Fox, Jonathan C.

Importance Transthyretin amyloid cardiomyopathy (ATTR-CM), a progressive disease caused by misfolded transthyretin (TTR), occurs as wild-type (ATTRwt-CM) or variant (ATTRv-CM) forms. p.Val142Ile is the most common variant in the US, linked to rapid progression and increased mortality. Acoramidis achieves near-complete (≥90%) TTR stabilization and showed clinical benefit in the 30-month ATTRibute-CM trial and through month 42 in the ongoing open-label extension (OLE). Objective To evaluate the efficacy of acoramidis in ATTRwt-CM, ATTRv-CM, and variant subgroups (p.Val142Ile and non-p.Val142Ile). Design, Setting, and Participants This international, multicenter, phase 3, randomized placebo-controlled study took place from April 2019 to May 2023 with ongoing OLE (month 42). ATTRibute-CM enrolled 632 participants with ATTR-CM; 611 of 632 were included in the modified intention-to-treat (mITT) population. There were 380 participants who continued into the OLE. These data were analyzed from January 2025 to July 2025. Interventions Oral acoramidis, 712 mg, or placebo twice daily for 30 months, followed by 12 months of open-label treatment. Main Outcomes and Measures All-cause mortality (ACM), cardiovascular-related hospitalizations (CVH), serum TTR, 6-minute walk distance, Kansas City Cardiomyopathy Questionnaire Overall Summary score, and N-terminal pro B-type natriuretic peptide in participants with ATTRwt-CM and ATTRv-CM. Post-hoc analyses were conducted in variant subgroups, including p.Val142Ile. Results Overall, 552 participants with wild-type ATTR-CM (mean [SD] age, 78 [6.3] years; 92.0% male and 8.0% female) and 59 participants with variant ATTR-CM (mean [SD] age, 73 [7.7] years; 77.3% male and 22.7% female) were randomized (mITT population), including 35 with p.Val142Ile. Consistent efficacy was observed in wild-type and variant subgroups for ACM/CVH through month 30 and ACM through month 42. At month 30, acoramidis reduced the risk of ACM/first CVH vs placebo by 31% in ATTRwt-CM (hazard ratio [HR], 0.69; 95% CI, 0.52-0.90; P = .007) and by 59% in ATTRv-CM (HR, 0.41; 95% CI, 0.21-0.81; P = .01). ACM was reduced through month 42 with HRs of 0.70 (95% CI, 0.50-0.98; P = .04) and 0.41 (95% CI, 0.19-0.93; P = .03) in the ATTRwt-CM and ATTRv-CM groups, respectively. Consistent treatment benefit was observed in participants with ATTRwt-CM and ATTRv-CM for secondary end points. Within variant subgroups (p.Val142Ile vs non-p.Val142Ile), consistent treatment benefits were observed for ACM/CVH through month 30 and ACM through month 42. Conclusions and Relevance The beneficial effect of acoramidis was observed consistently in ATTRwt-CM and ATTRv-CM groups. These hypothesis-generating results indicate that further studies are warranted to better characterize the therapeutic benefit of acoramidis in variant subgroups. Trial Registration ClinicalTrials.gov Identifiers: NCT03860935 ; NCT04988386

Introduction: Acoramidis, an oral transthyretin (TTR) stabilizer achieving near-complete (≥90%) TTR stabilization, is now approved in the USA, EU, Japan, and UK for the treatment of TTR amyloid cardiomyopathy (ATTR-CM). In the 30-month phase 3 ATTRibute-CM study, acoramidis reduced all-cause mortality (ACM) or first cardiovascular-related hospitalization (CVH) vs placebo. Through Month 42 (M42) of the open-label extension (OLE; 30 months ATTRibute-CM + 12 months OLE), the clinical benefit of acoramidis was sustained, resulting in a 36% and 43% risk reduction in ACM and ACM/first CVH, respectively, compared with the placebo to acoramidis group Research Question: Are the long-term clinical benefits of acoramidis on ACM and ACM/first CVH in ATTR-CM over 42 months consistent across patient subgroups? Methods: ATTRibute-CM study design has been previously described. At the end of the 30-month double-blind period, patients enrolled into OLE continued acoramidis or switched from placebo to acoramidis; all patients received open-label acoramidis HCI 800 mg BID. Data cut was performed after 12 months in OLE. Subgroup analysis for ACM and ACM/first CVH through M42 were conducted for randomization stratification factors (genotype, NT-proBNP, and eGFR levels) and other pre-specified subgroups. ACM included death due to any cause, cardiac mechanical assist device placement, and heart transplant. CVH included CV hospitalizations (≥24 h) and urgent visits (<24 h) for decompensated heart failure requiring IV diuretics and was adjudicated by an independent Clinical Events Committee. Results: Overall, 389 patients enrolled in the OLE (263 continuous acoramidis and 126 placebo to acoramidis). The analyses of ACM/first CVH ( Figure 1 ) and ACM ( Figure 2 ) through M42 consistently favored patients initially randomized to acoramidis across all patient subgroups, including those based on sex, age, country, ATTR-CM genotype, baseline NT-proBNP, baseline eGFR, NYHA class, and NAC stage. The largest effect size for the reduction in ACM/first CVH (HR <0.50) was observed in the following subgroups: female, non-Caucasian patients, variant ATTR-CM, or NAC stage 2. Conclusions: The long-term benefit of acoramidis was consistently shown in patients initially randomized to acoramidis treatment compared with placebo to acoramidis switch after 30 months across multiple clinically relevant subgroups, underscoring the importance of early initiation of acoramidis to reduce the long-term risk of ACM or CVH.