The reagent, pharmaceutical formulation, kit, and methods of the invention provides a new approach for treating pancreatic cancers. The invention provides the use of Na.sup.+e/K.sup.+-ATPase inhibitors, such as cardiac glycosides (e.g. ouabain and proscillaridin, etc.), either alone or in combination with other standard therapeutic agents (chemo- or radio-therapies, etc.) for treating pancreatic cancers. The subject Na.sup.+/K.sup.+-ATPase inhibitors, such as cardiac glycosides, including bufadieneolides or their corresponding aglycones (e.g., proscillaridin, scillaren, and scillarenin, etc.), especially in oral formulations and/or solid dosage forms containing more than 1 mg of active ingredients.