## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: FGFR2 Activity Inhibition Test: The in vitro activity of FGFR2 was determined by assaying the phosphorylation level of the substrate in the kinase reaction, by means of an HTRF kinase assay kit. The reaction buffer comprised the following components: 5-fold diluted Enzymatic buffer/kinase 5× (Cisbio, Catalog number 62EZBFDD) (main ingredient: 50 mM HEPES, pH 7), 5 mM MgCl2, 1 mM DTT; the human recombinant FGFR2 catalytic structural domain protein (amino acids 400-821) was commercially available from Beijing Sino Biological Inc. (Zhonghe Street 14, B-203, Beijing Economic and Technological Development Zone, 4008909989), diluted with the reaction buffer to a 0.04 ng/μL kinase solution; the substrate reaction solution comprised a biotin labeled tyrosine kinase substrate diluted with the reaction buffer to 800 nM (Cisbio, catalog number 62TKOPEC), and 50 μM ATP, and the assay solution comprised an Eu3+ labeled cage-shaped antibody (Cisbio, Catalog number 61T66KLB) diluted with the assay buffer (Cisbio, Catalog number 62SDBRDF) to 0.12 ng/μL, and 50 nM streptavidin labeled XL665 (Cisbio, Catalog number 610SAXLB).The compound was dissolved and diluted in 100% DMSO to 100 μM, then 4-fold-series diluted with DMSO to a minimum concentration of 0.01 μM, and each concentration point was then 40-fold diluted with the reaction buffer. If the IC50 value of the compound was very low, the initial concentration of the compound could be reduced.4 μL of a compound solution and 2 μL of an FGFR2 kinase solution were added into a 384 well assay plate (Thermo, Catalog number 264706), mixed uniformly and then incubated for 15 min at room temperature; subsequently, 4 μL of the substrate reaction solution was added therein, and the reaction mixture was incubated for 60 min at room temperature; and then 10 μL of an assay solution of an equal volume to the reaction was added therein and mixed uniformly, followed by placement at room temperature. After 60 min, the enzyme reaction was terminated by EDTA in the assay solution, and the phosphorylated products were identified by both the Eu3+ labeled cage-shaped antibody (donor) and the streptavidin labeled XL665 antibody (receptor) at the same time. After the excitation with laser, the donors and receptors that were close to each other experienced energy resonance transfer, and the energy transferred from the donor (620 nm) to the receptor (665 nm) could be detected with Envision (Perkin Elmer, company located in in Limon City, Calif., USA). The ratio of 665/620 is in positive correlation to the phosphorylation degree of the substrate, thereby to detect the FGFR2 kinase activity. In this experiment, the group without the FGFR2 protein added was used as a negative control (100% inhibition), and the group with the FGFR2 protein but without the compound added was used as a positive control (0% inhibition). The inhibition percentage of the compound against FGFR2 activity could be calculated with the following formula:Inhibition percentage=100−100*(signalcompound−signalnegative control)/(signalpositive control−signalnegative control)The IC50 value of the compound was calculated by the following formula, from 10 concentration points, with software XLfit (ID Business Solutions Ltd., UK):Y=Bottom+(Top−Bottom)/(1+10{circumflex over ( )}((Log IC50 −X)*slope factor))Where, Y is the inhibition percentage, Bottom is the bottom plateau value of the S-type curve, Top is the top plateau value of the S-type curve, X is the log value of the compound concentration to be measured, and slope factor is the slope coefficient of the curve.
- Assay organism: Homo sapiens
- Target name: Fibroblast growth factor receptor 2
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: CC#CN1CC(c2nc(C#Cc3cc(OC)cc(OC)c3)c3c(N)nccn23)C1
- Properties:
- ChEMBL ID: CHEMBL5870549
- Molecular weight: 387.44
- Heavy atoms: 29
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 6
- TPSA: 77.91
- LogP: 2.11
- Rotatable bonds: 3
- Ring count: 4
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.27
- QED: 0.69

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 6.56
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 275; units nM; pChEMBL 6.56; comment 945306

## Query Molecule B
- Canonical SMILES: C/C=C/C(=O)N1CC(c2nc(C#Cc3cc(OC)cc(OC)c3)c3c(N)nccn23)C1
- Properties:
- ChEMBL ID: CHEMBL5751080
- Molecular weight: 417.47
- Heavy atoms: 31
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 6
- TPSA: 94.98
- LogP: 2.23
- Rotatable bonds: 4
- Ring count: 4
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.26
- QED: 0.52

## Molecule Similarity
- Weighted Tanimoto: 0.66

Answer: 6.56