In patients with transthyretin amyloid cardiomyopathy, tafamidis was associated with reductions in all-cause mortality and cardiovascular-related hospitalizations and reduced the decline in functional capacity and quality of life as compared with placebo. (Funded by Pfizer; ATTR-ACT ClinicalTrials.gov number, NCT01994889 .).

Tafamidis is an effective treatment for transthyretin amyloid cardiomyopathy (ATTR-CM) in the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT). While ATTRACT was not designed for a dose-specific assessment, further analysis from ATTRACT and its long-term extension study (LTE) can guide determination of the optimal dose.

Background: The objective of the present study was to evaluate the long-term safety and efficacy of tafamidis in treating hereditary transthyretin amyloid polyneuropathy. Methods: A prospectively planned interim analysis was conducted on an on-going, phase III, open-label extension study following an 18-month, randomized, controlled study and 12-month, open-label extension study in ATTRV30M patients and a single-arm, open-label study in non-ATTRV30M patients. Thirtyseven ATTRV30M patients received placebo for 18 months, then switched to tafamidis and 38 ATTRV30M patients and 18 non-ATTRV30M patients continuously received tafamidis from day 1, up to 6 years. Results: Long-term tafamidis was associated with a favourable safety/tolerability profile, without any unexpected adverse events. Patients initiating tafamidis at the start of the randomized study had less polyneuropathy progression versus those switching to tafamidis following 18 months of placebo and were less likely to progress to the next ambulatory stage after up to 6 years follow-up. In the patients who switched from placebo to tafamidis, polyneuropathy progression and deterioration in quality of life slowed significantly during long-term tafamidis treatment as compared with the previous placebo treatment. In non-ATTRV30M patients, some polyneuropathy progression was observed across all efficacy measures. Conclusions: These data provide evidence for the long-term (up to 6 years) safety and efficacy of tafamidis. ClinicalTrials.gov: NCT00925002

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Background: Tafamidis is approved in many countries for the treatment of transthyretin amyloid cardiomyopathy. This study reports data on the long-term efficacy of tafamidis from an ongoing long-term extension (LTE) to the pivotal ATTR-ACT (Tafamidis in Transthyretin Cardiomyopathy Clinical Trial). Methods: Patients with transthyretin amyloid cardiomyopathy who completed ATTR-ACT could enroll in an LTE, continuing with the same tafamidis dose or, if previously treated with placebo, randomized (2:1) to tafamidis meglumine 80 or 20 mg. All patients in the LTE transitioned to tafamidis free acid 61 mg (bioequivalent to tafamidis meglumine 80 mg) following a protocol amendment. In this interim analysis, all-cause mortality was assessed in patients treated with tafamidis meglumine 80 mg in ATTR-ACT continuing in the LTE, compared with those receiving placebo in ATTR-ACT transitioning to tafamidis in the LTE. Results: Median follow-up was 58.5 months in the continuous tafamidis group (n=176) and 57.1 months in the placebo to tafamidis group (n=177). There were 79 (44.9%) deaths with continuous tafamidis and 111 (62.7%) with placebo to tafamidis (hazard ratio, 0.59 [95% CI, 0.44–0.79]; P <0.001). Mortality was also reduced in the continuous tafamidis (versus placebo to tafamidis) subgroups of: variant transthyretin amyloidosis (0.57 [0.33–0.99]; P =0.05) and wild-type transthyretin amyloidosis (0.61 [0.43–0.87]; P =0.006); and baseline New York Heart Association class I and II (0.56 [0.38–0.82]; P =0.003) and class III (0.65 [0.41–1.01]; P =0.06). Conclusions: In the LTE, patients initially treated with tafamidis in ATTR-ACT had substantially better survival than those first treated with placebo, highlighting the importance of early diagnosis and treatment in transthyretin amyloid cardiomyopathy. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01994889 and NCT02791230.