The present invention generally relates to the fields of
cancer therapy and
cancer prevention. More particularly, the present invention generally relates to a
diagnostic marker for predicting the
efficacy of
topoisomerase I (topo I) inhibitors in the treatment of cancers. More specifically, the present invention relates to methods, machines, computer systems, computable readable media and kits which can be used to identify and determine the effectiveness of
topoisomerase I (topo I) inhibitors in the treatment of cancers, and in some embodiments, the level of sensitivity or resistance of a tumor
cell to a
topoisomerase I inhibitor, such as
camptothecin (CPT), or CTP analogues such as
topotecan and
irinotecan and derivatives thereof. More specifically, the present invention related to methods, machines, computer systems, computable readable media and kits which can be used to determine the presence of
phosphorylation of topoisomerase I polypeptide, in some embodiments
phosphorylation at residue
serine 10 (S10) of a topoisomerase I polypeptide, wherein the presence of
phosphorylation, in particular the phosphorylation at
serine 10 of a topoI polypeptide indicates a
cancer is likely to be unresponsive to a topo I inhibitor, whereas the absence of phosphorylation, in particular, the absence of phosphorylation at residue
serine 10 (S10) identifies a cancer is likely to be responsive to a topo I inhibitor. Other aspect of the present invention relate to phospho-serine 10 topoisomerase I antibodies and other
protein binding moieties, and uses thereof.