Conversely, a single-arm phase II trial exploring the combination of the HDAC inhibitor panobinostat and the mTOR inhibitor everolimus in children and young adults with advanced or recurrent gliomas harboring H3.1 or H3.3 K27M mutation has been withdrawn due to low accrual (NCT03632317) [50] (Table 5). Here, HDAC9 is linked to central nervous system cancer.