XL844

XL844 is a potent inhibitor of the checkpoint kinases CHK1 and CHK2, which induce cell cycle arrest in response to a variety of DNA damaging agents. Activation of these checkpoints following DNA damage allows for DNA repair and protects tumor cells from the cytotoxic effects of chemo- and radio-therapy. XL844 abrogates these cell cycle blocks and enhances tumor cell killing by a wide variety of chemotherapeutic agents and radiation in in vitro assays. XL844 has good pharmacokinetic properties and oral bioavailability, and in in vivo tumor models increases the efficacy of chemotherapeutic agents without increasing systemic toxicity.