In one aspect, the present invention provides a composition and a kit comprising a combination of topoisomerase inhibitor and PARP inhibitor for treatment of cancer. In another aspect, the invention provides a method of treating cancer comprising administering to a subject a combination of topoisomerase inhibitor and PARP inhibitor. In particular, the invention provides compositions and methods for treating cancer in a subject by inhibiting a poly-ADP-ribose polymerase and a topoisomerase, as well as providing formulations and modes of administering such compositions.