## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: pCHK1 Cellular Assay: Inhibitors of ATR kinase are effective at inhibiting the ATR-driven phosphorylation of the downstream target Chk1 kinase at Serine 345, following the addition of 4-nitroquinoline N-oxide, a chemical used to induce DNA damage. Cellular IC50 for the inhibitors of ATR described herein were measured in HT-29 colorectal adenocarcinoma cells. HT-29 cells were routinely maintained in McCoy's 5A media (ATCC Catalog #30-2007) supplemented with 10% fetal bovine serum (Sigma Catalog # F2442) and 1× Penicillin-Streptomycin (Gibco Catalog #15140-122) using a humidified incubator (37° C., 5% CO2, and ambient 02).In preparation for the CHK1 (p-Ser345) ALPHASCREEN SUREFIRE assay, cells were harvested and resuspended in McCoy's 5A media supplemented with 10% fetal bovine serum and 1× Penicillin-Streptomycin. Cells were seeded onto a 384-well black CELLSTAR Tissue Culture Plate (VWR Catalog #89085-314) at a density of 13,000 cells/well in a volume of 40 uL. The microplate was incubated overnight (approximately 20 hours) at 37° C. with 5% CO2 and ambient 02. Stock solutions of the test compounds were prepared in 100% DMSO (Sigma, Catalog # D2650) and serially diluted 1:3 using 100% DMSO. Compounds were additionally diluted 1:33 in culture medium, and 10 ul/well were transferred to the tissue culture plate. Following the compound addition the microplate was incubated at 37° C. for 90 minutes. 10 uL of 4-nitroquinoline N-oxide (Sigma Aldrich Catalog # N8141-1G) diluted in media (final concentration 12 uM) were added to the tissue culture plate followed by a 120 minute incubation at 37° C. The cells were then washed with PBS and lysed using 10 uL/well SUREFIRE® Kit lysis buffer diluted to 1× in water (PerkinElmer Catalog # TGRCHK1S50K), with mixing on an orbital shaker at 500 rpm for 20 min at RT. Lysates were frozen at −20° C. overnight.4 uL/well of lysate was then transferred from the tissue culture plate to a 384-well, white, low volume, PROXIPLATE (PerkinElmer Catalog #600828). 5 uL/well of the acceptor bead solution, prepared by diluting SUREFIRE Kit activation buffer (PerkinElmer Catalog # TGRCHK1S50K) and ALPHASCREEN Protein A acceptor beads (PerkinElmer Catalog #6760617R) in SUREFIRE Kit reaction buffer (PerkinElmer Catalog # TGRCHK1S50K), were added to the lysates under subdued light and incubated at room temperature for 120 min. 2 uL/well of the donor bead solution, prepared by diluting ALPHASCREEN Streptavidin donor beads (PerkinElmer Catalog #6760617R) in SUREFIRE Kit dilution buffer (PerkinElmer Catalog # TGRCHK1S50K), were added under subdued light and incubated at room temperature for an addition 120 minutes. The pCHK1 ALPHASCREEN signal was measured using an ENVISION® plate reader (PerkinElmer). IC50 values were calculated using a four-parameter logistic curve fit using Genedata Screener software.
- Assay organism: Homo sapiens
- Target name: Serine/threonine-protein kinase Chk1
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: C[C@@H]1COCCN1c1cc(C2CCOCC2)nc(-c2ccnc3[nH]ccc23)n1
- Properties:
- ChEMBL ID: CHEMBL5983671
- Molecular weight: 379.46
- Heavy atoms: 28
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 6
- TPSA: 76.16
- LogP: 3.14
- Rotatable bonds: 3
- Ring count: 5
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.48
- QED: 0.75

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 6.78
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 166; units nM; pChEMBL 6.78; comment 964945

## Query Molecule B
- Canonical SMILES: C[C@@H]1COCCN1c1cc(C2CCN(C)C2=O)nc(-c2ccnc3[nH]ccc23)n1
- Properties:
- ChEMBL ID: CHEMBL5828432
- Molecular weight: 392.46
- Heavy atoms: 29
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 6
- TPSA: 87.24
- LogP: 2.19
- Rotatable bonds: 3
- Ring count: 5
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.43
- QED: 0.74

## Molecule Similarity
- Weighted Tanimoto: 0.74

Answer: 6.3