ATR and hepatocellular carcinoma: 38 Moreover, XL413 was found to collaborate with mTOR inhibitor to drastically inhibit HCC growth by blocking feedback re-activation of mTOR signaling, delivering so called “one-two-punch” strategy. In another study, XL413 was implied to potentiate ATR-CHK1 signaling inhibition in HCC.38 However, the therapeutic efficacy of combining DDK inhibitor and immune checkpoint blockade has not yet been investigated so far.