Effect of panobinostat pretreatment on CD33 expression and AMG 330-induced cytotoxicity. Parental OCI-AML3 (A) and KG-1a (B) cells were either left untreated or pretreated with panobinostat for 72 hours. Subsequently, CD33 expression was quantified, and cells treated with/without AMG 330 (0-250 pg/mL) and various E:T cell ratios using healthy donor T cells. Forty-eight hours later, cell counts were determined and cytotoxicity was assessed with DAPI staining to quantify drug-specific cytotoxicity. Results are shown as mean ± SEM from 3 independent experiments performed in duplicate wells using a single healthy donor as source for exogenous T cells.