Design of new disubstituted imidazo[1,2-b]pyridazine derivatives as selective Haspin inhibitors. Synthesis, binding mode and anticancer biological evaluation

Abstract

Haspin is a mitotic protein kinase required for proper cell division by modulating Aurora B kinase localisation and activity as well as histone phosphorylation. Here a series of imidazopyridazines based on the CHR-6494 and Structure Activity Relationship was established. An assessment of the inhibitory activity of the lead structures on human Haspin and several other protein kinases is presented. The lead structure was rapidly optimised using a combination of crystal structures and effective docking models, with the best inhibitors exhibiting potent inhibitory activity on Haspin with IC₅₀ between 6 and 100 nM in vitro. The developed inhibitors displayed anti-proliferative properties against various human cancer cell lines in 2D and spheroid cultures and significantly inhibited the migration ability of osteosarcoma U-2 OS cells. Notably, we show that our lead compounds are powerful Haspin inhibitors in human cells, and did not block G2/M cell cycle transition due to improved selectivity against CDK1/CyclinB.

Graphical Abstract

Keywords:

• Imidazopyridazine
• Haspin kinase
• co-crystallisation and docking
• cellular effects
• 3D spheroids

Acknowledgements

The authors thank the staff at Diamond Light Source for their assistance during data collection.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This research was supported by grants from by “la Ligue contre le Cancer du Grand-Ouest” committee (districts: 29, 22, 56, 35, 45 and 79) and “Région Bretagne” of which O.F was a recipient. The authors thank the Cancéropôle Grand Ouest “Marine Molecules, Metabolism and Cancer network”, The Ministère de l'Enseignement, de la Recherche et de l'Innovation (MENRT grant MP), the Labex Synorg (11-LABX-0029) and IRON (11-LABX-0018) for financial support. We thank the staff at Diamond Light Source for their assistance during data collection. SK and AC are grateful for support by the SGC, a registered charity (number 1097737) that receives funds from AbbVie, Bayer Pharma AG, Boehringer Ingelheim, Canada Foundation for Innovation, Eshelman Institute for Innovation, Genome Canada, Innovative Medicines Initiative (EU/EFPIA), Janssen, Merck KGaA Darmstadt Germany, MSD, Novartis Pharma AG, Ontario Ministry of Economic Development and Innovation, Pfizer, São Paulo Research Foundation-FAPESP, Takeda, and Wellcome. SK is also supported by the Frankfurt Cancer Institute (FCI) and the DKTK translational cancer network.