In one or more embodiments of the invention, a method is provided, the method comprising the steps of administering to a cancer patient: (a) an IL-2Rβ-activating amount of a long-acting, IL-2Rβ-selective agonist； and (b) an IL-15R-activating amount of a long- acting, IL-15 moiety. In one or more embodiments of the invention, a composition is provided, the composition comprising: an IL-2Rβ-activating amount of a long-acting, IL-2Rβ-selective agonist； and an IL-15R-activating amount of a long-acting, IL-15 moiety. In one or more embodiments of the invention, a kit is provided, the kit comprising: an IL-2Rβ- activating amount of a long-acting, IL-2Rβ-selective agonist； an IL-15R-activating amount of a long-acting, IL-15 moiety； and instructions for use of the IL-2Rβ-selective agonist and the long-acting, IL-15 moiety.
