## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: In Vitro Inhibitory Activity Against BTK(wt)/BTK(C481S) (Determination of IC50 Value): The substrate solution was prepared by adding the substrate poly(Glu, Tyr) sodium salt (Sigma Aldrich, St. Louis, Mo.) to the substrate reaction buffer (20 mM Hepes (pH 7.5), 10 mM MgCl2, 1 mM EGTA, 0.02% Brij35, 0.02 mg/mL BSA, 0.1 mM Na3VO4, 2 mM DTT and 1% DMSO) (final substrate concentration in the reaction solution was 0.2 μM). Test compound was formulated into stock solutions at 10 mM concentration with 100% DMSO, and 3-fold serial dilution for 10 doses was performed in a 384-well cyclic olefin copolymer LDV microplate. BTK(wt) or BTK(C481S) kinase (recombinant human full-length protein, histidine tag, expressed in insect cells, Invitrogen, Carlsbad, Calif.) was added to the substrate solution and mixed gently (final BTK concentration in the reaction solution was 8 nM). Test compound in 100% DMSO was then added to the kinase reaction mixture by acoustic liquid transfer technology (Echo 550; nanoliter range) (Labcyte Inc, Sunnyvale, Calif.) and incubated for 20 min at room temperature. 33P-ATP (specific activity 10 μCi/μL) was added to the reaction mixture to initiate the reaction, followed by incubation at room temperature for 2 h. A small portion of the reaction mixture was dropped onto P-81 ion exchange filter paper (Whatman). After washing the unbound phosphate from the filter paper with 0.75% phosphate buffer (three times) and drying, the remaining radioactivity on the filter paper was measured. The kinase activity was expressed as the percentage of the remaining kinase activity in the test sample to the kinase activity in the vehicle (dimethyl sulfoxide) blank control. IC50 values were calculated by curve fitting the data obtained using Prism (GraphPad Software).
- Target name: Tyrosine-protein kinase BTK
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: Nc1nccn2c(C34CCC(NC(=O)c5ccccc5)(CC3)C4)nc(-c3ccc(C(=O)Nc4cc(C(F)(F)F)ccn4)cc3)c12
- Properties:
- ChEMBL ID: CHEMBL5895576
- Molecular weight: 611.63
- Heavy atoms: 45
- Hydrogen bond donors: 3
- Hydrogen bond acceptors: 6
- TPSA: 127.3
- LogP: 6.03
- Rotatable bonds: 6
- Ring count: 7
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.24
- QED: 0.22

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 8.26
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 5.5; units nM; pChEMBL 8.26; comment 1199221

## Query Molecule B
- Canonical SMILES: Nc1nccn2c(C34CCC(NC(=O)c5cccnc5)(CC3)C4)nc(-c3ccc(C(=O)Nc4cc(C(F)(F)F)ccn4)cc3)c12
- Properties:
- ChEMBL ID: CHEMBL5954269
- Molecular weight: 612.62
- Heavy atoms: 45
- Hydrogen bond donors: 3
- Hydrogen bond acceptors: 7
- TPSA: 140.19
- LogP: 5.42
- Rotatable bonds: 6
- Ring count: 7
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.25
- QED: 0.23

## Molecule Similarity
- Weighted Tanimoto: 0.89

Answer: 8.26