A method for treating a subject suffering from a cancer, in particular a multidrug-resistant cancer includes administrating a cobalt-polypyridyl complex to the subject. A method for suppressing the growth of cancer cells, in particular inducing autophagy of the cancer cells, inducing cell cycle arrest of the cancer cells and/or inhibiting cell invasion of the cancer cells and for specifically targeting cancer cells with multidrug-resistance includes contacting said cancer cells with the cobalt-polypyridyl complex. A pharmaceutical composition and a kit are provided and include the cobalt-polypyridyl complex. Unexpectedly, the cobalt-polypyridyl complex is especially suitable to treat cancer, in particular multidrug-resistant cancer with an exceptionally increased cytotoxic activity towards multidrug-resistant cancer cells.
