Maurer, Mathew S.

BACKGROUND: Transthyretin amyloidosis with cardiomyopathy is a progressive, fatal disease characterized by deposition of extracellular misfolded transthyretin (TTR) in the myocardium. Eplontersen is an N-acetylgalactosamine ligand–conjugated antisense oligonucleotide targeting hepatocyte TTR messenger RNA to reduce the production of circulating TTR. METHODS: CARDIO-TTRansform is a Phase 3, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of eplontersen in transthyretin amyloidosis with cardiomyopathy. Key inclusion criteria include histological evidence of amyloid deposits or grade 2 to 3 cardiac uptake on cardiac scintigraphy in the absence of plasma cell dyscrasia, New York Heart Association class I–III, and end-diastolic interventricular septum thickness >12 millimeters. Participants were randomized 1:1 to receive eplontersen 45 mg or placebo, administered subcutaneously every 4 weeks for up to 140 weeks, followed by a 20-week post-treatment evaluation period or open-label extension. Participants received locally available standard of care, including unrestricted use of TTR stabilizers. The primary end point is a composite of cardiovascular mortality and recurrent clinical cardiovascular events through 140 weeks. Secondary end points, in order of testing hierarchy, include changes from baseline in 6-minute walk distance and Kansas City Cardiomyopathy Questionnaire overall summary score, recurrent cardiovascular events, all-cause mortality, the primary end point in the patient subgroup receiving stabilizers at baseline, and cardiovascular mortality. Echocardiography was performed in all participants, with cardiovascular magnetic resonance imaging and technetium scintigraphy in a subset. CONCLUSIONS: CARDIO-TTRansform is fully enrolled, with 1432 randomized participants who were dosed with study drug or placebo. As the largest transthyretin amyloidosis with cardiomyopathy study to date, it will evaluate whether eplontersen improves cardiovascular outcomes in patients receiving locally available standard of care, including TTR stabilizers. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04136171. URL: http://ClinicalTrialsRegister.eu ; Unique identifier: EudraCT number 2019-002835-27.

Background Transthyretin amyloid cardiomyopathy (ATTR‐CM) has a specific pathophysiology, with myocardial stiffening and systolic dysfunction only in advanced stages. We aimed to investigate the response to cardiac resynchronization therapy (CRT) in ATTR‐CM compared with heart failure. Methods In this multicenter, observational study, patients with ATTR‐CM receiving CRT (n=101) were matched to patients without amyloid cardiomyopathy by sex, age, and implantation type (CRT with versus without defibrillator versus conduction system pacing, upgrade versus first implant). We evaluated changes in QRS duration and echocardiographic parameters following CRT implantation and at the most recent available assessments. The study end points were all‐cause death alone or combined with heart failure hospitalization. Results Patients with ATTR‐CM (median age, 76 [interquartile range, 72–83] years, 98% men, left ventricular (LV) ejection fraction 30% [26–33]) showed greater QRS shortening after CRT implantation ( P =0.012), but not after a median of around 1 year ( P =0.152). There were no significant differences in the absolute LV ejection fraction changes immediately after implantation (+7 [+2/+10] versus +3 [0/+9] units; P =0.124), or to the last echo ( P =0.796), which was performed after 1.3 years in patients with ATTR‐CM and 2.9 years in patients without amyloid cardiomyopathy. Patients with ATTR‐CM had a shorter survival than controls ( P <0.001 for both end points). Patients with ATTR‐CM experiencing an early improvement in LV ejection fraction had a longer survival (log‐rank, 4.3; P =0.038). Conclusions Following CRT implantation, patients with ATTR‐CM show QRS narrowing and improvement in LV ejection fraction, not different from patients without amyloid cardiomyopathy. Early favorable LV remodeling seems to be associated with a lower risk of all‐cause death.

BACKGROUND: Transthyretin amyloidosis with cardiomyopathy is a progressive disease caused by the deposition of transthyretin (TTR) as amyloid in the myocardium. Current therapies may slow disease progression but do not clear existing deposits. Coramitug is a humanized monoclonal antibody that targets misfolded transthyretin, designed to promote clearance of transthyretin amyloid through antibody-mediated phagocytosis. METHODS: This phase 2, double-blind, placebo-controlled trial randomized participants with transthyretin amyloidosis with cardiomyopathy to receive infusions every 4 weeks of either coramitug at 2 dosages (10 mg/kg or 60 mg/kg) or placebo in a 1:1:1 ratio for 52 weeks. The primary end points were the change from baseline to week 52 in the 6-minute walk test and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels. Safety was assessed for up to 64 weeks by assessing treatment-emergent adverse events, all-cause mortality, and number of cardiovascular events (comprising hospitalization caused by cardiovascular events or urgent heart failure visits). RESULTS: In total, 104 participants (median age, 77 years; 93% men; 84% New York Heart Association class II; 13% with variant transthyretin amyloidosis with cardiomyopathy) were randomized and dosed: 34 to 10 mg/kg of coramitug, 35 to 60 mg/kg of coramitug, and 35 to placebo. Median NT-proBNP was 1985 pg/mL (interquartile range, 1224, 3406). In total, 90% of participants were receiving disease-modifying therapy; 84% were treated with tafamidis and 7 (6.7%) with transthyretin silencers (patisiran, n=4; vutrisiran, n=3). From baseline to week 52, 60 mg/kg of coramitug significantly reduced NT-proBNP levels compared with placebo (–48% [95% CI, –65% to –22%]; P =0.0017). The change in 6-minute walk test from baseline to week 52 was not statistically different from placebo with either dose. Coramitug (60 mg/kg) was associated with improved functional echocardiographic parameters and was well tolerated. CONCLUSIONS: This phase 2 trial showed that coramitug, an antibody targeting misfolded transthyretin in transthyretin amyloidosis with cardiomyopathy, was well tolerated and, at a dose of 60 mg/kg, resulted in a statistically significant reduction in NT-proBNP, a validated marker of disease progression, with no statistically significant effect on 6-minute walk test within 52 weeks. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05442047.

