To determine if the observed combined effect of bomedemstat and venetoclax could enhance activity against AML cells in vivo, we employed a PDX model with two primary AML samples. In the first model system (monosomy 7), co-treatment resulted in a significant reduction in human CD45-positive cells as compared to vehicle (P <0.001) and single-agent treatments with venetoclax (P= 0.011) and bomedemstat (P <0.001).