TTR and primary systemic amyloidosis: Several clinical observations support a potential benefit of doxycycline treatment against ATTR, AL and Aβ2Mwt amyloidosis (Obici et al., 2012; Montagna et al., 2013; Piccoli et al., 2017; Wechalekar and Whelan, 2017; Karlstedt et al., 2019) and several ongoing clinical trials are currently investigating the potential therapeutic effect of doxycycline against different forms of systemic amyloidosis.