HDAC9 and alveolar rhabdomyosarcoma: In ARMS, Entinostat, an HDAC-inhibitor, which has been found to reduce PAX3-FOXO1 expression and induce subsequent chemotherapy sensitization in preclinical models [43, 44], is currently being evaluated in combination with nivolumab in a phase I/II trial (INFORM2) [45] after it was tolerated well in an earlier phase I study (ADVL1513) [46].