• Acute lymphoblastic leukaemia
• Acute myeloid leukaemia
• Apcin
• CDC20 inhibitors
• Mitotic regulation

CDC20 is a vital part of the mitotic checkpoint, and it is upregulated in high-risk leukaemia with complex karyotypes. Various CDC20 inhibitors, including Apcin, have been designed to target cancer cells, albeit having limited in vivo applicability due to the high effective doses. This study assesses the efficacy and mechanism of action of novel Apcin-like compounds in acute myeloid leukaemia (AML) and Philadelphia negative B-acute lymphoblastic leukaemia (ALL). We produced five structural analogues of Apcin named M1-M5 by a multistep approach. Cells’ viability was assessed by dose-response curves on four AML and two ALL cell lines. Compared to Apcin, M3 and M4 were the most efficient, with significantly lower IC50 values (five to ten-fold reduction). M3 compound also reduced the clonogenic capacity of patient-derived ALL cells. Both M3 and M4 induced apoptosis, G2/M cell cycle arrest and activation of the G2/M cell cycle checkpoint. Based on the observed effects on the cell cycle and mitosis regulation, we tested the combination of M3 or M4 with AZD6738, a specific ATR kinase inhibitor or with mitotic poisons (Vincristine and Paclitaxel). We observed a reduction of cells’ viability in the treated cell lines, with either synergistic or additive effects. Our data confirm that CDC20 activity is crucial for the survival of acute leukaemia cells. Inhibition of CDC20 synergizes with ATR kinase inhibitor, as well as with tubulin polymerization or depolymerization inhibitors.