Example 201
BTKWT binding affinity of each compound tested was determined using a time-resolved fluorescence resonance energy transfer (TR-FRET) methodology. 2.5 nM Recombinant BTKWT kinase, varying concentrations of inhibitor, 2 nM LanthaScreen™ Eu anti-His Antibody and 15 nM Kinase Tracer 236 was incubated in 1× LanthaScreen™ Kinase Buffer A for 5 h. Recombinant BTK kinase and all LanthaScreen™ components were purchased from Invitrogen. Measurements were performed in a reaction volume of 30 μL using half-area 96-well assay plates. The TR-FRET signal was read on a plate reader with an excitation wavelength of 340 nm and detection wavelengths of 615 and 665 nm. Binding affinity was determined for each compound by measuring TR-FRET signal at various concentrations of compound and plotting the relative fluorescence units against the inhibitor concentration to estimate the IC50 from log[Inhibitor] vs response using the Variable Slope model in Graphpad prism from Graphpad software (SanDiego, Calif.).
Results of the BTKWT Binding Affinity are shown below in Table 4
Table 4 shows the BTKWT Binding affinity, as determined by the assay described above, for compounds of formula (I), categorised based on the BTK IC50 value of the compound as “A”, “B”, “C”, “D” and “E”.
IC50: A≤10 nM; 10 nM<B≤100 nM; 100 nM<C≤1 μM; 1 μM<D≤10 μM; E>10 μM