Witteles, R

Abstract Background Tafamidis is a near-complete transthyretin kinetic stabiliser for the treatment of patients with transthyretin amyloid cardiomyopathy (ATTR-CM). It is administered orally, once daily, and has demonstrated a statistically significant reduction in mortality at 30 months vs placebo. Purpose Report findings from patients who received up to 7.5 years treatment with tafamidis in the phase 3 trial and its long-term extension (LTE) study. Methods In ATTR-ACT, patients were randomised (2:1:2) to blinded tafamidis meglumine 80 mg, 20 mg, or placebo for 30 months. Patients continued their blinded tafamidis dose into the up to 60-month LTE study, until commercial prescription availability, or study termination. Those who received placebo in ATTR-ACT were randomized (2:1) to blinded tafamidis meglumine 80 mg or 20 mg in the LTE study. All patients were subsequently switched to open label tafamidis free acid 61 mg (bioequivalent to meglumine 80 mg). Outcomes were assessed over the entire 90-month follow-up. Results Of the 264 patients randomised to tafamidis in ATTR-ACT, 173 completed the trial and 170 continued to receive tafamidis the LTE study (Taf/Taf group). Of 177 patients randomised to placebo in ATTR-ACT, 85 completed the trial and 82 initiated tafamidis in the LTE study (Pbo/Taf group). Over a median follow-up of 54.2 months in the Taf/Taf group and 30.5 months in the Pbo/Taf group, incidence of all-cause mortality (ACM) was 54.5% and 71.2%. Median time to ACM was 47.5 and 30.3 months, resulting in a hazard ratio of 0.62 (95% CI: 0.49-0.79; P=0.0001; Figure). Incidence of cardiovascular-related mortality (CVM) was 42.0% and 57.1% in the Taf/Taf and Pbo/Taf groups. Median time to CVM was 47.6 and 30.3 months, resulting in a hazard ratio of 0.61 (0.47-0.81; P=0.0005). The total annual rate of all-cause hospitalisation in the LTE study was 0.69 in the Taf/Taf group and 1.14 in the Pbo/Taf group, and the total annual rate of cardiovascular-related hospitalisation was 0.36 and 0.63. Among patients remaining at each LTE study visit and with available data, improvement in New York Heart Association functional classification was more commonly seen in the Taf/Taf vs Pbo/Taf group. Mean observed reduction from baseline in Kansas City Cardiomyopathy Questionnaire Overall Summary score was significantly smaller in the Taf/Taf vs Pbo/Taf group at most LTE study visits. Treatment-related adverse events occurred in 11.2% of the Taf/Taf and 23.2% of the Pbo/Taf groups during the LTE study and were consistent with the known safety profile of tafamidis. Conclusions With up to 7.5 years of follow-up data, this analysis of ATTR-ACT trial and its LTE study is the longest reported to date for an ATTR-CM population treated with disease-modifying therapy. Findings demonstrate better long-term outcomes including survival, hospitalisation rates, quality of life, and heart failure symptoms with long-term tafamidis treatment. For image description, please refer to the figure legend and surrounding text.

Abstract Background The clinical efficacy of tafamidis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) was demonstrated during the phase 3, multinational, randomised, placebo-controlled Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT).(1) In ATTR-ACT, the risk of any cardiovascular (CV)-related hospitalisation was significantly reduced among patients who received tafamidis meglumine 80 mg (the approved dose) vs placebo (relative risk ratio 0.70 [95% CI 0.57, 0.85]; P=0.0005).(2) The benefit of tafamidis treatment was largest among patients with New York Heart Association (NYHA) class I/II vs III symptoms at baseline.(1,3,4) Purpose ATTR-CM is a progressive disease with a natural history that typically includes an increasing frequency of CV-related hospitalisation as the condition worsens. This post hoc analysis adds to current knowledge by evaluating the risk of recurrent (≥1) CV-related hospitalisation by baseline NYHA class in ATTR-ACT patients taking the approved dose of tafamidis or placebo. Methods Patients aged 18 to 90 years with biopsy-confirmed wild-type or variant ATTR-CM and NYHA class I-III symptoms took part in ATTR-ACT between 2013 and 2018. During the trial, the cause of hospitalisation was adjudicated by an independent committee. The hazard ratio (HR) for first CV-related hospitalisation was calculated using a Cox proportional hazards model. The HR for recurrent CV-related hospitalisation was calculated using the Liu-Wei-Yang-Ying (LWYY; also known as the modified Anderson-Gill) model. Models compared tafamidis meglumine 80 mg vs placebo and adjusted for transthyretin genotype (wild-type or variant). In the overall population, the LWYY model was also adjusted for baseline NYHA class. Results The frequency of adjudicated CV-related hospitalisations during ATTR-ACT by NYHA class are shown in the Figure. Across patients who were NYHA class I-III at baseline, the risk of recurrent CV-related hospitalisation was 37% lower in those who received tafamidis vs placebo treatment (HR 0.627 [95% CI 0.463, 0.848]; P=0.0025; Table). Among those who were NYHA class I/II at baseline, a lower proportion of tafamidis- vs placebo-treated patients (44% vs 61%) had ≥1 CV-related hospitalisation. The risks of first and recurrent CV-related hospitalisation were 40% (HR 0.601 [95% CI 0.420, 0.861]; P=0.0055) and 55% (HR 0.449 [95% CI 0.305, 0.661]; P<0.0001) lower with tafamidis vs placebo treatment. Consistent with the survivor bias previously observed in ATTR-ACT,(1-4) the risk of recurrent CV-related hospitalisation was statistically similar in tafamidis- and placebo-treated patients who were NYHA class III at baseline (HR 1.113 [95% CI 0.688, 1.799]; P=0.6624). Conclusions Building on previous findings, this analysis found the risk of recurrent CV-related hospitalisation to be reduced by tafamidis meglumine 80 mg treatment in patients with early stage ATTR-CM.