IntroductionTafamidis meglumine, available as 20 mg capsules, is approved around the world for the treatment of transthyretin amyloidosis in early stage polyneuropathy (20 mg) and more recently in cardiomyopathy (80 mg). A new formulation, tafamidis free acid 61 mg (a single capsule bioequivalent to tafamidis meglumine 80 mg), was subsequently developed as a more convenient option for patients with transthyretin amyloid cardiomyopathy (ATTR-CM) and further characterization of its safety profile would be of value.MethodsPatients who completed the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT) were eligible to enroll in a long-term, extension study (LTE). The LTE was subsequently expanded to include ATTR-CM patients not previously enrolled in ATTR-ACT, with all patients receiving tafamidis free acid 61 mg (tafamidis 61 mg). As of 20 July, 2018, patients in the LTE were transitioned to tafamidis free acid 61 mg (data assessed for patients treated with tafamidis 80 mg in the LTE who transitioned to tafamidis free acid 61 mg tafamidis 80/61 mg). Adverse events (AEs) during the LTE are described (as of 1 Aug, 2019) and compared with AEs with tafamidis 80 mg in ATTR-ACT.ResultsThere were 164 patients treated with tafamidis 80/61 mg and 715 newly enrolled patients treated with tafamidis 61 mg; with 157 (95.7%) AEs with tafamidis 80/61 mg and 458 (64.1%) with tafamidis 61 mg. The most common AEs by system organ class were cardiac disorders (Table). AEs with tafamidis 80/61 mg were broadly similar to those with tafamidis 80 mg in ATTR-ACT (previously shown to be similar to placebo). While there were fewer AEs with tafamidis 61 mg, the notably shorter exposure time in this group limits direct comparisons. Nevertheless, no new safety concerns emerged in patients who transitioned to, or started, tafamidis 61 mg.ConclusionsFor patients with ATTR-CM, tafamidis free acid 61 mg is a safe treatment which also offers improved patient convenience.