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Effect of CHK1 Inhibition on CPX-351 Cytotoxicity in vitro and ex vivo

CPX-351 is a liposomally encapsulated 5:1 molar ratio of cytarabine and daunorubicin that recently received regulatory approval for the treatment of therapy-related acute myeloid leukemia (AML) or AML with myelodysplasia-related changes based on improved overall survival compared to standard cytarabine/daunorubicin therapy. Checkpoint kinase 1 (CHK1), which is activated by DNA damage and replication stress, diminishes sensitivity to cytarabine and anthracyclines as single agents, suggesting that CHK1 inhibitors might increase the effectiveness of CPX-351. The present studies show that CPX-351 activates CHK1 as well as the S and G2/M cell cycle checkpoints. Conversely, CHK1 inhibition diminishes the cell cycle effects of CPX-351. Moreover, CHK1 knockdown or addition of a CHK1 inhibitor such as MK-8776, rabusertib or prexasertib enhances CPX-351-induced apoptosis in multiple TP53-null and TP53-wildtype AML cell lines. Likewise, CHK1 inhibition increases the antiproliferative effect of CPX-351 on primary AML specimens ex vivo, offering the possibility that CPX-351 may be well suited to combine with CHK1-targeted agents.

Related Products

Cat.No. Product Name Information Publications Customer Product Validation
S2626 Rabusertib (LY2603618) Rabusertib (LY2603618, IC-83) is a highly selective Chk1 inhibitor with potential anti-tumor activity in a cell-free assay. IC50=7 nM, showing approximately 100-fold more potent against Chk1 than against any of the other protein kinases evaluated. Rabusertib (LY2603618) induces cell cycle arrest, DNA damage response and autophagy in cancer cells. Rabusertib (LY2603618) induces bak-dependent apoptosis in AML cell lines. (63) (7)

Related Targets

Chk