll in an open-label extension study (OLE). We report the efficacy and safety data of acoramidis in participants who completed ATTRibute-CM and enrolled in the ongoing OLE. METHODS: Participants who previously received acoramidis through month 30 in ATTRibute-CM continued to receive it (continuous acoramidis), and those who received placebo through month 30 were switched to acoramidis (placebo to acoramidis). Participants who received concomitant tafamidis in ATTRibute-CM were required to discontinue it to be eligible to enroll in the OLE. Clinical efficacy outcomes analyzed through month 42 included time to event for all-cause mortality (ACM) or first cardiovascular-related hospitalization (CVH), ACM alone, first CVH alone, ACM or recurrent CVH, change from baseline in NT-proBNP (N-terminal pro-B-type natriuretic peptide), 6-minute walk distance, serum transthyretin, and Kansas City Cardiomyopathy Questionnaire Overall Summary score. Safety outcomes were analyzed through month 42. RESULTS: Overall, 438 of 632 participants in ATTRibute-CM completed treatment, and 389 enrolled in the ongoing OLE (263 continuous acoramidis and 126 placebo to acoramidis). The hazard ratio for ACM or first CVH was 0.57 (95% CI, 0.46–0.72) at month 42 based on a stratified Cox proportional hazards model ( P <0.0001) favoring continuous acoramidis. Similar analyses were performed on ACM alone and first CVH alone, with hazard ratios of 0.64 (95% CI, 0.47–0.88) and 0.53 (95% CI, 0.41–0.69), respectively, at month 42. Treatment effects for NT-proBNP and 6-minute walk distance also favored continuous acoramidis. On initiation of open-label acoramidis in the placebo-to-acoramidis arm, there was a prompt increase in serum transthyretin. Quality of life assessed by Kansas City Cardiomyopathy Questionnaire Overall Summary score was well preserved in continuous-acoramidis participants compared with the placebo-to-acoramidis participants. No new clinically important safety issues were identified in this long-term evaluation. CONCLUSIONS: Early initiation and continuous use of acoramidis in the ATTRibute-CM study through month 42 of the ongoing OLE study were associated with sustained clinical benefits in a contemporary transthyretin amyloid cardiomyopathy cohort, with no clinically important safety issues newly identified. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04988386.