Lessons from (S)-6-(1-(6-(1-Methyl-1H-Pyrazol-4-Yl)-[1,2, 4]Triazolo[4,3-B]Pyridazin-3-Yl)Ethyl)Quinoline (Pf-04254644), an Inhibitor of Receptor Tyrosine Kinase C-met with High Protein Kinase Selectivity But Broad Phosphodiesterase Family Inhibition Leading to Myocardial Degeneration in Rats.
Cui, J.J., Shen, H., Tran-Dube, M., Nambu, M., Mctigue, M., Grodsky, N., Ryan, K., Yamazaki, S., Aguirre, S., Parker, M., Li, Q., Zou, H., Christensen, J.(2013) J Med Chem 56: 6651
- PubMed: 23944843 
- DOI: https://doi.org/10.1021/jm400926x
- Primary Citation of Related Structures:  
3ZBX, 3ZC5, 3ZCL - PubMed Abstract: 
The hepatocyte growth factor (HGF)/c-Met signaling axis is deregulated in many cancers and plays important roles in tumor invasive growth and metastasis. An exclusively selective c-Met inhibitor (S)-6-(1-(6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-b]pyridazin-3-yl)ethyl)quinoline (8) was discovered from a highly selective high-throughput screening hit via structure-based drug design and medicinal chemistry lead optimization. Compound 8 had many attractive properties meriting preclinical evaluation. Broad off-target screens identified 8 as a pan-phosphodiesterase (PDE) family inhibitor, which was implicated in a sustained increase in heart rate, increased cardiac output, and decreased contractility indices, as well as myocardial degeneration in in vivo safety evaluations in rats. Compound 8 was terminated as a preclinical candidate because of a narrow therapeutic window in cardio-related safety. The learning from multiparameter lead optimization and strategies to avoid the toxicity attrition at the late stage of drug discovery are discussed.
Organizational Affiliation: 
La Jolla Laboratories, Pfizer Worldwide Research and Development , 10770 Science Center Drive, San Diego, California 92121, United States.