Structure-Guided Optimization Provides a Series of TTK Protein Inhibitors with Potent Antitumor Activity

Area of Science:

• Medicinal Chemistry
• Oncology
• Molecular Biology

Background:

• TTK (monopolar spindle 1 kinase) is a key enzyme in cell division, crucial for the spindle assembly checkpoint.
• Overexpression of TTK is linked to tumor cell proliferation and observed across various cancer types.
• Triple-negative breast cancer (TNBC) is an aggressive subtype with limited targeted therapies.

Purpose of the Study:

• To design and optimize novel TTK inhibitors with improved potency, selectivity, and drug-like properties.
• To evaluate the in vitro and in vivo efficacy of these inhibitors in TNBC models.
• To identify a lead candidate for further preclinical development.

Main Methods:

• Structure-based drug design and iterative chemical synthesis.
• In vitro biochemical assays to determine TTK inhibition (IC50).
• Cell-based proliferation assays using TNBC cell lines (e.g., CAL-51).
• In vivo efficacy studies in a TNBC xenograft mouse model, assessing tumor growth and body weight.

Main Results:

• A series of potent and selective TTK inhibitors were identified, building upon a previously reported tricyclic scaffold.
• Compound 25 demonstrated strong TTK inhibition (IC50 = 3.0 nM) and potent antiproliferative activity in TNBC cells (CAL-51 IC50 = 16.0 nM).
• Compound 25 exhibited significant single-agent efficacy in a TNBC xenograft model following intravenous dosing, with no observed body weight loss.

Conclusions:

• The structure-enabled optimization campaign successfully yielded compound 25, a highly potent and selective TTK inhibitor.
• Compound 25 displays promising efficacy as a single agent in a preclinical TNBC model.
• These findings support the potential of targeting TTK for the treatment of triple-negative breast cancer.