Target Residence Time-Guided Optimization on TTK Kinase Results in Inhibitors with Potent Anti-Proliferative Activity

The protein kinase threonine tyrosine kinase (TTK; also known as Mps1) is a critical component of the spindle assembly checkpoint and a promising drug target for the treatment of aggressive cancers, such as triple negative breast cancer. While the first TTK inhibitors have entered clinical trials, little is known about how the inhibition of TTK with small-molecule compounds affects cellular activity. We studied the selective TTK inhibitor NTRC 0066-0, which was developed in our own laboratory, together with 11 TTK inhibitors developed by other companies, including Mps-BAY2b, BAY 1161909, BAY 1217389 (Bayer), TC-Mps1-12 (Shionogi), and MPI-0479605 (Myrexis). Parallel testing shows that the cellular activity of these TTK inhibitors correlates with their binding affinity to TTK and, more strongly, with target residence time. TTK inhibitors are therefore an example where target residence time determines activity in in vitro cellular assays. X-ray structures and thermal stability experiments reveal that the most potent compounds induce a shift of the glycine-rich loop as a result of binding to the catalytic lysine at position 553. This "lysine trap" disrupts the catalytic machinery. Based on these insights, we developed TTK inhibitors, based on a (5,6-dihydro)pyrimido[4,5-e]indolizine scaffold, with longer target residence times, which further exploit an allosteric pocket surrounding Lys553. Their binding mode is new for kinase inhibitors and can be classified as hybrid Type I/Type III. These inhibitors have very potent anti-proliferative activity that rivals classic cytotoxic therapy. Our findings will open up new avenues for more applications for TTK inhibitors in cancer treatment.

 

Comments:

It seems like you're sharing a summary of a research study or an article about the protein kinase threonine tyrosine kinase (TTK) and its inhibitors, particularly focusing on the development of a selective TTK inhibitor (NTRC 0066-0) and its comparison with other inhibitors developed by different companies. The study highlights the importance of target residence time in determining the activity of TTK inhibitors in cellular assays.

The research demonstrates that TTK inhibitors, especially those inducing a shift in the glycine-rich loop by binding to the catalytic lysine at position 553, disrupt the catalytic machinery, leading to their anti-proliferative effects. The development of TTK inhibitors with longer target residence times and a new binding mode offers promising possibilities for cancer treatment, potentially rivaling traditional cytotoxic therapies.

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Related Products

Cat.No.	Product Name	Information
S7488	MPI-0479605	MPI-0479605 is an ATP competitive and selective inhibitor of mitotic kinase Mps1 with IC50 of 1.8 nM, >40-fold selectivity over other kinases.

Related Targets

MPS1