## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: CDK Kinase Assays: To demonstrate that the compounds exhibit affinity for CDK kinases (CDK2/CycA2, CDK4/CycD3, CDK6/cycD3), CDK kinase assays were performed.Reaction buffers were prepared as follows: kinase base buffer for CDK2,6 (50 mM HEPES, pH 7.5; 0% Brij-35; 10 mM MgCl2; 2 mM DTT); Kinase base buffer for CDK4 (20 mM HEPES, pH 7.5; 0.01% Triton X-100; 10 mM MgCl2; 2 mM DTT); Stop buffer (100 mM HEPES, pH 7.5; 0.01% Brij-35; 0.2% Coating Reagent #3; 50 mM EDTA).Enzyme Reaction Protocol:1) Dilute the compound to 50X of the final desired highest concentration in reaction by 100% DMSO. Transfer 100 μL of this compound dilution to a well in a 96-well plate. Then, serially dilute the compound by transferring 30 μL to 60 μL of 100% DMSO in the next well and so forth for a total of 10 concentrations. Add 100 μL of 100% DMSO to two empty wells for no compound control and no enzyme control in the same 96-well plate. Mark the plate as source plate.2) Prepare intermediate plate by transferring 10 μL of compound from source plate to a new 96-well plate containing 90 μL of kinase buffer as the intermediate plate.3) Transfer 5 μL of compound from the 96-well intermediate plate to a 384-well plate in duplicates.4) Add 10 μL of 2.5× enzyme solution to each well of the 384-well assay plate.5) Incubate at room temperature for 10 min.6) Add 10 μL of 2.5× substrate solution prepared by adding FAM-labeled peptide and ATP in the kinase base buffer. Reaction concentrations for enzymes and substrates as following table (Table 13):TABLE 13Enzyme ATP PeptideEnzyme (nM) (μM) Peptide concentration(μM)CDK2 10 30 P18 3CDK4 10 280 P8 3CDK6 15 800 P8 37) Incubate at 28° C. for specified period of time.8) Add 25 μL of stop buffer to stop reaction.9) Collect data on Caliper. Then convert conversion values to inhibition values.Percent inhibition=(max−conversion)/(max−min)*100.max stands for DMSO control and min stands for low control herein.10) Curve fitting using percent inhibition in XLFit excel add-in version 4.3.1 to obtain IC50 values. Equation used is: Y=Bottom+(Top-Bottom)/(1+(IC50/X){circumflex over ( )}HillSlope). Wherein, Y is inhibition percentage (%); X is concentration of the test compound.
- Assay organism: Homo sapiens
- Target name: CDK2/Cyclin A2
- Target type: PROTEIN COMPLEX
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: CCN1CCN(Cc2ccc(Nc3ncc(F)c(-c4cc(F)c5nc(C)n(C(C)C)c5c4)n3)nc2)CC1
- Properties:
- ChEMBL ID: CHEMBL3301610
- Preferred name: ABEMACICLIB
- Molecule type: Small molecule
- Max clinical phase: 4
- Molecular weight: 506.61
- Heavy atoms: 37
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 7
- TPSA: 75
- LogP: 4.94
- Rotatable bonds: 7
- Ring count: 5
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.41
- QED: 0.38

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 7.41
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 39; units nM; pChEMBL 7.41; comment 1083625

## Query Molecule B
- Canonical SMILES: CC1(C)CCCc2nc3c(F)cc(-c4nc(Nc5ccc(N6CCN(C7COC7)CC6)cn5)ncc4F)cc3n21
- Properties:
- ChEMBL ID: CHEMBL5749652
- Molecular weight: 546.63
- Heavy atoms: 40
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 8
- TPSA: 84.23
- LogP: 4.5
- Rotatable bonds: 5
- Ring count: 7
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.45
- QED: 0.39

## Molecule Similarity
- Weighted Tanimoto: 0.42

Answer: 7.4