Abstract 4365531: Acoramidis Effect on All-Cause Mortality in Patients with p.V142I (V122I) Variant ATTR-CM: Findings From the ATTRibute-CM Study

Introduction: Transthyretin (TTR) amyloid cardiomyopathy (ATTR-CM) arises from amyloidogenic aggregates of destabilized TTR protein in variant (ATTRv-CM) or acquired wild-type TTR (ATTRwt-CM). The p.V142I (V122I) variant is the most common pathogenic TTR allele in the USA and has higher mortality vs wild type. Acoramidis, an oral TTR stabilizer achieving ≥90% stabilization, is approved in USA, UK, Europe, and Japan for treating ATTR-CM in adults. In ATTRibute-CM (NCT03860935), acoramidis showed a reduction in all-cause mortality (ACM) or first cardiovascular-related hospitalization (CVH) vs placebo (PBO), with consistent benefit in ATTRwt-CM and ATTRv-CM (all variants). We report clinical outcomes in participants with p.V142I ATTRv-CM. Research Question: What was the efficacy of acoramidis for clinical outcomes (ACM, CVH) in participants with p.V142I ATTRv-CM in ATTRibute-CM? Methods: In ATTRibute-CM, 632 participants were randomized 2:1 to receive acoramidis HCl 800 mg or PBO twice daily for 30 months. All participants enrolled in open-label extension (OLE) received acoramidis only. Exploratory post hoc analyses were done in the p.V142I ATTRv-CM subgroup. Time-to-event analyses used a stratified Cox proportional hazards model using treatment group as an explanatory factor and baseline 6MWD as a covariate, stratified by randomization factors: serum NT-proBNP and eGFR. ACM was analyzed at Month 42 (ATTRibute-CM 30 months + 12 months OLE). Results: Of the 59 patients with ATTRv-CM reported at randomization, 35 (59.3%) had p.V142I (23 acoramidis, 12 PBO) with comparable baseline characteristics; 4 were homozygous for p.V142I (1 acoramidis, 3 PBO). Through Month 30, ACM/first CVH occurred in 43.5% (10/23) of acoramidis vs 83.3% (10/12) in PBO (HR 0.311; 95% CI 0.120–0.805; Figure 1 ). Through Month 42, ACM occurred in 26.1% (6/23) of continuous acoramidis vs 66.7% (8/12) in PBO to acoramidis (HR 0.307; 95% CI 0.097–0.973; Figure 2 ). Conclusions: In participants with p.V142I ATTRv-CM, acoramidis use was associated with 69% risk reduction in ACM/first CVH through Month 30 and ACM through Month 42 vs PBO. This is the first report of clinical benefit of this magnitude observed in this high-risk population. These findings have biologic plausibility and may reflect the near-complete stabilization observed experimentally with acoramidis in p.V142I ATTR fibrils. These observations require confirmation in larger cohort studies.