The Discovery of 3-((4-Chloro-3-methoxyphenyl)amino)-1-((3R,4S)-4-cyanotetrahydro-2H-pyran-3-yl)-1H-pyrazole-4-carboxamide, a Highly Ligand Efficient and Efficacious Janus Kinase 1 Selective Inhibitor with Favorable Pharmacokinetic Properties.
Siu, T., Brubaker, J., Fuller, P., Torres, L., Zeng, H., Close, J., Mampreian, D.M., Shi, F., Liu, D., Fradera, X., Johnson, K., Bays, N., Kadic, E., He, F., Goldenblatt, P., Shaffer, L., Patel, S.B., Lesburg, C.A., Alpert, C., Dorosh, L., Deshmukh, S.V., Yu, H., Klappenbach, J., Elwood, F., Dinsmore, C.J., Fernandez, R., Moy, L., Young, J.R.(2017) J Med Chem 60: 9676-9690
- PubMed: 29156136 
- DOI: https://doi.org/10.1021/acs.jmedchem.7b01135
- Primary Citation of Related Structures:  
5WO4 - PubMed Abstract: 
The discovery of a potent selective low dose Janus kinase 1 (JAK1) inhibitor suitable for clinical evaluation is described. As part of an overall goal to minimize dose, we pursued a medicinal chemistry strategy focused on optimization of key parameters that influence dose size, including lowering human Cl int and increasing intrinsic potency, bioavailability, and solubility. To impact these multiple parameters simultaneously, we used lipophilic ligand efficiency as a key metric to track changes in the physicochemical properties of our analogs, which led to improvements in overall compound quality. In parallel, structural information guided advancements in JAK1 selectivity by informing on new vector space, which enabled the discovery of a unique key amino acid difference between JAK1 (Glu966) and JAK2 (Asp939). This difference was exploited to consistently produce analogs with the best balance of JAK1 selectivity, efficacy, and projected human dose, ultimately culminating in the discovery of compound 28.
Organizational Affiliation: 
Department of Medicinal Chemistry, ‡Department of Discovery Process Chemistry, §Department of Modeling & Informatics, ∥Department of In Vitro Pharmacology, ⊥Department of Structural Chemistry, #Department of Pharmacokinetics Pharmacodynamics and Drug Metabolism, ∇Department of Discovery Pharmaceutical Sciences, ○Department of Molecular Biomarkers, ¶Department of In Vivo Pharmacology, $Department of Respiratory and Immunology, Merck & Co., Inc. , 33 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States.