LY2603618 showed variable activity in primary AML samples tested ex vivo, with no correlation between CHK1 transcript abundance and sensitivity. In Ewing sarcoma cells, brief co-exposure to LY2603618 and gemcitabine enhanced growth inhibition and produced synergistic combination indices; non-Ewing controls were less responsive under the tested conditions. [1,2]
Variable single-agent sensitivity in primary AML samples
Cell-based study · Primary AML blast samples: 22 initial-diagnosis and 4 relapse samples, tested ex vivo [1]
LY2603618 sensitivity varied across specimens. There was no significant diagnosis-versus-relapse difference and CHK1 transcript abundance did not correlate with sensitivity. These are ex vivo observations, not patient treatment outcomes.
Literature-Reported Treatment Conditions
- Treatment concentration
- Variable LY2603618 concentrations; assay IC50 values are endpoints, not treatment doses.
- Exposure duration
- 72 h
- Method
- MTT viability relative to vehicle control; CHK1 RT-PCR normalized to GAPDH.
- Reported limits
- Test material salt, analytical stereochemical confirmation and lot not specified in the reviewed material. Vehicle identity not specified in the reviewed MTT description.
Methods and source locations
Compound reported in the paper: LY2603618 (rabusertib); Compound label in the paper: LY2603618
Evidence concerns the named compound in the reported models; it does not validate an Adooq lot or establish clinical efficacy.
Results: AML cells are sensitive to LY2603618; Table 1; Figure 1A–B; Methods: clinical samples, MTT, RT-PCR, statistical analysis
Metabolic viability relative to vehicle control: MTT at 72 h; each patient IC50 is mean of duplicates from one experiment because sample was limited. — Table 1; Figure 1A caption; Methods MTT
Diagnosis versus relapse IC50 distribution: Mann–Whitney two-sample U test; 22 diagnosis and 4 relapse samples. — Results first paragraph; Figure 1A; Statistical analysis
CHK1 transcript level versus LY2603618 sensitivity: Relative CHK1 transcript levels normalized to GAPDH. — Figure 1B; RT-PCR and statistical methods
DNA damage and partial protection by CDK inhibition
Cell-based study · U937 AML cells and one primary AML sample (AML#111) [1]
LY2603618 increased alkaline-comet DNA migration. Roscovitine attenuated but did not eliminate the response, supporting a partial CDK contribution. The alkaline comet endpoint is not specific for double-strand breaks.
Literature-Reported Treatment Conditions
- Treatment concentration
- U937: LY2603618 4 μM; AML#111: LY2603618 8 μM.
- Exposure duration
- 16 h
- Method
- Alkaline comet assay; approximately 50 comets scored per gel.
- Co-treatment
- Roscovitine: 5 μM in U937; 10 μM in AML#111; each drug alone, combination and control.
- Reported limits
- Test material salt, analytical stereochemical confirmation and lot not specified in the reviewed material.
Methods and source locations
Compound reported in the paper: LY2603618 (rabusertib); Compound label in the paper: LY2603618
Evidence concerns the named compound in the reported models; it does not validate an Adooq lot or establish clinical efficacy.
Figure 3C–F; adjacent Results; Methods: alkaline comet assay and Drugs
DNA migration in alkaline comet assay: Median percent DNA in tail from 4 replicate gels ± s.e.m.; Figure 3D ** p < 0.005 and *** p < 0.0005; Figure 3F ** p < 0.005. No exact bar heights extracted. — Figure 3C–F and caption; alkaline comet assay methods
Gemcitabine sensitization in Ewing sarcoma cells
Cell-based study · EW8 and A673 dose-response; EW8 and TC71 constant-ratio combination analysis; additional Ewing and non-Ewing control lines [2]
LY2603618 enhanced gemcitabine activity in brief-exposure assays. Non-Ewing control lines lacked toxicity under the tested 10 nM gemcitabine/250 nM LY2603618 schedule; U2OS clonogenic growth was not significantly inhibited by this combination. Selectivity is restricted to these conditions.
Literature-Reported Treatment Conditions
- Treatment concentration
- LY2603618 250 nM with varying gemcitabine; fixed combination 250 nM LY2603618 plus 10 nM gemcitabine.
- Exposure duration
- 6 h exposure; viability 42 h after drug removal; clonogenic growth approximately 10–14 days.
- Method
- AlamarBlue/resazurin viability and clonogenic assays; constant-ratio synergy analyzed with CompuSyn.
- Vehicle
- DMSO control shown in Figure 4B–C; final percentage not specified.
- Co-treatment
- Gemcitabine; single agents and vehicle controls.
- Reported limits
- Test material salt, analytical stereochemical confirmation and lot not specified in the reviewed material.
Methods and source locations
Compound reported in the paper: LY2603618 (rabusertib); Compound label in the paper: LY2603618
Evidence concerns the named compound in the reported models; it does not validate an Adooq lot or establish clinical efficacy.
Figure 4B–F and adjacent Results; Methods: Chemical compounds, Cell viability, Clonogenic assay
Gemcitabine dose-response with LY2603618: Reported approximate shift, not an exact estimate read from curves; representative of two independent experiments; mean ± SD of three technical replicates. — Results adjacent to Figure 4C; Figure 4C caption
Constant-ratio gemcitabine/LY2603618 combination in EW8 and TC71: 6 h drug exposure followed by 42 h recovery; Chou–Talalay/CompuSyn. — Results adjacent to Figure 4D; Figure 4D caption; Cell viability methods
Non-Ewing control cell response to fixed combination: AlamarBlue for control panel; clonogenic validation in EW8, TC71 and U2OS. — Figure 4E–F; adjacent Results and captions
