Discovery of Aminothiazole Inhibitors of Cyclin-Dependent Kinase 2:  Synthesis, X-ray Crystallographic Analysis, and Biological Activities

• Published in: Journal of medicinal chemistry 2002-08, Vol.45 (18), p.3905-3927
• Main Authors: Kim, Kyoung Soon, Kimball, S. David, Misra, Raj N, Rawlins, David B, Hunt, John T, Xiao, Hai-Yun, Lu, Songfeng, Qian, Ligang, Han, Wen-Ching, Shan, Weifang, Mitt, Toomas, Cai, Zhen-Wei, Poss, Michael A, Zhu, Hong, Sack, John S, Tokarski, John S, Chang, Chieh Ying, Pavletich, Nikola, Kamath, Amrita, Humphreys, William G, Marathe, Punit, Bursuker, Isia, Kellar, Kristen A, Roongta, Urvashi, Batorsky, Roberta, Mulheron, Janet G, Bol, David, Fairchild, Craig R, Lee, Francis Y, Webster, Kevin R
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic agents; Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - pharmacokinetics; Antineoplastic Agents - pharmacology; Benzeneacetamides; Biological and medical sciences; CDC2-CDC28 Kinases; Cell Cycle - drug effects; Combinatorial Chemistry Techniques; Crystallography, X-Ray; Cyclin E - metabolism; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinases - antagonists & inhibitors; DNA Polymerase I - metabolism; Drug Screening Assays, Antitumor; Enzyme Inhibitors - chemical synthesis; Enzyme Inhibitors - pharmacokinetics; Enzyme Inhibitors - pharmacology; Female; General aspects; Histones - metabolism; Humans; Male; Medical sciences; Mice; Mice, Inbred BALB C; Mice, Inbred DBA; Models, Molecular; Oxazoles - chemical synthesis; Oxazoles - pharmacokinetics; Oxazoles - pharmacology; Pharmacology. Drug treatments; Phosphorylation; Protein Binding; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Retinoblastoma Protein - metabolism; Structure-Activity Relationship; Thiazoles - chemical synthesis; Thiazoles - chemistry; Thiazoles - pharmacokinetics; Thiazoles - pharmacology; Tumor Cells, Cultured
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm0201520

High throughput screening identified 2-acetamido-thiazolylthio acetic ester 1 as an inhibitor of cyclin-dependent kinase 2 (CDK2). Because this compound is inactive in cells and unstable in plasma, we have stabilized it to metabolic hydrolysis by replacing the ester moiety with a 5-ethyl-substituted oxazole as in compound 14. Combinatorial and parallel synthesis provided a rapid analysis of the structure−activity relationship (SAR) for these inhibitors of CDK2, and over 100 analogues with IC50 values in the 1−10 nM range were rapidly prepared. The X-ray crystallographic data of the inhibitors bound to the active site of CDK2 protein provided insight into the binding modes of these inhibitors, and the SAR of this series of analogues was rationalized. Many of these analogues displayed potent and broad spectrum antiproliferative activity across a panel of tumor cell lines in vitro. In addition, A2780 ovarian carcinoma cells undergo rapid apoptosis following exposure to CDK2 inhibitors of this class. Mechanism of action studies have confirmed that the phosphorylation of CDK2 substrates such as RB, histone H1, and DNA polymerase α (p70 subunit) is reduced in the presence of compound 14. Further optimization led to compounds such as water soluble 45, which possesses a favorable pharmacokinetic profile in mice and demonstrates significant antitumor activity in vivo in several murine and human models, including an engineered murine mammary tumor that overexpresses cyclin E, the coactivator of CDK2.