A selective effector cell activator protein and agonist of the intermediate-affinity interleukin-2 (IL-2) receptor with potential immunostimulating and antineoplastic activity. Upon administration, intermediate-affinity interleukin-2 receptor agonist ALKS 4230 binds to and signals through the intermediate-affinity IL-2 receptor complex; this may selectively stimulate and activate natural killer (NK) cells and memory CD8 T cells, leading to tumor cell elimination, while circumventing the activation of immunosuppressive cells that may prevent the anti-tumor response. IL-2 is a cytokine signaling molecule that plays a critical role in the immune response.