Abstract: A method of treating a cancer in a mammalian subject afflicted with the cancer, consisting essentially of administering to the subject a therapeutically effective amount of a platinum-based anticancer agent, and administering to the subject a therapeutically effective amount of a pentaaza macrocyclic ring complex corresponding to the Formula (I) below, prior to, concomitantly with, or after administration of the platinum-based anticancer agent, whereby response of the cancer to the platinum-based anticancer agent is increased.