HDAC9 and Miyoshi myopathy: Despite the impressive in vitro efficacy of both 5‐azacytidine and HDAC inhibitors in MM, shown in several studies (Kiziltepe et al., 2007; Maiso et al., 2006; Ocio et al., 2010; Sanchez et al., 2011; Tian et al., 2013), their performance in clinical studies, when used as monotherapy, has been quite disappointing.