A recent synthetic lethal screen showed that ATR‐ or CHK1‐inhibitors potentiate caspase‐dependent apoptosis in POLD1‐deficient cancers.[38] Another study showed that pharmacologic blockade of B‐family DNA polymerases using aphidicolin combined with CHK1 inhibitors also led to synergistic inhibition of cancer cell proliferation.[39] However, aphidicolin is too toxic to be used in humans, and currently no other suitable drug candidates are able to block the DNA polymerase family exist. This evidence concerns the gene POLD1 and cancer.