title: Multidimensional profiling of CSF1R screening hits and inhibitors: assessing cellular activity, target residence time, and selectivity in a higher throughput way.
abstract: Over the past years, improvements in high-throughput screening (HTS) technology and compound libraries have resulted in a dramatic increase in the amounts of good-quality screening hits, and there is a growing need for follow-on hit profiling assays with medium throughput to further triage hits. Here the authors present such assays for the colony-stimulating factor 1 receptor (CSF1R, Fms), including tests for cellular activity and a homogeneous assay to measure affinity for inactive CSF1R. They also present a high-throughput assay to measure target residence time, which is based on competitive binding kinetics. To better fit k(off) rates, they present a modified mathematical model for competitive kinetics. In all assays, they profiled eight reference inhibitors (imatinib, sorafenib, sunitinib, tandutinib, dasatinib, GW2580, Ki20227, and J&J's pyrido[2,3-d]pyrimidin-5-one). Using the known biochemical selectivities of these inhibitors, which can be quantified using metrics such as the selectivity entropy, the authors have determined which assay readout best predicts hit selectivity. Their profiling shows surprisingly that imatinib has a preference for the active form of CSF1R and that Ki20227 has an unusually slow target dissociation rate. This confirms that follow-on hit profiling is essential to ensure that the best hits are selected for lead optimization.
authors.affiliation: Merck Research Labs, Oss, the Netherlands. joost.uitdehaag@ntrc.nl
authors.forename: Joost C M
authors.initials: JC
authors.lastname: Uitdehaag
authors.forename: Cecile M
authors.initials: CM
authors.lastname: Sünnen
authors.forename: Antoon M
authors.initials: AM
authors.lastname: van Doornmalen
authors.forename: Nikki
authors.initials: N
authors.lastname: de Rouw
authors.forename: Arthur
authors.initials: A
authors.lastname: Oubrie
authors.forename: Rita
authors.initials: R
authors.lastname: Azevedo
authors.forename: Michael
authors.initials: M
authors.lastname: Ziebell
authors.forename: Elliott
authors.initials: E
authors.lastname: Nickbarg
authors.forename: Willem-Jan
authors.initials: WJ
authors.lastname: Karstens
authors.forename: Simone
authors.initials: S
authors.lastname: Ruygrok
mesh_terms: D001667:Binding, Competitive; D002460:Cell Line; D019295:Computational Biology; D057166:High-Throughput Screening Assays; D006801:Humans; D007700:Kinetics; D020935:MAP Kinase Signaling System / Q000187:drug effects; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D047428:Protein Kinase Inhibitors; D016186:Receptor, Macrophage Colony-Stimulating Factor