## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: Jak2 Tyrosine Kinase Assay: Compounds with activity against Jak2 tyrosine kinase have been observed to cause thrombocytopenia, anemia and neutropenia in human patients in clinical trials (see, for example, Pardanani, A., Leukemia, 26:1449-1451 (2012)). Jak2 signaling occurs thru EPO and TPO, which control erythrocyte and platelet proliferation, respectively. Thus, inhibition of Jak2 tyrosine kinase can potentially lead to side-effects in the clinic. Btk inhibitors with improved selectivity over Jak2 tyrosine kinase are desired in order to minimize off target side-effects related to the inhibition of Jak2 tyrosine kinase.The assays were performed in V-bottom 384-well plates. The final assay volume was 30 μl prepared from 15 μl additions of enzyme and substrates (fluoresceinated peptide and ATP) and test compounds in assay buffer (100 mM HEPES pH 7.4, 10 mM MgCl2, 25 mM beta-glycerophosphate, 0.01% Brij 35 surfactant and 4 mM DTT). The reaction was initiated by the combination of Jak2 tyrosine kinase with substrates and test compounds. The reaction mixture was incubated at room temperature for 60 minutes and terminated by adding 45 μL of 35 mM EDTA to each sample. The reaction mixture was analyzed on the Caliper LABCHIP® 3000 by electrophoretic separation of the fluorescent substrate and phosphorylated product. Inhibition data were calculated by comparison to no enzyme control reactions for 100% inhibition and vehicle-only reactions for 0% inhibition. The final concentration of reagents in the assays is ATP, 30 μM; Jak2 fluorescent peptide, 1.5 μM; Jak2, 1 nM; and DMSO, 1.6%. Dose response curves were generated to determine the concentration required inhibiting 50% of kinase activity (IC50). Compounds were dissolved at 10 mM in DMSO and evaluated at eleven concentrations, each in duplicate. IC50 values were derived by non-linear regression analysis.
- Assay organism: Homo sapiens
- Target name: Tyrosine-protein kinase JAK2
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: Cc1c(-c2c(C#N)cc(C(N)=O)c3[nH]c4cc(C(C)(C)O)ccc4c23)cccc1-n1c(=O)cc2c(Cl)cccn2c1=O
- Properties:
- ChEMBL ID: CHEMBL3965224
- Molecule type: Small molecule
- Molecular weight: 578.03
- Heavy atoms: 42
- Hydrogen bond donors: 3
- Hydrogen bond acceptors: 5
- TPSA: 146.38
- LogP: 4.91
- Rotatable bonds: 4
- Ring count: 6
- Aromatic rings: 6
- Formal charge: 0
- Fraction Csp3: 0.12
- QED: 0.27

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 6.11
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 770; units nM; pChEMBL 6.11; comment 828394

## Query Molecule B
- Canonical SMILES: Cc1c(-c2c(Cl)cc(C(N)=O)c3[nH]c4c(c23)CC[C@H](C(C)(C)O)C4)cccc1-n1c(=O)[nH]c2c(F)cccc2c1=O
- Properties:
- ChEMBL ID: CHEMBL3945408
- Molecule type: Small molecule
- Molecular weight: 575.04
- Heavy atoms: 41
- Hydrogen bond donors: 4
- Hydrogen bond acceptors: 4
- TPSA: 133.97
- LogP: 4.9
- Rotatable bonds: 4
- Ring count: 6
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.26
- QED: 0.24

## Molecule Similarity
- Weighted Tanimoto: 0.4

Answer: 5.05