GDC-0575 (ARRY-575) is a highly-selective oral small-molecule Chk1 inhibitor(IC50 of 1.2 nM).

GDC-0575 is significantly more potent in promoting DNA damage, replication stress and cell death than V158411, LY2603618, and MK-8776 in a panel of melanoma cell lines[1]

CHK1 inhibitor (CHK1i) GDC-0575 enhances AraC-mediated killing of AML cells both in vitro and in vivo, thus abrogating any potential chemoresistance mechanisms involving DNA repair. Importantly, this combination of drugs does not affect normal long-term hematopoietic stem/progenitors[2].

For in vivo experiments, aliquots of GDC-0575 (10 mg/mL) were stored at ?20℃and diluted in 100 mM sodium citrate buffer immediately prior to each experiment. GDC-0575 was used at 1.8 mg/ml for female mice (~25 g) and 2.6 mg/ml for male mice (~35 g) via oral gavage (final concentration 7.5 mg/kg). For in vitro experiments, aliquots of GDC-0575 (100 μM) were stored at ?20 ℃ and used at a final concentration of 100 nM. AraC (Cytosine β-D-arabinofuranoside C1768, Sigma) was used at 10 mg/kg (commonly used in clinical practice) for in vivo and at 100 nM and 500 nM for in vitro experiments. For in vivo experiments, toxicity of GDC-0575 was assessed in non-engrafted NSG mice using a range of concentrations of GDC-0575 in combination with AraC. 7.5 mg/kg GDC-0575 was the highest concentration to have no significant or lasting adverse effects in mice. Similarly, for in vitro experiments, 100 nM GDC-0575 in combination with 500 nM AraC was the highest concentration non-cytotoxic to MS5 stoma cell. ATR inhibitor was used at a final concentration of 0.5 μM[2].