Introduction: Patients with transthyretin amyloid cardiomyopathy (ATTR-CM) typically have low serum transthyretin (sTTR) levels, worsening heart failure, and increased mortality. A recent study has shown the association of sTTR levels ≥20mg/dL with reduced risk of all-cause mortality and cardiovascular mortality (CVM). It has also been shown that regardless of baseline sTTR level, greater increases in sTTR levels are associated with greater improvements in cardiovascular outcomes. Acoramidis, a near-complete (≥90%) TTR stabilizer, demonstrated a rapid and sustained increase from baseline in sTTR by Day 28 and reduced risk of cardiovascular outcomes in patients with ATTR-CM. Hypothesis: Acoramidis-mediated early increase in sTTR levels ≥20 mg/dL (lower limit of normal) at Day 28 reduces risks of CVM and cardiovascular-related hospitalizations (CVH) in patients with ATTR-CM. Methods: Analyses were conducted in the ATTRibute-CM modified intention-to-treat (mITT) population (acoramidis: 409; placebo: 202). The sTTR concentrations (normal range is 20-40 mg/dL) were assessed using an immunoturbidimetric method (Abbott ARCHITECT system) in a central laboratory. The proportion of participants with sTTR levels below normal at baseline and Day 28 were determined. The relationship between sTTR levels <20 or ≥20 mg/dL, at Day 28 across the pooled acoramidis and placebo treatment groups, and subsequent risk of CVM and of CVH over 30 months were analyzed using a stratified log-rank test. Results: At baseline about 25% of study participants had sTTR levels below normal in both treatment groups. At Day 28, less than 2% of participants had sTTR levels <20 mg/dL in the acoramidis arm compared with 26% in the placebo arm ( Table 1 ). When acoramidis and placebo treatment groups were pooled based on sTTR levels <20 or ≥20 mg/dL at Day 28, participants with sTTR ≥20 mg/dL were associated with a lower risk of the composite endpoint of CVM or first CVH at Month 30 in comparison with <20 mg/dL ( p <0.0001) ( Figure 1A ). Comparable findings were observed for the individual components (CVM, first CVH) ( Figure 1B and C ). Conclusion: Across treatment groups, sTTR levels above normal range (≥20 mg/dL) at Day 28 were associated with a lower risk of cardiovascular outcomes at Month 30, when compared with sTTR levels below normal range (<20 mg/dL). Thus, these observations demonstrate that higher sTTR levels over time may have the potential for clinical benefits in both CVM and CVH.

Abstract Background and Aims Accurate differentiation of cardiac amyloidosis (CA) from phenotypic mimics remains challenging using current clinical and echocardiographic techniques. The accuracy of a novel artificial intelligence (AI) screening algorithm for echocardiography-based CA detection was assessed. Methods Utilizing a multisite, multiethnic dataset (n = 2612, 52% CA), a convolutional neural network was trained to differentiate CA from phenotypic controls using transthoracic apical four-chamber video clips. External validation was conducted globally across 18 sites including 597 CA cases and 2122 controls. Classification accuracy was assessed on the entire external validation dataset, and subgroup analyses were performed both on technetium pyrophosphate scintigraphy referrals, and individuals matched for age, sex, and wall thickness. Model accuracy was also compared with the transthyretin CA score and the increased wall thickness score within a subset of older heart failure with preserved ejection fraction patients with increased wall thickness. Results Cardiac amyloidosis patients and controls displayed similar age, sex, race, and comorbidities. After the removal of uncertain AI predictions (13%), model discrimination and classification were excellent for the entire external validation dataset [area under the receiver operating characteristic curve (AUROC) 0.93, sensitivity 85%, specificity 93%], irrespective of CA subtype (sensitivity: light-chain = 84%, wild-type transthyretin = 85%, and hereditary transthyretin = 86%). Performance was maintained in subgroup analysis in patients clinically referred for technetium pyrophosphate scintigraphy imaging (AUROC 0.86, sensitivity 77%, specificity 86%) and matched patients (AUROC 0.92, sensitivity 84%, specificity 91%). The AI model (AUROC 0.93) also outperformed transthyretin CA score (AUROC 0.73) and increased wall thickness (AUROC 0.80) scores. Conclusions This AI screening model—using only an apical four-chamber view—effectively differentiated CA from other causes of increased left ventricular wall thickness.

Cardiac amyloidosis is an underdiagnosed cause of infiltrative cardiomyopathy, leading to heart failure across the spectrum of ejection fractions. Although there are approved disease-modulating therapies for the transthyretin subtype (transthyretin amyloid cardiomyopathy [ATTR-CM]), the role of heart failure medications remains uncertain and challenging in clinical practice. Their effects on clinical outcomes, such as mortality and hospitalization, are unknown for ATTR-CM. This review aims to explore the use of these medications in ATTR-CM, considering the disease’s stage and patient-specific issues, such as fluid homeostasis, autonomic dysfunction, conduction disorders, low and fixed stroke volumes, and decreased functional capacity. As our understanding of this condition deepens, it is important to reassess the impact of contemporary heart failure medication in ATTR-CM. Finally, the relevance of guideline recommendations for heart failure drugs based on left ventricular ejection fraction should be reconsidered in the context of ATTR-CM.

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.