Efficacy and Tolerability of Pyrazolo[1,5-a]pyrimidine RET Kinase Inhibitors for the Treatment of Lung Adenocarcinoma.
Mathison, C.J.N., Chianelli, D., Rucker, P.V., Nelson, J., Roland, J., Huang, Z., Yang, Y., Jiang, J., Xie, Y.F., Epple, R., Bursulaya, B., Lee, C., Gao, M.Y., Shaffer, J., Briones, S., Sarkisova, Y., Galkin, A., Li, L., Li, N., Li, C., Hua, S., Kasibhatla, S., Kinyamu-Akunda, J., Kikkawa, R., Molteni, V., Tellew, J.E.(2020) ACS Med Chem Lett 11: 558-565
- PubMed: 32292564 
- DOI: https://doi.org/10.1021/acsmedchemlett.0c00015
- Primary Citation of Related Structures:  
6VHG - PubMed Abstract: 
RET (REarranged during Transfection) kinase gain-of-function aberrancies have been identified as potential oncogenic drivers in lung adenocarcinoma, along with several other cancer types, prompting the discovery and assessment of selective inhibitors. Internal mining and analysis of relevant kinase data informed the decision to investigate a pyrazolo[1,5- a ]pyrimidine scaffold, where subsequent optimization led to the identification of compound WF-47-JS03 ( 1 ), a potent RET kinase inhibitor with >500-fold selectivity against KDR (Kinase insert Domain Receptor) in cellular assays. In subsequent mouse in vivo studies, compound 1 demonstrated effective brain penetration and was found to induce strong regression of RET-driven tumor xenografts at a well-tolerated dose (10 mg/kg, po, qd). Higher doses of 1 , however, were poorly tolerated in mice, similar to other pyrazolo[1,5- a ]pyrimidine compounds at or near the efficacious dose, and indicative of the narrow therapeutic windows seen with this scaffold.
Organizational Affiliation: 
The Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, United States.