a, Top, effect of different dosages of epigenetic modifiers on the viability of LLC1, HNM007 and 4T1 cells in vitro (72 h, Cell Counting Kit-8). Graphs show the mean of 3 independent experiments; two-sample, two-sided t-tests compared with mock. Bottom, effect of low-dose 5-azacytidine (100 nM) plus entinostat (50 nM) on the proliferation of LLC1, HNM007 and 4T1 cells in vitro. A total of 1 × 105 viable cells was plated per well. Cells were collected at 24, 48 and 72 h and counted using a cell counter (Bio-Rad) after Trypan blue exclusion. Graphs show the mean of 3 independent experiments; significance at 72 h was determined by one-way ANOVA followed by Tukey’s test for multiple comparisons. b, The effect of low-dose 5-azacytidine (100 nM) plus entinostat (50 nM) on the viability of MDSCs from bone marrow (day 3) of LLC mice (top) and HNM007 mice (bottom) in vitro (Cell Counting Kit-8). Graphs show the mean of 3 independent experiments. c, The effect of low-dose 5-azacytidine (100 nM) plus entinostat (50 nM) on the apoptosis of MDSCs from bone marrow (day 3) of LLC and HNM007 mice in vitro. Cell apoptosis was measured by FACS at 48 h. The bottom right quadrant (annexin-V+/7-AAD−) and top right quadrant (annexin-V+/7-AAD+) represent early and late apoptotic cells, respectively. Graphs show the percentage of total apoptosis (early and late apoptosis) in mock and treatment groups (n = 3 biological replicates). d, Tumour growth and body weight of NSG mice bearing LLC tissue that were treated with different doses of entinostat plus 5-azacytidine. Significance at day 12 (top) and day 14 (bottom) was determined by one-way ANOVA followed by Tukey’s test for multiple comparisons. e, Summary table of tumour growth, body weight and treatment-related death of NSG mice bearing LLC tissue. Regimens in red indicate dosages with no effect on tumour growth, weight loss or treatment-related death. f, Tumour growth and body weight of NSG mice bearing HNM007 tissue that were treated with 5-azacytidine at 0.5 mg kg−1 d−1 plus entinostat at 5 mg kg−1 d−1 or vehicle. Significance at day 14 was determined by two-sample, two-sided t-test. g, h, The effect of low-dose AET on the proliferation (g) and apoptosis (h) of donor-derived CD45.1+ MDSCs from bone marrow in CD45.2 LLC mice. Proliferation and apoptosis of immature (MHC-II−) and mature (MHC-II+) CD45.1+ cells were measured by FACS at 36 h after transfusion (day 2). Graphs in g show the percentage of Ki67+ cells (n = 3 mice per group). Graphs in h show the percentage of total apoptosis (early and late apoptosis) in mock-treated and low-dose-AET groups (n = 3 mice per group). In b, c, g, h, two-sample, two-sided t-tests were used. All bars show mean ± s.e.m. *P < 0.05. Source Data