Fontana, M

Abstract Background The National Amyloidosis Centre (NAC) staging system for transthyretin amyloid cardiomyopathy (ATTR-CM) is used to classify patients into prognostic categories based on N-terminal pro-B-type natriuretic peptide (NT-proBNP) level and estimated glomerular filtration rate (eGFR). The NAC staging system has been shown to predict ongoing survival throughout the course of ATTR-CM, with survival progressively decreasing from stage I to stage III. Acoramidis, a highly selective, oral transthyretin stabilizer that achieves near-complete (≥90%) transthyretin stabilization, has recently been approved in Europe and the USA for the treatment of wild-type or variant ATTR-CM in adults. In the phase 3 ATTRibute-CM study, acoramidis treatment was well tolerated and led to a 42% relative risk reduction in the composite of all-cause mortality and recurrent cardiovascular hospitalizations over 30 months compared with placebo (p=0.0005). Purpose To evaluate the ability of acoramidis treatment, as compared with placebo, to stabilize or improve NAC stage after 30 months in participants with ATTR-CM from the ATTRibute-CM study. Methods Participants in ATTRibute-CM were randomized 2:1 to receive acoramidis or placebo for 30 months. Efficacy analyses were conducted in the modified intention-to-treat population, which consisted of all randomized participants who had received at least one dose of acoramidis or placebo, had at least one efficacy evaluation after baseline and had a baseline eGFR ≥30 mL/min/1.73 m2. NAC stage at baseline and Month 30 was assessed. Changes from baseline to Month 30 were categorized as "stable", "improved" or "worsened". The "stable" category comprised participants who stayed within the same NAC stage at baseline and Month 30. The "improved" category comprised participants who moved from a higher NAC stage at baseline to a lower stage at Month 30. The "worsened or missing" category comprised participants who moved from a lower NAC stage at baseline to a higher stage at Month 30 and participants whose Month 30 NAC stage was missing. The change in NAC stage was compared between treatment groups using a stratified Cochran-Mantel-Haenszel test with stratification factors of genotype, NT-proBNP level and eGFR as recorded in the interactive voice/web response system at randomization. Results Overall, 611 participants were analysed (acoramidis: n=409; placebo: n=202). Baseline characteristics were comparable between treatment groups. Most participants had NAC stage I at baseline (acoramidis: 58.9%; placebo: 59.4%; Table). At Month 30, NAC stage remained stable or improved in 52.1% of acoramidis participants compared with 43.1% of placebo participants (p=0.0351; Figure). Conclusions Acoramidis treatment resulted in a greater proportion of participants whose NAC stage improved or remained stable at Month 30 compared with placebo, indicating better stabilization of their disease.

Abstract Background/Introduction Patients with ATTR-CM can have lower circulating TTR levels, which is associated with worsening of cardiac function and increased risk of cardiovascular mortality.[1] Acoramidis has been shown to reduce cardiovascular mortality and hospitalization, while increasing circulating TTR levels, in the ATTRibute-CM phase 3 study.[2] Purpose I. Evaluate serum TTR levels in participants (pts) receiving acoramidis vs those who received tafamidis in the placebo group in ATTRibute-CM at Month 30. II. Evaluate serum TTR levels in pts who transitioned from placebo+tafamidis to acoramidis in the open-label long term extension (OLE) study. Methods ATTRibute-CM study: Eligible pts with ATTR-CM were randomized in a 2:1 ratio to receive acoramidis or placebo for 30 months. Pts in both groups had the option of initiating open-label, commercially available tafamidis after 12 months in the study. Upon completion of Month 30, pts were invited to participate in the OLE study. In OLE, pts who had previously received acoramidis continued acoramidis, and those who had previously received placebo+tafamidis were switched to acoramidis-only treatment. All pts in the OLE study received acoramidis only. Change in serum TTR levels in ATTRibute-CM and OLE at data cutoff (Oct 9, 2023) are summarised using descriptive statistics. Results In the phase 3 study, efficacy analyses were performed in 611 pts, of which 61 of 409 (14.9%) and 46 of 202 (22.8%) received tafamidis in acoramidis and placebo groups, respectively. The median time until tafamidis initiation was 17.8 and 16.1 months, respectively; median exposure duration was 11.6 and 10.5 months, for acoramidis and placebo groups, respectively.[3] Change from baseline (CFB) in serum TTR levels remained unchanged at Month 30 in the placebo-only group (mean [SD] = –0.4 [4.92] mg/dL). Characteristics of pts analysed are described in Fig. 1. A total of 380/611 pts (62.2%) entered the OLE study (229 pts continued acoramidis only, and 23 switched from placebo+tafamidis to acoramidis). At the time of data cutoff, 214 pts who had received acoramidis only completed Month 6 in OLE versus 18 who switched from placebo+tafamidis to acoramidis. At Month 30 in ATTRibute-CM, CFB in serum TTR levels were higher for patients who received acoramidis only than those receiving placebo+tafamidis (Fig 2A). Serum TTR levels increased further in pts who switched from placebo+tafamidis to acoramidis in OLE (Fig. 2B). The OLE study is ongoing, and this analysis includes pts who completed the Month 6 visit at time of data-cut. Conclusion(s) CFB in serum TTR levels were higher in pts receiving acoramidis only than those receiving placebo+tafamidis at Month 30 in the double-blind study. A further significant increase in serum TTR levels was observed in those who received placebo+tafamidis and switched to acoramidis in OLE.